integrity assessment of rock mass behind the shotcreted slope using thermography this paper presents the results of a field study of using thermography to identify the existence of eroded caves behind shotcrete protected slopes the temperature variation calculated from the highest and lowest temperatures measured at each point on the shotcrete surface is utilized to evaluate the integrity of the rock mass behind the concrete in addition ground penetration radar gpr is performed at three selected locations near the toe of the slope of concern while the necked eye observation and knocking tests are conducted at two of the selected areas the soils taken out from the rock mass and the abnormal echo as well as strong gpr reflection patterns confirm the existence of eroded caves behind the shotcrete surface the agreement of the locations that show both strong gpr reflection and large temperature variation verifies the applicability of thermography in evaluating the integrity of rock mass behind the shotcrete surface

the influence of phase boundary deflection on velocity anomalies of stagnant slabs in the transition zone 1 although the behavior of subducted slabs in the mantle transition zone remains uncertain images from seismic tomography provide insight into a rather complex geodynamic evolution of slabs in this region using a numerical mantle convection model we consider in more detail the dynamics of subducted slabs around an endothermic phase change at 660 km depth the time dependent temperature fields from the flow simulation are used to derive perturbations from a radially stratified seismic velocity model we find that the positive velocity anomalies of the cold descending slabs may be significantly decreased at the phase change owing to the slab induced downward phase boundary deflection and associated velocity discontinuity across the boundary the slab may be completely or partially rendered seismically undetectable depending on the amount of phase boundary deflection the results have implications for the seismic interpretation of the dynamics of subducted slabs interacting with a phase transition

impact of the 2008 wenchuan earthquake in china on subsequent long term debris flow activities in the epicentral area abstract the 2008 wenchuan earthquake triggered the largest number of landslides among the recent strong earthquake events around the world the loose landslide materials were retained on steep terrains and deep gullies in the period from 2008 to 2015 numerous debris flows occurred during rainstorms along the provincial road 303 pr303 near the epicentre of the earthquake causing serious damage to the reconstructed highway approximately 5 24 10 6 m 3 of debris flow sediment was deposited shortly after the earthquake this paper evaluates the evolution of the debris flows that occurred after the wenchuan earthquake which helps understand long term landscape evolution and cascading effects in regions impacted by mega earthquakes with the aid of a gis platform combined with field investigations we continuously tracked movements of the loose deposit materials in all the debris flow gullies along an 18 km reach of pr303 and the characteristics of the regional debris flows during several storms in the past seven years this paper presents five important aspects of the evolution of debris flows 1 supply of debris flow materials 2 triggering rainfall 3 initiation mechanisms and types of debris flows 4 runout characteristics and 5 elevated riverbed due to the deposited materials from the debris flows the hillslope soil deposits gradually evolved into channel deposits and the solid materials in the channels moved towards the ravine mouth accordingly channelized debris flows became dominant gradually due to the decreasing source material volume and changes in debris flow characteristics the triggering rainfall tends to increase from 30 mm h 1 in 2008 to 64 mm h 1 in 2013 and the runout distance tends to decrease over time the runout materials blocked the river and elevated the riverbed by at least 30 m in parts of the study area the changes in the post seismic debris flow activity can be categorized into three stages i e active unstable and recession

system reliability analysis of rock wedge stability considering correlated failure modes using sequential compounding method abstract probabilistic analysis of wedge failure has been used as an effective tool to evaluate inherent uncertainty of the variables in this paper a system reliability analysis of rock wedge stability is presented to perform reliability analysis a cut set system is used for wedge analysis the reliability indices of the individual components and the correlations between the components are determined by the first order reliability method form the sequential compounding method scm is used as an efficient numerical procedure to determine the reliability indices of failure modes and system reliability index considering correlations between failure modes which are calculated by defining equivalent linear safety margin for each failure mode the predicted system reliability indices and corresponding probabilities of failure from the proposed method are compared with those of the monte carlo simulation mcs the results of sensitivity and parametric analyses show that the water pressure parameters are the most effective parameters in rock wedge stability it is also demonstrated that the relative influences of failure modes on the system reliability differ considerably furthermore the probabilistic rock wedge stability curves are presented to evaluate the system probability of failure as a function of safety factor and its coefficient of variation

fragmentation processes and xenolith transport in a proterozoic minette dyke grenville province quebec the mesoproterozoic rivard minette dyke provides a case example of dyke parallel fracturing induced by propagation of low viscosity melts at deep crustal levels the dyke constitutes a xenolith choked intrusion breccia and provides samples of an extensive section of the lithosphere underlying the southwestern grenville province of quebec at 1 08 ga the xenoliths occupy approximately 50 of the volume of the breccia they are extremely diverse and include pyroxenites and mafic granulites from the upper mantle and lower crust and grenvillian gabbroids gneisses and quartzites wall rock fragments are detached to various extents along dyke parallel fractures and apophyses the host lamprophyre magma has a calculated viscosity of ca 40 pa s rapid ascent of magma and turbulence are suggested by the presence of large dense fragments and the brittle to ductile deformation at the margins of some xenoliths a minimum ascent velocity of ca 50 cm s 1 is estimated from the settling velocity of a 40 cm long pyroxenite xenolith the progressive addition of xenoliths increased the effective viscosity of the liquid solid mixture to 103 pa s during emplacement this favoured bingham behaviour and laminar flow of the magma and xenolith suspension field evidence suggests that xenoliths were formed through 1 early fracturing of wall rock by inelastic deformation during dyke propagation and 2 continuous delamination of wall rock by intrusion of magma along the dyke parallel fractures this led to removal of chilled margins and to fluid infiltration partial melting and microbrecciation in the wall rock pre existing discontinuities played a minor role in the fracturing process xenoliths may thus be abundant in alkaline magmas not only because these magmas ascend rapidly and can transport xenoliths but possibly also because their low viscosities promote intense fracturing of wall rock

instability of saturated and unsaturated coarse granular soils abstractit is well known that saturated silt and fine sand are susceptible to instability during undrained shearing coarse granular soils may also be unstable during undrained shearing or during rainfall infiltration starting at an unsaturated state this paper investigates the instability of three saturated and unsaturated granular soils with different fines contents f 50 32 and 10 isotropic consolidation tests and mercury intrusion porosimetry tests were first conducted to investigate the instability of the microstructures of these granular soils then drained and undrained triaxial tests were conducted to investigate the instability behavior under the saturated condition subsequently wetting tests under the constant shear stress condition were carried out on unsaturated specimens to investigate the instability of the same soils during water infiltration the instability in the microstructures is in accordance with the compressibility of the soils the instability during undrained shearing under

integrated geostructural seismic and infrared thermography surveys for the study of an unstable rock slope in the peloritani chain ne sicily abstract this paper presents a multidisciplinary study about the instability of a rock slope on peloritani chain northeastern sicily several rockfalls affected the studied slope in the last decades also causing the disruption of the main road connecting the shore villages to the city of messina the complex geology and tectonics are the main causes of the poor mechanical properties of the rocks exacerbated by high fracturing and weathering geostructural surveys allowed identifying the main discontinuity sets most of which matches with the regional fault systems kinematic and stability analyses were carried out to define the main failure typologies and to realize two models describing the past rockfalls as well as possible future events for the deep investigation of the slope horizontal borehole drilling and seismic active prospecting were performed so to estimate the thickness of the rock with poor mechanical properties the contours of the most unstable areas along the slope have been better outlined through infrared thermography images giving information about the thermal radiance behavior of the rock constituting the surface slope the integrated approach of different methodologies besides defining the instability features of the study area demonstrates the reliability of such techniques particularly in a geologically complex region where rockfalls represent one of the main causes of landslide fatalities

three dimensional modeling of earthquake generated acoustic waves in the ocean in simplified configurations the low frequency 4 40 hz acoustic waves generated by undersea earthquakes are of great importance to monitor the low level seismic activity associated with seafloor spreading ridges to better understand the near source interaction of seismic waves with the seafloor and the resulting generation of low frequency acoustic waves the wave propagation in a solid medium the earth s crust and in the overlaying fluid medium the ocean were jointly simulated using a three dimensional 3d spectral finite element code specfem3d due to numerical limitations of 3d simulations the focus was on simple model configurations with a 1 hz source located below a gaussian seamount or ridge the simulated acoustic waves 0 2 5 hz propagate as rayleigh modes and are affected by modal dispersion their horizontal speed increases away from the source and reaches the sound speed about 140 km away the amplitude of the generated acoustic waves is affected by the shape of the seafloor topography above the seismic source as well as their travel times to hydrophones consequently localization of the acoustic sources by trilateration from arrival times may be biased by 3d effects and thus the seismic acoustic conversion zone may not match the epicenter the low frequency 4 40 hz acoustic waves generated by undersea earthquakes are of great importance to monitor the low level seismic activity associated with seafloor spreading ridges to better understand the near source interaction of seismic waves with the seafloor and the resulting generation of low frequency acoustic waves the wave propagation in a solid medium the earth s crust and in the overlaying fluid medium the ocean were jointly simulated using a three dimensional 3d spectral finite element code specfem3d due to numerical limitations of 3d simulations the focus was on simple model configurations with a 1 hz source located below a gaussian seamount or ridge the simulated acoustic waves 0 2 5 hz propagate as rayleigh modes and are affected by modal dispersion their horizontal speed increases away from the source and reaches the sound speed about 140 km away the amplitude of the generated acoustic waves is affected by the shape of the seafloor topography above the seismic source

phase equilibrium constraints on the viscosity of silicic magmas 1 volcanic plutonic comparison by using recently determined experimental phase equilibria we show that the viscosity of granitic magmas emplaced at upper crustal levels is approximately constant at 104 5 pa s irrespective of their temperature and level of emplacement magmas crystallizing as granitic plutons are not water poor and thus not more viscous than their extrusive equivalents instead comparison between pre eruption magma viscosities of extrusive silicic intermediate and intrusive granitic magmas shows that the former are on average slightly more viscous given the typical strain rates in silicic magma chambers magma rheological behavior is expected to be dominantly newtonian bubbles having a minor rheological influence at depth although exceptions can exist thus whether a silicic intermediate magma is erupted or frozen at depth depends primarily on the rheological properties of surrounding terranes or on external tectonic factors but not on the rheology of the magma itself however preemptive viscosities of extrusive magmas rarely exceed 106 pa s which suggests that crystal melt mushes with higher viscosities cannot leave the magma storage regions beneath volcanoes the narrow range of viscosities displayed by silicic intermediate magmas results from both the strong control that pressure exerts on volatile solubilities in silicate melts and thermal limitations required to produce acid magmas considerations of the relationships between magma crystallinities bulk sio2 and preemptive melt h2o contents show that the higher the melt h2o content is the higher the maximum crystallinity that a given magma will be while still being potentially erupted an empirical correlation is proposed that enables us to estimate preemptive melt h2o contents of erupted magmas by knowing their crystallinity and bulk sio2

stability analysis of rock wedge slide subjected to groundwater dynamic evolution abstract heavy rainfall may increase the infiltration rate raising the groundwater table after a short period time variation in the hydrostatic pressure on potential sliding surfaces and trailing edges of fissures in a rock slope may contribute to slope failure the failure mechanisms of rainfall triggered rock wedge slides have been widely studied in the literature however studies on the dynamic evolution of groundwater in rock failure are still limited in this study a typical rock wedge slide that occurred in chengkou county chongqing china is selected as a case study to analyze the stability of rock wedge with double planes and tension crack subjected to groundwater dynamic evolution model tests were designed and performed to reproduce the dynamic evolution of groundwater in the rock slope and analyze its role in wedge failure development and distribution characteristics of water pressure are investigated through monitoring the water pressure distributed along the surfaces of wedge failures from the experimental study it is found that the initial formation process of water pressure along the sliding surface consists of four types of distribution patterns i e triangular distribution type i trapezoidal distribution type ii trapezoidal distribution and type iii trapezoidal distribution based on the model tests and theoretical analysis the order of the calculated safety factors of the chengkou rock wedge slide are triangle type i trapezoid type ii trapezoid type iii trapezoid the existence of inflection points in the trapezoidal distribution mode significantly increases water pressure on both sides of rock wedge which contributes instability the new approach for investigation of the effect of dynamic evolution groundwater on stability of rock wedge slide is developed based on fundamental mechanism and experimental study it can be adopted for stability assessment of similar rock wedge slides in other areas

composite rock slope kinematics at the current randa instability switzerland based on remote sensing and numerical modeling abstract kinematic analysis of slope instabilities in brittle rock is crucial for understanding the reaction of the rock mass to external forcing factors in steep terrain inaccessibility often limits collection of relevant data and remote sensing techniques must be applied this is the case at the current randa rock slope instability in southern switzerland where a total volume of about 5 6 million m3 moves at a rate of up to 30 mm yr a large portion of the unstable rock mass is exposed in an 800 m high inaccessible cliff the main scarp of the may 1991 rock slope failure between 2005 and 2007 a comprehensive suite of remote sensing techniques including photogrammetry lidar and gb dinsar was combined with 3d geodetic measurements to characterize the rock mass structure and displacement patterns photogrammetry and lidar data were measured simultaneously from a helicopter using a system allowing for oblique view angles which provided optimal observations of the steep rock cliff we used these datasets to map large scale structures and extract their orientation and minimum persistence as well as to characterize the 1991 failure scarp the northern part of the may 1991 failure surface shows a transition from stepped planar sliding at the base to failed rock bridges in the center to tensile failure close to the vertical head scarp kinematic analysis of the discontinuity sets in the currently moving rock mass shows that both toppling and translational sliding are feasible failure mechanisms toppling is more likely for steep faces above 2200 m whereas translational failure is more likely in the lower portion of the instability interpretation of gb dinsar displacement maps revealed similar kinematic behavior and also allowed identification of a basal rupture zone and lateral release plane bounding the instability displacement vectors derived from geodetic surveying provided new insights into the 3d kinematic behavior of the instability all information extracted from different data sets were integrated in a conceptual model which was then investigated with 2d numerical simulation using the discontinuum code udec the numerical models were able to reproduce the hypothesized kinematic behavior well

spatial distribution analysis of landslides triggered by 2008 5 12 wenchuan earthquake china abstract the 2008 5 12 wenchuan earthquake seismic magnitude mw 7 9 according to the usgs triggered a great number of landslides a spatial database of landslides is built by interpreting the remote sensing rs data which covers 11 counties severely damaged by the earthquake with area of about 31 686 12 km2 the geological settings of the study area are detailed mapped including geologic structure and lithology the digital elevation model dem of the study area with resolution of 30 m 30 m is presented to address the topographic characteristics correlations between the occurrence of landslides with geological settings i e active faults the coseismic surface ruptures geological unit slope gradient slope elevation as well as slope aspect are analyzed using spatial modeling in gis with the aids of field investigations it can be concluded that the distance to the causative faults and slope gradient are much more important than other factors landslides are clustered distributed along the causative faults of f2 and f3 and landslides incidence are dramatically decreasing with the increasing of the distance to the causative faults the landslides incidence has an obvious increase near the active faults i e f1 landslide concentration lc landslides km2 has an obvious exponent increase with slope gradient however lc has no obvious relationship with geological unit and slope elevation the difference of lc value in each geological unit each slope elevation category maybe have been the result affected by slope gradient for each geological unit each slope elevation category and distance of each geological unit each slope elevation category to causative fault zone isoseismal map reflects the incidence of landslides in some degree and lc increases dramatically with intensity increasing almost all landslides occurred in the region above vi degree statistics result also indicates that in the near field of causative faults landslides tend to have the initial sliding direction similar to the movement of the causative faults and preliminary study shows that landslides incidence varies in different slopes with different structure and consequent slopes and obsequent slopes have a higher landslides incidence than other layered slopes

infrared thermography proposed for the estimation of the cooling rate index in the remote survey of rock masses abstract infrared thermography has been tested herein for the study of the fracturing condition of intensely jointed rock masses in order to find out what kind of information can be assessed although this technique is widely used in several scientific fields its direct application for rock mechanics purposes is still under development in this paper thermal imaging campaigns carried out in different climatic conditions are described a cooling rate index related to how fractured rock masses behave during the heat transfer towards the external environment is proposed such an index has been related to the degree of fracturing of the rock masses in order to find a relationship among thermal behavior and the main quantitative fracturing indexes results return interesting matches between some geostructural features and thermal outputs demonstrating the reliability of the application of such methodology to bare rock masses moreover new experimental considerations are proposed laying the foundations for future studies aimed to further validate the infrared thermography as an effective remote survey technique

geological causes and geomorphological precursors of the tsaoling landslide triggered by the 1999 chi chi earthquake taiwan the tsaoling landslide one of the largest landslide areas in taiwan has been affected by catastrophic events triggered by rain or earthquakes six times since 1862 these landslides including that caused by the 1999 earthquake have essentially not been reactivated old slides but were sequential new ones that developed upslope retrogressively the landslide area is underlain by pliocene sandstone and shale to form a dip slope with a bedding plane dipping uniformly at 14 the slip surface of the 1999 landslide was smooth and planar parallel to the bedding plane with a slightly stepped profile it formed within thinly alternated beds of fine sandstone and shale with ripple lamination or in a shale bed the shale is weathered by slaking and probably by sulfuric acid which is inferred to be one of the major causes of the intermittent retrogressive development of the landslides the weathering was likely accelerated by the removal of overlying beds during earlier landslides in 1941 and 1942 the top margin of the 1999 landslide in plan view coincided with a v shaped scarplet which can be clearly recognized on aerial photographs taken before the landslide this geomorphological feature indicates that this landslide had already moved slightly before its 1999 occurrence providing precursory evidences

remote sensing techniques for landslide studies and hazard zonation in europe abstract an inventory is presented of researches concerning the use of remote sensing for landslide studies and hazard zonation as mainly carried out in the countries belonging to the european community an overview is given of the applicability of remote sensing in the following phases of landslide studies 1 1 detection and classification of landslides special emphasis is given to the types of imagery required at different scales of analysis 2 2 monitoring the activity of existing landslides using g p s photogrammetrical techniques and radar interferometry 3 3 analysis and prediction in space and time of slope failures the different factors required in a landslide hazard study are evaluated and the optimum remote sensing imagery for obtaining each of these factors is indicated examples are given of research work carried out in these three phases from ec countries finally an evaluation is given of the aspects of uncertainty associated with the use of remote sensing data and conclusions are given as to the incorporation of remote sensing techniques within the overall framework of techniques

evaluation of factors controlling earthquake induced landslides caused by chi chi earthquake and comparison with the northridge and loma prieta events over 10 000 landslides were triggered by the september 21 1999 chi chi earthquake a large number of these landslides have been mapped from spot images and a smaller number were described in a detailed field investigation geographic information systems gis was used to conduct a spatial characterization of the slope failures including distribution of type size slope angle bedrock geology ground motion and distance from earthquake source the most abundant landslides were shallow disaggregated rock and soil slides landslides occurred primarily in tertiary sedimentary rocks which are well known for their susceptibility to landsliding in many parts of the world landslide concentration values diminish beyond epicentral distances of 40 and 70 km from the epicenter and the surface projection of the fault plane respectively ground motion was found to be the most significant factor in triggering the shallow landslides in the chi chi earthquake overall 74 of all slope failures occurred in regions with vertical ground motions greater than 0 2g and 81 of all slope failures occurred in the region with mean horizontal peak ground accelerations pga greater than 0 15g these factors were used to compare landslides generated by the chi chi earthquake to the landslides triggered by the 1989 loma prieta earthquake and the 1994 northridge earthquake the major difference in distribution of landslides between the chi chi earthquake and the two california earthquakes was the distribution of slope angles in the chi chi earthquake 90 of the failures occurred on slopes steeper than 45 while more than 80 of failures occurred on slopes less than 50 in california apparently reflecting much steeper and tectonically more active geologic setting in taiwan

a view on some hydrological triggering systems in landslides abstract in this paper different types of hydrological triggering systems for debris flows shallow and deeper landslides are described the generation of surface run off and high peak discharges in first order alpine catchments is an important triggering mechanism for debris flows failure conditions in shallow landslides can occur when at a critical depth which is determined by the cohesion of the soil and the slope angle the moisture content in the soil becomes close to saturation resulting in a considerable reduction of soil strength deeper landslides 5 20 m depth are in most cases triggered by positive pore pressures on the slip plane induced by a rising ground water level the assessment of meteorological threshold conditions for shallow landslides 1 2 m needs more detailed meteorological information than for deeper landslides in the analyses of the hydrological triggering systems of deeper landslides the presence of a permeable top layer and fissures has to be taken into consideration

landslide susceptibility map refinement using psinsar data abstract landslide susceptibility maps lsm are commonly used by local authorities for land use management and planning activities representing a valuable tool used to support decision makers in urban and infrastructural planning the accuracy of a landslide susceptibility map is affected by false negative and false positive errors which can decrease the reliability of this useful product in particular false negative errors are generally worse in terms of social and economic losses with respect to the losses associated with false positives in this paper we present a new technique to improve the accuracy of landslide susceptibility maps using permanent scatterer interferometric synthetic aperture radar psinsar data the proposed approach uses two different data sets acquired in ascending and descending geometry the ps velocity measured along the line of sight is re projected into a new velocity along the steepest slope direction v slope integration between the lsm and the ground deformation velocity map along the slope was performed using an empirical contingency matrix which takes into account the average v slope and the susceptibility degree obtained using the random forests algorithm the results show that the susceptibility degree increased in 56 41 km 2 of the study area the combination of psinsar data and the landslide susceptibility map lsm improved the prediction reliability of slow moving landslides which particularly affect urbanized areas the use of this procedure can be easily applied in different areas where psi data sets are available this approach will help planning and decision making authorities produce reliable landslide susceptibility maps correcting some of the lsm errors

flume tests to study the initiation of huge debris flows after the wenchuan earthquake in s w china abstract in the wenchuan area in the southwest of china a huge amount of loose co seismic landslide material was deposited on slopes during the wenchuan earthquake of may 2008 these loose deposits formed the source material for rainfall induced debris flows or shallow landslides in the years after the earthquake on august 13 2010 about 20 large debris flows were triggered by heavy rainfall in the area around the epicenter of the wenchuan earthquake field reconnaissance revealed that the initiation of these post earthquake debris flows was closely related to severe erosion of the loose deposits flume tests were carried out to study the initiation mechanism of these post earthquake debris flows and the related influencing factors the flume was instrumented with ten combination sets of suction and pore pressure sensors these sensors were accompanied by tdr probes to measure the soil water content the flume has a length of 2 5 m and a width of 1 5 m a series of 26 tests was conducted to study the influence of slope gradient and discharge on the initiation mechanism and scale of the debris flows the amount of debris flow discharge was obtained by collecting the washed out deposits every 20 s the experimental results showed that the initiation mechanism of debris flows for gentle slopes and steep slopes was different on steeper slope incision by run off water was very rapid initiating directly the start of a debris flow the debris flow volume increased rapidly by a chain of subsequent cascading processes starting with collapses of the side walls damming and breaching leading to a rapid widening of the erosion channel at gentler slopes less intensive run off incision caused an accumulation of material down slope which after saturation failed as shallow slides transform in a second stage into debris flows it was demonstrated that the slope was the dominant factor in controlling the scale of the debris flows while the effect of discharge on erosion and the size of the debris flows was less clear

landslides triggered by the 7 august 2009 typhoon morakot in southern taiwan abstract landslides triggered by typhoon morakot with an area over 576 m2 were mapped from formosat 2 images recognition and calculation of the number and area of landslides show that at least 22 705 landslides with a total area of 274 km2 were recognized in the 7811 km2 study area among these landslides 17 417 with a total area of 150 km2 are recognized as new ones and 5288 with a total area of 124 km2 are classified as enlarged from pre existing ones out of the 22 705 landslides there were 22 221 recognized with an area smaller than 10 ha 298 recognized in the range of 10 to 20 ha twenty two landslides with an area of over 60 ha have also been identified and the total area of these landslides is 20 km2 which is equal to 7 37 of the total landslide area with respect to exposed rock type the landslides mainly occurred in eocene miocene slate and miocene sandstone and shale in addition morakot induced landslides mainly occurred in areas with cumulative precipitation in the range of 800 to 2600 mm and the magnitude of landslide concentration is roughly linearly proportional to the amount of cumulative rainfall

effects of rainwater softening on red mudstone of deep seated landslide southwest china abstract red mudstone landslides are widespread in southwest of china the development and distribution of deep seated landsides with slow inclination are closely related to the special soft rock properties of the red mudstone layers most previous studies focused on the failure mechanisms of rain induced shallow landslides studies on deep seated landslides in red layer zones are still limited in order to ascertain the basic failure mechanisms of red layer landslides with a gentle inclination a fatal landslide named as shibangou landslide which occurred in sichuan china was investigated this paper aims to 1 conduct laboratory tests on the reduction in shear strength of a red layer to identify the water rock coupling effect 2 investigate variations in the microscopic structure of the soft rock found within a red layer after rainfall infiltration 3 discuss the failure mechanisms of red layer landslides with slow inclination results from shear test of mudstone from the shibangou landslide revealed that there is a tendency that behavior of soft rock can be transferred to soil in different days of immersion the delineation threshold of shear strength of the red layer is determined as 6 days of immersion microstructures of clay minerals become loose and porous due to the contacts between the particles transferred from the face edges face face associations into edge edge and face edge associations therefore the intramolecular and cemented expansions of illite are the basic mechanisms which lead to structural damage structural decay and strength attenuation of soft rock in red layer under the condition of rainwater infiltration

impacts of the chi chi earthquake on subsequent rainfall induced landslides in central taiwan abstract the influence of the chi chi earthquake on subsequent rainfall induced landslides was evaluated by comparing the occurrence of landslides in the choushui river watershed through eight spot images that covered the period from 1996 to 2001 the chi chi earthquake not only triggered serious coseismic landslides itself but also extensively disturbed surface strata around the epicentral area after surface strata have been highly disturbed heavy rainfalls in 2000 and 2001 have triggered more landslides than the earthquake itself compared with the data obtained from images before the earthquake it is obvious that the density of rainfall induced landslides increased significantly after the earthquake and the places where landslides occurred changed as well although typhoon herb in 1996 brought more precipitation than typhoon toraji in 2001 only 9 77 km 2 landslides were induced by herb while 48 8 km 2 landslides almost five times larger than those caused by herb were triggered by toraji besides landslides induced by herb were mainly distributed in mid slope areas with slopes of 20 30 after the chi chi earthquake the rainfall induced landslides occurred mainly in places with slopes between 40 and 50

a new method for analyzing the stability of rock wedges in the analysis of rock slope stability the method of wedge analysis proposed by hoek and bray in their classic textbook rock slope engineering 1981 1 and the computer program swedge rocscience 2001 18 which was developed based on this method are widely applied especially in practical engineering situations in the hoek bray method wedge failure modes are identified by the effective normal forces that act on the two discontinuities forming the wedge the effective normal forces obtained using this method may be distorted with respect to certain conditions since discontinuities usually cannot bear tensile stress this may lead to inaccurate estimations of failure modes and incorrect solutions for safety factors this paper establishes criteria for normal forces to identify failure modes according to kinematic conditions of wedge failure and proposes a modified hoek bray method for the analysis of wedge stability considering the scattering in discontinuity orientation data an optimization procedure for wedge stability is proposed this involves a genetic algorithm ga for searching the critical failure surface with the minimum factor of safety and provides a low limit solution with conservative advantages for engineering support design to ensure the stability and safety of the rock slope

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

internal structure and deformation of an unstable crystalline rock mass above randa switzerland part i internal structure from integrated geological and geophysical investigations 6m 3 of material occurred in fractured gneissic rock whose principal foliation faults and fracture zones dip into the slope above the scarp of the second rockslide the mountain continues to move at rates of up to 2 cm year in an attempt to understand failure mechanisms in fractured crystalline rock masses we have carried out a comprehensive multidisciplinary study that included detailed geological mapping borehole logging and imaging and surface and borehole geophysical surveys an integrated interpretation of the resultant data has revealed the presence of three prominent fault and fracture zone sets that define the internal structure of the rock mass some faults and fracture zones could be traced up to 85 m into the subsurface using borehole radar reflection methods the dips of the faults and fracture zones estimated from surface mapping matched those from radar reflection and borehole televiewer surveys no evidence was found for significant faults or persistent weakness planes that paralleled the 1991 rockslide failure surfaces instead the new observations were consistent with dominant failure mechanisms that involve the progressive development of major shear and brittle fracturezones and the eventual destruction of intact rock bridges immediately prior to catastrophic collapse this integrated study provides the first reliable model of the 3 d fault structure associated with and contributing to a large rock slope instability in a brittle crystalline rock mass

seismic tomography imaging of an unstable embankment abstract seismic tomography imaging was employed to make a diagnosis and choose a remedy for an embankment supported by a retaining wall showing clear evidence of structural instability the geometry and structural characteristics of the wall the inside geometry of cracks and the physical parameters of the underground materials were the primary objectives of the geophysical survey seismic data were acquired along two vertical sections each one delimited by the lines of the sources within an inclined borehole and of the receivers lying on the ground for each section a total of 744 travel times were inverted to obtain compressional wave velocities on a regular rectangular grid of squared cells 1 m 1 m using an inversion algorithm which is based on the simultaneous iterative reconstruction technique sirt ultrasonic tests carried out in laboratory on intact specimens together with other supplemental site information improved tomography resolution allowing global and node constraints that forced the solution of the inverse problem to match known boundary values tomography imaged two high velocity zones separated by a curved shape low velocity zone the first ones were found to be compatible with the concrete retaining wall and with the schist materials ranging from highly weathered to intact schist while the low velocity zone was interpreted as filling materials and or completely decomposed rock schist the combination of seismic tomography and laboratory measurements allowed extrapolation of important parameters over a large volume of rock mass otherwise only representative of small rock samples near boreholes it also enabled engineering characterization of subsurface rock mass providing useful and accurate information to design a remedy for the embankment

landslides induced by the 2008 wenchuan earthquake sichuan china the 2008 wenchuan earthquake with a magnitude of mw 7 9 induced numerous slope movements on the hanging walls of fault surface ruptures and on steep inner valleys along the minjiang river landslide moving directions showed preferred orientations normal to the fault ruptures indicating the effect of the directivity of the seismic wave the most common landslides were of carbonate rocks which are easily dissolved and decrease the contact surfaces the largest non volcanic landslide in history was induced in bedded dolomite by the earthquake and was preceded by gravitational deformation with ridge top depressions valley fill materials were mobilized at 36 locations probably by pore water pressure build up

age constraints on late paleozoic evolution of continental crust from electron microprobe dating of monazite in the peloritani mountains southern italy another example of resetting of monazite ages in high grade rocks in situ monazite microprobe dating has been performed for the first time on trondhjemite and amphibolite facies metasediments from the peloritani mountains in order to obtain information about the age of metamorphism and intrusive magmatism within this still poorly known sector of the hercynian belt all samples show single stage monazite growth of hercynian age one migmatite and one biotitic paragneiss yielded monazite ages of 311 4 and 298 6 ma respectively these ages fit with previous age determinations in similar rocks from southern calabria indicating a thermal metamorphic peak at about 300 ma at the same time as widespread granitoid magmatism the older of the two ages might represent a slightly earlier event possibly associated with the emplacement of an adjacent trondhjemite pluton previously dated by shrimp at 314 ma no evidence for pre hercynian events and only a little indication for some monazite crystallization starting from ca 360 ma were obtained from monazite dating of the metasediments suggesting either a single stage metamorphic evolution or a significant resetting of the monazite isotope system during the main hercynian event ca 300 ma rare monazite from a trondhjemite sample yields evidence for a late hercynian age of about 275 ma this age is interpreted as representing a post magmatic stage of metasomatic monazite crystallization which significantly postdates the emplacement of the original magmatic body

rheometry of a dacitic melt experimental results and tests of empirical models for viscosity estimation this paper reports on experimental measurements of the viscosity of a dacitic melt by means of the technique of of concentric cylinder rheometry the measurements were done in a temperature range of 1000 to 1150 degrees c and at different shear rates the results were compared with empirical models which are commonly used to estimate the viscosity of single phase melts of silicates this data is of great use to the study of magma transport

on the influence of slopes source seabed and water column properties on t waves generation at shore the term t waves is generally associated with acoustic waves generated by seismic events that subsequently travel horizontally in the ocean at the speed of sound in this paper we use a time domain spectral element method to perform a parametric study of the influence of seafloor slope source position and media properties for a typical downslope t wave generation scenario we find that the energy and duration of these waves are particularly sensitive to the environment in particular the slopes and physical characteristics of the seabed play a crucial role for both the generation and the conversion of these waves likewise the depth and position of the earthquake relative to the slope is of great importance with the presence of privileged areas for the generation of t waves which we map

effects of curvature related dem contact model on the macro and micro mechanical behaviours of granular soils a comprehensive comparison between the hertz mindlin model and the linear spring model in true triaxial shear simulations of granular soils was conducted using the discrete element method dem th

characteristics of earthquake and rain induced landslides near the epicenter of wenchuan earthquake abstract numerous landslides were triggered by the 12 may 2008 wenchuan earthquake in china particularly near the epicenter during the rainy season in 2010 after the earthquake much of the landslide debris was reactivated causing a large number of fatalities the earthquake has a significant impact on the subsequent rain induced landslides based on interpretation of satellite images taken in 2008 and 2010 combined with yearly field investigations this paper attempts to 1 map the earthquake induced landslides near the epicenter 2 present the distribution of the landslides occurring during a subsequent extreme storm in the same area and 3 compare the distribution characteristics of the earthquake induced landslides and the rain induced landslides through this study the following findings were obtained 1 the internal relief of the landslides in the study area is much higher than that in other affected regions of the wenchuan earthquake zone 2 the landslide area in hard rocks i e the granite and diorite zones is much larger than that in alluvium 3 the volume of hill slope loose deposits decreased while the volume of channel deposits increased during the process of mass transportation caused by rainfall after the earthquake 4 during the rainy seasons after the earthquake the density of landslides increased while the area of landslides decreased significantly and the type of landslides transformed from debris slides to debris flows and 5 the rain induced landslides are less steeper than the earthquake induced landslides

development of three dimensional numerical manifold method for jointed rock slope stability analysis abstract this paper presents a three dimensional numerical manifold method nmm for jointed rock slope stability analysis the main barriers for realistic rock slope stability analysis are discussed and the unique features of the nmm which make it stand out in slope analysis are emphasized the framework of the 3 d nmm is established via a regularly patterned tetrahedral mesh based mathematical cover system a contact detection algorithm is then customized to fit the 3 d nmm characteristics the developed code is first calibrated by two simple cases inclined plane sliding and tetrahedral wedge sliding and then applied to a more complex slope scenario the complete failure process involving large displacement and rotation of multiple interaction blocks is exhibited dynamically two typical stabilization protection techniques are also investigated the developed 3 d nmm could be potentially used to find the trigger failure mechanism of jointed rock slopes so as to optimize the slope stabilization or protection design

distribution and causes of landslides in the eastern peloritani of ne sicily and western aspromonte of sw calabria italy abstract the peloritani and aspromonte areas are tectonically active mountainous regions of ne sicily and sw calabria respectively where landslides are the most common hillslope mass wasting process this study aims to elucidate the primary controls on the distribution and size of landslides in these two different landscapes these regions either side of the messina strait have similar lithologies but show different morphological characteristics in response to varied neo tectonic activity and climate landslides were identified utilising aerial photographs and landsat images frequency area statistics were calculated to determine the length scale of the most frequent interpretable landslides and compare our results with previous studies the frequency area power law exponents 1 99 in peloritani and 1 94 in aspromonte fall within the range of values that have been observed 2 0 0 5 in similar landscapes the peloritani ridge sicily has range parallel normal fault segments with the majority of landslides occurring in their footwalls there seems to be a strong coupling between tectonic activity and landslides where slope instability is exacerbated by faulting fracturing or jointing in otherwise low permeability gneiss and granite bedrock conversely in aspromonte calabria landslides are restricted to steep valley walls and are absent from interfluves this is because landslides are controlled by fluvial incision processes these observations confirm a relationship between the spatial distribution of landslides and the processes controlling slope failures

investigation on rainwater infiltration into layered shallow covers in pyroclastic soils and its effect on slope stability abstract in recent years a number of flowslides and debris flows triggered by rainfall affected a wide mountainous area surrounding the piana campana southern italy the involved slopes are covered with unsaturated air fall layered pyroclastic deposits which stability is guaranteed by the contribution of suction to shear strength to understand the mechanisms of infiltration and to assess the soil suction distribution in such layered deposits infiltration experiments have been carried out in small scale slopes the interpretation of the results has been made with the aid of a 2d mathematical model the results highlight that the presence of coarse textured unsaturated pumiceous layers interbedded between finer ashy layers can delay the wetting front advancement thus initially confining the infiltration process within the uppermost finer layer a diversion of the flow from the vertical towards the slope direction occurs when the soil approaches saturation however whereas a high hydraulic gradient establishes across pumices water infiltration into the deepest layer begins and part of the water crosses the pumices before the complete saturation of the uppermost soil profile

stability investigation and stabilization of a heavily fractured and loosened rock slope during construction of a strategic hydropower station in china abstract this paper presents a case history of the 205 m high intake slope at the huangjinping hjp hydropower station on the dadu river deformation and cracks developed on the cut slope during excavation and the deformation extended onto the natural slope above the cut giving rise to serious safety concerns research was conducted to study the engineering geological conditions and the deformation characteristics of the slope during excavation in situ monitoring data and possible causes of cracking were analyzed the results show that the zone of loosened rock mass extended much deeper into the rock mass than it did at other sites in the region because of the tectonic history of the site and cutting the empirically designed cable anchors with lengths of 40 m or 45 m were insufficient to stabilize the slope while the remedial cable anchors as long as 100 m successfully stabilized the slope the analytic method and procedure used in this paper could be useful to similar projects

geotechnical characterization of limestones employed for the reconstruction of a unesco world heritage baroque monument in southeastern sicily italy a detailed laboratory characterization of limestones employed for the reconstruction of saint nicholas cathedral a unesco world heritage monument in southeastern sicily is presented herein with the purpose of achieving a complete knowledge on the behavior of such rocks under stress whose engineering geological aspect had not been investigated before for scientific purposes specimens were sampled at three sites where this rock is quarried from two lithofacies of the same geological formation and are similar to other limestone varieties quarried worldwide and employed as construction material although slight differences between the samples occur at a macroscopic scale geotechnical tests highlighted relevant differences from the physical and mechanical points of view in order to look for one or more factors responsible of such dissimilarities a statistical analysis was carried out and interesting outcomes were achieved with the help of a microscopic analysis of the specimens moreover attention was paid on the modes of failure of tested specimens under compression whose attitude was described and correlated to selected properties of the rock results have both a practical implication because of the employment of this rock type as engineering material worldwide and a scientific relevance due to the peculiar behavior that such rock offered under stress

behavior of rock in slopes the behavioral modes to which a rock slope is susceptible are many and complex this article discusses a long but not exhaustive list of common failure styles highlighting observable characteristics that distinguish one from another slopes in both strong and weak rock masses are considered principles are stated to explain how and why different failure modes develop in different rocks the discussion is illustrated with examples of diverse failure modes in foliated metamorphic rocks developed in the walls of an eroded spillway runout

influence of a fault system on rock mass response to shaft excavation in soft sedimentary rock horonobe area northern japan abstract this paper focuses on the stress field that produced a fault system in the horonobe area of japan and considers the relationship between the fault system and the rock mass response to shaft excavation in soft sedimentary rocks in this area hydraulic fracturing investigations in boreholes and tectonic plate movements indicate that the major horizontal principal stress is oriented e w however during shaft excavation the greatest convergence in the shaft was oriented nne ssw therefore it is necessary to understand the influence of the fault system on the rock mass response to shaft excavation we performed a fault slip analysis of faults in the shaft wall and reconstructed the paleostress field that produced the fault system the maximum horizontal principal stress was oriented mainly nne ssw and the minimum horizontal principal stress was oriented mainly wnw ese these directions are similar to the directions of maximum and minimum convergence in the shaft respectively the results show that a fault system can affect the rock mass response to shaft excavation in soft rock and it is considered that the rock mass deformation is controlled by the fault system in addition it may be possible to assess and predict the rock mass behavior by focusing on paleostress field that produced the fault system