Anti-slide Pile Research Articles

Effect of the inclined pile-soil arch in a soil landslide reinforced with anti-sliding piles

Aiming at the stability of a highway slope reinforced with anti-sliding piles, the mechanical behaviour of the inclined pile-soil arch in a soil slope reinforced with anti-sliding piles was analysed. Based on the pile-soil arching effect, a mechanical calculation model of the inclined pile-soil arch was established. According to the limit equilibrium condition of the inclined pile-soil arch, the analytical solution for pile width on the vault was obtained when the earth pressure on the pile side was distributed in triangular and parallelogrammic shapes. Based on the positional relationship of the vault of the pile-soil arch axis, the equations for inclined and horizontal pile-soil arches and the corresponding arching conditions were obtained. Analysis of a case study indicated that the sliding force of the pile-soil arch, pile width, cohesion, and internal friction angle of soil all influenced the arching condition of the inclined pile-soil arch and the designed pile spacing. When the sliding force exceeded 3500 kN/m, the calculated results according to the inclined pile-soil arch and horizontal arching models could not satisfy the arching condition. When the sliding force exceeded 2000 kN/m, the clear pile spacings calculated according to the inclined and horizontal pile-soil arch models were similar; in the case that the internal friction angle exceeded 15°, the clear pile spacings calculated based on the two models were similar; at a low internal friction angle, the results calculated according to the two models could not satisfy the arching condition; at a large internal friction angle, the results calculated based on the inclined pile-soil arch could satisfy the arching condition, while those based on the horizontal arching could not; when the pile width was less than 1 m, the results calculated based on the above two models could not satisfy the arching condition. Therefore, it is more reasonable to perform analysis by utilising the equation for the inclined pile-soil arch and the pile spacing calculated when the pile-soil load was distributed in triangular form was lower than that when the pile-soil load was distributed in parallelogrammic shape.

Arch Antislide Pile-Wall Structure System: Model and Optimization

For the problems of unreasonable force and large deformation of traditional antislide structure system, three new arch antislide pile-wall structure systems are designed for a loess landslide treatment project in Northern Shanxi province. The working performances of four kinds of antislide structures are numerically simulated and analyzed to realize the optimization of the antislide structure system. The results show that the arch antislide pile-wall structure system is a rigid connection between the piles and cap beam, and the antislide pile, cap beam, and sliding bed soil form a spatial nearly rigid structure. Cap beam can better transfer the bending moment generated by the larger thrust in the landslide middle to the piles with less force on both sides of the landslide, so that the stress and deformation of the whole antislide system tend to be uniform, which makes the antislide system “joint operation.” And this structural form increases the overall stiffness and bending capacity and reduces the possibility that the middle pile is destroyed first and loses its working capacity due to large thrust. Compared with the traditional antislide structure system (Model-1), the average displacement of the pile head is reduced by about 60%, and the total control bending moment of the system is reduced by about 6%. The purpose of Model-3 and Model-4 (anchorage arch antislide pile-wall structure system and pull-rod arch antislide pile-wall structure system) is to restrict the deformation of cap beam in both positive and negative directions of x-axis in arch antislide pile-wall structure system, which plays a certain role in coordinating the deformation of antislide structure and better coordinating the stress of each pile. The arch antislide pile-wall structure system (Model-2), anchorage arch antislide pile-wall structure system (Model-3), and pull-rod arch antislide pile-wall structure system (Model-4) can better adapt and adjust the unbalanced thrust between the landslide piles; therefore, they have higher structural robustness than that of traditional antislide structure system. When achieving the management target with a 95% structural reliability probability of the same landslide, the structural robust degrees of Model-1, Model-2, and Model-4 are 0.58, 0.76, and 0.81, respectively. Therefore, the pull-rod arch antislide pile-wall structure system (Model-4) has the best performance among the other antislide structures. These studies lay a foundation for the engineering structural optimization of arch antislide pile-wall structure system.

Application of circular anti slide pile with plum blossom arrangement in Expressway Engineering

By using the finite element numerical simulation method, the simplified Bishop method and strength reduction method are used to analyze the stability of a high slope which is protected and treated by anti slide pile combined with prestressed anchor cable grading scheme in Guangdong Province, and the similarities and differences between rectangular pile and plum shaped circular pile in slope treatment effect are compared. Through calculation and analysis of field measured data, it is proved that the circular anti slide pile with plum shaped layout has similar effect with the traditional rectangular anti slide pile, and has the advantages of high degree of mechanization construction and low construction safety risk, so it can be used as the alternative scheme of rectangular pile

Internal Force of the Anti-slide Pile in Soil Based on the Deep Beam Model

According to the deep beam model, the bury conditions, the geometry characteristics and the load condition, we established a load transfer model based on the tie rod arch and an internal force model for the loaded and anchored segments of the anti-slide pile. Then, we analyzed the shear, bending shear and local compressive failures of the pile, caused by the equivalent concentrated thrust force, the lateral frictional force, active earth pressure, and passive earth pressure, etc. With the laboratory results of the deep beam model, the relation between the shear span ratio and the tie rod arch was presented. According to the mechanical balance conditions of the cantilever beam, we obtained the power function curve of the tie rod arch and the influence factors. Subsequently, we established the equations of the horizontal displacement and the deflection angle at the bearing segment by superposing the load and the displacement of the strip nodes. According to the deformation characteristics of the Timoshenko deep beam element, the equations of the horizontal displacement and the deflection angle at the anchored segment were proposed. With the established calculation model and the material mechanics, the displacement, shear force and bending moment curves at the loaded and anchored segment of the anti-slide pile were proposed. Finally, the case study indicates that the displacement and the internal forces are nonlinear in the pile. The results obtained using the preliminary beam are larger than the numerical results, which is the smallest results than the other two methods.

Shaking Table Tests on a New Antislide Pile under Earthquakes

A retaining form of a shock-absorbing antislide pile is proposed for slope engineering. A flexible material (shock-absorption layer) is filled in front of an ordinary antislide pile, which is used to absorb a large amount of seismic energy, thereby decreasing the transmission of seismic energy to the antislide pile. The flexible material thus reduces the seismic response, hence improving the aseismic capacity of the antislide pile. To verify the seismic performance of the shock-absorbing antislide pile, a shaking table contrast test was conducted and the results were compared with those from an ordinary antislide pile. The test results show that the flexible material absorbs a portion of the seismic deformation of the slip mass, decreasing the final displacement of the shock-absorbing antislide pile compared to that of the ordinary antislide pile, thereby reducing the sensitivity of the pile body to the displacement. Under the same conditions, the acceleration response of the slope body at the same height is lower for the shock-absorbing antislide pile than that for the ordinary pile, with the seismic performance of the former being superior to that of the latter. Furthermore, the shock-absorbing antislide pile is similar to the ordinary pile in terms of the dynamic earth pressure distribution form of the pile shaft; however, its value is relatively smaller, and the former exhibits better dynamic stress performance than the latter. The test results should prove useful for aseismic design of slopes.

Characteristics and emergency mitigation of the 2018 Laochang landslide in Tianquan County, Sichuan Province, China

This paper describes a recent landslide event, which occurred at Liucheng village in Tianquan County, Sichuan Province, China, on July 15, 2018. The Laochang landslide described in this research is an outstanding and valuable reference for understanding the characteristics of such kind of landslides that are geologically similar to the landslide. The deformation characteristics of the landslide are investigated based on field investigations, drilled boreholes, and exploratory trenches. The 225 residents of 64 households living on the flat platform were threatened by the landslide. Therefore, to guarantee the safety of human life and property becomes the primary emergency task. The anti-sliding piles were taken to stabilize the landslide and mitigate impacts caused by the landslide. Based on the analysis of the monitoring data, the effectiveness of anti-sliding piles is evaluated. The results indicate that the anti-sliding piles are effective in increasing the stability of the landslide, and this work can provide a reference for similar slope engineering projects.

Analysis of loess landslide mechanism and numerical simulation stabilization on the Loess Plateau in Central China

Loess landslides have complicated deformation mechanisms. Accurately describing the internal failure deformation of loess landslides and establishing a theoretical method of landslide instability evaluation for the prevention of subsequent landslides have become important topics in western development project construction in China. This paper presents a case study of the Zhonglou Mountain landslide in Shaanxi Province, China. Based on field investigation results, a two-dimensional stability analysis model was constructed using the finite element method. Taking the deformation characteristics of the landslide as the research basis, the distribution laws of the displacement, stress, and shear strain of this landslide were identified with the strength reduction finite element numerical simulation method. Additionally, the safety factor was evaluated under normal and storm conditions. The numerical simulation results show that the horizontal tensile stress of the landslide was mainly distributed in the middle and upper parts of the landslide under normal conditions, while the vertical tensile stress was distributed near the sliding surface. Under heavy rainfall, the sliding force increased, and the anti-sliding force and anti-sliding section decreased; the location of the maximum shear strain shifted down from the middle and upper parts of the landslide body to the area with a shear crack, and the plastic shear strain area expanded along nearly the entire the sliding surface, leading to the occurrence of a landslide. Thus, the use of anti-slide piles to stabilize the landslide was proposed and tested. Monitoring points were arranged along the sliding surface to evaluate the displacement, stress, and strain responses. The on-site observation results agreed with the modeling results. The use of anti-slide piles was demonstrated to be an effective stabilization method for the Zhonglou Mountain landslide.

Model Test of Interaction Between Load-Caused Landslide and Double-Row Anti-slide Piles by Transparent Soil Material

The double-row anti-slide pile is one of the main measures for treating medium and large-scale landslides. However, the pile–soil interaction mechanism and the influence of the row spacing and the pile spacing on the interaction are not very clear in the process of the load-caused landslide evolution. Based on the interaction model test of the double-row anti-slide pile and the load-caused landslide is carried out by using transparent soil model technology. The research results show that the transparent soil technology has advantages in capturing “wave-type” distribution of the displacement isoline and studying the pile–soil interaction and the soil arching effect in the landslide. The pile–soil interaction process can be divided into three stages, the initial deformation stage, the soil arch stability stage, and the deformation stage of the soil arch. With the increase in the row spacing, the reinforcement effect of the front pile to the rear pile is weakened. With the increase in the pile spacing, the phenomenon of soil flow around piles is more likely to happen. Pile spacing has a significant effect on landslide displacement control. And when the row spacing and the pile spacing are too large, there is no soil arch stability stage in the process of the landslide evolution. The conclusion has specific guiding significance for engineering practice.

A laboratory and field-monitoring experiment on the ability of anti-slide piles to prevent buckling failures in bedding slopes

Buckling failure is a special form of a landslide, and it has been little debated in the literature so far. There have been few studies conducted on this type of slope failure, and the corresponding reinforcement measure research has also been rarely conducted. Therefore, it is nearly impossible to provide systematic guidance for the reinforcement and monitoring of such a slope. In this study, a new type of slope test system is developed, and the reinforcement effect of double-row piles was studied using simplified laboratory tests. Under the conditions of no pile and piles, load tests on the sliding body were carried out, and the ultimate loads that can be borne by the slope sliding body under these two conditions were analyzed. The multivariate information evolution of stress, displacement, and pile deformation under these two conditions were studied using multiple monitoring methods. The results showed that anti-slide piles can significantly improve the ability of the sliding body to withstand external loads. For the condition of no piles, 4 kN/m (20.55 kPa) was the critical value and the critical load the slope could bear reached 10 kN/m (51.38 kPa) after the installation of piles. The first row of piles withstood more load than the second row of piles, and double-row pile reinforcement can effectively improve the anti-slip safety reserve. In addition, monitoring of the deformation of the slope and anti-sliding piles should focus on the position of the sliding body and the slip face. Based on the results of laboratory tests, on-site field monitoring was then conducted on the target slope, including displacement monitoring at different positions on the slope before and after anti-slide pile construction, deformation monitoring of anti-slide piles, and rock stress monitoring around anti-slide piles. Monitoring results showed that the slope deformation and rock mass stress tended to be stable after anti-sliding pile construction, and the anti-slide piles were conducive to a safe state. The results of this study provide a useful reference for the reinforcement and monitoring of buckling failure in an actual slope.

The Anti sliding Mechanism of Adjacent Pile‐Anchor Structure considering Traffic Load on Slope Top

In view of the fact that the anti sliding effect analysis of the current anchor cable and anti slide pile structure is not yet complete, research on the synergy mechanism of adjacent pile‐anchor composite structures under traffic load is carried out. Firstly, a free vibration analysis for the slope dynamic model is carried out by using a three‐dimensional finite element numerical simulation method. By improving the slope boundary conditions of time‐domain analysis, the time‐domain equation of the dynamic model of traffic load acting on the top of the slope is solved accurately, and the response law of the internal force of the pile anchor composite structure is also described. The mechanism by which the pile anchor composite structure resists against the slope sliding through the internal force increment is proposed: this internal force increment is estimated to be 73.4%, while that of anchor cable is 26.6%. The composite structure presents the coordinated sharing for sliding force. The internal force of the lower row of anchor cables is 89.48 kN larger than that of the upper row, and the internal force increment is four times larger, indicating that the lower anchor cable is more effective in slope reinforcement. As the deformation at the top of the slope is greater, the prestress of the upper anchor cable should be increased to avoid the “chain failure” caused by excessive deformation. As a result, the coordination law of internal force of pile anchor is revealed, and the anti sliding sharing mechanism is clarified. A design idea of the adjacent pile‐anchor composite structure is proposed, which takes 0.2‐0.3 times the remaining sliding force as the design value of prestressed anchor cable. The idea fully considers the anti sliding effect of prestressed anchor cables and reduces the design size of anti slide pile section, providing a theoretical support for optimization design of combined anti slide structure and saving project investment.

Research on the Interaction Mechanism between Landslide and Tunnel Engineering

The landslide at the entrance of a railway tunnel is large scale, and serious diseases are prone to appear under natural disasters, which threaten the safety of the tunnel. According to its characteristics, on‐site long‐term monitoring experiments and numerical analysis were carried out, and the mechanism of interaction between landslide and tunnel engineering was analyzed. The results show that under the impact of rainfall and earthquake, the original internal stress balance in the landslide body is disturbed, leading to the increase in landslide thrust and damage of the tunnel lining. Simultaneously, the excavation of the tunnel can slack the surrounding rock to increase the landslide thrust and make the landslide be finally formed; this landslide conversely acts on the tunnel, resulting in deformation and destruction of the tunnel. During the monitoring, under the influence of rainfall and earthquake, the stress of the secondary lining was continuously increased by 25%. Tunnel construction caused a maximum deformation of 30 mm in the antislide pile at a distance of 2.12 m, and the slope and the tunnel were also affected. Under extreme conditions such as rainfall and earthquake, shear failure occurred at the vault, bottom, and waist of the right‐line tunnel located at the junction of soil and rock; at this time, the tensile strength of the tunnel reached 93.8% of the limit value of concrete, which seriously affected the safety of the tunnel. As for the weakened tunnel structure, measures such as dense planting and strengthening of concrete strength should be adopted to enhance the safety of the tunnel structure.

Underground Structure Inspection in Geological Groundwater Environment Base on Geologic Radar Technology

How to accurately detect the anti-slide pile and the surrounding rock hole is the key to the correct application of the concrete quality treatment method, at the same time, it can ensure the control effect to a certain extent, and make the treatment project more economical and effective. The presence of water in the reinforced concrete layer, coupled with the void shape, and the irregular nature of the water in the hole, may be filled with air, mud, soil and other media factors, so there is considerable complexity. The number of abnormal bodies in the contrast enhancement diagram increases significantly, which is helpful for us to observe the loose area of anti-slide pile. We can find the pixel value corresponding to the feature by detecting the abnormal data of the pile one by one.

Analysis of High Slope Seepage Influence Based on Multi-scale Measurement Data

In order to study the influence of seepage on high slope stability, the impact of drainage hole blockage on slope stability is analyzed by in-situ test technology, near-field photogrammetry and indoor test and numerical simulation.According to the groundwater monitoring of the water meter and pore pressure meter, when the drainage hole blockage exceeds 80%, the pore water pressure increases by about 13m, by 25kPa; is monitored by the steel gauge and anchor gauge. When the drainage hole blockage exceeds 80%, the shear force of the slope anti-sliding pile increases by 20%, about 30kN; analyzes the slope deformation by the near-view photography technique, when the drainage hole blockage exceeds 80%, and the slope deformation of 44mm, exceeds the slope deformation warning value of 30mm,.After theoretical calculation and numerical simulation analysis, the groundwater level and support structure under different blockage conditions. Numerical simulation results show that when the drainage hole is less than 60%, the supporting structure and slope deformation grow linearly, while when the blockage degree exceeds 80%, the support structure increases sharply, and according to the finite element strength, when the blockage degree exceeds 60%, the slope stability coefficient decreases sharply and the risk of instability.

抗滑桩合理桩间距分析

抗滑桩合理桩间距分析

Correspondence analysis method of anti-slide pile information monitoring and slice model

In order to effectively grasp the real-time working status of anti-slip piles and the reinforcement effect of slopes, timely information monitoring of anti-slip piles is carried out, and the reinforcement range is modeled, and the analysis and evaluation method of slicing model numerical calculation and information monitoring data is proposed, and the information monitoring data is compared with numerical simulation to achieve effective grasp of By comparing the information monitoring data with the numerical simulation, we can effectively grasp the timely working condition of the anti-slip pile and the reinforcement effect of the soil around the pile. This is a very important engineering practice for the evaluation of anti-slip pile reinforced slope areas.

Deformation of Combined Retaining Structure in Geological Environment

As a new type of sliding support structure, composite support structure has excellent performance. It is a structure in which two rows of reinforced concrete piles are placed in an appropriate position and the front pile head is connected with the back pile body by a rigid beam. It will form a double row spatial structure, similar to the seating. h-type anti-slide pile can save (or even do not need) anchoring components, form a double-row pile supporting structure system, and achieve good supporting performance. By adjusting the position of tie - beam, the new type anti - slide pile has wider universality and applicability. We can make assumptions in the actual calculation.h - type anti - slide pile has strong anti - overturning ability. The compressive strength of the front pile and the tensile strength of the back pile can form a pair of effective anti-overturning bending moments, and the rigid joints also improve the anti-overturning ability.

Research on the Mechanism of the Influence of Earthquake‐Induced Landslides on the Stress and Deformation Characteristics of Tunnel

The landslide at the entrance of a railway tunnel in the southwestern region is relatively large, especially due to earthquakes and other factors, which are prone to severe disasters and threaten the safety of the tunnel. Through the long‐term monitoring test and numerical calculation analysis on‐site, the mechanism of the influence of the earthquake‐induced landslide on the characteristics of the tunnel’s force and deformation is studied. The research results show that the earthquake caused the landslide thrust to increase. Because of the existence of the supporting structure, the landslide thrust was consumed, and the remaining part resulted in the compression failure of the tunnel. During the seismic monitoring period, the stress loss of the antislide pile anchor cable was 3.73% and the stress of the second lining of the tunnel increased by 25%. Under the condition of extreme seismic, shear failure occurred at the vault, bottom, and waist of the right‐line tunnel, and the tensile strength of the right‐line tunnel reached 93.8% of the limit value. For the weak links of the tunnel structure, dense reinforcement planting and strengthening of concrete strength should be adopted to enhance the safety of the tunnel structure. While designing the supporting structure, the rock‐socketing depth of the antislide piles and the number of antislide piles should be considered a priority. The impact of the antislide pile spacing is relatively small.

Influences on Antislide Piles Used for Slope Reinforcement: Numerical Simulation Based on the Soil Arching Effect

This study explores the pile-soil interaction mechanism and the optimal use of antislide piles for slope reinforcement based on finite difference numerical modelling. The force and displacement principles of slopes and antislide piles are analysed. The influences of various factors are investigated, such as postpile filling parameters, pile embedding methods, and pile cross-sectional shapes. Numerical modelling is used to determine the optimal layouts of antislide piles for push and traction landslides. The findings indicate that the cohesive force of the fill has a greater influence on the piles and slope than the friction angle and is the primary control factor. Fully buried antislide piles provide a better antisliding effect than semiburied ones. With fully buried piles, the best controlling effect is obtained when the ratio of the length of the pile’s free section to the height of the sliding body is approximately 4/5. Moreover, stepped-cross-section piles provide better slope reinforcement than those with rectangular, T-shaped, or trapezoidal cross-sections. In practical applications, end-bearing arches can be utilized as the primary control structures, with friction arches used for secondary control to improve the soil arching effect as much as possible, thereby enhancing the stability of the piles and slope. To control landslides of various thrust forms, antislide piles should be set in the active section, the core sliding section, or both, as required. This paper provides guidance for improving the design of antislide piles.

Reinforcement effects and safety monitoring index for high steep slopes: A case study in China

High and steep slopes which have developed fractures and intercalations are a great threat to the operation of dams and reservoirs. In this work, the geological conditions and potential modes of failure of the slope found in the right bank of Suofengying hydropower station are investigated for the slope stability and the results are presented. In order to strengthen the slope, an innovative stabilization scheme is employed. The stabilization techniques include development of anti-shear tunnels, anti-slide piles, anchor cables, concrete support structure, etc. Further, the slope stability and reinforcement effects using various stabilization techniques are studied by using finite element strength reduction method. Moreover, in situ monitoring is carried out and the data obtained is analyzed. From the results, it is observed that the deformations that are detected using multipoint extensometers have decreased after the installation of remedial reinforcements. From the analysis of remedial reinforcement methods, it is found that the most critical reinforcement is the development of anti-shear tunnels. In order to monitor the stresses in stirrups and the propagation of cracks in the anti-shear tunnels, three levels of safety monitoring index are proposed. The safety monitoring index is developed based on the results obtained by the simulation of the process of failure of the reinforced slope. The developed safety monitoring index is further applied to the Suofengying project in order to evaluate the overall stability of the slope. The results obtained by monitoring indicate that the performance of the reinforcement structures is satisfactory and the slope has better stability. The methodology proposed in this work shall be useful for similar projects to obtain stability of slopes.

Large-scale shaking table test on seismic behaviour of anti-slide pile-reinforced bridge foundation and gravel landslide: a case study

This study aimed to illustrate the seismic response and instability process of a double-row anti-slide pile-reinforced bridge foundation and gravel landslide. Selecting the gravel slope of Jiuzhai Valley along the under-construction Chengdu-Lanzhou high-speed railway as the site prototype, large-scale shaking table tests were first conducted at a similitude ratio of 1:70, with sine waves and El Centro waves as the seismic wave inputs. The amplitudes of the input seismic waves were increased, while the acceleration, dynamic earth pressure, and strain distribution were monitored in the gravel landslide. The dynamic response patterns of anti-slide pile-reinforced bridge foundations in gravel landslides were illustrated. The front-row and back-row anti-slide piles should be a reasonable distance from the bridge foundation. The response acceleration manifested an elevation amplification effect with an increasing elevation in the slope behind the anti-slide piles. Back-row anti-slide piles reinforcing the bridge foundation can reduce the effect of landslide thrust on the bridge foundation and maintain a uniform distribution of earth pressure behind the bridge foundation, mitigating seismic effects. The dynamic earth pressure peaked at the top of the bridge foundation and then decreased along the depth. The back-row anti-slide piles displayed greater resonance coupling and unloading effects before and after reaching the load-carrying limit, respectively. In seismic strengthening design involving bridge foundations and gravel landslides, when the earthquake-induced resonance coupling effect on inclined, loosely packed land masses is fully considered, pre-reinforcement measures (e.g., high-pressure grouting and anchor spraying) should be carried out on the gravel slopes.