detection and monitoring of water filled voids using transient electromagnetic method a case study in shanxi china shanxi province is a major coal base for the rapid development in china but heavy production of coal resources has left abundant water filled voids creating significant geologic hazards around coal mines it is necessary to quickly investigate the position and distribution of voids with effective geophysical methods the feasibility of transient electromagnetic tem method in detecting and monitoring water filled voids is analyzed using 3d finite element numerical simulation results as well as a case study in this paper the case study was mainly to analyze and monitor the conditions around the site of a power transfer station under construction in the west of shanxi province where many water filled mined out voids existed central loop tem sounding was carried out three times from january 2010 to april 2011 around the building footprint the low resistivity abnormal area had been repeatedly located and the survey results showed that the area of voids increased with time which indicated that the ground at the site was in an unstable and dangerous state the surveys provided more detailed geological information to the government for further safety arrangement and building re design

exploration of deep magnetite deposit under thick and conductive overburden with ex component of sotem a case study in china in northern china thick loess strata with low resistivity are widely present and can shield the deep induced electromagnetic field signal and influence the accuracy of deep targets while electromagnetic prospecting is being performed to achieve deep target exploration with high resolution a new technique known as the short offset transient electromagnetic method sotem is applied in this research area this method can be used to perform near source configuration surveys but shows no obvious difference between the deep magnetite deposit and low resistivity layer in this survey area therefore it cannot explore the magnetite deposit directly using the traditional magnetic component hz of sotem the ex component which can more effectively distinguish the high resistivity surrounding rock and overlying low resistivity layer than the hz component is used for exploration first 2d forward modeling and sensitivity analysis of the high resistivity body are carried out to determine the different responses of the ex and hz components respectively moreover to better determine the interface between the surrounding rock and low resistivity layer 1d occam inversion and the generalized inverse matrix inversion method are used furthermore aiming at the static effect of the ex component in field exploration joint inversion of the ex and hz components is carried out for comprehensive interpretation finally a field test is conducted and the drilling results are used for verification the research results can provide an effective geophysical model for the exploration of contact metasomatic magnetite deposits

the effect of rock strength on weathering rates of sandstone used for angkor temples in cambodia abstract this study determined the weathering rates from the depths of hollows formed by the deterioration of sandstone blocks used to build angkor temples in the 7th 12th centuries due to capillary processes these hollows generally develop at the bases of building components such as doorframes false doorframes window frames and pillars in this study 55 locations in 29 temples were selected to measure maximum hollow depth based on the ages of the temples the weathering rate was calculated to be in the range 7 92 mm ka 1 the weathering rate was found to be independent of building component type and aspect the calculated weathering rate corresponds to the physical weathering rate of sandstone caused by the wetting drying cycles that result from the tropical environment along with the dry season an equation that can estimate the maximum depth of a hollow in a sandstone block was proposed based on temple age and the coefficient obtained from two types of rock hardness values the equation coefficient is an effective index that can help predict the deterioration of stone cultural artifacts such as the angkor temples

arcades products of stress controlled and discontinuity related weathering abstract weathering patterns on sandstone cliff faces and sloping surfaces were studied from the viewpoint of gravity induced stress combined with the presence of planar discontinuities in the rock critical evaluation of hundreds of photos taken in various regions around the world numerical modelling using finite element method including automatic stress controlled element removal technique of erosion modelling and physical in situ modelling of friable sandstone revealed the formation of a specific sub group of weathering forms related to planar discontinuities due to their striking similarity with elements known from architecture these pits are introduced as arcades or arcade like forms these pits and cavities vary in size but they are similar in shape coalesced into trains along the discontinuities and separated from each other by hourglass shaped pillars in their origin and geometry these forms differ from widely known cavernous weathering forms such as honeycombs and tafoni we have shown that arcade shape and size are controlled by the redistribution of gravity induced stress along planar discontinuities and the resulting stress shadows the stress shadow zones along the discontinuities are characterized by material loss owing to various weathering and erosional mechanisms although overlooked as yet stress controlled weathering along discontinuities has a strong effect on rock surface morphology and arcades can be taken as its principal example

salt weathering simulations under hot desert conditions agents of enlightenment or perpetuators of preconceptions because of access difficulties and inhospitable environmental conditions our understanding of rock weathering in hot deserts has been strongly influenced by laboratory simulations however a risk exists that results may come to owe more to experimental design than to actual environmental conditions experienced at the atmosphere rock surface interface this was especially true in early salt weathering simulations that seemingly sought to reinforce the orthodoxy of a physically dominated weathering environment driven by extremely high absolute temperatures and large diurnal temperature ranges however improvements in environmental sensors over the last 20 years have established the complexity of desert climates and the importance of microclimatic controls and allowed considerable refinement of experimental design this overview evaluates the implications of recent simulation studies and presents new information on possible fatigue effects of differential thermal expansion of salts and the salt weathering of test blocks under compressive loading in doing so it demonstrates how physical rock properties change during experimentation the importance of short term surface temperature fluctuations distinctions between the weathering of unconfined debris and larger rock surfaces the importance of moisture and salt applications that replicate their availability in deserts the importance of rock thermal properties in controlling their weathering response in environments dominated by radiative heating and cooling and the overall complexity of weathering regimes

daytime rock surface temperature variability and its implications for mechanical rock weathering tenerife canary islands summary summer and winter rock surface temperature measurements are presented from three sites along an altitudinal gradient significant between and within site variability is recognised related to insolation cloud cover and air temperature differences maritime influences and time of year the variability argues against the use of a single rock temperature regime to characterise hot desertic environments in for example weathering simulation studies superimposed upon diurnal patterns of heating and cooling are numerous short 3 15 minutes and medium term 1 2 hours fluctuations related to wind speed and cloud cover variations rates of surface temperature change are very high during these fluctuations 3 c minute and it is proposed that they may enhance the operation of a number of mechanical rock weathering mechanisms

reliability of dipole dipole electrical resistivity tomography for defining depth to bedrock in covered karst terranes sinkhole collapse is one of the main limitations on the development of karst areas especially where bedrock is covered by unconsolidated material studies of sinkhole formation have shown that sinkholes are likely to develop in cutter enlarged joint zones as a result of subterranean erosion by flowing groundwater because of the irregular distribution of pinnacles and cutters on the bedrock surface uncertainties arise when hit or miss borehole drilling is used to locate potential collapse sites a high resolution geophysical technique capable of depicting the details of the bedrock surface is essential for guiding the drilling program dipole dipole electrical resistivity tomography ert was used to map the bedrock surface at a site in southern indiana where limestone is covered by about 9 m of clayey soils forty nine transects were conducted over an area of approximately 42 037 m2 the electrode spacing was 3 m the length of the transects varied from 81 to 249 m the tomographs were interpreted with the aid of soil borings the repeatability of ert was evaluated by comparing the rock surface elevations interpreted from pairs of transects where they crossed each other the average difference was 2 4 m with a maximum of 10 m the discrepancy between interpreted bedrock surface elevations for a transect intersection may be caused by variations in the subsurface geology normal to the transect averaging the elevation data interpreted from different transects improved the ert results a bedrock surface map was generated using only the averaged elevation data at the transect junctions the accuracy of the map was further evaluated using data from four exploratory boreholes the average difference between interpreted and actual bedrock surface elevations was less than 0 4 m the map shows two large troughs in the limestone surface one coinciding with an existing sinkhole basin while the other is in alignment with a small topographic valley because sinkholes were observed at the same elevation interval in similar valleys in the vicinity the delineated trough may have implications for future land use at the site

multicomponent magnetization in western dolpo tethyan himalaya nepal tectonic implications abstract a palaeomagnetic study has been carried out in the tethyan himalaya th the northern margin of greater india twenty six palaeomagnetic sites have been sampled in triassic low grade metasediments of western dolpo two remanent components have been identified a pyrrhotite component characterized by unblocking temperatures of 270 335 c yields an in situ mean direction of d 191 7 i 30 9 k 29 5 95 5 7 n 23 sites the component fails the fold test at the 99 confidence level kin situ kbed 6 9 and is therefore of postfolding origin for reason of the low metamorphic grade this pyrrhotite magnetization is believed to be of thermo chemical origin geochronological data and inclination matching indicate an acquisition age around 35 ma the second remanence component has higher unblocking temperatures 400 c and up to 500 580 c range and resides in magnetite a positive fold test and comparison with expected triassic palaeomagnetic directions suggest a primary origin the postfolding character of the pyrrhotite component and its interpreted age of remanence acquisition implies that the main himalayan folding is older than 35 ma in the western dolpo area this study also suggests that the second metamorphic event neo himalayan was more significant in the dolpo area than the first eo himalayan one a clockwise rotation of 10 15 is inferred from the pyrrhotite component which is compatible with oroclinal bending and or rotational underthrusting models this rotation is also supported by the magnetite component indicating that no rotation of the tethyan himalaya relative to india took place before 35 ma

monitoring mountain permafrost evolution using electrical resistivity tomography a 7 year study of seasonal annual and long term variations at schilthorn swiss alps 1 a combined geophysical and thermal monitoring approach for improved observation of mountain permafrost degradation is presented time lapse inversion of repeated electrical resistivity tomography ert measurements allows both active layer dynamics and interannual permafrost conditions to be delineated analysis of a comprehensive ert monitoring data set from a 7 year study at schilthorn swiss alps confirmed the applicability of ert monitoring to observations of freezing and thawing processes on short term seasonal and long term scales long term resistivity changes were evaluated on the basis of seasonal resistivity variations showing an annual cycle with high resistivities in frozen and low resistivities in unfrozen state one important result is the detection of a sustained impact of the extraordinarily hot european summer of 2003 on the permafrost regime which is more severe than previously assumed from borehole temperatures combined analyses of ert monitoring and borehole temperature data revealed substantial ground ice degradation as a consequence of the 2003 summer which did not recover in the following years despite suitable subsurface temperature conditions resistivity changes that are nonconforming to long term temperature evolution are attributed to the limited availability of liquid water and or changes in material characteristics e g pore volume changes as a result of subsidence

salt weathering of sandstone at the angkor monuments cambodia identification of the origins of salts using sulfur and strontium isotopes abstract the angkor monuments in northwestern cambodia which are primarily made of sandstone are suffering from deterioration due to salt weathering in order to elucidate the sources of the salts and salt weathering process this paper analyzed bulk chemical compositions and s sulfur and sr strontium isotopic ratios for the salts and surrounding environmental materials at places where bats inhabit the structures various kinds of sulfate and phosphate salts are formed on the surface of the sandstone the results of the analysis demonstrate that the s and p phosphorus components in the salts are primarily derived from bat guano moreover ca calcium which is the major element in the salts is suggested to be derived from both bat guano and the sandstone the isotopic data strongly suggests that bat guano is related to salt weathering removal of these animal excrements is essential for future conservation of these monuments on the other hand exfoliation of sandstone commonly occurs due to crystallization of calcite caco 3 on platform surfaces of pyramid type monuments a large amount of ca in calcite is suggested to be derived from calcite cement of the building sandstone

single borehole and cross borehole resistivity anomalies of thin ellipsoids and spheroids hole to hole resistivity measurement is a useful method of detecting deeply buried fractures and ore deposits in the subsurface with drilling costs continually rising there is a growing need for developing methods of borehole geophysics such as this in this study we present theoretical results relating to detection of thin oblate spheroids and ellipsoids with arbitrary attitude if we assume that individual fractures within a fracture zone are connected to each other and are of finite lateral and vertical extent then we can model the fracture zone as a thin conductive oblate ellipsoid or spheroid with arbitrary orientation of the major axis detection of such deeply buried fracture zones is the object of this study here the effects of the surface of the earth are neglected and the body is assumed to be enclosed within an infinite homogeneous mass the surface of the body is divided into a series of subsurfaces and a numerical solution of the fredholm integral equation is applied once a solution fo

geoelectric investigations into sandstone moisture regimes implications for rock weathering and the deterioration of san rock art in the golden gate reserve south africa the clarens sandstone in the golden gate reserve south africa is the canvas for a collection of san bushmen rock art dating from neolithic times until as recently as 150 years ago this rock art is under threat from human interference but also to a greater degree from weathering processes on the rock surface the dominant weathering processes occurring in the rock shelters which host the rock art are flaking and honeycombing two rock shelter sites in the reserve have been investigated using electric resistivity tomography ert and supportive methods for measuring surface moisture protimeter and surface hardness equotip these non destructive techniques can be used in situ to assess the extent of weathering within a rock outcrop and are especially suited for investigations in sensitive areas such as rock art sites moisture movement has been mapped and related to the weathering processes observed on the surface the aim of the study is to aid rock art conservation in the golden gate reserve through a better understanding of the driving processes of surface weathering the evidence shows that the extensive flaking and honeycombing found in the rock shelters is most likely caused by water pockets in the near surface zone which are replenished through internal moisture transport driving the superficial weathering processes these weathering processes pose a significant problem rock art in the golden gate reserve shows severe deterioration due to flaking conservation strategies should therefore take internal processes into account as much as their superficial expression

scale issues in weathering studies a review of the major scale issues in weathering studies reveals concerns over the fundamental spatio temporal distributions of weathering phenomena as well as issues of upscaling microscope based observations and linking different scales of observations in explanations of landform development various strategies are proposed which can be used to tackle these issues many rooted in non linear dynamical systems ideas as an initial step spatio temporal scale distributions are estimated here for weathering processes landforms and controls based on a range of empirical data two case studies of phytokarst in grand cayman and blistering and scaling of building stones are presented to illustrate the types of data that might be used to establish more convincing scale linkages in weathering investigations

researches on detection of 3 d underground cave based on tem technique because of unreasonable coal mining in china there are many unknown underground caves and the inhabited environment of humans is threatened by many geologic hazards such as cracking of the buildings ground subsidence etc to make the coal companies aware of the harmfulness of these hazards it is urgent to determine the reasons for the hazards in this paper transient electromagnetic method tem is used to detect the ground resistance caves instead of the time consuming and expensive direct drilling survey numerical results of the 3 d synthetic model and real field survey data are given the results showed that the tem method can be used to detect a complicated air filled underground 3 d cave and coincide with the results of direct drilling survey

hole to surface resistivity measurements hole to surface resistivity measurements over a layered volcanic tuff sequence illustrate procedures for gathering reducing and interpreting hole to surface resistivity data the magnitude and direction of the total surface electric field resulting from a buried current source is calculated from orthogonal potential difference measurements for a grid of closely spaced stations a contour map of these data provides a detailed map of the distribution of the electric field away from the drill hole resistivity anomalies can be enhanced by calculating the difference between apparent resistivities calculated from the total surface electric field and apparent resistivities for a layered earth model lateral discontinutities in the geoelectric section are verified by repeating the surface field measurments for current sources in several drill holes a qualitative interpretation of the anomalous bodies within a layered earth can be made by using a three dimensional 3 d resistivity model in a homogeneous half

depth of investigation in electromagnetic sounding methods the time or frequency at which the electromagnetic em response of a buried inhomogeneity can first be measured is determined by its depth of burial and the average conductivity of the overlying section it is relatively independent of the type of source or receiver and their separation the ability to make measurements at this time or frequency however depends on the sensitivity and accuracy of the instrumentation the signal strength and the ambient noise level these factors affect different em sounding systems in surprisingly different ways for the magnetotelluric mt method it is possible to detect a buried half space under about 1 5 skin depths of overburden the maximum depth of investigation is virtually unbounded because of high signal strengths at low frequencies transient electromagnetic tem soundings on the other hand have a limited depth of penetration but are less affected by static shift errors for tem a buried inhomogeneity can be detected under about one diffusion depth of overburden for conventional near zone sounding in which induced voltage is measured impulse response the depth of investigation is proportional to the 1 5 power of the source moment and ground resistivity by contrast if the receiver is a magnetometer step response system the depth of investigation is proportional to the 1 3 power of source moment and is no longer a function of resistivity magnetic field measurements may therefore be superior for exploration in conductive areas such as sedimentary basins far zone or long offset tem soundings are traditionally used for deep exploration the depth of investigation for a voltage receiver is proportional to the 1 4 power of source moment and resistivity and is inversely proportional to the source receiver separation magnetic field measurements are difficult to make at long offsets because instrumental accuracy limits the measurement of the very slow decay of the magnetic field frequency domain controlled source systems are ideally suited for sounding at the very shallow depths needed for engineering archaeological and groundwater applications because of the relative ease of extending the measurements to arbitrarily high frequencies and also because geometric soundings can be made at low induction numbers

technology and geomorphology are improvements in data collection techniques transforming geomorphic science in recent years technological developments have revolutionized our ability to collect data in geomorphology enhanced data collection not only enables us to provide deeper answers to a wider range of fundamental questions about the earth s surface but also encourages us to pose new questions this paper considers in more detail the relationships between science technology and the development of geomorphological tools and techniques reviews the spectrum of tools and techniques now available to geomorphologists and critically assesses what impact new technologies are having on geomorphology it focuses on the role of technology in biogeomorphology and weathering research and how it is advancing theoretical empirical and applied dimensions of these growing sub fields of geomorphology five areas of important technological development are reviewed remote sensing dating geophysical techniques field and laboratory based analysis and sensing of physical and chemical characteristics and field and laboratory based analysis of biological properties there is good evidence that taken together technological developments are revolutionizing geomorphology through opening the doors to better cross scalar investigations blurring the boundaries between laboratory field and computer model and facilitating cross disciplinary and democratized research

assessment of fractures in some columns inside the crypt of the cattedrale di otranto using integrated geophysical methods we investigate the problem of internal fracturing of the columns of a building of cultural importance the crypt of the cattedrale di otranto apulia italy using a multi disciplinary approach integrating different non destructive techniques microclimatic and geophysical in fact historic buildings over centuries may accumulate a high concentration of water and or moisture that increases significantly the deterioration rate diminishing the mechanical resistance it is well known that the distribution of moisture within stone strongly depends on ambient conditions i e temperature and relative humidity no suitable environmental condition in the crypt and the presence of wet buried structures in the ground involved in the process of deterioration have been indeed assessed in previous surveys actually we perform a ground penetrating radar gpr investigation in reflection mode in order to reveal the existence of fractures inside the columns because of the important rising of water from pavement the reconstruction of the fracture distribution is fundamental to plan the safeguard and the restoration of the columns themselves and also the stability of the crypt and of the uppermost cathedral such survey was performed on seven columns using gpr technique moreover the electrical resistivity tomography ert and gpr traveltime tomography tt methods were applied on the most damaged column the results obtained with these different methodologies are in good agreement however the 2d electrical resistivity tomography seems to be less resolutive than gpr while the gpr traveltime tomography is more time expensive than gpr reflection mode method the gpr method in reflection mode allows to reconstruct the main fractures inside the columns also in virtue of its penetration power we think that the joining of different methodologies permits to better understand the complex physical mechanisms in the phenomenon of deterioration of the cultural heritage in order to achieve useful information for possible future restoration works 2006 elsevier ltd all rights reserved

detecting shallow caverns in china using tem to detect shallow anomalies under certain conditions electromagnetic methods can be more effective in reconnaissance surveying than high resolution surface seismic this case study describes the results of the transient electromagnetic method tem in an environment where initial field trials showed that surface seismic was difficult to employ effectively and expensive to implement

contour scaling of a sandstone by salt weathering under simulated hot desert conditions a laboratory study has been used to investigate relationships between salts and contour scaling a weathering feature commonly observed on rock surfaces in salt rich environments surface disaggregation and essentially surface parallel cracks were produced in sandstone blocks using 10 per cent solutions of sodium sulphate and magnesium sulphate applied daily to single exposed surfaces for sixty days a control block soaked once in saturated magnesium sulphate and subsequently wetted daily with distilled water showed extensive surface disaggregation but no cracking both surface disaggregation and subsurface cracking were associated with relative concentrations of microcrystalline salt a tentative model of contour scaling is proposed which involves linking together potential cracks by salt induced fracturing of intervening crack stopping grains further control blocks treated respectively with 10 per cent and saturated sodium chloride showed no evidence of subsurface cracking and only limited surface disaggregation of the saturated block

three dimensional model results for an electrical hole to surface method application to the interpretation of a field survey an important objective of borehole geophysics is to maximize information about inhomogeneities in the vicinity of existing boreholes three dimensional models parallelepipedic inhomogeneities in a homogeneous half space are used here to characterize the responses of an electrical hole to surface method elecent electrode enterree where conductive or resistive inhomogeneities orebodies occur in the vicinity of a borehole two types of surface measurements are carried out simultaneously at each station electrical potential v as in mise a la masse and associated electrical field e these two measured parameters give rise to three other parameters two apparent resistivities one for each v and e case and another parameter quantifying the orientation of the e field the influence of various geometrical and electrical parameters such as the horizontal and vertical distances between the current source the stations and the inhomogeneity and the size and resistivity of the inhomogeneity on the five

analysis and application of a non conventional underwater geoelectrical method in lake geneva switzerland the electrical method presented is used for determining the resistivity of lake bottom sediments and is based on the d c electrical sounding principles the electrode array called the fishing rod fr is of pole pole type and is orientated vertically on a line perpendicular to the surface of the water the technique is used for mapping resistivity anomalies located deep underwater this paper presents an analysis of the resolution capabilities of the fr method and the results of a case study carried out in lake geneva where measurements were interpreted using a one dimensional 1d multilayer earth model the analysis of the uncertainty in the model parameters of a 1d multilayer earth model is carried out using the covariance matrix of the linearized inversion problem the results of the analyses show that when the thickness and resistivity of the water layer is known the resistivity of the sediment layer is well determined under most circumstances the thickness of the sediment layer is well determined when resistivity contrasts are not too low in lake geneva the fr method has been used to study an old depression with a resistive channel this application shows the efficiency of the method compared with conventional electrical methods where water depth becomes a limiting factor the use of an automated iterative inversion scheme in this particular case is advantageous as a joint interpretation of the three different data sets measured with the fr method can be carried out finally the result of the inversion is compared with the trial and error interpretations of a previous study

appraisal of an array tem method in detecting a mined out area beneath a conductive layer the transient electromagnetic method has been extensively used for the detection of mined out area in china for the past few years in the cases that the mined out area is overlain by a conductive layer the detection of the target layer is difficult with a traditional loop source tem method in order to detect the target layer in this condition this paper presents a newly developed array tem method which uses a grounded wire source the underground current density distribution and the responses of the grounded wire source tem configuration are modeled to demonstrate that the target layer is detectable in this condition the 1d occam inversion routine is applied to the synthetic single station data and common middle point gather the result reveals that the electric source tem method is capable of recovering the resistive target layer beneath the conductive overburden by contrast the conductive target layer cannot be recovered unless the distance between the target layer and the conductive overburden is large compared with inversion result of the single station data the inversion of common middle point gather can better recover the resistivity of the target layer finally a case study illustrates that the array tem method is successfully applied in recovering a water filled mined out area beneath a conductive overburden

cave detection in limestone using ground penetrating radar ground penetrating radar gpr is becoming a more common component of the standard array of geophysical techniques that are used by archaeologists in this paper we report on the use of gpr to survey an area of archaeologically important karst topography at kitley caves in devon u k we describe the use of gpr to detect voids within a limestone outcrop as an aid to locating cave systems which might contain sediments suitable for excavation the performance of the gpr equipment is analysed and the results compared to those obtained with an electrical resistance survey carried out at the same location in particular the depth of penetration of the gpr is estimated and we report discernible echo signals from a much greater depth than is usually reported in archaeological applications of gpr

capillary moisture flow and the origin of cavernous weathering in dolerites of bull pass antarctica flow of water through joint blocks that exhibit cavernous weathering was modeled for the ferrar dolerite in bull pass antarctica a peculiar moisture regime allows an analytical solution under steady state saturated conditions the presence of surface coatings on the top surface of the blocks causes the matric potential gradient within the blocks to be horizontal near the surface deflecting the flow of migrating water toward the uncoated sides during evaporation because weathering of the rock interior is proportional to the moisture flux the extent of rock weathering will be similar along similar contours of the matric potential gradient as granular disintegration occurs it will also follow the lines of equipotennal and cavernous weathering will result if those lines are concave

pre miocene deformation of the himalayan superstructure hidden valley central nepal abstract throughout the himalaya the tethyan sedimentary sequence forms the detached carapace or superstructure to exhumed mid crustal rocks in central nepal low metamorphic grade cambrian to jurassic rocks of this carapace preserve five phases of deformation structurally dominated by second phase d 2 north verging back folds that oppose the vergence of the orogen the folds are overprinted and cross cut by the c 22 ma south tibetan detachment system and the manaslu leucogranite new structural mapping in hidden valley provides further constraints on the character of d 2 megascopically large asymmetric north verging folds define d 2 microscopically it is characterized by an axial planar cleavage balanced cross sections and bed length restoration of f 2 folds indicate a minimum of 32 38 shortening and 180 thickening during d 2 these data indicate that north verging folds played a significant role in pre miocene crustal thickening of the himalayan superstructure the formation of these folds is compatible with wedge extrusion or channel flow of the underlying mid crustal rocks whereby their geometry reflects early coupling between the upper and middle crust

the role of rock surface hardness and internal moisture in tafoni development in sandstone the development of cavernous weathering features such as tafoni remains poorly understood in particular the roles played by internal moisture and case hardening remain unclear in this study electric resistivity tomography ert has been used to map moisture distribution within inner walls of tafoni developed in sandstone and an equotip device used to measure rock surface hardness as a proxy measure of the degree of weathering and case hardening seven large tafoni in the golden gate highlands national park south africa varying in size and degree of development have been monitored a dynamic relationship between surface hardness degree of weathering and internal moisture regimes has been found we propose a new conceptual model which illustrates the complex interaction between case hardening and internal moisture and suggests a new direction for cavernous weathering research copyright 2011 john wiley sons ltd

estimating depth of investigation in dc resistivity and ip surveys in this paper the term depth of investigation refers generically to the depth below which surface data are insensitive to the value of the physical property of the earth estimates of this depth for dc resistivity and induced polarization ip surveys are essential when interpreting models obtained from any inversion because structure beneath that depth should not be interpreted geologically we advocate carrying out a limited exploration of model space to generate a few models that have minimum structure and that differ substantially from the final model used for interpretation visual assessment of these models often provides answers about existence of deeper structures differences between the models can be quantified into a depth of investigation doi index that can be displayed with the model used for interpretation an explicit algorithm for evaluating the doi is presented the doi curves are somewhat dependent upon the parameters used to generate the different models but the results are robust

an updated global review of solutional weathering processes and forms in quartz sandstones and quartzites abstract quartz is considered one of the less soluble minerals of the earth s crust and thus hardly affected by chemical weathering despite this for more than forty years it is clear that the formation of caves and peculiar solutional weathering dominated landforms in quartz rich lithologies is common and shares several similarities to the well known karstic ones in carbonate rocks in the last thirty years great strides have been made in furthering our knowledge of the distribution of these forms around the world and the geochemical processes involved these studies have clearly shown that solutional weathering is a fundamental process acting through intergranular dissolution of quartz increasing the rock porosity and decreasing the rock strength to erosion this process has been described in the concepts of arenization and phantomization and the widespread evidences of the fundamental role of quartz solution in landform genesis has even developed to the extent of several geomorphologists reassessing the definition of the term karst and its application to these peculiar lithologies nonetheless the process is complicated by several factors related both to environmental conditions water chemistry and availability as well as to the compositional and textural characters of the lithology presence of clays iron hydroxides carbonate cement etc all these aspects have to be taken carefully in consideration in order to understand if solution is a dominant or accessory process in the landscape evolution in this review the state of knowledge on the relevant chemical processes weathering mechanisms and speleogenesisk involved in the surface and underground karstification and clear examples of quartz solution and solutional landforms from different world locations are outlined and discussed

quantitative study of a rapidly weathering overhang developed in an artificially wetted sandstone cliff those factors controlling the weathering and erosion of sandstone on the field scale are still not well understood in this study a specific sandstone overhang and its surroundings with artificially induced and extremely high erosion rates was subjected to a complex investigation contrast between the erosion rate of the wet and dry portions of the same cliff enabled isolation of the factors responsible for rapid sandstone retreat erosion rates moisture and salt content as well as suction were monitored in the field mineral phases and water chemistry were analyzed the measurement of tensile strength laboratory frost weathering tests and numerical modeling of stress were performed the acquired data show that an increase of moisture content in pores in the area of the studied overhang decreased tensile strength of the sandstone to 14 of its dry value and increases the sandstone weathering and erosion rate by nearly 4 orders of magnitude compared to the same sandstone under natural moisture condition outside on the cliff area consequently frost weathering in combination with wetting weakening was found to play a major role in weathering erosion of the sandstone cliff and overhang frost weathering rate in both the laboratory and field increases up to 15 times with decreasing gravity induced stress the results also indicate that sandstone landforms in temperate climates may potentially develop very rapidly if the pore space is nearly saturated with water and will later remain relatively stable when the moisture content decreases as a general implication it is suggested that overhangs in central europe and elsewhere might be the result of rapid frost weathering of nearly saturated sandstone during the last glacial this article is protected by copyright all rights reserved

a new method for geoelectrical investigations underwater1 a new electrical method is proposed for determining the apparent resistivity of multi earth layers located underwater the method is based on direct current geoelectric sounding principles a layered earth model is used to simulate the stratigraphic target the measurement array is of pole pole type it is located underwater and is orientated vertically this particular electrode configuration is very useful when conventional electrical methods cannot be used especially if the water depth becomes very important the calculated apparent resistivity shows a substantial quality increase in the measured signal caused by the underwater targets from which little or no response is measured using conventional surface electrode methods in practice however different factors such as water stratification underwater streams or meteorological conditions complicate the interpretation of the field results a case study is presented where field surveys carried out on lake geneva were interpreted using the calculated apparent resistivity master curves

centrifuge modeling of slope instability this paper demonstrates the use of a centrifuge modeling technique in studying slope instability the slope models were prepared from sand and sand mixed with 15 and 30 fines by weight compacted at optimum water content the validity of the modeling technique was confirmed using slope models of different heights inclinations and soil types the soil behavior was studied under triaxial and plane strain conditions and the extended mohr coulomb failure criterion was found relevant for expressing the strength of unsaturated compacted soil based on the angle of internal friction and apparent cohesion the bishop s circular mechanism together with the extended mohr coulomb failure criterion was able to simulate the slope failure reasonably well the rainfall of different intensities was then induced on the 60 stable slopes of sand with 15 fines it was found that the failure of slope under rainfall may be interpreted as a reduction in apparent cohesion the centrifuge tests also allowed the rainfall intensity duration threshold curve local curve to be generated for the test slopes and the accumulated rainfall corresponded well to some of the reported field observations

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

a tracer test in a shallow heterogeneous aquifer monitored via time lapse surface electrical resistivity tomography we illustrate a case study of a saline tracer test in a shallow highly heterogeneous aquifer monitored by means of surface time lapse ert the test was aimed at identifying the system s hydraulic properties some of the expected limitations of the method particularly caused by the strong decrease in ert resolution with depth and the consequent problems with mass balance and moment calculation could be partly balanced by the use of direct measurements of groundwater electrical conductivity and tracer concentration at one selected location the vast heterogeneity of the system ranging in lithology from clay to gravel at a scale of meters to tens of meters reflects itself in the tracer migration and distribution over time the tracer is trapped in the low permeability regions and from these it is slowly released over time high resolution surface ert proves effective at picturing this system behavior over time the extreme heterogeneity is also a challenge in the attempt to translate bulk electrical

use of transient electromagnetics to define local hydrogeology in an arid alluvial environment to characterize a local groundwater system in an arid alluvial environment a transient electromagnetic tem survey was performed with a dense station spacing along intersecting profiles structural features of significance to groundwater development were clearly evident in the color modulated apparent resistivity versus time pseudosections that were used to display the apparent resistivity data modeling results in conjunction with pseudosections were used to determine exploratory drill sites comparing the modeled results with electric logs from test holes demonstrated that 1 d modeling is not suitable for areas where rapid lateral change occurs these areas are easily identified in the apparent resistivity versus time pseudosections sites not located in fault zones with a resistivity greater than a few tens of ohm m were considered to be preferred locations for production wells hydraulic testing confirmed this interpretation philosophy the survey demonstrates the utility of closely spaced tem sound

a new technique for non destructive field measurement of rock surface strength an application of the equotip hardness tester to weathering studies tafone like depressions have developed on the aoshima sandstone blocks used for a masonry bridge pier in the coastal spray zone a thin layer of partial granular disintegration was found on the surface in depressions to evaluate quantitatively the strength of the thin weathered layer the hardness was measured at the surface of the sandstone blocks using both an equotip hardness tester and an l type schmidt hammer comparison of the two testing results indicates that the equotip hardness value is more sensitive in evaluating the strength of a thin layer of weathered surface rock than the schmidt hardness value by applying two methods i e both the repeated impact method and the single impact method the equotip tester can evaluate the strengths of fresh internal and weathered surficial portions of rocks having a thin weathering layer comparison of the two strengths enables evaluation of strength reduction due to weathering copyright 2007 john wiley sons ltd

rapid salt weathering in the coastal namib desert implications for landscape development data on the rate and style of breakdown on naturally occurring rock types are important to improving geomorphological understanding of landscape development in arid environments two years exposure of rock blocks cut from an english limestone bath stone as well as locally relevant namibian rocks karibib marble and damara granite within four distinctive microenvironments in and around a coastal salt pan environment reveals high rates of breakdown in the bath stone blocks observable breakdown in the marble blocks and weight gains and strength increases in the granite blocks breakdown is associated with high conductivities and large amounts of halite and gypsum within the surface sediments frequency of wetting and drying appears to be a major control on the resultant breakdown rates these findings can be compared with recent data from further inland in the namib desert which suggest very slow rates of breakdown of similar blocks of damara granite and karibib marble even where salts are readily available high rates of rock breakdown within coastal salt pans appear to contribute to dust production and the effective flattening of relief along the coastal strip

avulsion and anastomosis in the panhandle region of the okavango fan botswana abstract gps water surface elevation data from the panhandle region of the okavango fan northwestern botswana show that a prominent anastomosed reach occurs within a relative valley gradient depression inferred to represent a small graben structure the okavango river undergoes an abrupt change in pattern as it approaches the upstream fault zone of the graben developing small meander loops and higher sinuosity in response to increased valley slope induced by faulting four channels split from and ultimately rejoin the okavango trunk channel to define the anastomosed reach the oldest filipo channel diverted from the okavango on the upstream horst block rejoining the trunk channel 26 km downstream within the graben the younger channels b c and d all developed subsequent to the filipo avulsion by forming linkages between the okavango trunk and floodplain tributaries that had evolved by headward extension and incorporation of older abandoned channel segments diversion of the three younger anastomosed channels was likely abetted by increased aggradation of the trunk channel following down faulting neotectonic movement although involving only slight displacement is seen to be the underlying cause of avulsion anastomosis and certain channel pattern changes in the okavango panhandle this contrasts with other parts of the okavango fan system where avulsion appears to result more from autogenic in channel sedimentation conditioned by various roles of vegetation

identification of gypsum karstification using an electrical resistivity tomography technique the case study of the sivas gypsum karst area turkey abstract the sivas district is the most important gypsum karstified area in turkey the oldest evaporites in the region were formed during the sedimentation process of the oligocene period generally these units extend along the southern part of the sivas basin after the early miocene sea drained from this region extensive evaporite deposition developed an electrical resistivity tomography ert study was carried out between the hafik and imranli districts of the sivas gypsum karstified area in this research the prior aim was to determine the general characterization geometry sedimentary cover and resistivity properties of gypsums in addition the study includes the synthetic modelling of different gypsum karstification types the evaluation and interpretation were based on ert data that was collected from the hafik imranli region first the different karstifications were identified together with the characteristic features of gypsum in the area the ert studies showed that there are large and old karst structures between the hafik and zara district however the karst structures that are located between the zara and imranli regions were interpreted as smaller and younger the characteristics of both of the regions are different in terms of the morphometric properties it is certain that the kizilirmak river has an important impact on the formation of these structures ert studies have shown that the cover and bedrock type collapse sinkholes are very spread out across the area and their geometries are different throughout time the suffosion type of cavities formed inside the cover type sinkholes as a consequence of geological and geomorphological events the ert sections showed that certain parts of these structures collapsed and then alluvial materials filled in the shallow groundwater level in the drilling results and the conductive zone in the ert results are compatible with each other ert studies clearly determined the various karstification typologies of gypsums in the region which also contributed to the creation of a detailed conceptual geological model

investigations into the relationship between changes in internal moisture regimes and rock surface deterioration in cavernous sandstone features cavernous features commonly develop in sandstone but their development over time remains enigmatic it has been suggested that moisture movements within the rock mass play a key role in the location development and dynamics of cavernous features in this research the role of internal moisture movement is tested through monitoring moisture and surface deterioration dynamics in april 2008 and april 2009 within two large cavernous features mega tafoni in the golden gate highlands national park south africa gghnp data are presented from surveys of internal moisture using electrical resistivity tomography ert surface moisture using a protimeter and deterioration using surface hardness as recorded with an equotip as a proxy for surface deterioration across five 2 45 m long transects in addition a high resolution temperature record is presented to assess the influence of micro climates within the caverns the results indicate consistency in the gross spatial pattern of moisture flow within the rock mass over a one year period but significant changes in mean moisture contents and in the fine detail of moisture patterning some noticeably weakened areas had developed within the central parts of the cavernous features often linked to wetter subsurface conditions supporting the theory that core softening is a main driver of cavernous feature formation however in some areas surface hardening is also found to be associated with wetter subsurface conditions supporting the theory that case hardening is a main driver of cavernous feature formation in addition the presence of well established biofilms suggests an even more complex interaction between moisture surface development and biological activity a model is presented therefore which integrates this paradox by proposing a non linear relationship between moisture dynamics facilitation of biofilm formation and deterioration within cavernous features

variable weathering response in sandstone factors controlling decay sequences differences in weathering response characteristics of fine and coarse grained stanton moor sandstone samples were assessed in a laboratory weathering simulation experiment using a variable combination of salt weathering and freeze thaw cycles preliminary analysis of permeability characteristics identified similar mean values for each type of stanton sandstone but significant differences in the range of values between the two sample sets with coarse grained samples of stanton moor sandstone displaying a restricted range of values in comparison to fine grained samples which showed much greater within block variation data indicated that the greater the range in initial permeability values the greater the potential for salt and moisture ingress and retention and hence eventual disruption of the fabric of the stone experimental data also identified different stages in decay sequences with significant structural change occurring during the initial preparatory stage before material breakdown and loss became apparent evidence suggests that relatively minor structural and mineralogical differences between samples of the same stone type can have a significant influence on weathering behaviour resulting in distinct rates and patterns of breakdown copyright 2005 john wiley sons ltd

pseudo seismic wavelet transformation of transient electromagnetic response in engineering geology exploration 1 this paper presents some new theoretical analysis and numerical simulations of that transient electromagnetic diffusion field response is transformed into a pseudo seismic wavelet in engineering geology exploration it can clearly reveal the electric interface under ground to simplify the integral equation used in the transformation the integral range is separated into seven windows and each window is compiled into a group of integral coefficients then the accuracy of the coefficients is tested and the calculated coefficients are used to derive the pseudo seismic wavelet by optimization method finally several geo electric models are designed so that model responses are transformed into the pseudo seismic wavelet the transformed imaginary wave shows that some reflection and refraction phenomena appear when the wave meets the electric interface this result supports the introduction of the seismic interpretation in data processing of transient electromagnetic method

new challenges for tafoni research a new approach to understand processes and weathering rates cavernous tafoni type weathering is a common and conspicuous global feature creating artistic sculptures which may be relevant for geochemical budgets weathering processes and rates are still a matter of discussion field evidence in the type locality corsica revealed no trend of size variability from the coast to subalpine elevations and the aspect of tafoni seems to be governed primarily by the directions of local fault systems and cleavage and only subordinately by wind directions or the aspect of insulation rem analysis of fresh tafone chips confirmed mechanical weathering by the crystallization of salts as conchoidal fracturing of quartz is observed the salts are only subordinately provided by sea spray as calcium and sodium sulfates rather than halite dominate even close to the coast characteristic element ratios compare well with aerosols from mixed african and european air masses sulfates are largely derived from sahara dust indicated by their sulfur isotopic composition salt crystals form by capillary rise within the rock and subsequent crystallization in micro cracks and at grain boundaries inside rain protected overhangs siderophile bacteria identified by raster electron microscopy rem analysis of tafone debris contribute to accelerated weathering of biotite and tiny sulfide ore minerals by applying 10be exposure dating weathering rates of large mature tafone structures were found to be about an order of magnitude higher than those on the exposed top of the affected granite blocks copyright 2010 john wiley sons ltd

instability caused by a seepage impediment in layered fill slopes the underlying cause of loose fill slope failures in hong kong has been attributed to static liquefaction during heavy rainfall a series of centrifuge model tests and numerical analyses were condu

environmental impact on construction limestone at humid regions with an emphasis on salt weathering al hambra islamic archaeological site granada city spain case study al hambra is an immense and valuable archaeological site in spain built on sabika hill with red brick and natural sandy limestone it exhibits weathering features indicating salt weathering process the main aim of this study is to examine weathering processes and intensity acting on al hambra rock petrography and mineralogical composition have been examined using thin sections scanning electron microscope x ray diffraction and x ray fluorescence limits of rock s physical parameters using ultrasonic waves and mercury porosimeter rock salt content through hydrochemical analysis salts attacking this structure are mainly from wet deposition of air pollutants on the long term chemical alteration of rock s carbonate content to its equivalent salts the salts concentration limit within the examined rock samples is considerably low but it is effective on the long run through hydration of sulphate salts and or crystallization of chloride salts rock texture type and its silica as well as clay content reduces its resistance to internal stresses by salts as well as wetting and drying cycles at such humid area the recession in limits of physical parameters examined for deep seated and weathered limestone samples quantitatively reflects weathering intensity on al hambra

quantification of rock control in geomorphology abstract rock control the influence of rock properties on landform development has for long been a relatively under researched topic but numerous techniques have been developed especially by geotechnical engineers and stone conservationists that are now being applied to geomorphological issues by geomorphologists these techniques range in scale from the quantification of major discontinuities through to analysis of micro pores rock control studies that have taken place over the last few decades have contributed important insights into our understanding of such diverse phenomena as 1 river terraces bedrock channel forms and gradients pot hole development drainage density and gully badland development 2 slope forms and failures especially with respect to rock mass strength 3 the form of glacial troughs and of subglacial erosional landforms 4 weathering controls on rock durability and the association of weathering with porosity 5 classic karst features including various types of karren 6 sandstone landforms 7 inselbergs and tors and 8 cliffs and shore platforms

large depth hydrogeological detection in the north china type coalfield through short offset grounded wire tem the north china type coalfield is the most important coalfield in china with the development of chinese economy shallow coal resources 600 m have been exhausted and large depth detection is being conducted water inrush is disastrous for coal mining however large depth 600 1200 m detection of water filled zones in the north china type coalfield is a difficult geophysical task due to its low resistivity coverage the traditional loop source transient electromagnetic method tem cannot realize large depth detection on the other hand high resolution detection of lotem is limited by the problem of recording points and large volume effect to explore the large depth targets with high resolution short offset grounded tem sotem was applied in the north china type coalfield sotem is one branch of grounded wire tem the response of sotem is calculated using superposing dipole method rather than the direct dipole approximation which is used in the calculation of the response of lotem this paper analyzes the comparison of the resolution and detection depth between sotem and loop source tem at first compared to the loop source tem with frequently used parameters the detection depth of sotem with the usual setup parameters is about twice of magnitude and the resolution capability of sotem at large depth is higher than that of loop source tem then the resolution capability and detection depth between lotem and sotem are analyzed for the grounded wire tem offsets are strictly related to the detection depth so the detection depth of lotem with larger receiver transmitter offset will be greater however at the depth of 600 1200 m the resolution capability to conductive targets of sotem is higher than that of lotem at last sotem with a 1000 m long source and 1000 2000 m offset is applied to the 1200 m depth exploration of water filled zones in the north china type coalfield the induced voltage is observed and transformed into magnetic field then the data is inverted using the least mean fourth algorithm the distribution of water on the top and bottom surface of the large depth no 4 coal seam is given and is verified by the drilling result

the use of the schmidt hammer and equotip for rock hardness assessment in geomorphology and heritage science a comparative analysis rapid field based measurements of rock hardness are of use in investigating many geomorphological and heritage science problems several different methods are now available for taking such measurements but little work has been done to assess their comparability and strengths and weaknesses we review here the capabilities of two types of schmidt hammer classic n type and silver schmidt bl type alongside two types of equotip standard type d and piccolo for investigating rock hardness in relation to rock weathering on various types of sandstone and limestone as well as basalt and dolerite whilst the two schmidt hammers and the two equotips show comparable results when tested at 15 individual sites interesting differences are found between the equotip and schmidt hammer values which may reveal information about the nature of weathering on different surfaces operator variance is shown to be an issue in particular for the equotip devices which also exhibit higher variability in measurements and necessitate larger sample sizes carborundum pre treatment also has varying effects on the data collected depending on the nature of the surface studied the equotip devices are shown to be particularly useful on smaller blocks and in situations where edge effects may affect schmidt hammer readings we conclude that whilst each device contributes to geomorphological research they do not necessarily produce comparable information indeed using schmidt hammer and equotip in combination and looking at any differences in results may provide invaluable insights into the structure of the near surface zones and the nature of weathering processes copyright 2010 john wiley sons ltd

rock moisture measurements techniques results and implications for weathering rock moisture is an important factor for the intensity and distribution of frost weathering processes however quantitative measurements are scarce which is partly due to the lack of reliable measurement techniques this paper presents five different techniques for obtaining rock moisture data while collecting rock pieces and two dimensional geoelectric measurements allow determination of the spatial moisture distribution the temporal variability can be derived from conductivity and time domain reflectometry records computer simulations using rock properties and climatic records as input data render it possible to clarify the important aspects that are responsible for the moisture distribution it proved to be advisable to use several methods to check and validate the results the results obtained in study areas in the bavarian alps make it clear that direct rainfall is the main source of rock moisture the influence of snow is limited to the immediate vicinity of the snow fields and is not equally pronounced at different times and positions rock moisture levels are higher in summer than they are in winter since in winter less water is supplied in liquid form northerly exposed rockwalls are generally more moist than those exposed in a southerly direction which is due to the different insolation as well as to the wind direction during rainfall in every position the rock is on average wetter on the inside than it is on the surface this means that shallow frost cycles as typical for south exposed sites are not affecting weathering since they take place at a depth level that is mostly dried out numerous spatial and temporal patterns of rockfall found in the same study areas can be explained through variations in rock moisture thus the moisture content of the rock is considered to be one of the major controlling factors of the frost shattering rate copyright 2005 john wiley sons ltd

inland notches lithological characteristics and climatic implications of subaerial cavernous landforms in israel inland notches are elongated concave shape indentations that develop on the carbonate rocky cliffs of mountainous zones down to the desert fringe these rock shelters form as a result of the interaction between specific petrologic characteristics and climatic controls emphasizing the importance of environment upon rock decay inland notches are shaped due to slight differences 1 15 in the porosity of the visor and cavity bed the cavity bed is more porous so more likely to erode by exfoliation and dissolution thus the cavity bed retreats at a faster rate compared to the slower subaerial dissolution of the visor bed until a critical point is reached where the visor collapses in israel inland notches inhabit the same lithostratigraphic units as do large caves the vast majority 71 of inland notches are formed in hard dense and crystalline limestone deposited throughout the turonian age another 27 are cut into the dolomitic sequence of the upper albian and lower cenomanian the rest 2 are dispersed in the various formations of the cenomanian and eocene eras notches are most common in semi arid and in mediterranean climates but mainly in areas with annual rainfall of between 400 mm and 850 mm in more humid areas 900 mm yr notches are negligible or completely absent due to the rapid rate of chemical dissolution of carbonate rocks in the desert fringe 200 300 mm yr mechanical decay is accelerated and notches exhibit disintegration processes visor collapse and rock falls in the desert area 200 mm yr salt decay replaces the chemical decay characteristic of inland notches encouraging tafoni formation in addition notches form through fluvial activity or on account of greater petrophysical differences between consecutive beds i e elongated cavities may form in soft rocks shaded by harder visors or crusts copyright 2017 john wiley sons ltd

rock moisture content in the field and the laboratory and its relationship to mechanical weathering studies rock moisture content is a major control of mechanical weathering particularly freeze thaw and yet almost no data exist from field situations this study presents moisture content values for rocks taken from a variety of positions and conditions in the maritime antarctic additional information regarding the amount of water the rock could take up as observed from laboratory experiments is also presented the results show that the approaches used in simulation experiments particularly that of soaking a rock for 24 hours may produce exaggerated results it was found that the saturation coefficient s value was a good indicator of frost susceptibility based on water content but that the derivation of that value may underestimate the potential of some rocks the distribution of moisture within rocks is seen as an important but unkown factor the results of these field moisture contents suggest that for simulations of freeze thaw or hydration to be meaningful then they should have rock water contents based on field observations

near surface site investigation and imaging of karst cave using comprehensive geophysical and laser scanning a case study in shandong china the karst development of jiao dong peninsula in shandong province has formed a unique karst landform and has become one of the typical karst areas in the north of china karst collapse occurred during the construction of high speed railways and caused many environmental problems to reveal the development situation of karst area in shandong the conventional surface geophysical techniques were used for karst exploration and location of key area and the results of drilling verification were in good agreement with the results of geophysical exploration at the same time the new technology in the field of surveying and mapping 3d laser scanning technology is cited in the engineering geophysical exploration and the key issue is the shape and size of the karst it makes up for the shortcomings of traditional geophysical exploration technology that can only be qualitative and cannot be quantitatively analyzed it realizes the transformation of karst exploration from regional detection to single cave exploration and better implements the concept of information construction it has contributed to the smooth progress of the project and environmental protection