Slope Reinforcement Research Articles

Bearing Capacity Factor of Shallow Foundation on Reinforced Sloped Clayey Soil

The placement of buildings and structures on/or adjacent to slopes is possible, but this poses a danger to the structure due to failures that occur in slopes. Therefore, a solution or improvement should be determined for these issues of the collapse of the structure as a result of the failure of the slopes. A laboratory model has been built to test the impact of some variables on the bearing capacity factor. The variables include the magnitude of static axial load applied at the center of footing, the depth of embedment, the spacing between geogrid reinforcement layer and the numbering of the geogrid sheet under the footing, the inclination angle of slope clayey soil (β), the spacing between the footing's edge and the slope's end (b/H). The results show that the critical case of reduction in bearing capacity is mobilized at (b/H˂ 0.25) and (β˃ 30°). A design chart has been obtained to the case of unreinforced slope soil under a footing to describe the reduction in (Nc) when increasing the inclination angle and another design chart of the case of reinforced slope soil with (N=1, 2 and 3) has been obtained to show the increase in value of (Nc) with increasing the number of the reinforced layer at different values of (β) and finally simple equations have been obtained in order to calculate the ultimate bearing capacity of foundation on sloped clayey soil at different number of reinforcement.

Application of the Nailing Technique to Stabilize a Slope in a Section of the Twinning of Road and Rail Infrastructure

Nailing is one of the most widely used stabilization techniques because of its technical and economic advantages. It is a practical and effective solution for the reinforcement of in-place slopes. It consists of placing in the soil high resistance nails to increase the cohesion of the soil and its resistance to traction and shear, which allows having a new material of great capacity. In this paper, we present the slope stability study in a section twinning of the road and railroad infrastructures between the kilometer points (KP) 105+938 and 106+263 of the line connecting Casablanca to Marrakech. The railroad track's topographic constraints and geometric requirements made the nailing method appeal to the realization of the new railroad in this area. The objective of this work is, on the one hand, to present the stability analysis of the slope before the earthwork and the implementation of the new railroad and, on the other hand, to evaluate the performance and stability of the nailed walls. The stability analysis of the soils in this section was verified in terms of safety coefficient using the calculation software TALREN. In the end, it can be concluded that the stability calculation results are conclusive and allow for highlighting the effectiveness of the innovative solution of nailing. This technique can be considered a good alternative to improve the safety and performance of excavation walls.

Research on influence of anchor cable failure on slope dynamic response

Anchor cables are an important branch of geotechnical engineering and are widely used in slope reinforcement. The Wenchuan earthquake showed that the anchor cable fracture can cause the instability of the slope. The anchor cables in the numerical software obey the ideal elastic-plastic law and cannot simulate fracture and failure. To achieve the fracture effect, the anchor cable model is modified. Based on stepped slopes, the dynamic response characteristics are analyzed, and the effect of pre-tension is discussed. The results show that: 1) The influence of anchor cable failure on slope safety cannot be ignored. After the failure conditions are met, the free segment no longer transmits tension, and the anchored segment degenerates into soil nails. 2) When the slope is unstable, the anchor cable will show a continuous fracture phenomenon. The fracture first occurred in the dangerous parts such as the slope toe, and then turned to the top. 3) The fracture of the anchor cable will lead to the release of the soil stress, accompanied by the change of the acceleration amplitude and frequency, and finally manifested as a larger residual displacement. Slope reinforcement not only needs to consider the anchoring force, but also the coordination relationship.

Design Review of Leuwikeris DAM Acces Road Pakage 4

Abstract: The construction of the Leuwikeris Dam requires materials to be used for stockpiling. Therefore, it is necessary to access the road from the quarry in question to the location of the dam. This access road is located in Cibodas Village RT 32 / RW 15 Ciharalang Village, Cijeungjing District, Ciamis Regency, West Java. The construction of access roads needs to build bridges connecting the valleys which requires making embankments to reach the elevation of the road plan. The embankment is made up to ± 15 m using embankment material around the site. This design review was carried out because a landslide occurred on one of the embankment slopes which did not rule out the possibility that it could occur on the opposite slope. This design review uses the help of the SLOPE/W program to determine the level of slope safety and alternative slope reinforcement designs. It should be noted that the data used are secondary data obtained from related parties. Some things that can be concluded from the design review are as follows: 1) The landslide occurred due to the failure of the existing gabion foundation to withstand the load of the slope. 2) Repair the gabion foundation by enlarging and deepening the dimensions (attached image), so that it can cut the landslide area. The dimensions of the large foundation are expected to provide sufficient counter weight. 3) The landslide material must be cleaned and start compaction per layer from the beginning. Ensure that the backfill is of maximum density. 4) Improved gabion design so as to obtain sufficient volume weight of at least 1.5 t/m3. The installation of bamboo chimneys is still being carried out as additional reinforcement. Keywords: Safety factor; Gabion; Road; Embankment; Slopes stability; Slope-W.

Experimental Study on the Mechanical Mechanism of Arch-Chord-Coupled Antisliding Structure

Arch-chord-coupled antisliding structure is a new type of structure composed of multiple small-diameter piles for strengthening small- and medium-sized landslides, especially suitable for the reinforcement of slopes that are sensitive to deformation. In order to further explore the mechanical properties of the antisliding structure, physical model tests under four cases were carried out to study the deformation and stress characteristics of the structure under different types, and the optimal structural type was determined. The displacement test results show that even if there is no crown beam at the top of the piles, all the piles can deform in coordination, and when the number of rear piles is large, all the piles can basically deform synchronously. The test results of the bending moment of the pile body show that the crown beam has a great influence on the extreme value of the bending moment of each pile. For the structural type with more piles arranged in the rear row, the standard deviation of the extreme value of the bending moment of the pile body before and after adding the crown beam decreases from 2.0 to 1.03; the presence of crown beams effectively adjusts the internal force of each pile. The comprehensive analysis results show that the arch-chord-coupled antisliding structure with more piles in the rear row is the best.

Intelligent optimization of a bolt support scheme for a single-stage slope

A rock slope in an unstable state usually needs bolt support to avoid major disasters, but due to the complexity and uncertainty of the factor of safety (FOS) and the attributes of bolting parameters are not unified, it is not easy to acquire a satisfactory scheme. In this article, a modelling optimization method based on feedforward neural network (FNN) and particle swarm optimization (PSO) algorithm is proposed. Firstly, the process of slope bolting is simulated to obtain the FOS and an FNN model with growth mechanism is established. Secondly, the PSO algorithm is improved to realize the comprehensive consideration of discrete and continuous parameters and reduce the computational complexity with high dimensions. Finally, the accuracy of the FNN model is tested by cross-validation, and the experimental results show that the optimized bolting scheme can enhance slope stability and provide reference values for the reinforcement of slopes in actual engineering situations.

Stability Evaluation of Diversion Tunnel Portal Slopes at Lau Simeme Dam Site, Indonesia, using Limit Equilibrium Method

Construction of the Lau Simeme Dam used a tunnel as a diversion channel. Slopes at the diversion tunnel portals were prone to failure due to the tunnel excavation and earthquake. Earthquake load was not considered in the designs of the inlet and outlet portal slopes. This research evaluated stability of the tunnel portal slopes under static and earthquake loads using limit equilibrium methods of the Bishop Simplified and Morgenstern-Price. Input material properties for the slope stability analyses were obtained from evaluations of soil and rock cores, including determination of lithology type and rock mass quality based on Geology Strength Index (GSI), and laboratory testing. Evaluations of soil and rock cores indicated that the inlet portal slope consisted of residual soil, good quality tuff breccia, and good quality sandstone. The outlet portal slope consisted of residual soil, poor quality sandstone, poor quality tuff breccia, fair quality sandstone, fair quality tuff breccia, and good quality tuff breccia. The earthquake load coefficient determined by the seismic analyses based on the peak ground acceleration map for 10% probability exceedance in 50 year was 0.125 g. The slope stability analyses showed that the designed inlet and outlet portal slopes were stable under static and earthquake loads. The Bishop Simplified and Morgenstern-Price resulted in relatively similar Fs values. The Fs values of the inlet and outlet portal slopes decreased with the earthquake load application. Although Fs values of the outlet slope under static and earthquake loads met the requirements specified by SNI 8460:2017, the rock mass conditions, particularly the poor rock masses of layers 2 and 3, required special attention. Application of slope reinforcement methods, such as shotcrete, is suggested to further increase the slope stability.

Reliability assessment of reinforced slopes with unknown probability distribution

In the proposed study, reliability assessment of the reinforced slope (RFS) is carried out using an efficient and accurate technique of Fourth Moment Normal Transformation (FMNT). The probabilistic analysis is performed using both analytical and numerical methods. FMNT can estimate the probability of failure (Pf) of a RFS with unknown marginal distribution of input random variables. Only the first four moments of any random variable with unknown distribution are required to estimate the Pf of RFS. The use of FMNT with commercially available numerical software packages is precisely explained. The accuracy of the proposed technique, when used with different distributions of random variables, is also illustrated. The present results show considerable efficiency of FMNT in estimating the Pf when used in the analytical domain as well as with a numerical software. A detailed comparison in terms of the efficiency of the proposed formulation is also made with similar literature. FMNT is very useful for the designers to perform the reliability-based analysis of RFS. The present analytical method is also capable of incorporating the pseudo-static seismic forces into calculations.

STABILITY ANALYSIS OF SLOPE ON TRANS SULAWESI ROAD, PONTOLO VILLAGE, MANANGGU SUB-DISTRICT, BOALEMO DISTRICT, GORONTALO PROVINCE

The research location is in Pontolo Village, Mananggu Sub-district, Boalemo District, Gorontalo Province. The research location has rock slopes with a discontinuity area in the form of fractures in the rock body, which is a factor causing landslides. The research aims to determine geological conditions, rock mass quality, types of potential landslides, and recommendations for slope stability. The methods used are direct field observation, Scanline Mapping, Rock mass Rating (RMR), kinematics analysis, and Slope Mass Rating (SMR). The results of the geomorphological research of the research area are units of lava flow plains and units of intrusive hills. The lithology of the research area is in the form of granodiorite units and porphyry dacite units, while the geological structure is in the form of joints. Scanline mapping is carried out in 4 segments: segment 1, segment 2, segment 3 and segment 4. The rock mass class consists of 2 classes, a good class and a fair class. Types of landslides consist of wedge sliding and toppling sliding. SMR consists of 2 classes, stable and unstable, the results of observations that unstable slopes need to be handled in slope reinforcement.

Analysis of Flood Control Effectiveness in Kali Sadar Regency and City of Mojokerto

Kali Sadar is part of the main drainage system in some areas of Mojokerto Regency and City. The main channel of Kali Sadar has a length of ± 23,211 Km with a drainage area of ± 614,92 Km². And has an upstream elevation of + 900 meters and an elevation of + 20 meters downstream from sea level. Flood control planning is carried out through river normalization analysis, slope reinforcement work planning, and embankment planning. All schemes are carried out so that the planned flood discharge is able to reach the ideal condition of the flood water level in the river. The study also reviewed through the planning of drainage facilities in the form of pump houses and retention ponds. In the results of the HEC-RAS analysis the results of the planned discharge used were a 25-year return period with a maximum discharge of 1080 m2/s. After simulating there is a cross section experiencing overtopping, to overcome overtopping, parape embankments are installed and with slope reinforcement work (revetment) on the slopes of the right and left sides of the river. The purpose of slope reinforcement is to accelerate the direction of river flow towards downstream so that there is no sediment erosion, by changing the manning value. However, after the flood control circuit, the cross section of the stream is only able to accommodate a maximum discharge capacity of 151.98 m2/s. For that, it is necessary to plan a pump house. Drainage facilities, in tackling the problem of excess runoff, pump houses are used in 5 locations with a plan of 80,000 m2 and a depth of 4.5 m. The plan uses 3 pump units with a capacity of 4.32 m2/s through an operating system of 4 inflow gates and 4 outflow gates which have a door width of 4.125 m and a height of 3.5 meters. pumps turn on when the water level is 0.08 m, 2 pumps will turn on when the water level is 0.30 m, and 3 pumps will turn on when the water level is 0.39 m.

Slope displacement and soil pressure of soilbag-retaining wall influenced by arrangement

Soilbags have a good effect on slope reinforcement. In this paper, five kinds of physical model tests were carried out on slopes strengthened by reinforced soilbag-retaining wall, namely analysis of the failure mode and failure pressure of the slope, the variation trend of horizontal displacement of the slope, the maximum horizontal displacement and the horizontal transmission and vertical distribution of earth pressure. Thus, the influence of the arrangement mode of the soilbags on the slope reinforcement effect were studied. The results show that the alternate arrangement between layers (arrangement mode 1) had the deepest slip surface, the maximum bearing capacity and the minimum horizontal displacement, thus its reinforcement effect was the best. In addition, the reinforcement effect of the slope was related to the amount of tail embedded into the slope body, the interaction of soilbags in the layer and the embedment between the upper and the lower layers of soilbags. It was found that when the embedding degree of the tails into the slope was higher, the horizontal deformation constraint of the slope was stronger, resulting in a deeper sliding surface and a higher ultimate bearing capacity of the slope. This shows that the slope reinforcement effect was better with soilbags.

Experimental Study on the Effect of Hemp Fiber on Mechanical Properties of Stabilized Clayey Soil

ABSTRACT Clayey soils have fine particles and contain clay minerals. Therefore, they are sensitive to water and cause stability problems. Nowadays, soil stabilization is an accepted method to resolve the problem of stability. In this study, hemp fiber was used as an additive material for stabilization of clayey soil. The use of fibers in the stabilization of clayey soils is becoming widespread, particularly with regard to applications involving the stabilization or reinforcement of shallow steep earth slopes and steep cover systems for landfills. In these applications, the use of natural fibers use is very important due to their environmentally friendly properties. Hemp legally planted in different countries is used in several industries, such as paper, textiles, clothing, biodegradable plastics, construction, body products, health food, and biofuel. In this study, hemp fiber was preferred because of its natural and environmentally friendly properties. To observe the effect of hemp fiber on the compressive strength of clayey soil material, the unconfined compression tests and shear box tests were carried out under laboratory conditions. The experimental results showed that hemp fiber is effective on the compressive strength of clayey soils. As a result, hemp fiber can be used successfully in clayey soil stabilization as an environmentally friendly material.

Mitigation measures of debris flow and landslide risk carried out in two mountain areas of North-Eastern Italy

The design of remediation works for the mitigation and prevention of the associated risk is needed where these geological hazards affect anthropized areas. Remedial measures for landslides commonly include slope reshaping, plumbing, drainage, retaining structures and internal slope reinforcement, while debris flow control works consist in open or closed control structures. The effectiveness of the remedial works implemented must be assessed by evaluating the reduction of the risk over time. The choice of the most appropriate and cost-effective intervention must consider the type of hazard and environmental issues, and selects, wherever possible, naturalistic engineering operations that are consequently implemented according to the environmental regulations or the design and specification standards imposed by the competent public administrations. The mitigation procedures consist of five basic steps: (a) acquisition of the knowledge of the hazard process; (b) risk assessment with identification of possible disaster scenarios; (c) planning and designing of specific remedial measures to reduce and/or eliminate the potential risk; (d) slope monitoring after application of remedial measures, (e) transfer of knowledge to the stakeholders. This paper presents two case studies describing the practice for the design of the mitigation measures adopted for debris flow and active landslide sites in North-Eastern Italy. The first case study is a debris flow site, for which, based on observation of past events and numerical simulations using the software FLOW-2D, the most suitable mitigation measures were found to be the construction of a debris basin, barriers and breakers. The second case study deals with an active landslide threatening a village. Based on the landslide kinematics and the results of numerical simulations performed with the code FLAC, hard engineering remedial works were planned to reduce the driving forces with benching and by increasing the available resisting forces using jet grout piles and deep drainage.

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.

Shaking table test for reinforcement of soil slope with multiple sliding surfaces by reinforced double-row anti-slide piles

Shaking table test for reinforcement of soil slope with multiple sliding surfaces by reinforced double-row anti-slide piles

DEM-Based Numerical Investigation of Seismic Stability of Rock Slope in Terms of Rigid Block Displacement

Abstract For the seismic behavior of a rock slope or more specifically a rock wedge, the limit equilibrium method is frequently utilized to determine the static and pseudo-static safety factor, and the Newmark method is usually applied to estimate the permanent dynamic displacement. However, the two methods are relatively complex, which negatively affects their usage in engineering practice. A new idea to analyze the static and dynamic stability of a complex rock slope was provided in this paper by combing the rigid discrete element method (DEM), shear strength reduction (SSR) method, and Newmark method. The research results show that (1) by setting the joint contact stiffness to a very large magnitude, the joint displacement caused by the reduction of joint contact stiffness during the SSR calculation process can be considered ignorable, making the contact behavior between the respective two joints approximately satisfy the rigid-plastic assumption. In this manner, it is feasible to calculate the static and pseudo-static safety factor (SF) and the permanent dynamic displacement of a rock wedge with the rigid DEM. (2) The SF and sliding forces of wedges can be directly calculated by this new method without any auxiliary assumption of motion direction or sliding type. Additionally, the new method is suitable for complex wedges, which is important to practical design. (3) The rigid DEM can be realized in 3DEC, which is testified in this paper by 5 classic static examples and 3 typical dynamic examples. (4) The effect of some important parameters, such as the excitation acceleration amplitude and dip of intersection line between two joints, on the dynamic displacement and SF under dynamic excitation was analyzed. The parameter analysis revealed that evaluating the seismic performance of a rock slope only with the pseudo-static SF would potentially underestimate the seismic displacement, under some special conditions. (5) An example case was presented in this paper that the seismic stability assessment of a block was performed with the proposed approach in terms of seismic displacement. And the slope reinforcement scheme was suggested with respect to exceedance probability. It is noted that the reinforcement scheme obtained from the rigid DEM has a better cost-saving benefit under the same SF. Overall, the knowledge gained in this paper may offer a new idea for the static and dynamic analysis to the rock slope stability.

Research on Seepage Field and Slope Stability Considering Heterogeneous Characteristics of Waste Piles: A Less Costly Way to Reduce High Leachate Levels and Avoid Accidents

Due to the characteristics of high heap and large volume, the complex layers of waste, high-water level of leachate, environmental pollution, and slope instability are easily produced. Although many researchers have studied landfill two-dimensional leachate migration law, three-dimensional seepage and stability of landfill sites have been rarely studied. This paper focuses on the heterogeneous characteristics of the landfill piles and analyzes the seepage field and slope stability of the landfill using statistical and numerical analysis methods. The calculated results are compared with the field measurement and literature research data to verify the reliability of the model, which may provide the basis for the design and safe and eco-friendly operation of the landfill. Taking an actual landfill as the research object, the saturated–unsaturated transient model of heterogeneous waste is applied to practical engineering. Considering the landfill process and heterogeneous permeability, the calculated maximum water level is higher. Compared with the homogeneous material, the difference in the water level of each waste layer is about 0.08∼1.88 m, which is not good for the stability of the landfill. Combined with the engineering characteristic distribution of a landfill, the heterogeneous stability model is applied to the actual project to study the influence of different unit weight and shear strength distribution on landfill stability. The established model is suitable for the study of two-dimensional and three-dimensional slope stability of landfill sites. Through the slope stability analysis of the three-dimensional landfill site, it is found that the bank slope of the reservoir is steep and prone to instability failure. In most studies, only the instability of the landfill is of concern, but the bank failure is ignored. In the process of landfill operation and management, while considering the capacity of the landfill, the stability of the bank slope should also be paid attention to, and if necessary, bank slope reinforcement or slope ratio improvement should be carried out.

A New Prestress Loss Calculation Model of Anchor Cable in Pile–Anchor Structure

Pile–anchor structures are widely used in foundation excavation and slope reinforcement due to their safety and reliability. However, the pile–anchor structures have the common problem of the prestress loss of anchor cables, which may reduce the stability of the structures. To accurately predict the prestress loss of anchor cables, a new prestress loss calculation model was established, and the availability of the prestress loss calculation model was verified through engineering cases. Meanwhile, aiming at the long-term prestress loss of anchor cables, the coupled creep behavior of anchor cable–rock and soil was studied and an anchor cable–rock and soil coupled creep model suitable for pile–anchor structures is proposed. The model test confirms that the coupled creep model could accurately describe the coupled creep behavior of the anchor cable and the rock and soil mass. The models provide a theoretical basis for the study of the prestress of anchor cables in pile–anchor structures, and have a guiding significance for the design and construction in foundation excavation and slope engineering.

Geotechnical Practice of Slope Reinforcement

Geotechnical construction is one of the most important branches of the construction of zero parts of objects for various purposes. The existing rich potential of geotechnical technologies allows us to successfully perform the tasks of building foundations for buildings in any engineering and geological conditions and on any territory, including slopes, ravines, embankments. Very often there are cases of erection of objects on rugged territories with alternating structurally unstable soils, moreover, additionally loaded with artificial leaning slopes. In geotechnical practice, there are still cases of construction on such slopes without proper engineering and technical support, i.e. without the presence of actually carried out engineering surveys, as well as developed antilandslide measures. Ultimately, in most cases, the neglect of generally accepted standards leads to undesirable consequences, expressed in deformations of the constructed buildings. This article considers one such case.

Optimal design of anchor cables layout and length for slope reinforcement based on PSO algorithm

Optimal design of anchor cables layout and length for slope reinforcement based on PSO algorithm