Anti-slide Pile Research Articles

Examining dynamic soil pressures and the effectiveness of different pile structures inside reinforced slopes using shaking table tests

To study the distribution and variation of dynamic soil pressures in reinforced soil slopes and the effectiveness of different stabilizing structure types, we conducted a series of shaking table tests on soil slopes reinforced by two types of stabilizing structures: constrained anti-slide pile (beam-pile) and pre-stressed anchor slab-pile walls (anchor-pile), under different shaking intensities. Through examining the recorded dynamic responses (the soil pressures and accelerations measured at different locations in model slopes) and the observed post-test behaviors in the slope models, we analyzed the distributions of response dynamic soil pressures, accelerations, spectral displacements (Sd) and the displacements and inclinations for two stabilizing structure models under different shaking intensities. We found that the frequency contents of the dynamic soil pressures change with a shift in the predominant frequency in the spectrum under high shaking intensity, and the changes in the dynamic soil pressure mainly occur on those components in some relatively low frequency bands, and we infer that these changes may mainly result from the change in the response acceleration within the reinforced slope. Finally, through comparing the spectral displacements in slopes, the measured displacements and the inclinations of pile blocks under different shaking intensities, we found that anchor piles can better support the slope than beam-piles, under similar shaking conditions. These results help us better understand the features of the dynamic soil pressures and also provide evidence to select stabilizing structures for reinforcing the slope against earthquakes.

The influence of the second row of piles in double-row pile retaining walls with the stabilization of landslide

In the practice of designing anti-landslide pile structures along with the single-row walls find use in General multi-row two-row and retaining walls. This assumes that the second row of piles will greatly enhance the bearing capacity of retaining structure. The joint work of the piles in the rows and methods of their calculation are presented in a number of works of domestic and foreign. At the same time conditions the most effective use of the second row in the double row pile retaining walls remain to be studied. Since double-row pile retaining wall, the combined grillage represents a frame of flexible piles on an elastic Foundation, the load distribution between the piles from the existing on the wall of landslide pressure will depend on the flexibility of the piles, the ordinates of the load from the landslide pressure on the first row, the soil properties of landslide slope. To determine the valid picture of the work of anti-slide pile structures was tasked to establish the role of the second row in the work of double-row pile retaining walls. The article presents the results of analytical studies frame construction flexible piles, the combined grillage hard, perceiving landslide pressure. Effective capacity utilization of the second row of piles was assessed using the utilization of the bearing capacity of piles second through 4,000 different designs double row of walls made of piles of various cross-sections, length, their reinforcement, the depth of application of landslide pressure, as well as with different variants of soil conditions. Due to the significant complexity of the implementation many variants of the analytical calculations were carried out with the use of computers.

Load-computational methods of anti-slide piles

Anti-slide piles composed of reinforced concrete are commonly used in landslide mitigation engineering. How to calculate the load acting on the piles plays a crucial role in their design process. To estimate the load exerted on anti-slide piles based on the partial safety factor numerical method and limit equilibrium method, the landslide body is subdivided into two independent parts according to the positions of piles: the lower part of the landslide body and the upper one of the landslide body. The corresponding loads acting on the anti-slide piles are respectively computed, and the shear strength of the upper section of the landslide body can be determined according to the given designed safety factors. The locations of the piles are set as the fixed boundary, and the horizontal stress exerted on the anti-slide piles from the upper one of the landslide body is taken as the landslide thrust. The thrust forces are then applied to the lower portion of the landslide body, and the maximum force that the lower of the landslide body can effectively resist, and that satisfies well the given designed safety factors is taken as the maximum resistance of the lower portion of the landslide body. Comparing the results of the numerical computational method, the strict slice method and transfer coefficient method, it is found that the computational results agree well with each other. However, the numerical computational method is employed here in this research because the load distribution can be directly derived, which favors the subsequent calculation process and shortens the computational time.

Experimental and numerical studies on the deformation response and retaining mechanism of h-type anti-sliding piles in clay landslide

This paper performs systematical studies on deformation response and retaining mechanism of a novel retaining structure, i.e., an h-type anti-sliding pile, which has been used to stabilize slopes in mountain areas. The present systematical studies can be divided into two parts, including experimental studies and numerical investigations. Firstly, the physical scale model tests are conducted to study the effect of anchor depths on distributions of sliding thrust and resistant forces on the h-type anti-sliding pile in clay landslides. Four kinds of h-type anti-slide piles with different anchor depths are tested in the physical scale clay slope subjected to static loads. Secondly, the above four physical models are simulated using finite element method. The numerical results are in good agreement with the experimental data, which prove the ability and accuracy of the present numerical simulations. In addition, several different numerical models are performed to investigate the effects of sliding surface angles, crossbeam lengths and different anchor depths on the deformation response and retaining mechanism of h-type anti-slide piles in the clay slope under static loads. It can be found from experimental and numerical results that deformation responses and retaining mechanism of h-type anti-sliding piles are not only related to sliding surface angles, but also related to crossbeam lengths and anchor depths. Finally, some design suggestions of h-type anti-slide piles are proposed based on the experimental and numerical studies. This work is expected to improve understanding of h-type anti-slide piles in clay landslide and to provide some references to engineers in design.

Analysis of the Influence of Anti-sliding Pile on Slope Stability Under Action of Groundwater

In order to effectively reinforce the slope of rich groundwater, the reinforcement effect of anti-slide pile on this kind of slope is studied through OptumG2 simulation. This paper firstly simulates the influence of groundwater on the slope of anti-slide piles, and then the position of optimal pile position on different slope under groundwater is explored. The results show that the groundwater has a great influence on the slope of the reinforced slope, and the best pile position of different slope is different.

Mechanical Response of a Novel “Anti-slide Pile + Support Column” Composite Retaining Structure

Mechanical Response of a Novel “Anti-slide Pile + Support Column” Composite Retaining Structure

Field monitoring and deformation characteristics of a landslide with piles in the Three Gorges Reservoir area

Landslides often occur within the reservoir area behind dams. In China, a common strategy for stabilizing these landslides is to install large piles through the landslide and into the stable ground below. The piles interact with the landslide and constitute a landslide-stabilizing pile system. The deformation of this system under the reservoir operation is more complicated than the deformation of the landslide itself. Understanding the behaviour of this system is very important to the long-term safety of landslides stabilized with piles in reservoirs. The Majiagou landslide, which was selected as a case study, was triggered by the first impoundment of the reservoir behind the Three Gorges dam. A row of anti-slide piles was installed in the landslide in 2007, but monitoring results found these were ineffective at stabilizing the landslide. Subsequently, in 2011, two longer test piles and an integrated monitoring system were installed in the landslide to better understand the failure mode of the landslide and to measure the deformation characteristics of the landslide-stabilizing pile system. Monitoring results show that the Majiagou landslide is a translational landslide with three slip surfaces. The test piles provided local resistance and partially slowed down the sliding mass behind the piles, and the landslide deformation response to external factors decreased for a time. However, after 2 years, the deformation of the landslide-stabilizing pile system reverted to seasonal stepwise cumulative displacements influenced by cycles of reservoir drawdown and rainfall. The monitoring results provide fundamental data for evaluating the long-term performance of anti-slide piles and for assessing long-term stability of the stabilized landslide under the reservoir operation.

H型抗滑桩室内物理模型实验研究

h型抗滑桩室内物理模型实验研究

Progressive Deformation on Defective Pile Reinforced Slope

The slopes reinforced by anti-slide piles were simulated in this paper. The setting position, pile spacing and anchorage depth of integrated piles were discussed with strength reduction method. The results show that the pile position should depart slope into two stages, and the further strain would be limited. When the spacing of the anti-slide piles is 2-3 times of pile diameter, it has a soil arching effect to wedge the soil. The anchorage depth can affect the form of the potential sliding surface. Three kinds of defective piles were studied to research deformation of slope reinforced by defective piles. The defective piles were namely expanded pile, necking pile and segregationpile. The equivalent plastic strain zone was used to judge the slope failure, and then the stability and deformation process of the three-dimensional slope were simulated. By comparing the plastic strain, safety coefficient curve and pile-soil stress curve, between the defective pile and integrated pile, the progressive failure process of the reinforced slope was analyzed, including the formation process of the macroscopic shear zone.

Limit analysis on seismic stability of anisotropic and nonhomogeneous slopes with anti-slide piles

This study employs the limit analysis method to evaluate the seismic stability of anisotropic and nonhomogeneous slopes stabilized with anti-slide piles. The pseudo-static approach is used to simplify the earthquake load. The yield seismic acceleration factor is obtained from the optimization procedure and the results are verified with the published data. Then, the seismically-unstable slope is reinforced with anti-slide piles, and the seismic stability of the reinforced slope is explored. The results show that the anisotropy and nonhomogeneity of soils have significant effects on the stabilizing force required from the anti-slide piles and the optimal location of the pile is near the toe of the slope.

Physical test study on double-row long-short composite anti-sliding piles

The double-row long-short composite anti-sliding piles system is an effective way to control the landslides with high thrust. In this study, The double-row long-short composite anti-sliding piles with different load segment length (cantilever length) and different pile row spacing were studied by a series of physical tests, by which the influences of load segment length of rear-row piles as well as pile row spacing on the mechanical response of double-row long-short composite anti-sliding pile system were investigated. Based on the earth pressures in front of and behind the piles obtained during tests, then the maximum bending moments of the fore-row and the rear-row piles were calculated. By ensuring a equal maximum moments in the fore-row and the rear-row piles, the optimum lengths of the rear-row piles of double-row long-short composite system under different piles spacing were proposed. To investigate the validity of the reduced scale tests, the full-scale numerical models of the landside were finally conducted. By the comparisons between the numerical and the physical test results, it could be seen that the reduced scale tests conducted in this study are reliable. The results showed that the double-row long-short composite anti-sliding piles system is effective in the distribution of the landslide thrust to the rear-row and the fore-row piles.

A back-propagation neural-network-based displacement back analysis for the identification of the geomechanical parameters of the Yonglang landslide in China

Xigeda formation is a type of hundred-meter-thick lacustrine sediments of being prone to triggering landslides along the trunk channel and tributaries of the upper Yangtze River in China. The Yonglang landslide located near Yonglang Town of Dechang County in Sichuan Province of China, which was a typical Xigeda formation landslide, was stabilized by anti-slide piles. Loading tests on a loading-test pile were conducted to measure the displacements and moments. The uncertainty of the tested geomechanical parameters of the Yonglang landslide over certain ranges would be problematic during the evaluation of the landslide. Thus, uniform design was introduced in the experimental design, and by which, numerical analyses of the loading-test pile were performed using Fast Lagrangian Analysis of Continua (FLAC3D) to acquire a database of the geomechanical parameters of the Yonglang landslide and the corresponding displacements of the loading-test pile. A three-layer back-propagation neural network was established and trained with the database, and then tested and verified for its accuracy and reliability in numerical simulations. Displacement back analysis was conducted by substituting the displacements of the loading-test pile to the well-trained three-layer back-propagation neural network so as to identify the geomechanical parameters of the Yonglang landslide. The neural-network-based displacement back analysis method with the proposed methodology is verified to be accurate and reliable for the identification of the uncertain geomechanical parameters of landslides.

Analysis of the Soil Arch Effect of the Mechanical Rotary Bored Anti-slide Piles and Ultimate Arch Thickness Calculation

Analysis of the Soil Arch Effect of the Mechanical Rotary Bored Anti-slide Piles and Ultimate Arch Thickness Calculation

Effectiveness of Fiber Bragg Grating monitoring in the centrifugal model test of soil slope under rainfall conditions

Centrifugal model tests are playing an increasingly important role in investigating slope characteristics under rainfall conditions. However, conventional electronic transducers usually fail during centrifugal model tests because of the impacts of limited test space, high centrifugal force, and presence of water, with the result that limited valid data is obtained. In this study, Fiber Bragg Grating (FBG) sensing technology is employed in the design and development of displacement gauge, an anchor force gauge and an anti-slide pile moment gauge for use on centrifugal model slopes with and without a retaining structure. The two model slopes were installed and monitored at a centrifugal acceleration of 100 g. The test results show that the sensors developed succeed in capturing the deformation and retaining structure mechanical response of the model slopes during and after rainfall. The deformation curve for the slope without retaining structure shows a steep response that turns gradual for the slope with retaining structure. Importantly, for the slope with the retaining structure, results suggest that more attention be paid to increase of anchor force and anti-slide pile moment during rainfall. This study verifies the effectiveness of FBG sensing technology in centrifuge research and presents a new and innovative method for slope model testing under rainfall conditions.

Stability Analysis of Slope Under Rainfall Infiltration and Optimal Design of Anti-slide Pile

Based on practical slope engineering, analysis model of seepage-stress coupling under continuous rainfall condition was established by Geo-Studio (geotechnical analysis software). The dynamic change process of slope safety factors with time was analyzed. The results show that in the same Infiltration, slope under small intensity but long duration rainfall has lower safety factor and higher risk. In this unfavorable condition, analyzed and optimized the retaining structure of the antislide piles, and puts forward the optimization of landslide treatment scheme and the rainfall instability threshold of the slope. The practical application shows that the treatment effect is obvious. The analysis method is simple and practical, which can provide reference for similar slope engineering analysis and management.

Analysis on the best position and the pile distance of anti-slide pile of reinforced soil slope

Regarding numerical calculation convergence and plastic zone through the slope as the criterion of slope instability, strength reduction method as calculating principle, the stability of soil slope was analyzed by using finite element software ABAQUS, and on the basis of analysis, the best position and pile distance of anti-slide pile of reinforced soil slope were studied. The numerical results showed that with the increasing of distance between anti-slide pile and toe position, safety coefficient raised firstly and then decreased, when the ratio between the horizontal distance of anti-slide to slope toe and horizontal distance of slope is around 0.6, which is the largest safety factor; The pile spacing had certain influence on the soil slope safety factor, with the different pile spacing, the safety factor was different. With the increase of the pile spacing, the safety factor decreased gradually.

Retaining mechanism and structural characteristics of h type anti-slide pile (hTP pile) and experience with its engineering application

Since the 1980′s a new h form type anti-slide pile (hTP pile) has been used to stabilize slopes. This paper describes the first systematic studies about the retaining mechanism and applicability of the hTP, on the basis of the analysis of the soil-pile interaction. Similar retaining structures such as the portal anti-slide pile – PASP and other traditional retaining structures as the anchored anti-slide pile – AASP, the common anti-slide pile – CASP are also considered in this study to analyze the differences between their behavior and that of the hTP and other structures. This study, also analyzes the economy and technology of its construction. Post construction monitoring is conducted to evaluate its final retaining effect. The results show that the retaining mechanism of hTP can be attributed to the form of the structure, the soil mass between the two rows of piles and the soil mass downslope of the hTP. All together they greatly improve the hTP's retaining effect over the traditional structures. The stress distribution of hTP is more appropriate than for the traditional types of retaining structure's due to a decreased stress concentration effect. From economic point of view, the hTP's is also to be preferred over other types of retaining structures. The post construction monitoring results show that when supported by hTP, the slope tends to be stable because a good retaining effect is obtained.

涪陵江东边坡治理方案有限元分析

边坡失稳易导致山体滑坡，抗滑桩被广泛应用于边坡治理工程中。依托于涪陵江东边坡治理工程，结合群桩承台基础、扶臂式挡墙及斜坡护岸结构体系对边坡进行治理。选取典型剖面建立计算模型，采用有限元程序CORE3D针对边坡在结构体系作用下的变形与稳定性进行了计算，对比分析了4排桩与5排桩体系作用下滑坡体与抗滑桩的变形与受力特性，为工程实践提供参考。研究结果表明：与5排桩结构体系相比，4排桩体系作用下边坡、挡墙的竖向与水平向位移较大；抗滑桩最大主拉应力与压应力亦较大。抗滑桩表现出明显的“S形”变形，并形成土拱效应。滑坡体单宽推力自后缘起逐渐增加，至抗滑群桩前推力达到峰值。推荐采用4排桩方案，注意在节点处加强纵向受力钢筋与箍筋作用。 Slope instability is easy to cause landslides, and anti-sliding piles are widely used in slope treat-ment. Based on the slope treatment project of the eastern Fuling River, the slope was treated by the system which coupled the pile groups, retaining wall and the slope revetment structure. The calculation model of the typical profile was established, and the finite element program CORE3D was used for calculating the deformation and stability of slope, and the deformation and stress characteristics of landslide and anti-sliding piles were compared between 4 piles and 5 piles sys-tem, which provide a reference for engineering practice. The results show that compared with the 5 piles system, the vertical and horizontal displacement of the slope and the retaining wall of the 4 piles system were larger, and the main tensile stress and compressive stress of anti-sliding pile were larger too. The anti-sliding piles showed “s-shaped” deformation, and the soil arching effect was formed. The single wide thrust of the slope increases gradually from the post, and attained the peak before the anti-sliding piles. It is recommended that 4 pile system is better, and the longitudinal rebar and stirrup at the nodes should be reinforced..

某施工诱发牵引式滑坡的稳定性分析及防治

牵引式边坡滑坡是高速公路建设中常遇到的边坡灾害类型之一。K7滑坡为一发生于贵州省江口至瓮安高速公路境内的中型滑坡，是由于工程建设而引发的牵引式滑坡。基于工程地质分析法，对该滑坡的工程地质条件、滑坡稳定性影响因数及破坏机制进行了分析，通过计算该滑坡的稳定性系数及定量地评价开挖及降雨对滑坡稳定性的影响，得出该滑坡在开挖及降雨作用下处于不稳定状态，且开挖和降雨都会对安全系数及稳定性状态产生较大的影响。并对该滑坡采取了抗滑桩、排水、封闭坡体裂缝相结合的加固措施。通过监测表明，K7滑坡原因分析正确，综合治理方案合理。 Retrogressive landslide is one of the common types of slope disaster in the highway construction. K7 landslide caused by engineering construction is a medium landslide which occurred in highway of Jiangkou to Weng’an in Guizhou province. Based on the engineering geology analysis, the engineering geological conditions of the landslide, the landslide stability influence factor and failure mechanism was analyzed. Furthermore, we calculated the landslide stability coefficient and evaluated the influence of excavation and the rainfall on landslide stability quantificationally, coming to the conclusion that excavation and rainfall had great influence on state stability and the stable factor of the landslide , and the excavation and rainfall will larger influence on safety coefficient and stability state. And we took the comprehensive management measures including anti-slide pile, drainage, closing the cracks of the slope and so on to treat the landslide. The monitoring results show that the cause analysis of the K7 landslide is correct, and the comprehensive treatment scheme is reasonable.

RESEARCH ON NEW TYPE EPS ANTI-SLIDE PILE AND LARGE-SCALE SHAKING TABLE CONTRAST TEST

Anti-sliding pile is a common engineering method in treatment of geological hazards, which is widely used in rail, road, and water conservancy engineering. And engineer pay more and more attention to the seismic problem of this anti-slide structure, it has already been an important research direction to study how to improve the seismic performance of retaining structures. Currently, it has caught the engineers' attention and achieved good results to improve the seismic performance by adding EPS flexible materials to engineering. Based on this, in order to improve and meet seismic performance request of anti-sliding pile in engineering, EPS material is applied to anti-sliding and a new anti-sliding is designed called EPS pile. By shaking table test, the dynamic response and seismic performance of EPS pile and ordinary pile indoor are researched and compared. Conclusions could be drawn from trail that:(1) the acceleration magnified effect is different with different seismic waves; with more lager EL seismic peak acceleration, the more obvious of acceleration magnified effect; (2) the acceleration magnified effect of ordinary pile is more obvious than of EPS pile under the same peak acceleration of seismic wave.(3) Pile head angle and acceleration magnified effect show that: EPS anti-sliding has better seismic performance; EPS material can clearly improve the passive earth pressure of anti-sliding pile under pole shaking condition and Bi-directional vibration.(4) Besides, it can be found in this experimental that sliding surface cracks to the deep extension and may induce deep sliding with the increase of seismic wave speed.