Search Results (14)

The fluctuation of reservoir water levels is a critical factor influencing the evolution of reservoir landslide–anti-slide pile systems. To investigate the reinforcement mechanism of anti-slide piles in reservoir landslides under the effect of reservoir water level fluctuations, this study employs numerical simulation methods to establish a three-dimensional slope model, simulating the drawdown process of the reservoir water level from 175 m to 145 m. The displacement and strain fields of the reservoir landslide during the water level drawdown are analyzed. Furthermore, the strain characteristics of the anti-slide pile-reinforced reservoir landslide under stress–seepage coupling are studied, and the prevention effectiveness of the landslide–anti-slide pile interaction system is explored. The results indicate that the drawdown of the reservoir water level can lead to the gradual expansion of the strain and displacement zones in the landslide, as well as a reduction in the safety factor. Under the effect of anti-slide piles, the maximum deformation of the reservoir landslide is significantly reduced. The optimal reinforcement effect is achieved when the anti-slide piles are arranged in the middle of the reservoir landslide, with a pile spacing of four times the pile diameter and an embedded depth reaching the critical depth. The findings of this study can provide a scientific basis for analyzing the instability mechanisms and mitigation of reservoir landslides. Full article

Landslides on the Jiaxi Highway in Qinghai Province threaten construction safety and quality. The on-site data analysis shows that excavation at the foot of the slope and heavy rainfall are the key factors causing the displacement of the Q1 monitoring point by 1825 mm. This article uses numerical simulation methods combined with the strength reduction method to study the stability changes of slopes under different working conditions. Numerical simulations identified the landslide location and predicted a 1960 mm slip and a safety factor of 1.26 under natural conditions, indicating risks. The study adopted a strategy combining slope cutting, load reduction, and sheet pile wall reinforcement. After the first treatment, the safety factor rose to 1.83 with a 40 mm displacement; after the second, it reached 2.36 with a 37 mm displacement. Continuous monitoring showed a 50 mm displacement over six months, indicating stability. Rainfall simulations before and after treatment explained the stability evolution and local slope stability. Treatments increased the safety factor to 2.16 with a 17.6 mm displacement. This study significantly improved highway landslide stability and verified treatment effectiveness, providing a reference for similar geological conditions. Full article

Aiming at the problem of insufficient slope stability in deep foundation pit engineering, this paper takes the integrated urban and rural water supply project in Lingao County as the research object, simulates and analyzes the landslide process of the slope by using the strength discount method, and explores the mechanical response characteristics of the anti-slip piles in depth. It is found that the traditional anti-slip pile is prone to early failure due to bending and tensile damage in the middle of the pile back, which leads to the decline of slope stability. For this reason, this paper designs and studies the high-toughness anti-slip pile material and carries out numerical simulation analyses on C30 concrete anti-slip piles and high-toughness concrete anti-slip piles, respectively, for 9 working conditions, for a total of 18 working conditions. The results show that the bending and tensile toughness and strength of the anti-slip piles are significantly improved by using high-toughness material, which effectively avoids bending and tensile damage, and the slope safety coefficient is increased by 32.10%. Furthermore, the optimized design of anti-slip piles in terms of material, pile length, and pile position can effectively improve the stability of slopes and prolong the service life of the anti-slip piles, which provides a new way of thinking and methodology for the safety design of the deep foundation pit project. Thus, this study has important theoretical significance and engineering application value. Full article

Rainfall is one of the most important factors affecting slope stability. This study employed multi-source monitoring devices to observe the slope displacements in real time under rainfall infiltration and performed numerical simulations to investigate the effects of different rainfall conditions and anti-slip pile configurations on slope stability. Specifically, multi-source monitoring operations were conducted on the high and steep slopes along the Yunmao Expressway. Real-time data on slope deformation, rainfall, and displacement at the tops of anti-slip piles were collected and analyzed, and numerical simulations were conducted using Geo Studio finite-element software. The findings indicated that abrupt deformation of slopes occurs once a threshold rainfall amount is surpassed and sustained over a specific duration. Slope displacement decreased with increasing slope depth above the potential slip fracture surface, with a more rapid reduction in deformation rates observed in slopes reinforced with anti-slip piles. For equivalent rainfall amounts, short-duration, intense rainfalls led to a rapid decrease in the slope safety factor, which also recovered rapidly once the rainfall ceased, in contrast to long-duration, mild rainfalls. The presence and location of anti-slip piles significantly influenced slope stability; therefore, project implementation should carefully consider factors such as cost and duration for optimal decision making. Full article

To examine the effects of different peak accelerations on the stability of the accumulation slope and the effectiveness of anti-slide piles under seismic loads, this paper used the Fanlingqian landslide as the main research object and combined it with digital image correlation (DIC) technology in order to carry out a shaking table test. Then, the acceleration response, displacement field, strain field, the bending moment distribution of the 0.05–0.3 g ground motion accumulation slope, and the anti-slide pile reinforcement were studied. The results of the test show the following: the amplification coefficient of the measuring points A1–A6 of the accumulation slope reaches the maximum at a peak acceleration of 0.2 g, and its values are between 1.25 and 1.3, respectively. Finally, it shows a decreasing trend at a peak acceleration of 0.3 g, and its corresponding values are, respectively, between 1.1 and 1.2. In the anti-slip pile reinforcement test, due to the obstruction of the anti-slip pile, the damping of the soil around the pile increases. As the peak value of the seismic wave input increases, the amplification factor shows an overall decreasing trend. A1–A6 correspond to a peak acceleration of 0.3 g. The amplification factors are all close to 1. During different peak accelerations, the accumulation slope mainly experienced the earthquake-induced stage, tensile failure stage, creeping deformation stage, and overall instability stage. In the anti-slide pile reinforcement test, under the same conditions, the slope mainly experienced the earthquake-induced stage, tensile failure stage, lower sliding surface formation stage, and soil shedding stage in front of the pile. At the same time, the displacement and strain fields of each stage of the two groups of tests are compared, and it is found that the displacement and strain values of the accumulation slope test are greater than those of the anti-slide pile reinforcement test, and the horizontal displacement difference at the top of the slope is the most significant, reaching 2.3 times at the maximum. The bending moment of the anti-slide pile first increases and then decreases with the increase in acceleration, the reverse bending point of the pile appears at 5 times the pile diameter below the soil surface, and the maximum bending moment of the middle pile, corresponding to a peak acceleration of 0.05–0.3 g, is between 7.5 N·m and 47 N·m, respectively, while the maximum bending moment of the outer pile is between 6.5 N·m and 52 N·m, respectively. It is important to apply DIC image processing technology to the monitoring of landslide structure and the evaluation of slope stability in practical engineering. Full article

Anti-sliding short piles, a novel technique for slope stabilization, have been applied in engineering practices. Nonetheless, a mature structural calculation theory for these piles is still lacking. In this paper, the study presents an internal force solution model for anti-sliding short piles using the finite difference method. By extending the Euler–Bernoulli beam theory and defining boundary conditions, this study develops a set of finite difference equations for computing the structural forces of anti-sliding short piles. Furthermore, this study conducted laboratory model tests on soil landslide cases reinforced with anti-sliding short piles. By comparing the internal forces and deformations of these piles, the test validates the proposed calculation model for anti-sliding short piles. The results suggest that treating the load-bearing and embedded sections as a unified entity during the calculation process, instead of applying continuity conditions separately at the sliding surface as performed in traditional methods, simplifies the complex solving procedure. Moreover, under identical loading conditions, the displacement, bending moment, and shear force data obtained through the finite difference method closely coincide with the measurements from the model tests, confirming the reliability of the anti-sliding short pile calculation model. Additionally, this study demonstrates that reducing the spacing between nodes along the entire anti-sliding short pile, i.e., decreasing the value of the differential segment length ‘h’, results in more precise computational outcomes. This research offers valuable insights and references for sustainable solutions in the realm of geological disaster prevention and control. Full article

Pre-stressed high-strength concrete pipe piles (PHC pipe piles) have been widely used in actual soft foundation treatment projects due to their reliable quality, fast construction, assembly line production, and environmental friendliness. However, large-scale slip damage still occurs in construction projects. In order to reduce and avoid such accidents, a highway in Guangdong (section K31+100~K31+388) was taken as an example for this study. Plaxis 2D software (V22.01.00) was used to establish a PHC pipe pile composite roadbed model and investigate the effects of tie beam form, pile lengths, pile spacings, pile verticality, and embankment filling loading modes on the settlement and stability of the composite roadbed. The results show that the original treatment plan, which had the form of a PHC pipe pile with caps, had a low horizontal bearing capacity and a poor anti-disturbance ability, leading to the occurrence of a landslide accident. A comparison of different structural forms revealed that the longitudinal and transverse tie beam form was the most stable, followed by the transverse tie beam form, longitudinal tie beam form, PHC pipe pile form with caps, and PHC pipe pile form without caps. Compared to the structural form of PHC pipe piles with pile caps, the stabilities of the transverse tie beam form and the longitudinal tie beam form were improved by 42.47% and 38.61%, respectively, while that of the longitudinal and transverse tie beam form was improved by 50.87%. The application of longitudinal and transverse tie beams effectively reduced the settlement of the composite roadbed, as confirmed by both measured data and finite element analysis. This structure achieved the desired vertical settlement control and lateral anti-slip effects. Full article

In order to deeply study the mechanism of prestressed anchor anti-slide pile, an indoor model experimental device was developed, and a finite difference and particle flow numerical analysis model of slope anchor cable anti-slide pile was established based on the reinforcement project of prestressed anchor cable anti-slide pile in a mountain road slope. Based on the analysis of the force and displacement characteristics of the anti-slide pile, the influence of the prestress of the anchor cable, the inclination angle of the anchor cable, the width and column spacing of the anti-slide pile and the inclination angle of the landslide, the height and nature of the filling soil on the force and deformation characteristics of the pile are discussed, and some design parameters are optimized. Results show that the larger the prestress of the anchor cable, the smaller the displacement of the pile body, but the excessive stress is not conducive to the safety of the pile body. The optimal tension should be 50–70% of the designed tension of the anchor cable. With the increase in the inclination angle of the anchor cable, the displacement of the pile decreases first and then increases, and there is an optimal inclination angle of the anchor cable. In the double row piles, with the increase in pile spacing, the front row piles gradually change from supporting the soil between the double row piles to supporting the sliding body with the back row piles, and the double row piles are plum-shaped. When the pile spacing is 2.5 times the pile diameter, the force of the front and rear piles is the most reasonable. In the process of soil arching evolution, the influence of cohesion on the soil arching effect is greater than that of the internal friction angle. Full article

The physical and mechanical properties of the reservoir bank slope deteriorate under the fluctuation of water level, causing bank debonding and slippage, which can produce different degrees of damage to the bridge foundation, piers, and superstructure, a condition that is difficult to treat. In this paper, for a Yangtze River Bridge bank slope instability problem in the Three Gorges reservoir area, a numerical model of the bank slope and bridge was established using the finite element-SPH conversion coupling algorithm, and the pile pier damage development law and damage mode (deformation and stress–strain curves of the bank slope and pile foundation) were obtained according to the geological conditions of the bridge location. Additionally, combined with the characteristics of bank destabilization in the reservoir area of the Three Gorges Yangtze River Bridge, landslide management is proposed by using soil drainage and anti-slip pile reinforcement measures. In addition, for the characteristics of bridge pier deflection, a comprehensive deflection correction reinforcement method of pushing deflection correction, adding pile foundation, expanding pile bearing, and increasing pier cross-sectional area is proposed, so as to provide a theoretical basis for the prevention and control of reservoir bank landslides, the service life of pile structure, and the disposal of diseases. Full article

Micropile groups (MPGs), combined with the advantages of the anti-slip pile and anchor cable, offer an efficient support system that can be used as countermeasures for stabilizing the talus slopes. However, the performance of MPGs in stabilizing the talus slopes is rarely numerically investigated from the continuous-discontinuous viewpoints. To fulfil this knowledge gap, a numerical method coupled with the discrete element method (DEM) with the finite element method (FEM) is proposed first, and validated to be with good accuracy by the centrifuge model tests. A series of cross-scale analysis cases are then adopted to assess the behavior of MPG in the talus slopes, in which the influencing factors are also taken into account. The numerical results indicate that the MPGs reinforcement can significantly improve the stability of the talus slopes, avoiding the potential progressive shallow slip. For the MPGs with different pile spacing, the distribution laws of deformation and internal force are rather similar, but the one whose pile spacing is four times the pile diameter shows better performance. Moreover, the effective anchorage length of MPG is approximately 1/3 of the pile length, and the axial force distribution is influenced by the type of pile bottom constraint and the tangential contact between the micropile and the bedrock. Finally, the “bidirectional anchorage” attributed to the platform and the bedrock can greatly improve the performance of the MPG, which is a non-negligible part of the anti-slip mechanism of the MPG. This study is of great significance for facilitating the design of MPG in stabilizing the talus slopes. Full article

The accumulation slope is widely distributed in the mountainous area of China; this paper takes the slope of the Chengdu–Lanzhou Railway as the engineering background and analyzes the stability of the slope and the mechanical properties of the anti-slip pile under symmetrical train loads. First, the finite element software Midas GTS NX was used to analyze the effect of the slope after the anti-slip pile support and the stability of the slope at different pile spacings, pile row distances, and pile positions. Then, the finite element analysis results of the pile-side earth pressure and landslide thrust were compared with those of earth pressure theory, the standard method, and field-measured data. The results of this paper are as follows: (1) The anti-slip pile support increased the slope stability coefficient from 1.175 to 1.680. (2) The slope stability gradually decreased with increases in anti-slip pile spacing and pile row distance and rose first and then decreased with an increase in pile position. (3) The active earth pressure values behind the pile by Coulomb theory were slightly smaller than the finite element analysis result; the theoretical values of the passive pressure before the pile were much larger than the finite element analysis results. (4) The landslide thrust was calculated by the transfer coefficient method when the safety factor K = 1.00. The results of explicit method and implicit method were the same, which were 8–19% higher than the finite element simulation value; when the safety factor K = 1.35, the theoretical value of the explicit method was about three times the simulated value, and the theoretical value of the implicit method was about 2.3 times the simulated value. (5) The measured values verified that the simulated values had a certain degree of reliability, and the relative deviation between the two was 5–17%. Full article

In order to study the instability development process of the slope reinforced by anti-slide piles under earthquake conditions, the dynamic response characteristics of the slope are usually taken as the main characteristics, and the model test and numerical simulation are the main research methods. In this paper, a shaking table model test is designed and completed to investigate the influence of anti-slide piles with different initial damage on the failure mode of high and steep slope under earthquake conditions. The changes in velocity, strain and natural frequency during slope vibration are tested in combination with cloud maps when sinusoidal waves of different accelerations with a peak value of 5 Hz are applied. Thus, the differences of slope failure development process and dynamic response characteristics are obtained. The experimental results show that the anti-slide pile with different initial damage has obvious influence on the slope instability process. Under the condition of good anti-slide pile quality, the failure development of the slope behind the pile is limited to soil sliding on top of the slope, slope sliding and overburden sliding; the front slope foot of pile mainly forms shear belt and local sliding. With the decrease in the initial mass of the anti-slide pile, the slope failure develops into topsoil sliding, slope sliding and deep integral sliding; analogously, the failure of the slope in front of the pile develops into a whole slip along the slip belt. The natural frequency cloud map can directly reflect the damage location of the slope, and the frequency change rate is positively correlated with the cumulative shear strain. It shows that the macro-failure characteristics of the model slope change well when the natural frequency is used as the sensitive index to measure the influence of vibration on the model slope. The threshold value of the natural frequency change rate can distinguish different development stages of the slope; 1% is the threshold value of stage II, and 1.5% is the threshold value of stage III. Full article

Geocells are increasingly used in engineering applications, but the design of riverbank slope reinforcements that use only geocells limits reinforcement performance. Moreover, the design and use of anti-slide piles with geocells are mainly based on experiences that are unsupported by theoretical models. In this paper, by combining the confinement effect and vertical action mechanism of geocells, the horizontal friction mechanism of the geocell layer and the vertical support mechanism of piles, a theoretical model of riverbank slope reinforced by anti-slide piles with geocells was constructed. In addition, to describe the mechanical behavior of a riverbank slope reinforced by anti-slide piles with geocells, the slip-resisting mechanism of the anti-slide pile with interaction between geocells and their internal filler is considered in the model. Furthermore, to investigate the influence of changes in water level on riverbank slope stability, the developed model takes into account settlement, lateral displacement, pile bending moment and pile axial force. The model predications were validated by the field measurement data. The results from a series of parametric studies show that the use of anti-slide pile and geocells can effectively reduce the settlement and the lateral displacement of a riverbank slope. The developed model could contribute to an optimal design of anti-slide pile with geocells for enhancing the stability of a riverbank slope. Full article

Anti-slide piles were used in the region of the Zhenzilin landslide in Sichuan, China. The horizontal displacement of these piles exceeds specifications. Deterioration in bedrock properties may cause deformation, thereby causing landslide destabilization. An approach was developed for the analysis of anti-slide pile in two bedrocks with different strengths below the slip surface. A relationship has been established between the modulus of subgrade reaction of the first weak bedrock and reasonable embedded length for landfill slopes with strata of various strengths. Furthermore, the influence of embedding length on deformation has been studied to determine the reasonable embedded length, which helps reduce deformation and ensure landslide stability. The results reveal that (1) at a constant embedded length, horizontal displacement increases with the thickness of the first soft bedrock, meanwhile the maximum shear force remains constant, and the bending moment first increases followed by subsequent decrease; (2) with an increase in the embedded length, horizontal displacement and the maximum shear force of the pile in the embedded bedrock decrease, whereas the bending moment increases; (3) the maximum internal forces and horizontal displacement increase with a decrease in the subgrade reaction modulus of the first weak rock; and (4) the reasonable embedded length of an anti-slide pile increases with a decrease in the subgrade reaction modulus of the first weak bedrock. The proposed approach can be employed to design anti-slide piles in similar landslide regions to control pile-head deformation. Full article