factors affecting the durability of selected weak and clay bearing rocks from turkey with particular emphasis on the influence of the number of drying and wetting cycles weathering can induce a rapid change of rock material from initial rock like properties to soil like properties the resistance of a rock to short term weathering is described through a durability parameter called the slake durability index as durability is an important engineering parameter particularly for weak and clay bearing rocks it was assessed by a number of tests the main purpose of this study is to assess the influence of the number of drying and wetting cycles and controls of mineralogical composition and strength on durability for this purpose 141 samples of different types of weak and clay bearing rocks were selected from different parts of turkey and relationships between the above mentioned rock characteristics were statistically investigated the samples were subjected to multiple cycle slake durability testing x ray diffraction xrd analysis and uniaxial compression testing in addition to assess the influence of mineralogical composition on durability the mineral contents of the original material and the material passing from the drum of the slake durability apparatus after each cycle were also determined by xrd the results indicate that the type and amount of clay minerals are the main factors influencing the variations of the slake durability index in all samples the durability of the clay bearing rocks studied correlates best with the amount of expandable clay minerals a strong relationship between the uniaxial compressive strength and the fourth cycle slake durability index is found only for the marls among the rock types studied assessment of gradation results of the spoil pile materials consisting of clay bearing rocks also reveals that the increase in percentage of fines in old piles is indicative of material degradation as is evident by multiple cycle slaking it is emphasized that two cycle conventional slake durability testing did not appear to offer an acceptable indication of the durability of weak and clay bearing rocks when compared with multiple cyclic wetting and drying comments on the performance of the test are made that aim to make the testing process and interpretation of the results more reliable

chemical mineralogical and textural properties of the kope formation mudstones how they affect its durability abstract the kope formation is a rock unit that extends over southwest ohio and adjacent areas of kentucky and indiana usa it is characterized by meter scale cycles of mudstones and limestones where thick mudstone is sandwiched between thin limestone layers kope formation mudstones are less durable than the mudstones in the area they cause abundant slope failures in areas of their outcrops this study evaluates chemical mineralogical and textural properties of kope mudstones to determine why it is less durable the two cycle slake durability index id 2 was measured on thirty mudstones belonging to three consecutive cycles of the kope formation chemical composition and mineralogy of kope mudstones do not show significant relationship with the id 2 instead a relationship to fabric was found kope mudstones with two main fabric types were observed in the field laminated mudstones and non laminated mudstones detailed micro fabric analysis on kope mudstones was done using the scanning electron microscope laminated mudstones with turbostratic fabric showed higher id 2 and lower moisture content than the non laminated mudstones with matrix fabric the difference in the id 2 of laminated mudstones and non laminated mudstones is statistically significant both mudstone types exist in many cycles of the kope formation thus core samples should be selected from both types for preliminary tests in geotechnical practice to obtain more accurate estimations of the geotechnical properties of the kope mudstones the results and data interpretations of this study can be correlated with the mudstones and shale in different areas of the world specifically a great attention should be paid to the macro and micro textural properties of any rock type regardless of their classification

assessment of granitic rocks degradability susceptive to acid solutions in urban area granitic rocks have been used in wide range of studies when using these rocks the most important aspect to be considered is their weathering potential especially in acidic and wet environments in these conditions acid rainfall that is generated from atmospheric pollutions can accelerate the weathering trend of these rocks the aim of this article is to assess the relationship between the weathering processes and environmental conditions for this purpose four types of alvand granitic rocks were collected then using optical microscopy and x ray diffractometry the textural and mineral compositions of the rocks were studied as the second step the physical properties of these rocks were determined to assess the effect of ph on the degradability of rocks three solutions with different ph were prepared by adding sulfuric acid finally slake durability test for each type in sulfuric acid with ph 2 5 4 and 5 5 up to 15 cycles was performed the results indicated that these rocks posses a very high durability and their use as building stones are recommended in spite of these facts long term effects such as the weathering process can cause serious problems to ancient buildings as in the inscription of darius

the role of ph in red stratum mudstone disintegration in the three gorges reservoir area china and the associated micromechanisms abstract the well known slide prone red stratum mudstones in the three gorges reservoir tgr area are currently undergoing sharp changes in i water level driven by the impounding discharging operation of the three gorges dam and ii the rain water h concentration driven by recent rapid industrial agricultural development and these changes are expected to impact geohazards this potential impact emphasizes the importance of understanding the role of ph in the drying wetting disintegration of red stratum mudstones although many investigations have focused on the role of ph in mudstone disintegration the red stratum mudstones in the tgr area differ from mudstones elsewhere and the role of ph has seldom been studied in these rocks this work adds to the limited body of research by 1 experimentally investigating the possible role of ph in red stratum mudstone drying wetting disintegration and 2 revealing the micromechanisms responsible for this role in the experiment six disintegration performance indexes and two mechanical indexes i e particle size gradation slake durability index decay constant surface energy box dimension fractal dimension cohesion and friction angle were monitored throughout the disintegration process a tri piecewise linear fractal model is proposed to better describe the particle size distribution this research shows that the acid enhancements stimulate the disintegration of red stratum mudstones and significantly affect shear strength in comparison alkaline environments inhibit the mudstone fragmentation and slightly degrade the shear strength two possible micromechanisms and three potential effects of acid or alkaline agents are presented to account for the role of ph the findings provide insights into the potential geohazard impacts of sharp changes in the exposure environment i e water level and h concentration of the red stratum mudstones in the tgr area

response of the changjiang yangtze river water chemistry to the impoundment of three gorges dam during 2010 2011 abstract the environmental impact of three gorges dam tgd in the changjiang yangtze river is an important topic of concern for scientific communities and the public however the changes in river water chemistry in response to the dam construction remain poorly constrained this study presents the seasonal variability of all major cations and some anions in the lower changjiang during a full hydrological year from 2010 to 2011 the concentrations of all ions except for hco 3 are higher after the tgd operation than before p

mechanism of the anlesi landslide in the three gorges reservoir china abstract many gentle dip translational rock slides have taken place in the three gorges reservoir china in order to study the mechanism of these translational rock slides the authors use the anlesi landslide as a typical case study to investigate in detail field investigations show that the slip zones of the anlesi landslide were formed from a white mudstone in jurassic red strata x ray diffraction and infrared ray analysis showed that the main mineral components of the slip zones are montmorillonite illite feldspar and quartz laboratory tests indicate that the slip zone soils are silty clay of medium swelling potential the shear strength decreasing significantly as the slip zone attracts water and saturates the main factors contributing to the anlesi landslide are recent tectonic activity incompetent beds and intensive rainfall recent tectonic activity had caused shear failure along the incompetent beds and joints within the sandstone with the effect of intensive rainfall water percolates to the incompetent beds along tectonic fissures resulting in swelling of the soil material and high groundwater pressures within fissures in the strata as a consequence the anlesi slope is prone to slide along these incompetent beds flac3d software was used to simulate the mechanism of the anlesi landslide considering the rheological properties of soil and rock the simulation results demonstrate that the stress displacement and failure area changes with simulated creep time the maximum displacement in the x direction reaches 7 59 m after 200 year simulated creep therefore the mechanism of the anlesi landslide can be illustrated considering the rheological properties of jurassic red strata

dissolution rates of actinolite and chlorite from a whole rock experimental study of metabasalt dissolution from 2 ph 12 at 25 c abstract the dissolution rates of the minerals actinolite and chlorite were determined from metabasalt element release rates measured at 25 c and 2 11 86 mol m 2 s mineral dissolution rates obtained in this study are within the range of corresponding values reported in the literature this observation suggests that the dissolution rates of major constituent minerals in a multi phase rock are not affected by the presence of the other minerals this conclusion validates the common assumption that the dissolution rate of an individual mineral is equal to that of the same mineral in a dissolving multi mineralogic rock at least for major constituents

slaking behavior of clay bearing rocks during a one year exposure to natural climatic conditions abstract slaking of clay bearing rocks upon exposure to natural climatic conditions is a common problem at many engineering projects depending upon the regional climate clay bearing rocks slake in response to heating and cooling wetting and drying and freezing and thawing cycles however laboratory methods used for assessing the slaking behavior of clay bearing rocks including the standardized methods by the american society for testing and materials astm and the international society for rock mechanics isrm involve only wetting and drying treatments in this study we investigated the slaking behavior of clay bearing rocks by exposing them to natural climatic conditions for a period of one year twenty clay bearing rocks consisting of 5 claystones 5 mudstones 5 siltstones and 5 shales were selected for the study twelve replicate samples of each rock type were prepared so that each sample consisted of 10 pieces each piece weighing 40 60 g with a total weight of 450 to 550 g the samples were placed in separate metallic pans and exposed to natural climatic conditions from september 2009 to september 2010 each month one replicate sample of each rock type was removed from natural exposure and its grain size distribution was determined disintegration ratio d r defined as the ratio of the area under the grain size distribution curve of the slaked material for a given sample to the total area encompassing all grain size distributions was used to evaluate the extent of disintegration upon slaking d r can range from 0 to 1 with 0 indicating 100 slaking and 1 indicating no slaking after 3 months of exposure to natural climatic conditions claystones mudstones siltstones and shales exhibited d r values of 0 223 0 302 0 698 and 0 494 respectively these results suggest that over a given period of time claystones slake the most and siltstones the least relating d r to clay content of the rocks studied reveals that rocks with higher clay contents slake more rapidly and extensively under natural climatic conditions than those with lower clay contents

slake durability study of shaly rock and its predictions more than 35 of the earth s crust is comprised of clay bearing rocks characterized by a wide variation in engineering properties and their resistance to short term weathering by wetting and drying phenomenon the resistance to short term weathering can be determined by slake durability index test there are various methods to determine the slake durability indices of weak rock the effect of acidity of water slaking fluid on slake durability index of shale in the laboratory is investigated these methods are cumbersome and time consuming but they can provide valuable information on lithology durability and weather ability of rock fuzzy set theory fuzzy logic and artificial neural networks ann techniques seem very well suited for typical complex geotechnical problems in conjunction with statistics and conventional mathematical methods a hybrid method can be developed that may prove a step forward in modeling geotechnical problems during this investigation a model was developed and compared with two other models i e neuro fuzzy systems combination of fuzzy and artificial neural network systems and artificial neural network system for the prediction of slake durability index of shaly rock to evaluate the performance of its prediction capability

study on the shear strength of soil rock mixture by large scale direct shear test abstract soil rock mixtures s rm which formed in the quaternary period are a type of extremely inhomogeneous and loose geomaterial with a certain percentage of rock blocks they are composed of rock blocks with various sizes and high strength fine grained soil and pores the meso failure mechanism and macro physical and mechanical characteristics of s rm are largely controlled by its rock block proportion and the granular distribution as we know when the rock blocks in the s rm are larger it is difficult to take an in situ sample for an on site test in addition it is difficult to obtain the granular distribution of rock blocks in s rm by traditional sieving tests this paper uses a new method called digital image processing dip in which the rock blocks in s rm samples are separated from the soil matrix and the proportion and distribution of the rock blocks is obtained quantitatively the results are used for the sample preparation of the large scale direct shear tests which provide a new method for the test study of s rm according to the results of large scale direct shear tests the rock block size proportion controls the deformation and fracture mechanism of the s rm the shape of the shear stress vs horizontal displacement curve and the vertical displacement vs horizontal displacement curve of the s rm samples are different from that of general soil and rock with the increment of the rock block proportion the shear band of the s rm increases when the rock block proportion lies in the range of 25 70 the increment of the internal friction angle linearly increases with the increment of the rock block proportion the cohesion of the s rm decreases compared with that of the soil when the rock block proportion is larger than 30 however there is only a little decrease in the cohesion with the increment of the rock block proportion

engineering geological problems in the three gorges project on the yangtze china the three gorges project formally commenced in december 1994 geological investigations however have been in progress since the 1950s the scope of this work was comprehensive covering all aspects of reservoir geology regional tectonics and seismicity as well as studies related to site selection and structural foundation conditions and construction materials in this paper a review of the geological studies is conducted with emphasis placed on the principle geological problems the following is concluded the damsite offers an excellent foundation in precambrian granite rocks the tectonic setting for the project is relatively simple the existing level of seismicity is anticipated to remain at the same low level no significant change in the stability of existing bank slopes is expected to occur due to the operation of the reservoir and no slides will endanger the construction and operation of the project

the krafla spreading segment iceland 1 three dimensional crustal structure and the spatial and temporal distribution of local earthquakes the geothermal seismicity of the krafla volcanic system ne iceland was monitored for 3 months in 1985 using a dense local seismometer network the seismicity was continuous and the spatial and temporal distributions were roughly known prior to monitoring the instruments could thereby be deployed in a well positioned array a total of 489 locatable events were recorded within the network and 1771 arrival times were inverted to calculate the three dimensional p wave velocity structure and hypocentral locations low velocity volumes were imaged beneath the krafla and namafjall geothermal areas and indicate zones of hydrothermal alteration high velocity bodies beneath the krafla caldera rim are interpreted as gabbroic intrusions using a three dimensional velocity structure instead of a refraction based one dimensional model to locate the hypocenters significantly improves their location quality and illustrates the shortcomings of using refraction based models to locate earthquakes in local anomalous areas seismic activity was concentrated within the krafla and namafjall geothermal areas and in a narrow zone where dike injections had occurred 8 and 5 years earlier the activity occurred in the depth range 0 3 km the seismic rate for the whole area was one magnitude 3 2 event per year and the b value was 0 77 0 10 most of the seismicity appears to result from geothermal processes in the manner proposed for other icelandic areas foulger and long 1984 foulger 1988b seismicity directly beneath the bjarnarflag well field within the namafjall area is probably induced partly by geothermal exploitation considerable seismicity also occurred immediately below leirhnjukur a site of intense geothermal activity in the center of the krafla caldera that overlies a roof pendant in the magma chamber below this volume of high seismicity is probably highly fractured and may provide a conduit for magma escaping from the magma chamber

impacts of simulated acid solution on the disintegration and cation release of purple rock mudstone in southwest china abstract rock disintegration and cation release not only impact on terrestrial geomorphology but also provide nutrients for plants further fractal theory has been widely used to characterize the distribution of fragments in rocks for measuring the degree of disintegration yet the effects of an acidic environment on the trajectory of fractal dimensions of rock disintegration and cation release are not fully clear therefore to investigate the impacts of a solution s ph on disintegration and cation release from the purple rock in southwest china a series of laboratory experiments were performed by soaking the purple rocks in solutions with phs from 2 5 to 7 0 over 24 treatment cycles the results show that the lower the ph the fewer cycles required to obtain a stable fractal dimension the fractal dimension of purple rock under different ph values approached three after 24 treatment cycles until decay ratios the mass of decayed rock of 90 acidic treatment increased cation release especially when the ph value of the solution was below 3 5 compared with a deionised water soaking solution the amounts of k na ca2 and mg2 were increased by 4 92 1 27 1 12 and 1 08 times with ph values of 2 5 3 5 4 5 and 5 6 soaking solution respectively at the disintegration stage in addition the release of ca2 and mg2 were more sensitive to acid than that of k and na and ca2 weathering occupied the dominant position in the cation weathering rates moreover due to disintegration processes that transformed each rock sample into fragments fresh surfaces were exposed from which cations were liberated creating a significant p

relative contribution of various climatic processes in disintegration of clay bearing rocks abstract the climatic processes of heating and cooling wetting and drying and freezing and thawing affect the disintegration characteristics of clay bearing rocks shales claystones mudstones and siltstones to varying degrees although heating and cooling wetting and drying and freezing and thawing are known to be the main processes responsible for physical disintegration of rocks under natural conditions most of the previous investigators have used methods based only on water content variations e g jar slake slake index and slake durability index tests to assess the disintegration of clay bearing rocks such assessments may not be adequate to explain the field behaviour of clay bearing rocks subjected to a full range of climatic processes in order to evaluate the combined effects as well as relative contributions of various climatic processes on the disintegration behaviour samples of selected clay bearing rocks consisting of 5 6 particles each weighing 85 150 g were subjected to multiple cycles of heating and cooling wetting and drying and freezing and thawing these treatments resulted in fragmentation of samples with fragments ranging from 50 to 2 mm and finer in dimensions a new approach referred to as the disintegration ratio and defined as the area under the grain size distribution curve of the disintegrated material to the total area encompassing all grain size distribution curves of the samples was used to account for fragmentation into varying sizes statistical analyses were performed to investigate the relationship between fragmentation mineralogical composition and physical properties

the effect of ph of water and mineralogical properties on the slake durability degradability of different rocks from the lesser himalaya india slake durability is an important geotechnical parameter and is a measure of degradability of rocks due to the process of mechanical and chemical breakdown it is closely related to the mineralogical composition and the texture of the rocks in this paper mineralogical examination along with slake durability tests under variable ph conditions both in acidic and alkaline environments on the limestone shale and siltsone were evaluated to understand the relationship between mineralogy and the degradability of rocks the study revealed that rocks rich in calcium carbonate and or magnesium carbonate are adversely affected in the acidic environment whereas the rocks rich in quartz feldspar and muscovite are independent of the ph of the slaking fluid which in turn is more influenced by the texture of the constituent minerals it has also been observed that fine grained rocks are more susceptible to degrade in comparison to the coarse grained rocks

energy evolution a new perspective on the failure mechanism of purplish red mudstones from the three gorges reservoir area china abstract purplish red mudstones from section four of the badong formation are broadly distributed in the three gorges reservoir area tgra and exhibit special characteristics distinct from the mudstones elsewhere this paper investigates the failure mechanism of such mudstones from a new perspective of energy evolution initially the complete failure process under three stress paths i e loading unloading and cyclic loading unloading is monitored and the related data are acquired methods to estimate the energy parameters i e total absorption energy tae cumulative dissipation energy cde and elastic strain energy ese under cyclic loading unloading conditions are presented two new parameters namely the proportion of cde pcde and proportion of elastic energy dissipation peed are introduced using the data the mechanical properties and energy properties are analyzed and the energy evolution is revealed the results show that the failure mechanism under the three stress paths is different from an energy evolution perspective the mechanical parameters deteriorate under unloading in comparison with those under loading the increase in the cde is similar to that in the tae and the ese strain relationship features a step shaped rise for cyclic loading unloading the tae and the pcde nearly linearly increase with cycle times this work provides a new perspective on the failure mechanism of the purplish red mudstones from the tgra

comments on determination of strength parameters and quality assessment of denizli travertines sw turkey ibrahim cobanoglu and sefer beran celik 129 130 2012 38 47

vibrator attribute leading velocity estimation accurate knowledge of the near surface velocity macromodel is vital for hydrocarbon exploration and reservoir characterization that utilize seismic data because this model is crucial for statics and depthing however determination of near surface velocities using direct measurements via uphole surveys is economically prohibitive consequently geophysicists face a problem when determining how to interpolate between sparse near surface well control when near surface velocity varies laterally with lithology that in turn does not vary equally in all directions therefore techniques are needed to estimate near surface velocity using other available data in order to minimize the associated risk resulting from incomplete knowledge of the near surface velocity model

geohazards in the three gorges reservoir area china lessons learned from decades of research abstract the impoundment of the 660 km long reservoir behind the huge three gorges dam the world s largest hydropower station increased regional seismicity and reactivated severe geohazards before the reservoir filling was initiated in 2003 the region had approximately two earthquakes per year with magnitudes between 3 0 and 4 9 after the full impoundment in 2008 approximately 14 earthquakes per year occurred with magnitudes between 3 0 and 5 4 in addition hundreds of landslides were reactivated and are now in a state of intermittent creep many landslides exhibit step like annual pattern of displacement in response to quasi regular variations in seasonal rainfall and reservoir level additional problems include rock avalanches impulse waves and debris flows the seriousness of these events motivated numerous studies that resulted in 1 better insight into the behavior and evolution mechanism of geohazards in the three gorges reservoir area tgra 2 implementation of monitoring and early warning systems of geohazards and 3 design and construction of preventive countermeasures including lattice anchors stabilizing piles rock bolts drainage canals and tunnels and huge revetments this paper reviews the hydro geologic setting of tgra geohazards examines their occurrence and evolution in the past few decades offers insight learned from extensive research on tgra geohazards and suggests topics for future research to address the remaining challenges

investigating the reliability of h v spectral ratio and image entropy for quantifying the degree of disintegration of weak rocks abstract characterization and quantification of disintegration behavior of weak rocks such as shales claystones mudstones and siltstones are usually a difficult task because of their extremely diverse nature these rocks present numerous stability problems along cut slopes around the world because they can change rapidly from rock like to soil like materials upon exposure to natural climatic conditions engineers often overestimate the design parameters for cut slopes in these rocks when laboratory tests are performed on fresh samples adjusting the design parameters for the anticipated amount of disintegration can be problematic because of the complex and time dependent nature of disintegration behavior in this study we investigate the reliability of using microtremor h v spectral ratio derived from microtremor signals and image entropy obtained from image analysis techniques for quantifying the varying degrees of disintegration during 2011 2014 both techniques were used to study disintegration of slopes cut through claystones mudstones and limestones along the 80 km stretch of a highway between bogota and tunja in central colombia for image analysis a new algorithm was developed to discriminate between varying degrees of disintegration across the complete color structure of the image avoiding the gray scale transformation that is usually time consuming the results indicate significant correlations between the degree of disintegration of the cut face the dominant frequency estimated from the microtremor h v ratio and the image entropy values suggesting that h v ratio and image entropy can be reliable techniques for quantifying the degree of disintegration

a decay function model for the integrity loss of rock when subjected to recurrent cycles of freezing thawing and heating cooling rocks are used in engineering works as monument or building stone and as architectural covering stone as a result they can be subjected to recurrent cycles of freezing and thawing and will be subjected to heating and cooling they loose some of their integrity under these cyclic temperature variations and the more frequent and severe these cycles the higher the integrity loss however the rates of progressive disintegration is not the same for different rock types or even within rock types this paper presents a mathematical model describing the integrity loss process when a rock is subjected to such recurrent cycles the model postulates a first order process and provides meaningful parameters for the integrity characteristic of rocks the validity of the model has been established by an experimental laboratory study carried out on 10 different rock types