Rock Slope Stability Analysis Research Articles

Three-Dimensional Discrete Element Analysis of Jointed Rock Slope Stability Based on the Universal Elliptical Disc Model

Three-Dimensional Discrete Element Analysis of Jointed Rock Slope Stability Based on the Universal Elliptical Disc Model

Method of Stress Field and Stability Analysis of Bedding Rock Slope Considering Excavation Unloading

The stress state of a slope and its analytical solution are prerequisites for stability analysis. Currently, the limit equilibrium method cannot consider the stress state of slopes, and the solution of bedding slope stress remains in numerical simulations for a long time. In this paper, based on the theory of the elastic stress solution of the wedge top under a concentrated load, the analytical solution of the stress field was obtained using Matlab programming. Unloading stress analysis method (USAM) for determining the sliding surface of the bedding rock slope, safety factor (Fs), and reinforcement forces (Fr) were proposed. The USAM is compared with the Limit Equilibrium Method (LEM) and Finite Element Method (FEM) in terms of the Fs, Fr, sliding surface position, and sliding surface stress. The results show: 1) The analytical stress of the slope can be obtained quickly and conveniently using the USAM, while subsequent programming helps in faster completion of the stability evaluation of the bedding rock slope. Fs, Fr, sliding surface position, and sliding surface stress are all close to the results obtained by the FEM. 2) The USAM is more suitable for analyzing slopes when the angle between the slope surface and structural plane is greater than 20° (θ > 20°) and the slope angle is greater than 45° (β > 45°). 3) Through the analysis of specific engineering cases, the safety factor calculated by USAM are 0.06 and 0.02 larger than those obtained by LEM and FEM, respectively, and the required reinforcement force for the slope is closer to that obtained by FEM. The novel stress and stability analysis method allows for the rapid evaluation and optimal engineering design of bedding rock slope.

Dominant Partitioning of Discontinuities of Rock Masses Based on DBSCAN Algorithm

In the analysis of rock slope stability and rock mass hydraulics, the dominant partitioning of discontinuities of rock masses is a very important concept, and it is still a key for establishing the three-dimensional (3-D) network model of random discontinuities. The traditional graphical analysis method is inadequate and greatly influenced by subjective experience. A new method using density-based spatial clustering of applications with noise (DBSCAN) algorithm is proposed for the dominant partitioning of discontinuities of rock mass. In the proposed method, we do not need to determine the centers of every cluster before clustering, and the acnodes or outliers can be eliminated effectively after clustering. Firstly, the spatial coordinate transformation of the discontinuity occurrence is carried out and the objective function is established by using the sine value of the angle of the unit normal vector as the similarity measure standard. The DBSCAN algorithm is used to establish the optimal clustering centers by searching the global optimal solution of the objective function, and the fuzzy C-means clustering algorithm is optimized and the mathematical model of the advantage grouping of rock discontinuities is established. The new method and the fuzzy C-means method are compared and verified by using the artificially randomly generated discontinuity occurrence data. The proposed method is a better method than the fuzzy C-means method in general cases, and it can provide more accurate results by eliminating the acnodes or outliers. Finally, the proposed method is applied to discontinuity orientation partition data at Maji dam site, Nujiang River, and there is good agreement with the in situ measurement.

Rainfall infiltration and three-dimensional stability analyses of fractured rock slopes considering preferential flow

Rainfall infiltration and three-dimensional stability analyses of fractured rock slopes considering preferential flow

Stability Analysis of Rock Slope under Rainfall Infiltration Based on A Zero-Thickness Cohesive Element

There are often a large number of joints, fissures and other water channels in rock slopes. Under the condition of short-term heavy rainfall or continuous rainfall, a large amount of rainwater enters the slope body, which can easily induce landslide disaster on rock slopes. Therefore, it is of great significance to study the stability of rock slope under the infiltration of rainfall. Based on the ABAQUS numerical simulation platform, this paper implements continuous-discontinuous simulation of the deformation and damage of rock slopes under rainfall conditions by embedding zero-thickness cohesive elements and focuses on the effects of rainfall intensity, rainfall duration and rainfall infiltration location on the slope stability using vector method safety factors as indicators. The results show that as the rainfall intensity and rainfall duration increase, the depth of fissures in the slope gradually becomes larger, and the stability of the slope gradually decreases. The farther the initial location of rainfall infiltration is from the shoulder of the slope, the shorter the rain-induced fissure extension length is and the better the stability of the slope is. The research results provide reference for the engineering treatment of rock slope under rainfall conditions.

A Partitioned Rigid-Element and Interface-Element Method for Rock-Slope-Stability Analysis

The stability analysis of rock slopes has been a prominent topic in the field of rock mechanics, primarily due to the widespread occurrence of discontinuous structural planes in rock masses. Based on this complex characteristic of rock slopes, this paper proposes a novel numerical method, the Partitioned-Rigid-Element and Interface-Element (PRE-IE) method. In the PRE-IE method, the structure is modeled as several rigid bodies and discontinuous structural planes, which are, respectively, divided into partitioned rigid elements and interface elements. Taking the contact force of node pairs and the displacement of the rigid body centroid as mixed variables, according to the principle of minimum potential energy, the governing equations of PRE-IE can be established using the Lagrange multiplier method and then solved using the nonlinear contact iterative method and the incremental method. A classic case study demonstrates that using the failure of all contact node pairs as the criterion for slope failure is appropriate. This criterion is objective and avoids the potential impact of personal bias on safety factor calculations. Two numerical examples of differently shaped slopes are provided to verify the correctness and validity of the PRE-IE method. By comparing the safety factor calculated using the PRE-IE method with those obtained from other different methods, as well as comparing the computational time, it is shown that the PRE-IE method, in combination with the SRM, can accurately and efficiently analyze the stability problems of rock slopes.

Dynamic stability analysis of jointed rock slopes using the combined finite-discrete element method (FDEM)

The combined finite-discrete element method (FDEM) is an advanced finite element and discrete element coupling method, which is commendably suitable for simulating the slope’s entire evolution process from cracking, expansion, penetration, sliding, collision to deposition under seismic load. The original FDEM has apparent shortcomings in simulating the dynamic instability process of earthquake-induced landslides, and some targeted improvements are made to the original program. Numerical tests are carried out to prove the accuracy and robustness of the improved FDEM, and the influence of the structural plane on the dynamic evolution mechanism and process of the slope is studied. The results show that the improved FDEM can accurately reproduce the entire dynamic evolution processes and failure forms of different jointed rock slopes under seismic load and can quantitatively evaluate the dynamic stability of jointed rock slopes (dynamic safety factor and critical failure surface). In addition, the results also emphasize that the slope failure degree significantly affects the dynamic response of the slope and suggest that the combination of the cut-through of the failure surface and the increase of kinetic energy should be used as the criteria for slope dynamic instability simulation by FDEM. This study provides scientific and technological support for revealing the failure mechanism of jointed rock slopes and disaster reduction and prevention.

Rock slope stability analysis in Melasti Beach area – Ungasan, Bali

Melasti Beach is one of the main tourist attractions developed by the Bali Government. This beach is located in the southern area of Bali, precisely in Ungasan village, Badung Regency, Bali. At the moment, the region administrator is constructing a tourism facility by excavating a rock mass near the beach. Therefore, to avoid damage to nearby shops and beach facilities, a study is needed to be conducted about the safety of the rock mass that is being excavated. Direct observation of the rock mass and rock mass classification is conducted to obtain the physic and mechanical characteristics of the rock. To do the stability analysis of the slope, Geo-Studio 2012 software is used by inputting the data obtained from the field and laboratory data. The result of this study is a mass rock in Melasti Beach is classified as limestone which has a Fair rock classification and the factor of the safety of the rock slope/cliff is 1.631 which means the cliff is safe and is no need to build an extra reinforcement on the slope/cliff.

Analysis of Andesite Rock Slope Stability with Bishop Method

Landslides are caused by disruption of the soil’s degree of stability. When a slope’s pushing force exceeds its restraining force, a land slide will result. Moreover, at Human activities, climate change and natural influences can disrupt the stability of the soil and rocks on slopes. Disruption of the level of soil stability causes landslides. A landslide occurs due to the driving force on the slope being greater than the resisting force of the slope. To prevent landslide, a slope stability analysis is necessary. Moreover, the research site tends to produce a gravitational force that moves the soil mass towards a higher surface. This occurs as a result of due to the area’s topography of the area, which has different elevations varying from gentle to step but however, the research location is an andesite rock mining located in Peseng Village, Gerung District, West Lombok Regency, West Nusa Tenggara. The slope stability is required to reveal the shear strength of the slope and its safety factor. The analysis was conducted by using a survey, especially a field method. The field method used was the Bishop method with 2D Slide Program Software. Based on the results of laboratory testing, the value of the bulk weight (ү) is 18.21 kN/m3, dry weight 18.14 kN/m3, wet weight 18.53 phi (Φ) is 13.50° and cohesion (c) is 136.8 kN/m3.

Analysis of Loose Surrounding Rock Deformation and Slope Stability at Shallow Double-Track Tunnel Portal: A Case Study

A low-clearance tunnel portal in the shallow-buried, joint-developed, broken, and loose surrounding rock slope deposit may cause safety issues during construction. In this study, the Guanyin Mountain Tunnel of the Chong-Ai expressway was taken as a case study, and the characteristics of the loose and broken surrounding rocks, their low clearance, and shallow buried bias were comprehensively studied. The three-dimensional numerical model of the Guanyin Mountain tunnel portal section was constructed by the Rhino, AutoCAD, and FLAC 3D software, and the whole construction process of the tunnel portal was simulated. Under the conditions of loose and broken surrounding rocks, the surrounding rock deformation, surface settlement, and slope stability at the portal of the shallow buried tunnel with a small clear distance during the construction of the center diaphragm (CD) method and circular reserved core soil method were studied. The following conclusions are drawn. During the simulated excavation of the tunnel, the maximum surface settlement is 10.74 mm, which meets the requirement of the specification. When the left tunnel is excavated, the surrounding rock deformation of the right arch shoulder should be carefully considered. The maximum deformation value can reach 14.314 mm. After excavation, the deformation rate of the right tunnel is large, and initial support should be installed in time. Since the stratum rock at the portal of the tunnel is strongly weathered, the uplift value of the arch bottom is large and gradually decreases along the axial direction. The tunnel arch bottom and arch foot are plastic areas prone to tensile damage. Therefore, it is imperative to strengthen the inverted arch support of the tunnel in the strongly weathered rock stratum. The excavation sequence of the tunnel portal section adopts the method of excavating the left tunnel first and then excavating the right tunnel, which is more conducive to ensuring the slope stability.

Stability analysis of rock slope under Sujiaba overpass in Chongqing City based on kinematic and numeric methods

Rock slopes have the characteristics of complex geological conditions, weak structural surface development, steep slope, and great damage. In this study, the Sujiaba overpass slope in Chongqing was selected as the evaluation object, and the main stability evaluation methods of rock slope were analyzed. Combined with the special geological conditions and geographical location of the rock slope, through a geological survey, the slope was qualitatively analyzed based on the stereographic projection method, and the slope stability safety factor was calculated by using the finite element strength reduction method. FLAC3D was used to simulate the initial stress state of the unstable rock mass, the limit state stability of the unstable rock mass before bolt support, and the stability after bolt support. The simulation results show that the stability coefficients of selected unstable rock masses W1, W2, W6, and W7 under the limit state before bolt support are, respectively, 1.22, 1.80, 5.90, and 2.10. Unstable rock masses separate from the parent rock, causing a large displacement due to their instability and downward sliding. After bolt support, stability coefficients for those four unstable rock masses are 1.60, 2.40, 8.60, and 3.20, respectively. Under the same reduction coefficient, rock masses are stable and the displacement is small. The results show that the calculation results of the initial stress state of the rock slope are consistent with the theoretical understanding and field investigation. After the implementation of bolt support, the anti-sliding stability of unstable rock is obviously improved. The research results have important scientific guiding significance and practical value for revealing the failure mechanism of rock slope and analyzing the stability of unstable rock mass.

3D limit analysis of rock slopes based on equivalent linear failure criterion with tension cut-off

Hoek-Brown (HB) failure criterion is widely used to predict the strength of intact or heavily jointed rock mass. For stability analysis of rock slopes governed by the HB failure criterion, the equivalent linearity to Mohr-Coulomb (MC) criterion is often adopted, leading to the well-known equivalent Mohr-Coulomb method (EMCM). Existing studies on EMCM analysis mainly consider the shear strength of rock material, while consideration of the tensile strength is rare. This contradicts the fact that the underlying tensile strength of rock mass has considerable impact on the rock slope stability in real world. In this regard, this paper proposes a limit analysis-based approach that can account for tension in the three-dimensional (3D) stability analysis of HB rock slope. This approach is established on the equivalent linearity of the HB criterion with consideration of tensile strength, known as the equivalent tension cut-off MC method (ETMCM), and using a horn-like 3D mechanism of limit analysis. The safety factor solutions given by the proposed approach are validated by previous studies and numerical results. Parametric studies are conducted to investigate the effect of rock tensile strength on slope stability. Results show that the consideration of tension leads to a more conservative safety factor and a sharper curvature of the failure surface, and these impacts tend to be more obvious with the increases in slope inclination and slope width. Finally, the stability of the HB rock slope under seepage conditions is studied using the proposed approach. The results indicate that the effect of tensile strength is highly remarkable in seepage circumstances.

Application of UAV Digital Photogrammetry in Geological Investigation and Stability Evaluation of High-Steep Mine Rock Slope

For the stability analysis of rock slope, it is very critical to obtain the spatial geometric characteristics of the structural surfaces of the rock mass accurately and effectively. As for a high-steep rock slope of an iron ore mine, in order to solve the problems of inefficiency and high risk of traditional manual geological survey, the geological survey and stability evaluation of the slope was carried out by adopting unmanned aerial vehicle digital photogrammetry (UAV-DP) technology. Firstly, a large number of high-resolution images of the slope were obtained by UAV-DP. Then, the structure from motion (SFM) method was used to construct the fine 3D point cloud model of the slope, which was subjected to coplanarity detection and K-means clustering for identifying the structural surfaces. Finally, the stability and failure model of the slope cut by the structural surfaces are analyzed by using the stereo-projection and discrete element methods. The research results show that the error between UAV-DP and manual measurement is within the acceptable range, which demonstrates the reliability of UAV-DP used in the geological investigation. Furthermore, the stability state and failure model of the slope is also consistent well with the field observation.

Rock Slope Stability Analysis Incorporating the Effects of Intermediate Principal Stress

Rock Slope Stability Analysis Incorporating the Effects of Intermediate Principal Stress

Stability analysis of rock slopes using the interface contact model and strength reduction method

The assessment of rock slope stability is usually controlled by the presence of discontinuities. The block theory is an established method in practical engineering to predict the stability of rock slopes. A maximum of two discontinuity planes are considered in the application of the block theory. It would lead to inaccurate prediction of slopes with multiple discontinuity planes. A novel method for estimating the safety margin of rock slopes is proposed, which is capable of considering the contribution of all discontinuities to the stability problem. The discontinuity planes are simulated by an interface contact model within the theoretical framework of the finite difference method. The factor of safety is obtained by the strength reduction method. The failure criteria of rock slopes are also discussed. The proposed model can simulate discontinuous planes in a more realistic manner and thus is more effective in engineering practice. To demonstrate the effectiveness of the proposed model, several numerical examples are presented, which showcase its superiority for predicting the stability of blocks composed of multiple discontinuities. Several numerical examples are analyzed to confirm the effectiveness of the proposed model and its superiority in stability prediction of blocks formed by multiple discontinuities.

A method for calculating permanent displacement of seismic-induced bedding rock landslide considering the deterioration of the structural plane

The mechanism of seismic-induced bedding rock landslide is distinct from that of slope instability/landslide in normal gravity conditions; their failure modes are mainly characterized by vibration deterioration effect of rock mass structural plane due to a seismic loading, which has a significant effect on the stability of the bedding rock landslide. Several advanced methods have been proposed to assess earthquake-induced bedding rock landslide. However, the quantitative evaluation of the vibration deterioration effect of structural plane, along with its application in the dynamic stability analysis of bedding rock slopes, remains a challenging topic that requires further study. In this study, on the basic of the analysis of the cyclic shear condition and the cyclic shear test of the structural plane, the expressions to calculate the dilatancy angle and basic friction angle of structural plane under cyclic shear loading are studied. A deterioration formula for structural plane shear strength is proposed, which fully considers the deterioration effect during cyclic shear. Furthermore, a new calculating method of the seismic-induced permanent displacement of the bedding rock landslide, which introduces the deterioration effect of the structural plane, is developed. A case study was used to compare the permanent displacement calculated with the proposed method with those obtained using the Newmark and Qi methods, which demonstrates the effectiveness and applicability of the proposed method.

Experimental Investigation of Non-Linear Seepage Characteristics in Rock Discontinuities and Morphology of the Shear Section in the Shear Process

Considering the increasing frequency of geological disasters related to groundwater activities, it is important to study the relationship between geological dislocation and groundwater flow for the safety assessment of engineering rock mass stability. To elucidate the non-linear seepage characteristics at rock discontinuities during shearing, a custom-made device was used to conduct seepage tests at discontinuities that exhibit varying undulation angles and different shear displacements. The results show that as the shear displacement increases, the shear stress at a structural plane involving different undulation angles fluctuates with an increasing trend. Based on an identical shear displacement condition, the shear strengths of the structural planes increase as the undulation angle increases, and this enhances the shear expansion. Concerning an identical fluctuation angle and hydraulic gradient, the seepage flow at a structural plane increases as the shear displacement increases. By contrast, both the linear term coefficient a and non-linear term coefficient b in the Forchheimer fitting equation decrease as the shear displacement increases. In addition, the critical Reynolds number initially increases, followed by stabilisation as the shear displacement increases, and this number varies between 9.65 and 1758.52. The shear fracture morphology of the structural plane exhibits obvious anisotropy. During shearing, the roughness coefficient decreases in all but the vertical direction. The dominant seepage channel is perpendicular to the shear direction. The findings can provide a valuable reference for the stability research and analysis of rock slopes with structural planes.

Engineering Geological Assessment at Grandview Heights, Paya Terubong, Pulau Pinang, Malaysia

Grandview Heights, Paya Terubong is an old apartment building situated on a coarse-grained biotite granitic bedrock hillside. Paya Terubong is a landslide prone area where various landslides have been reported since 1998. The granitic hill has been disturbed during construction of the apartment. Due to the possibility of future landslides, an engineering geological study was conducted to assess the stability of this rock hill beneath this apartment. The scopes of study included discontinuity surveys, geomechanical characterization of the rock mass and slope stability analysis. Based on the results of discontinuity surveys, four major joints sets-were identified and labelled as J1 (195°/62°), J2 (248°/65°), J3 (304°/63°) and J4 (230°/39°). One (1) potential planar failure J2 (248°/65°) and one (1) potential wedge failure J1-J2 intersection (213°/60°) were identified based on kinematic analysis. Dry rock density was from 2.56 g/cm3 to 2.61g/cm3. The water content was from 0.14 % to 0.15% with low porosity values from 0.50% to 0.54%. The point load strength index, Is(50) was 6.63 MPa. The Slope Mass Rating (SMR) for was 64 to 79 and classified as class II with the probability of failure of 0.2.

Reliability-based stability analysis of large rock slopes with different failure mechanisms using response surface methodology

Reliability-based stability analysis of large rock slopes with different failure mechanisms using response surface methodology

Some considerations on the role of joint spacing in rock slope stability analyses using a 3D discrete element approach

Stability assessment of potential wedge failures in rock slopes is usually carried out based on stereographic projection techniques and limit equilibrium analyses. Nevertheless, this methodology presents several limitations (i.e., lack of information on joint mechanical properties, oversimplification of the structure, etc.) that could lead to poorly accurate conclusions. In line with this idea, the main objective of this work is to evaluate the effect of joint spacing in the estimation of the factor of safety of rock slopes affected by potential wedge failures. For this purpose, a 3D numerical distinct element code (3DEC) was selected to carry out a substantial number of simulations in which the factor of safety of two types of slopes, affected by different discontinuity sets, was studied by using the shear strength reduction (SSR) method. Different values of joint spacing, cohesion, and friction angles were considered, combined with two angles of the slope face under study. A discrete fracture network (DFN) model was also implemented, with the aim of benchmarking results with those obtained from the original models. The joint spacing has been found to relevantly affect the values of the factor of safety of the slope, which showed variations of up to 40% in comparison with those obtained from limit equilibrium methods. This work provides an insight to a more realistic interpretation of rock slope analyses against wedge failures, particularly to better estimations of the factor of safety.