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Translational slope failures. Sliding on shale bedding surfaces in a UK surface coal mine, b Peace River Bridge slide, B.C., 1957 (modified after Brooker and Peck 1993), c Regina Beach landslide, Saskatchewan (after Clifton et al. 1986)
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Shales play a major role in the stability of slopes, both natural and engineered. This paper attempts to provide a review of the state-of-the-art in shale slope stability. The complexities of shale terminology and classification are first reviewed followed by a brief discussion of the important physical and mechanical properties of relevance to sha...
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Slope stability analysis are simply using concept the value of Safety Factor (SF), using a single value on each input parameter while the probabilistic methods offer a more systematic way of dealing with uncertainty conditions and provide an alternative to the approach the value of SF, namely Probability of Failure (PF). The objectives of this stud...
general presenattion of SSAP softrware ofr advancede mimit equilibrium method for slope stability analysis ofr soil anr rock massees under natural condition or
Brihadeeshwara temple (or the big temple) of Tanjavur in Tamil Nadu celebrated 1000 years of existence recently. It was built by the king Raja Raja Chola I. The temple complex is one of the UNESCO world heritage sites and stands tall as a spell-binding example of intricate and unparallel Indian architecture. The inner sanctum or Vimana of the main...
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... Generally, clay shale is known to have high clay contents, low permeability, high swelling pressure, high overconsolidation ratio, strong digenetic bond, and small-scale fissures [1]. Due to its high clay content, clay shale had poor engineering properties and increases its susceptibility to landslides [13]. Thus, it is important to understand the engineering properties of clay shale, especially its clay contents and minerals. ...
... Clay shale is known to have a weak soil-like character and showed characteristics of fissuring, dilatational behavior, softening, and negative pore-water pressures. Landslides of clay shale slopes are often associated with first-050008-4 time failures due to softening with the shear strength properties between peak and residual shear strength values or reactivated landslides mobilized at lower residual shear strength [13]. Thus, clay shale soils need to be understood in peak and residual shear strength conditions to accommodate both the landslide possibility. ...
... For example, shale and mudstone are the most representative weak rocks. The shales often present softening, fissuring, and dilatant behavior, leading to long-term progressive slope failures [15]. Under the influence of weathering process and water weakening, the progressive slope failure could convert into a catastrophic landslide [16]. ...
High cut-slopes are widespread in engineering constructions and often converted into landslides. Some extreme circumstances facilitate the landslide process, such as the weak bedding plane, rainfall, and faults. Therefore, this paper intends to offer insights into the influence of the weak bedding plane, extreme rainfall as well as faults on the landslide process of the high cut-slope. In this paper, the Anling landslide in Anhui Province, China, is selected as an example. Geological surveys, displacement monitoring, data analysis, as well as numerical simulation are carried out. The entire excavation construction and landslide deformation process are simulated to reveal the formation mechanism of the landslide using the finite difference code, FLAC3D. The effects of the fault on the landslide and the effectiveness of adjusting protection measures by adding piles are investigated on the basis of the finite difference analysis. According to monitoring data and numerical simulation, the weak bedding plane and extreme rainfall are considered the main factors leading to the Anling landslide. Field investigation and numerical experiments indicate that the fault shall facilitate and accelerate the landslide process. The construction of piles in a suitable position for the landslide is a reasonable and economical measure to stabilize the landslide.
... The importance of geometry of failure plane is important for assessing the overall stability of rock slopes. Researchers have widely agreed that instability in large rock slope involves development of progressive failure surface rather than sliding along pre-existing plane (Eberhardt et al. 2004;Stead et al. 2006;Stead 2016;Bolla and Paronuzzi 2020). In addition, an anisotropic rock affected by tectonic activity can create complex scenarios when exposed along cut slopes. ...
... Khanlari et al. (2015) conducted a series of tests on laminated sandstone and suggested that the anisotropic strength and failure pattern depend significantly on the angle between lamination plane and loading direction. Stead (2016) suggests the role of relative contrast in strength anisotropy observed in laminated rocks as the major contributor for kinematic release of blocks. Overall, the deformation mechanism controlling failure pattern in bedded sandstone can be understood by differential weathering, anisotropic strength and loading direction. ...
Anisotropic sedimentary rocks are common around the world. Several factors, such as presence of primary and tectonic structures, type of weathering and rate of cohesion loss due to strength degradation, have significant effect on stability of slopes. In the present research, Geological strength index (GSI) has been used for quantitative comparison of rock mass quality and to investigate the rock mass damage. Other indicators of rock mass strength degradation, such as slake durability index tests, weathering index, were studied to understand the loss of strength with time leading to progressive failure in slopes. The failure pattern in bedded sandstones is controlled by bedding inclination, primary structures, vertical fractures. Folding affects bedding plane inclination and modify the failure mode along cut slopes. The cross-stratification significantly reduces rock quality and creates overhangs. The shape and size of overhangs are controlled by the presence of vertical cracks in addition to the type and scale of cross-stratification and failure generally occurs by block fall rather than block slide. The peculiar steeply plunging wedges associated with vertical fractures are very common in sub-horizontal bedded sandstone. Failure usually occurs by wedge fall rather than slide. Differential weathering affects the pinching strata against the massive beds and the characteristic wedges are common occurrence above this considerably fractured zone. Tectonic structures such as folds modify the style of failure in rock slopes as seen from kinematic analysis. The overall trend of lineaments is parallel to the strike of bedding plane (roughly E-–W) and the lineaments may be associated with reactivation of the major fault passing through the area. This study illustrates that the impact of tectonic damage further enhances the strength degradation caused by weathering, and climatic slaking. Overall rock mass quality lies in good to fair category, but preliminary stability analysis depicts slope in partially stable to unstable condition along SH-5; however, rock mass quality and cut slopes are relatively stable along SH-5A.
... Soft rock shows significant seepage effect in heavy rainfall area. The resulting development of fractures and pores can lead to slope disasters [5,19,26,32,33,36,44]. However, research on the failure mechanism of soft rock is still at preliminary stage and effective measures for controlling the collapse of soft rock slope are lacking [3,13,18]. ...
... The microstructure parameters and mechanical parameters of the slope are obtained by model trial calculation and experience [14]. The seepage boundary condition was defined by simulating rainfall infiltration based on the average annual rainfall Compared with the failure of general soil slope and common rock slope [32,36,37], the failure of soft rock slope studied in this paper has its own special characteristics. Figure 22 shows the simulated failure stages of the soft rock highway slope located in southern China. ...
In the present study, a multiscale model was developed to investigate the failure process of a soft rock slope due to the change in rock microstructure (e.g. micro-fissure and pore development) over time. Through developing a coupled fissure and pore seepage particle discrete element model (DEM), the effects of the development of micro-fissures and pores on the stability of a soft rock slope were modelled by establishing the relationship between macroscopic mechanical properties of the soft rock and the microstructure characteristics of the rock. To validate the model, the three-dimensional geological model of a soft rock slope of a highway was developed to investigate the stability of the slope. While the DEM of pores and particles was developed based on the scanning electron microscopy (SEM) images of the rock samples of the slope, a granular DEM of coupled fissure–pore seepage was introduced to model the development of seepage channels based on time-dependent change in pores and micro-fractures. It shows that the numerical predictions fit the field monitoring data reasonably well. Furthermore, it demonstrates that the developed multiscale model has the capability of predicting the different stages of seepage-induced failure of the soft rock slopes.
... Most landslide studies have been driven by an applied viewpoint; therefore, slope stability analyses and hazard prediction have been a major focus of study (Martin et al. 2002). There are several numerical techniques available (continuum method, discontinuum methods, etc.) and are being widely used in slope stability analysis (Kanungo et al. 2013;Kainthola et al. 2014;Stead 2016;Singh et al. 2016;Fathani et al. 2017;Pradhan et al. 2019;Sanzeni et al. 2019). In this research, the pre-event slope condition is simulated under the 2D finite element method (FEM) using Phase 2 (Rocscience Inc. 2016) under both dry and saturated conditions to determine the corresponding critical strength reduction factor (SRF). ...
Slope failures are recurrent phenomena during the Indian Summer Monsoon (ISM) season in the mountainous regions of Arunachal Himalaya, NE India, with a consequent damaging impact on the landscape, life, and property of the people. Geodynamic conditions, fragile lithology, high magnitude seismicity together with high-intensity rainfall from ISM provide the potent mixture of conducive factors contributing towards a very high frequency of landslides in the region. The problem is further accentuated by anthropogenic activities that have increased in recent times. Here we present a case study of a vulnerable road segment between Doimukh and Haj along the National Highway (NH-229) in Papum Pare district of Arunachal Pradesh that witnesses recurring debris slides during the rainy season. We suggest that a minimum threshold value of 433 mm of rainfall can be a triggering factor for the landslides in this Himalayan terrane. Considering similar climatic and geologic factors, this threshold value may be extrapolated for other areas in the Arunachal Sub-Himalayan region. An attempt is also made to analyze the stability of slope (dry/saturated condition) through 2D numerical modeling. The results of the finite element method (FEM) are validated with the limit equilibrium method (LEM). Both critical strength reduction factor (SRF) and factor of safety (FoS) are significantly reduced due to saturation of the debris material. Pre-event simulation for dry and saturated conditions gives the critical SRF values of 1.12 and 0.72 in FEM and FoS of 1.009 and 0.786 in LEM, respectively. A conservative estimate shows at least ~ 15,352 m3 of sediments were generated from a single debris slide event. Predictably, a combined sediment volume from all the events contributes significant sediment load into the adjacent south-flowing Dikrong river. Heavy sediment flux leads to a cascading downstream impact with devastating floods, erosion, and aggradation besides frequent channel changes. This study is expected to contribute towards a better understanding of the disaster potential, cause and effect relationship in a highly landslide-prone terrane of the eastern Himalayas besides enhancing our understanding of upper catchment sediment generation and their trajectory in the Himalayan rivers. This also calls for the further analysis of space–time variability of the ISM to enable developing a landslide early warning system in Arunachal Himalaya.
... With the influence of longterm water intrusion, these carbonaceous rocks impose a serious threat on the safety and stability of infrastructure projects (Tabelin et al. 2008;Shen et al. 2013;Sedghi and Zhan 2019). The deteriorated engineering properties of carbonaceous rocks can easily lead to unacceptable settlement and even failure of slopes during both the rainy and high temperature seasons, if effective protection measures are not implemented (Jhanwar and Thote 2011;Stead 2016;Magesh et al. 2020). Fig. 1(a) shows a typical failure of carbonaceous rock slope that is located in Hechi city, Guangxi Province. ...
This study aimed to investigate the role of water intrusion on thermal conduction and durability of three types of carbonaceous rock with different mineralogical components. The soaking method was selected to simulate water intrusion, and the respective evolutions of thermal conductivity k and slake durability index Id2 during soaking period were assessed. Scanning electron microscopy was conducted to explore the mechanism controlling these revolutions. The results revealed that the magnitude of moisture content and density of carbonaceous rocks at their natural state was clearly correlated to the content of illite mineral. Water intrusion was beneficial to the thermal conduction of carbonaceous rocks, where thermal conductivity increased with an increase in soaking time and exhibited a moderate increment after 8 days of soaking. Slake durability index Id2 was sharply decreased as soaking progressed and reached a low level after soaking. This deterioration in durability was mainly attributed to the absorption of free water, which in turn yields the anisotropic expansion of specific minerals. An unstable structure with more pores and new morphology minerals were identified in carbonaceous rocks at the completion of soaking procedure. An empirical relationship was developed successfully for predicting slake durability index using thermal conductivity.
... e first kind mainly occurs in bedding sliding, the sliding deformation of the upper loose overburden along with the rock, and soil interface after the slope excavation. e second type is the collapse of surface rock mass caused by the changes of its properties after slope excavation, generally manifested as the spalling and disintegration of a surface rock mass [7,8]. After the carbonaceous rock slope is excavated and exposed, the carbonaceous rock is prone to softening and collapse under the action of water immersion, resulting in slope collapse and affecting the stability of the slope (Figure 1). ...
... e unique stratification of this rock also resulted in the 20-40 mm schistose fraction predominating in the 20~40 mm 10~20 mm 5~10 mm 2~5 mm <2 mm Figure 13: e change in the particle contents of the carbonaceous illite clay shales as the number of wetting-drying cycles increases. 8 Advances in Civil Engineering residue, while all of the other grain size fractions increased slowly. ...
To investigate the disintegration characteristics of the carbonaceous rocks in Guangxi Province, the typical carbonaceous rocks in the section exposed by the Hechi-Baise Expressway were investigated in this study. First, based on their mineral compositions and contents, the carbonaceous rocks were divided into four types: carbonate chert, carbonaceous argillaceous limestone, carbonaceous illite clay mudstone, and carbonaceous illite clay shale. Then, through indoor wet-dry cyclic disintegration test, the disintegration characteristics of the four types of rocks were studied. The test results showed the following: (1) the disintegration residues of the carbonate chert and the carbonaceous argillaceous limestone decrease linearly as the number of wetting-drying cycles increases. (2) The disintegration index of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale decreases exponentially as the number of wetting-drying cycles increases. (3) As the number of wetting-drying cycles increases, the disintegration index curves of the carbonaceous illite clay mudstone and the carbonaceous illite clay shale samples gradually become stable until the disintegration of the samples is completed. (4) The disintegration of carbonaceous rocks is mainly affected by the clay content, followed by the structural form, but it cannot be ignored.
... However, outside of these initiatives, in general, in the geotechnical domain little attention is paid to this problem even though single papers (see for example Stead, 2016) still deal with it. This is quite strange when considering that the Earth surface is largely covered by such materials, which pose great challenges. ...
... However, similar features are displayed by other deposits that, in general, are not considered to be "structurally complex", such as: i) highly overconsolidated stiff clays, which are often characterized by closely spaced and sometimes interconnected fissures that have not necessarily been induced by mechanisms of shear, and thus they could be classified as a variant of the type A2; ii) stiff clays crossed by sets of joints (such as the deposits described by D'Elia et al., 1998), which may be classified as A1 structurally complex formations; iii) the stiff moderately diagenized fine-grained deposits described by Morgenstern and Eigenbrod (1974) and by Stead (2016), who tried to classify this wide category of "structured" fine-grained materials. Finally, similar features may be very locally displayed by any other material, which has been subjected to intense deformation: fault zones that are often rather thick and include complex sets of shear discontinuities (Morgenstern and Tchalenko, 1967) represent a clear example. ...
A set of materials covering a wide class comprised between soils and fractured rocks displays a variable and complex hydraulic/mechanical response to external inputs that make quite complicated both the measurement of properties and the modeling of material behaviour. In fact, weak interparticle bonding and a network of irregular and often interconnected discontinuities can strongly and unevenly affect permeability, stiffness and shear strength, making difficult the interpretation of natural events, such as landslides, and uncertain the analysis and design of engineered slopes and of man-made works.
This paper reports some examples taken from the Authors' experience and from the literature, which illustrate the difficulty to correctly understand or analyze the behaviour of such complex materials through the classical approaches of Soil or of Rock Mechanics, highlighting at the same time the complex role that discontinuities play in groundwater flow and pore water pressure regime.
... Chi Mu et al. have also confirmed that underground mining can cause landslides by analyzing the mechanism of landslide disaster [18]. In the loess gullies, the slope stability is usually evaluated with G in the following formula as an index of terrain mining conditions [18,26,27] ...
Surface subsidence caused by coal mining has a great impact on the geological and ecological environments and causes damage to houses, roads, and industrial buildings. In order to understand the subsidence pattern in the mountainous mining regions, three mining faces of the Zhangjiamao mining area in the north of Shaanxi province, northwestern China are taken as case study. Firstly, the small baseline subset (SBAS) technology is used to process 12 images obtained in the mining area to investigate the subsidence data from December 2019 to April 2020. The boundary of surface deformation of the mining area interpreted by the SBAS-InSAR technology is inconsistent with the theoretical boundary suggested by coal mine subsidence theories. Especially, there are some areas in which the real subsidence are larger than estimated area. This discrepancy must be corrected as steep slopes near the theoretical boundary may increase the likelihood of landslides. Our research indicates that: (1) The accumulated displacement and the maximum deformation rate reached −120.759 mm and −270.012 mm/yr in the study area, and the subsidence boundary of the three mining faces is revealed; (2) the combination of the predicted boundary and slope stability analysis can effectively identify the landslide region at the edge of subsidence boundary; (3) the field surveys have proved the effectiveness of this method. The mining area subsidence revealed by our research helps to further understand the impact of land subsidence caused by mining in the mountainous areas and provides a practical method to predict subsidence boundaries and the likelihood for landslides.
... Strength reduction due to weathering of shale is a well-known phenomenon that is frequently mentioned in shale landslide descriptions. When exposed to weathering processes such as wetting and drying or freezing and thawing cycles, shales are weakened and disintegrate with time (Walkinshaw and Santi, 1996;Stead, 2016). Such a behavior can be observed along the Forkastningsfjellet cliff coast, where weak and degradable shales in different states of transition build a large part of the coastal cliff. ...
Based on a morphostructural analysis of a cliff coast segment of Forkastningsfjellet, back analysis of the August 12th, 2016 rock slide situated at 78°19′10”N/15°39′52″E was carried out. This rock slide comprises a volume of 175,000 m³, and indicates a partial reactivation at the front of the ~100 million m³ large postglacial Forkastningsfjellet rock slide. We studied the controlling and triggering factors of the reactivation using a 2-D limit-equilibrium calculations and a 3-D simulation with Scoops3D. Slope instability initiated along a pre-existing listric block fault that was inherited from the postglacial Forkastningsfjellet rock slide. The cause of the failure is attributed to a strength decrease and additional water pressures along the pre-existing sliding plane, possibly in combination with a degradation of the affected weak shales of the Rurikfjellet Formation, which build up a major part of the steep slope.
Although the analysis suggests a structural control on the type and mechanism of slope failure, a significant impact of climate-related factors is inferred. Increasing temperatures and changing precipitation trends are reported from Svalbard. These are interpreted to foster permafrost degradation and reduce bonding forces in the thawing ice-filled fractures at the site. In addition, progressive weakening by more frequent frost and thaw cycles of the slaking shales and the introduction of additional water pressures to the rock mass are considered to contribute to the instability. The final trigger of the 2016 failure is attributed to a two-day rainfall that had preceded the event.
The application of the Scoops3D software tool showed that it is capable of predicting the locations and affected volumes of landslides with reasonable accuracy, when the geological and structural setting is well established. Under such premises the tool can be used to support preliminary susceptibility assessments in study areas with comparable geological and morphostructural settings.
