Soil Arching Effect Research Articles

Study of Deflection of Buried HDPE Corrugated Pipeline under the Uneven Settlement of Soil

This paper aims to study the deflection of high-density polyethylene (HDPE) corrugated pipeline subjected to differential settlements of the ground using the finite difference method-discrete element method (FDM-DEM) coupling simulation method in 3D. Various physical characteristics of the pipeline, including diameters, corrugations, and elastic modulus have been investigated. Soil particles with different shapes are considered. The variation of soil settlement of soil particles with three different shapes under the uneven settlement condition is studied. The soil arching effects, including positive soil arch and negative soil arch, have been respectively analyzed. The results reveal that the change in pipe corrugation influences the stiffness of the pipe and the friction between the pipe and soil to some extent, which also causes the change of vertical deflection of the pipe. The soil composed of four particles is easier to form soil arch, which makes the soil more self-stabilized, thus alleviating the circumferential deformation of the pipeline.

Soil Arching of Piled Embankment in Equal Settlement Pattern: A Discrete Element Analysis

Soil arching, which occurs in the piled embankments, plays an important role in stress redistribution between the relatively soft subsoil and the stiffer piles. The formation of the soil arching depends on the differential settlement of the embankment fill above the pile and the subsoil. The soil arching effect is barely investigated in the literature from the perspective of differential settlement of piles and soils. Based on the discrete element method (DEM), this paper develops a classic trapdoor test model to investigate the differential settlement in piled embankment during the downward movement of the trapdoor, and to explore the formation mechanism of soil arching in equal settlement pattern by changing the width of the pile cap and the height of the embankment. Due to symmetry, only one section of the laboratory test model is simulated herein. It was found that the soil arching formed under the equal settlement pattern remained unchanged after a certain degree of development, and the height of the equal settlement did not change at 0.7(s-a), where s is the pile spacing, and a is the width of the pile cap. The height of the embankment (H) and the width of the pile cap (a) have a significant influence on the formation of the equal settlement pattern when the width of the trapdoor is kept constant. Both the decrease in “H” and the increase in “a” facilitate the differential settlement of the soil between the piles and the pile-soil, enabling the slip surface to develop upward gradually, thereby hindering the formation of the equal settlement pattern.

3D numerical study of the performance of geosynthetic-reinforced and pile-supported embankments

Geosynthetic-reinforced and pile-supported (GRPS) systems provide an economic and effective solution for embankments. The load transfer mechanisms are tridimensional ones and depend on the interaction between linked elements, such as piles, soil, and geosynthetics. This paper presents an extensive parametric study using three-dimensional numerical calculations for geosynthetic-reinforced and pile-supported embankments. The numerical analysis is conducted for both cohesive and non-cohesive embankment soils to emphasize the fill soil cohesion effect on the load and settlement efficacy of GRPS embankments. The influence of the embankment height, soft ground elastic modulus, improvement area ratio, geosynthetic tensile stiffness and fill soil properties are also investigated on the arching efficacy, GR membrane efficacy, differential settlement, geosynthetic tension, and settlement reduction performance. The numerical results indicated that the GRPS system shows a good performance for reducing the embankment settlements. The ratio of the embankment height to the pile spacing, subsoil stiffness, and fill soil properties are the most important design parameters to be considered in a GRPS design. The results also suggested that the fill soil cohesion strengthens the soil arching effect, and increases the loading efficacy. However, the soil arching mobilization is not necessarily at the peak state but could be reached at the critical state. Finally, the geosynthetic strains are not uniform along the geosynthetic, and the maximum geosynthetic strain occurs at the pile edge. The geosynthetic deformed shape is a curve that is closer to a circular shape than a parabolic one.

Soil Arch Evolution Characteristics and Parametric Analysis of Slope Anchored Anti-slide Pile

The soil arching effect can significantly impact the bearing characteristics of the slope anchored anti-slide pile. Therefore, it is very important to investigate the internal force characteristics of the soil arch and the mechanism of pile-soil interaction. In this paper, the evolution mechanism and influencing parameters of the soil arching effect of anchored anti-slide pile are analyzed, from a qualitative and quantitative perspective through model tests and numerical simulation methods. Findings are summarized as follows: 1) the formation and evolution of the soil arches can be roughly divided into three stages: the initial stage, the development and formation of soil arches, and the failure and re-formation of soil arches. The stable arch feet are firstly formed, and a complete arch is generated. Then the landslide thrust is transmitted to form a stable anti-slide pile structure, so the anchored anti-slide pile can play a role in slope anti-slide. 2) During the formation and evolution of the soil arches, the soil particles between the piles transfer the landslide thrust to the anti-slide pile through the soil arches. 3) The bearing capacity of the soil arches decreases with the increase of the pile spacing. And the increase of the soil compaction can efficiently increase the bearing capacity of the soil arches and give full play to the role of slope anti-slide. 4) The growing of soil particle size, the enhancement of soil particle friction coefficient, and the decreasing of corresponding soil void ratio are all conducive to the formation of the soil arches. These can benefit the anti-sliding effect of the anchored anti-slide piles in engineering application.

Earth Pressure and Internal Forces of Tunnel Lining in Jet Grouting Reinforced Mud Stratum

In this study, field measurements of the earth pressures and the main reinforcement strains were carried out at three shield tunnel linings in mud stratum reinforced by vertical jet-grouted piles during tunnel construction and post-construction. The measured strains were used to back-calculate the linings’ internal forces. The measured earth pressures and the back-calculated internal forces were compared to corresponding design values. The results indicate that the earth pressure and the internal forces increased rapidly, before exhibiting a fluctuating decrease and finally a long-term slow change, after lining assembly. The vertical jet-grouted piles were beneficial to mobilise the soil arching effect and led to the real earth pressure on the lining significantly smaller than the full overburden pressure, even with a relatively shallow buried depth. The vertical jet-grouted piles intensified the influence of backfill grouting on the earth pressure and caused the lining segments near the backfill grouting holes to continuously bear more radial pressure in the long-term. The resultant internal forces during lining assembly were large, and the Conventional Model failed to consider this element of the internal forces. The findings can provide a reference for the design and the construction of similar projects.

Investigation of Soil Arching under Cyclic Loading Using the Discrete Element Method

Abstract This paper presents an analysis of the soil arching effect associated with piled embankments under cyclic loading by developing a series of two-dimensional trapdoor discrete numerical mode...

Field investigation on the mechanical performance of corrugated steel utility tunnel (CSUT)

As a novel underground steel structure, corrugated steel utility tunnel (CSUT) has been considered as an effective alternative to traditional reinforced concrete utility tunnel. However, the current investigation of CSUT structure performance is urgently lacking. In this paper, a full-scale test was conducted to examine the mechanical performance and bearing capacity of a square arched double-cabin CSUT in soft clays using high-precision optical fiber sensing technology. Strains of all corrugated steel plates and typical bolts were monitored in real-time during the entire backfilling and loading processes, and also the crucial stress was compared with that calculated by circumferential compressive force method considering bending moment. Test results show that CSUT structure has not been damaged when backfill height is over three times the height of design. Stress of the top plate is much greater than that of other corrugated steel plates including crest section and trough section, and definitely becomes the most critical control factor for safety assessment, especially in the crown. The maximum plate stress is 375.7 MPa at backfill height of 10.0 m, which has not yet reached the yield strength of 390 MPa. Additionally, overlying soil generates a positive soil arch effect, which is conducive to improve applicability and bearing capacity. Bolt connection is feasible, but the construction process should be optimized. Simultaneously, numerical simulation method is used to analyze the influence of other parameters on CSUT. This study provides a significative reference for the popularization, construction, operation and maintenance of CSUT that is not currently common in China.

Analysis of Earth Pressure Variation for Partial Displacement of Retaining Wall

Parts of the retaining wall might produce displacement under different load conditions. The moveable wall could impact the adjacent fixed wall, mainly reflecting on the variation of earth pressure and formation of the soil arching effect. This paper conducted the horizontal trap-door test to explore the variation of active earth pressure caused by partial displacement of the retaining wall. Different trap-door width and three displacement modes were addressed as the influence factors. The results indicated that the horizontal soil arching effect was generated after the active displacement of the trap-door and the soil pressure was redistributed. The distribution of lateral soil pressure was approximately an “inverted bell” curve. For trap-door widths of 20 cm, 30 cm, and 40 cm, a secondary soil arching effect appeared in the test. The relationship between lateral earth pressure and displacement was different with the traditional limited theory due to the influence of the soil arching effect. The variation curve of earth pressure corresponding to displacement could be divided into three stages. In addition, the distribution of earth pressure along the trap-door height was non-linear. Trap-door width can significantly influence the maximum earth pressure on the fixed wall and the range where pressure changes. Finally, the effect of load sharing was explored and found to be related with displacement and width of trap-door as well as the displacement mode.

Model Test on the Soil Arching Effect of Pile-Supported Embankments Using Transparent Soil

Abstract Pile-supported embankments have been widely used in subgrade engineering for highways and high-speed railways. Soil arching has an important effect on the deformation characteristics of pile-supported embankments. In this study, a new model testing apparatus and its test method for the soil arching effect were developed based on the transparent soil method and particle image velocimetry technique. The composition of the apparatus and the test steps were elaborated in detail. The development of the soil arch with the settlement of foundation soil was explored. The variations in the settlement of the embankment at different elevations and distances from the pile center were analyzed, and afterwards, the effect of pile spacing on the embankment settlement was discussed. The results revealed that a basin-shaped soil arch gradually formed in the embankment, with the settlement of the soil between the piles. The settlement below the arch boundary was larger, and the settlement above the arch boundary was relatively small. An equal settlement plane appeared in the embankment. The elevation of the equal settlement plane increased with increased pile spacing. The maximum settlement occurred at the center of the soil between the piles on the pile cap top plane. The settlement of the embankment increased as the pile spacing increased. This study provides a new solution for understanding the spatial effect of soil arching in pile-supported embankments.

Influence of Soil-Arching Effect on Tunnel Face Stability

Abstract Based on the slip line theory and the upper-bound limit analysis theorem, a three-dimensional (3D) slip–rupture mechanism to design the shield tunnel face stability is proposed. This model...

Structural Behavior of Prefabricated Ecological Grid Retaining Walls and Application in a Highway in China

The retaining wall is a common slope protection structure. To tackle the current lack of sustainable and highly prefabricated retaining walls, an environmentally friendly prefabricated ecological grid retaining wall with high construction efficiency has been developed. Due to the asymmetrical condition of the project considered in this paper, the designed prefabricated ecological grid retaining wall was divided into the excavation section and the filling section. By utilizing the ABAQUS finite element software, the stress and deformation characteristics of the retaining wall columns, soil, anchor rods, and inclined shelves in an excavation section, and the force and deformation relationships of the columns, rivets, and inclined shelves in three working conditions in a filling section were studied. The study results imply that the anchor rods may affect the columns in the excavation section and the stress at the column back changes in an M-shape with height. Moreover, the peak appears at the contact point between the column and the anchor rod. The displacement of the column increases slowly along with the height, and the column rotates at its bottom. In the excavation section, the stress of the anchor rod undergoes a change at the junction of the structure. The inclined shelf is an open structure and is very different from the retaining plate structure of traditional pile-slab retaining walls. Its stress distribution follows a repeated U-shaped curve, which is inconsistent with the trend of the traditional soil arching effect between piles, which increases first and then decreases. For the retaining wall structure in the filling section, the numerical simulated vehicle load gives essentially consistent results with the effects of the equivalent filling on the concrete column.

Analytical solutions for the earth pressure of narrow cohesive backfill with retaining walls rotating about the top

Currently, knowledge of the failure mechanisms of narrow backfills with retaining walls rotating about the top (RT mode) is still lacking which leads to inaccurate estimations of the earth pressure. Numerical simulations using finite element limit analysis find that under the effects of backfill geometries, interface strengths, and soil properties, the upper soil layer supported by soil arching retains its integrity and the lower soil layer is sheared by multiple curved sliding surfaces in the limit state. Based on the failure mechanisms of narrow backfills, a calculation model is established which considers the soil arching effect, curved sliding surface, and cohesive soils. Analytical solutions for the earth pressure of narrow cohesive backfills with retaining walls rotating about the top are derived by using the limit equilibrium horizontal slice method. Compared with previous studies, the present method predicts the earth pressure distribution with higher accuracy. Several extensive parametric studies have also been conducted. Thus, decreasing the aspect ratio of backfills, increasing the inclined angle of natural slopes, interface strengths, and soil cohesion are beneficial for maintaining backfill integrity and reducing earth pressure against retaining walls.

Performance Evaluation of Buried Concrete Pipe Considering Soil Pressure and Crack Propagation Using 3D Finite Element Analysis

Numerous factors affect the soil pressure distributions around buried pipes, including the shape, size, and stiffness of the pipe, burial depth, and the stiffness of the surrounding soil. Additionally, to some extent, a pipe can benefit from the soil arching effect, where the overburden and surcharge pressure at the crown can be supported by the adjacent soil. As a result, a buried pipe only needs to support the portion of the load that is not transferred to the adjacent soil. This paper presents numerical investigations of the soil pressure distributions around buried concrete pipes and crack propagation under different environmental conditions, such as loading, saturation level, and the presence of voids. To this end, a nonlinear elastoplastic model for backfill materials was implemented using finite element software and a user-defined subroutine. Three different backfill materials and two different native soils were selected to examine the material-specific behaviors of concrete pipes, including soil pressure distributions and crack propagation. For each backfill material, the effects of the loading type, groundwater, and voids were investigated. These simulation results provide helpful information regarding pressure redistribution and buried concrete pipe behavior under various environmental conditions.

Numerical Analyses on Geogrid-Reinforced Cushion in Pile-Supported Composite Foundation

A numerical analysis is conducted on the performance of geogrid-reinforced cushion in PCC pile-supported composite foundation for highway embankment applications. The finite element method is employed to simulate the behavior of cushion under loads. Soil arching effect and tensile membrane effect are two factors affecting cushion behavior. Two parameters, i.e. geogrid tensile strength and laying arrangement, are found effective in measuring soil arching and tensile membrane effects. Numerical analyses indicate that an increased geogrid tensile strength contributes to a reduced embankment settlement. The effect of geogrid laying arrangement on settlement is relatively small.

SIMPLIFIED METHOD FOR CALCULATING THE PASSIVE EARTH PRESSURE OF COHESIVE BACKFILL AGAINST RIGID RETAINING WALLS

The horizontal slice element method for calculating the passive earth pressure against rigid retaining walls is extended to cohesive backfill. The formula of the nonlinear distribution of passive earth pressure is derived to satisfy the reciprocal theorem of shear stress. According to the Mohr-Coulomb theory, the lateral passive earth pressure coefficient can be determined, and a simplified expression of the total passive force is obtained. The influence of the shear stress increment between soil strips on the passive earth pressure is discussed by two calculation models. The results are compared with the existing classical theory. The comparison shows that the formula in this paper degenerates to the Rankine formula when there is no uniformly distributed load. If the backfill is cohesionless soil, the results are consistent with those in the literature that considered the soil arching effect. The calculated results are also consistent with the existing experimental results.

Influence of the Cutterhead Configuration and Operation Parameters on the Face Stability of EPB Shield Tunnels in Dry Granular Soils

This paper presents a study on the face stability of earth pressure balance (EPB) shield tunnels in dry granular soils using the discrete element model (DEM) method to replicate realistic excavation processes of the EPB machine. Analyses were conducted at different buried depths to determine the limit face pressures and the face failure model induced by the EPB shield machine with varying open ratios and rotation speeds of the cutterhead. The failure kinematics of the soil and the soil arching effect were also determined. The results showed that both the open ratio and the rotation speed of the cutterhead have significant effects on the stability of the face in terms of the failure kinematics, limit face pressures, and the soil arching effect. The failure zone was highly dependent on the open ratio, but it depended less on the rotation speed of the cutterhead. The stability of the face is overestimated when the excavation is conducted with a cutterhead that has a large open ratio, but it is underestimated when the excavation is conducted with a cutterhead that has a smaller open ratio. Ignoring the effect of the configuration of the cutterhead and the rotation speed results in unexpected and unrealistic results.

Engineering characteristics test on pile–net composite foundation in loess areas

To study the variation in pile–soil stress and settlement of a pile–net composite foundation in a collapsible loess area, a test section of the Gansu-Ningxia section of the Yinxi high-speed railway was analysed using an earth pressure box, a liquid level settlement system and a single-point settlement instrument. The monitoring results showed that for, the pile–net composite foundation, the earth pressure in the embankment was significantly affected by the geogrid and the soil arching effect. The geogrid enhanced the soil arching effect between the piles, resulting in an increase in earth pressure between the piles on the embankment. With an increase in the embankment filling height, the pile–soil stress ratio and load sharing ratio of the cement–fly ash–gravel (CFG) pile and cement–soil compaction (CSC) pile increased gradually and the pile–soil stress ratio of the CFG pile was greater than that of the CSC pile. The settlement patterns of the CFG pile top, CSC pile top and the soil between the piles was saddle-shaped. The settlement of the CSC pile was found to be much less than that of the CFG pile.

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.

Influence of curvature change on soil arching effect in underground space development

This paper mainly studies the behavior of axisymmetric radial interaction between soil and structure under radial stress. Considering the possible factors in the interaction, such as the soil arching effect caused by the finite curvature, a simplified model is established. The influence of curvature change on the stress field, strain field, displacement field and stress-strain relationship is analyzed. Finally, the status of various factors in the axisymmetric radial interaction and the influence of their changes on the interaction are proposed.

Simplified Calculation Method for Seismic Active Earth Pressure of Translational Retaining Wall considering Soil Arching Effect

At present, most seismic earth pressure theories have the limitations of complex derivation process and difficult solution. To solve these problems, considering the deflection of small principal stress caused by soil arching effect, the central arc soil arch was approximated to two inclined linear soil arches, which can greatly simplify the derivation process. Firstly, by improving the combination of differential thin‐layer element method and pseudostatic method, the theoretical formulas of seismic active earth pressure intensity, resultant force size, and resultant force action point under translation mode (T mode) were derived and were verified by experimental results. Then, the influence of soil internal friction angle, wall‐soil friction angle, and seismic coefficient on seismic active earth pressure theory was analyzed. The results show that the seismic active earth pressure is nonlinearly distributed, and the seismic horizontal coefficient has a greater influence than other influence factors. The theoretical results can provide reference for the seismic design of retaining wall.