Prevent Slope Failure Research Articles

Coal Mine Slope Stability Analysis Using the Rock Mass Rating (RMR), Slope Mass Rating (SMR) Method, and Morgenstren-Price Limit Equilibrium for the Low Wall Pit Area Y PT. Bina Sarana Sukses, Lahat Regency, South Sumatra

Open pit mining has a complex connection to excavation and stockpiling operations, which can potentially induce slope instability. The analysis of slope stability is crucial to prevent slope failure, which has the potential to result in major losses. The study on slope stability was performed at the low wall pit Y area of PT. Bina Sarana Sukses site MAS in Lahat Regency. This research aimed to analyze the rock mass classifications, determine the safety factor values, and provide recommendations for mitigating landslide occurrences. The techniques employed in this study include the RMR and SMR methods for assessing the susceptibility of landslides, collectively with the Morgenstern-price limit equilibrium approach for estimating the stability of the slope. Based on the analysis of the rock mass rating (RMR) and slope mass rating (SMR), Block B2 exhibits a 20% likelihood of experiencing landslides, specifically due to block joint characteristics. On the other hand, Blocks B4 and B5 show a 40% potential for landslides, primarily associated with flat or wedge-type block joints. The force produced by friction under saturated conditions is comparatively lower than that observed under dry conditions. During the final design phase in 2022, it was observed that Blocks B4 and B5 exhibit critical and dangerous safety factors when saturated. Hence, the proposal has been suggested to enhance slope stability. Further, it is recommended to monitor the geotechnical piles periodically. We hope this research results as a valuable resource for evaluating and assessing slope stability, including artificial and natural slopes.

Optimization Of Cantilever Retaining Wall Design Using Improved Teaching-Learning-Based Optimization Algorithms

Retaining structures play a crucial role in geotechnical engineering to support soil levels, prevent slope failure, and create flat surfaces for construction. Designing these structures involves optimizing internal and external stability while minimizing material usage and cost. This study focused on optimizing reinforced concrete cantilever retaining walls using the Teaching-Learning Based Optimization (TLBO) algorithm and an improved version (I-TLBO) with agents. In the context of the study, geometric-structural design variables, geotechnical -structural constraints, and optimization processes were examined. Minimizing weight and minimizing cost of the wall were the objectives considered in the cantilever retaining wall design process. The optimization results were compared with other algorithms in the literature, such as genetic algorithms, evolutionary strategies, and particle swarm optimization. The improved TLBO algorithm demonstrated superior performance, achieved lower design dimensions, and reduced costs. It provided more efficient solutions that pushed design constraints closer to their limits, resulting in a cost-effective and structurally sound cantilever retaining wall design. As a result of the study, the I-TLBO algorithm was found to be more cost and weight-effective than other methods in the optimization of cantilever retaining wall design.

STABILITY ASSESSMENT OF ROOT-REINFORCED SLOPES USING FINITE ELEMENT LIMIT ANALYSIS

Slope instability poses serious threats to infrastructure and environmental sustainability. As a result, numerous reinforcement techniques have been used as disaster mitigation attempts to prevent slope failure. Among various traditional slope reinforcement methods, the use of vegetion root is more cost-effective and environmentally friendly. This paper presents stability assessment of root-reinforced slopes. Firstly, slope models were built for case of bare and root-reinforced slopes. The slope angles were varied in the range of 15º ~ 55 º. The root cohesion and depth of root zone were adjusted within the ranges of 0 ~ 20 kPa and 0 ~1.5 m, respectively. The strength reduction finite element limit analysis method was applied to evaluate the stability of the slopes in this study. The results indicate that factor of safety increases with the increasing of root cohesion and depth of root zone. The best factor of safety was obtained for the case with root cohesion and depth of root zone of 20 kPa and 1.5 m, respectively. Shear dissipation contours of the slope models also show that root reinforcement reduces shear dissipation energy along the failure surface, consequently lowering the possibility of slope failure.

Mitigation of Soil Erosion and Enhancement of Slope Stability through the Utilization of Lignin Biopolymer.

Human activities have had a profound impact on the environment, particularly in relation to surface erosion and landslides. These processes, which are natural phenomena, have been exacerbated by human actions, leading to detrimental consequences for ecosystems, communities, and the overall health of the planet. The use of lignin (LIG) as a biopolymer soil additive material is regarded as an eco-friendly solution against soil erosion and slope failure which holds immense promise. However, significant research gaps currently hinder a comprehensive understanding of its mechanisms and effectiveness. Experimental studies offer a robust platform to address these gaps by providing controlled conditions for assessing soil stability, exploring mechanisms, and evaluating adaptability. Bridging these research gaps will contribute to the development of innovative and sustainable strategies for mitigating soil erosion and preventing slope failure, thereby promoting environmental resilience and resource conservation. This study aimed to investigate the effect of the LIG biopolymer on mitigation of soil erosion, slope failure and the enhancement of soil strength by conducting laboratory tests (UU triaxial, unconfined compressive strength (UCS), and soaking) as well as flume experiments under uniform rainfall events. The alterations in the engineering characteristics and erosion resistance of silty soil mixed with a LIG additive at concentrations of 1% and 3.0% by weight have been examined. The results show that the LIG-treated samples demonstrated an enhanced resistance to surface erosion and an enhanced prevention of slope failure, as well as improved shear stress, cohesion, stiffness, and resistance to water infiltration.

Infiltration and Failure Behavior of an Unsaturated Soil Slope under Artificial Rainfall Model Experiments

Slope disasters often include soil erosion and shallow landslides. These types of slope failure can occur in unsaturated soil. In this study, artificial rainfall is applied to a compacted soil slope in a laboratory to investigate the effects of rainfall intensity, initial moisture content and relative compaction on infiltration and failure behavior of an unsaturated soil slope subjected to rainfall infiltration. Soil moisture probes installed in the soil slope were used to monitor soil moisture content during the experiment. Test results show that the soil saturation at the toe of the slope was observed to be higher than other areas of the slope following the onset of rainfall. Gradually, the saturation advanced towards the crest, resulting in the formation of a wetting band along the slope surface. With increasing rainfall duration, the wetting band progressed further downwards along the slope. The failure of the slope began at the crest and junction of the slope, and the primary cause was soil erosion resulting from high-intensity rainfall. The most significant variable affecting infiltration behavior is relative compaction, followed by the initial moisture content of the compacted slope. During the experiment, the low hydraulic conductivity of the saturated soil caused most of the rainfall on the slope to become surface runoff, which minimized the impact of rainfall intensity on infiltration behavior. Specifically, the hydraulic conductivity of soil compacted at optimal moisture content and 90 R.C. is only 7.041 × 10-5 cm/sec or 2.53 mm/h, which is much lower than rainfall intensities of 80 mm/h and 160 mm/h. In addition, soil saturation contours facilitated visualization and quantification of the infiltration behavior of slopes, enabling a more detailed analysis of experimental results. These results help understand the behavior of unsaturated soil slopes under artificial rainfall conditions and aid in designing effective slope stabilization measures to prevent slope failure and minimize the risk of landslides.

Road Slope Stability Analysis with Limit Equilibrium Method

Purpose: Landslides are hydrometeorological disasters frequently occurring in many places, particularly during the wet season. Slope stability analysis is the initial stage in defining countermeasures to prevent slope failure and mitigate the negative consequences. This study aims to apply the Limit Equilibrium Method (LEM) to examine the slope stability of the Dufadufa - Jambula road, with the SLIDE version 6.0 application serving as an analytical tool.
 Design/methodology/approach: Researchers use field measurement data to build a slide application slope model. The soil data used as input parameters are derived using the Robertson chart to interpret the sonder test findings.
 Findings: According to the results, the minimal slope factor of safety (fs) at the area under consideration is 0.247. It demonstrates that the road slope, which is the study location, is in critical condition; in other words, the slope of the Jambula-Dufadufa road segment has the potential to undergo a slide.
 Paper type: Research paper

Intelligent Control of Groundwater in Slopes with Deep Reinforcement Learning.

The occurrence of landslides has been increasing in recent years due to intense and prolonged rainfall events. Lowering the groundwater in natural and man-made slopes can help to mitigate the hazards. Subsurface drainage systems equipped with pumps have traditionally been regarded as a temporary remedy for lowering the groundwater in geosystems, whereas long-term usage of pumping-based techniques is uncommon due to the associated high operational costs in labor and energy. This study investigates the intelligent control of groundwater in slopes enabled by deep reinforcement learning (DRL), a subfield of machine learning for automated decision-making. The purpose is to develop an autonomous geosystem that can minimize the operating cost and enhance the system's safety without introducing human errors and interventions. To prove the concept, a seepage analysis model was implemented using a partial differential equation solver, FEniCS, to simulate the geosystem (i.e., a slope equipped with a pump and subjected to rainfall events). A Deep Q-Network (i.e., a DRL learning agent) was trained to learn the optimal control policy for regulating the pump's flow rate. The objective is to enable intermittent control of the pump's flow rate (i.e., 0%, 25%, 50%, 75%, and 100% of the pumping capacity) to keep the groundwater close to the target level during rainfall events and consequently help to prevent slope failure. A comparison of the results with traditional proportional-integral-derivative-controlled and uncontrolled water tables showed that the geosystem integrated with DRL can dynamically adapt its response to diverse weather events by adjusting the pump's flow rate and improve the adopted control policy by gaining more experience over time. In addition, it was observed that the DRL control helped to mitigate slope failure during rainfall events.

Tunnelling-induced landslides: Trigging mechanism, field observations and mitigation measures

This paper reports a collapse accident of slope instability at the entrance of Taizhen Tunnel in Qujiang Section of Hangxinjing Expressway in China. The landslide instability mechanism was studied by field observation and testing. Considering the stability of the landslide and the disturbance effect of secondary tunneling construction, comprehensive reinforcement measures were proposed. The monitoring data showed that good results were achieved. In addition, the effectiveness analysis of the treatment scheme was further examined via numerical simulation. The analysis results show that slope reinforcement before tunnel excavation can not only prevent slope failure but also reduce the deformation of the supporting structure. The improved double side-wall heading method has less disturbance to the slope and is more conducive to the overall stability of the slope. Finally, the lessons learned were summarized, providing insights for preventing future similar incidents from reoccurring.

Preliminary Investigation of the Effect of Surcharge Load and Distance on NonHomogenous Man-Made Slope

Slope failure is a natural disaster that involves the movement of ground and rock under the influence of gravity. There are several factors influencing slope stability, including the excessive surcharge load imposed on the top of the slope. This study performs slope stability analysis to evaluate the performance of a non-homogenous man-made slope constructed on the UPNM campus. The methodology of this research comprises two parts. The first part is laboratory test, and the second part is simulation work. The laboratory tests conducted to determine the soil properties are sieve analysis, permeability test, and direct shear test. The limit equilibrium method using the SlopeW software is employed to determine the effect of imposing a gradually increasing surcharge load on the man-made slope from a varying distance. The value of Factor of Safety (FOS) and critical slip surface formation obtained using SlopeW were used to determine the maximum load carrying-capacity before failure. The results showed that the FOS decreased with an increasing surcharge load. However, the FOS increased as the distance of the load increase. Further analysis was carried out to enhance the stability of the slope. By reducing 40% of slope height, the stability of slope is increased to 44%. It is also suggested that no activity or development should be carried out on the slope crest to prevent slope failure occurrence in the future.

Stability analysis of geosynthetic-reinforced soil structures under steady infiltrations

Conventional approach for evaluation of the stability of geosynthetic-reinforced soil structures (GRSSs) is performed under either completely dry or saturated conditions, whereas soils are usually unsaturated in practice. Owing to the suction-induced effect, the behavior of soil is quite different, consequently leading to various stability conditions of GRSSs. This study presents a useful analytical solution for assessing the reinforcement effect of geosynthetics on the internal stability of unsaturated GRSSs under steady infiltration conditions using the kinematical approach of limit analysis, aiming at determining the reinforcement strength required for preventing slope failure. This analytical solution can take the effect of suction stress, unit weight of soil and tensile strength cut-off simultaneously into account. By comparing with the results of other solutions, the validity of the analytical solution is verified. An extensive parametric study is conducted in this paper. The obtained results show that the suction stress has a more significant effect than the tensile strength cut-off on the required normalized reinforcement; additionally, the required normalized reinforcement obtained by the extended M-C yield criterion is more conservative than that of the tension cut-off model in the presence of suction stress, and the hysteresis effect should be considered in the routine design.

Slope failure of biotreated sand embankments under rainfall conditions: experimental investigation and numerical simulation

Rainfall has become a main trigger of slope failure for embankments in most coastal areas in China. The microbially induced carbonate precipitation (MICP) technique has great potential to improve soil strength and slope stability. In this study, three small-scale biotreated sand embankments and one untreated embankment were first prepared using the injection method. Rainfall scouring tests were then conducted to investigate the slope failure of the embankments. Experimental results revealed that scouring/erosion resistance of biotreated sand embankments was significantly improved comparing to that of the untreated one. The failure time of the embankment increased as the treatment cycles increased. The failure mode of the untreated embankment was the general shear failure, whereas the failure was most likely to occur at shallow depth in biotreated embankments. Using the finite element method (FEM), flow analysis was conducted to simulate the rainfall infiltration in sand embankments and study the effect of biotreatment on the infiltration process. The simulation results were found to be consistent with the experimental results. This study preliminarily investigates the effectiveness of using the MICP technique to prevent slope failure of sand embankments. Considering the complicated environmental factors, more effort towards optimization is still needed for field implementation in the future.

Robust Geotechnical Design for Soil Slopes considering Uncertain Parameters

Designing the geometry of soil slope is an effective treatment for preventing slope failure. How to deal with the uncertainties involved in soil parameters in geotechnical design is a main concern of geotechnical engineers. In this study, a robust geotechnical design for soil slopes (RGDS) approach was proposed, in which the Uncertainty Theory was introduced to describe explicitly the uncertainties involved in soil parameters. The uncertain reliability is often used to describe the risk of slope failure. The design robustness describing the insensitivity between the variation in the system response and the variation of input uncertain soil parameters was evaluated by the signal-to-noise ratio. The objectives of this design are to maximize the design robustness, minimize the excavation cost, and guarantee the safety (maximize the uncertain reliability). Therefore, the RGDS was formulated as a multiobjective optimization, and the optimal design can be determined based on the concepts of Pareto front and knee point. The proposed RGDS approach was illustrated through a numerical case of a two-layer slope design. The numerical results indicate that the RGDS approach is not only more intuitive and easier to follow but also more computationally efficient.

An alternative model of retaining walls on sandy area to prevent landslides

Landslide is one of the potential disasters that can take life and material. A way to reduce disaster risk in slopes is to improve slope stability. A challenge in improving slope stability is how to make soil retaining walls that are simple, quickly built, and workable in the process. This research focuses on laboratory tests of gravity, segmental, and pre-cast retaining walls in sands. The tested models are slopes with different segmental, pre-cast, gravity walls made of un-reinforced concrete for static loads. The slope failure patterns were observed with their load variations. There are two wall models segmental. Each segmental wall observed a collapse pattern that occurred behind the wall. Static loading is carried out step by step until collapse occurs in the segmental wall. Observations and defects are carried out during the load process until the segmental wall collapses. This research shows that segmental pre-cast retaining walls with specific models and sizes can be selected to support certainly given loads to prevent slope failure.

Suitability of Tyre Derived Geomaterial Mixed with Gravel to be used in Gabion Type Retaining Wall

The disposal of scrap tyre is a major problem in developing countries. Material recycling is adopted in order to promote safer disposal (beside conventional dump and thermal recycling). Tyre derived geomaterial (TDGM) are proposed to be used in construction of gabion type retaining wall to prevent slope failure that has been a serious geotechnical threat in many countries. The reason of choosing tyre is not only to help in reducing the stockpiling of scrap tyre generated in environmental friendly way but also to reduce the dependency of gravel as the material to filled current gabion wall. In this study, laboratory scale model of gabion wall was developed to protect soil slope. Various proportion mixture of gravel:TDGM were used to construct the gabion wall. The protected slope was subjected to an artificial rainfall of 13mm/hour. Soil movement from commencement of the test until the slope failed was recorded by using transducers. Sieve analysis, specific gravity test and compaction test were conducted beforehand upon all materials used in the study to determine basic characteristics of the materials. From this study, it is found that, due to its lightweight properties, the use of TDGM (tyre chips and tyre buffer) as unique material in gabion wall was insufficient to reduce the displacement of the gabion wall. Larger displacement of gabion wall was recorded in the case of gravel:TDGM mixture was used to fill gabion wall. TDGM need to be mixed with large amount of gravel (at least 80% by volume) to increase the self-weight of the gabion wall and increase its stability.

Monitoring Slope Condition Using UAV Technology

Slope failure is a serious geologic hazard in many countries in the world including Malaysia. In order to prevent slope failure, the hazardous symptoms can be detected early in slope monitoring process. Nowadays, slope failure symptoms monitoring has been done by human by on site observation at the slope spot and it is dangerous for the human safety. Furthermore, it takes longer time to complete the investigation and some of the data collected are inaccurate because human view is limited. Therefore, this project is to evaluate the performances of Unmanned Aerial Vehicle (UAV) to monitor the slope condition. A slope at Taman Harmoni Vista at Pagoh, Johor has been selected as a study area. The measurement of slope studied was 150 meters in length and 20 meters in height respectively. The aim of this project is to evaluate the performances of Unmanned Aerial Vehicle (UAV) to monitor the risk slope. Visual image of 3D modelling was obtained from Pix4D Mapper and Global Mapper software was used to analyze the slope failure symptoms. There are defects that have been identified from 3D modelling of the slope which is tension crack on slope and surface crack on the drainage. The use of UAV is an alternative method to obtain quality picture and 3D model for inspection of the slope. This method expected to facilitate the work of inspection slopes in addition to saving time, energy and cost as well asreducing the risk of harm.

Potential of Tyre Derived Geomaterial as Alternative Material in Gabion Type Retaining Wall

The disposal of scrap tyre is a major problem in developing countries. Material recycling is adopted in order to promote safer disposal (beside conventional dump and thermal recycling). Tyre derived geomaterial (TDGM) are proposed to be used in construction of gabion type retaining wall to prevent slope failure that has been a serious geotechnical threat in many countries. The reason of choosing tyre is not only to help in reducing the stockpiling of scrap tyre generated in environmentally friendly way but also to reduce the dependency of gravel as the material to filled current gabion wall. In this study, various mixtures were considered in laboratory scale retaining wall namely, 100% gravel, 100% tyre and 50% of both materials. The retaining wall was functioned to retain a 60o of sand slope. The slope was then subjected to 0.8 mm/hour of artificial rainfall. The soil movement from commencement of the test until the slope failed was recorded. Several tests were carried out to determine basic characteristics (grains size distribution and standard Proctor test) of materials used in the study were conducted beforehand. The results showed that TDGM was able to mitigate slope failure as effective as using gravel. No significant horizontal movements were recorded compared to the slope without any countermeasure. However, slight settlement of gabion wall was recorded and need further testing for clarification.

Seismic stability of geosynthetic-reinforced walls with variable excitation and soil properties: A discretization-based kinematic analysis

Seismic stability of vertical slopes is investigated using the discretization-based kinematic analysis, aiming at determining the geosynthetic reinforcement force required for preventing slope failure. The earthquake effect is characterized by spatial and time varying seismic inputs in sinusoidal functions. Two modes of seismic inputs are proposed for describing the 2D rather than 1D spatial effect. Further, the change in cyclic amplitude of the acceleration time-history is incorporated into kinematic analysis. The reinforcement force is formulated from the work rate-based balance equation. The pseudo-static/dynamic solutions are sought and compared. Comparisons are highlighted between the numerical results from three different seismic inputs.

Application of woven waste tires gabion wall as slope reinforcement for preventing landslide in laboratory

This study presents the application of woven waste tires as slope reinforcement for preventing slope failure, reducing construction costs and minimizing environmental hazards associated with the increasingly large amount of waste tires in Indonesia. To this end, we performed laboratory experiments using five stripe distance variations of woven tires - i.e. 3, 4, 5, 6, and 7 cm as ribs of a gabion wall. Five gabion wall samples sized 50 cm x 50 cm x 25 cm each were made. Each sample was fastened using one of these woven tires. A loading test was conducted on each gabion wall sample and the strength was determined from the maximum capacity before failure. The correlation between the gabion wall strength and strip distance - boulder diameter ratio was used to infer the most effective model. The result suggests that the strip distance - boulder diameter ratio of 0.4 is optimum with a corresponding strength value of 1718 kg.

Pseudo-static stability analysis of rock slopes reinforced by passive bolts using the generalized Hoek–Brown criterion

The stability analysis of passive bolt-reinforced rock slopes under seismic loads is investigated within the framework of the kinematic approach of limit analysis theory. A pseudo-static method is adopted to account for the inertial forces induced in the rock mass by seismic events. The strength properties of the rock material are described by a modified Hoek–Brown strength criterion, whereas the passive bolts are modeled as bar-like inclusions that exhibit only resistance to tensile-compressive forces. Taking advantage of the ability to compute closed-form expressions for the support functions associated with the modified Hoek–Brown strength criterion, a rotational failure mechanism is implemented to derive rigorous lower bound estimates for the amount of reinforcement strength to prevent slope failure. The approach is then applied to investigating the effects of relevant geometry, strength and loading parameters in light of a preliminary parametric study. The accuracy of the approach is assessed by comparison of the lower bound estimates with finite element limit analysis solutions, thus emphasizing the ability of the approach to properly predict the stability conditions and to capture the essential features of deformation localization pattern. Finally, the extension of the approach to account for slipping at the interface between reinforcements and surrounding rock mass is outlined.

SCREW-IN SOIL NAIL FOR SLOPE REINFORCEMENT AGAINST SLIP FAILURE: A LAB-BASED MODEL STUDY

Slope failures occur when the shear resistance along the slip plane is exceeded. This can be caused by excessive load imposed at the slope crest or compromised stability of the slope, e.g. disturbed dimensions of the slope. In order to prevent slope failure, stabilisation or reinforcement measures need to be taken. A common solution is to intercept the slope failure plane with reinforcement elements, such as soil nails and ground anchors. In soil nailing, reinforcement bars are installed on the slope to effectively resist the additional shear forces from the imposed loads, hence reducing the probability of failure in the long run. This paper describes the innovation of soil nail with screw-in installation mechanism instead of the conventional push-in approach. The screw-in installation ensures better soil-nail grip and less disturbance during the slope stabilisation procedure, especially in terms of noise and spoils. In addition, the novel nail has a hollow stem which improves shear resistance with greater soil-nail surface contact on the inner wall. The opening at the nail head also enables displaced air to escape as the nail is screwed into the slope and soil pushed into the inner hollow cavity. The prototype nails were tested in a slope model with different configurations, and were found to reduce the Angular Distortion Ratio by 37 % and the Volumetric Deformation Index as much as 33 % respectively. The novel screw-in soil nail could be potentially used to stabilize natural and man-made slopes, though full-scale simulations are recommended to formulate the installation procedure and to validate the effectiveness.