Soil Squeezing Research Articles

Field testing performance of prebored precast piles with enlarged base in soft ground

Prebored precast piles with an enlarged base (PPEB piles) are constructed using an innovative and environmentally sustainable method, which notably reduces noise, soil squeezing, and mud discharge. Although PPEB piles have been widely applied in many cities in China, their bearing performance, including side friction and end resistances, on soft ground remains relatively unelucidated. This paper focuses on case studies of vertical-bearing PPEB piles based on a group of vertical static load field tests in Shanghai. The following conclusions are drawn: (1) Compared with traditional hammered-driven piles, PPEB piles exhibit better construction quality and load-bearing performance, as well as a relatively slow increment of settlement even under ultimate loading. (2) The resistance of the enlarged base section of the PPEB pile was approximately 16.3% of the total resistance under ultimate loading. (3) Compared with the values proposed in the Shanghai Foundation Design Code, the side friction resistance of the PPEB pile in deep silty sand (34.5–39 m) exhibited a considerable increase of approximately 156%. Additionally, the side friction in the soft ground was close to the values proposed in code. The case studies provide practical guidelines for the application of PPEB piles in soft ground.

Experimental Study on Bearing Behavior and Soil Squeezing of Jacked Pile in Stiff Clay

In order to study the bearing behavior and soil-squeezing of jacked piles in stiff clay, two groups of pile penetration tests were performed, with a rough pile that can reproduce the quick-shear behavior of the pile–soil interface, i.e., group 1 in stiffer clay, and group 2 in softer clay for comparison. For each group, the adjacent pile was additionally penetrated at different pile spacings to study the soil-squeezing effect on an adjacent pile. The results show that the penetration resistance increased rapidly at the beginning and then increased at a lower rate. This is because the resistance at the pile end increased rapidly at the beginning and then kept stable with fluctuations, whereas the resistance at the pile side continually increased due to the increasing contact area. Therefore, the ratio of the resistance at the pile end to the total penetration resistance exhibited a softening behavior, which first increased to a peak and then gradually decreased. In addition, there was soil-squeezing stress and soil-squeezing displacement in the ground and adjacent piles due to pile penetration. In stiffer clay, the soil-squeezing stress was larger than that in softer clay due to the higher strength, whereas the soil-squeezing displacement was smaller than that in softer clay due to the low compressibility. In addition, the nonlinear equation form y = ae−bx can be employed to describe the effect of pile spacing on the vertical flotation, horizontal deviation, and pile strain of the adjacent pile.

Investigation on the Stratigraphic Response and Plugging Effect Induced by Press-In Open Caisson in Mucky Soil

Press-in open caisson method, which sinks into soil with the aid of mechanical pressure without excavation, is becoming an important method of construction in extremely soft foundations. However, many engineering problems are prone to occur in the construction of caissons, such as sinking and large deformation. In this study, the stratigraphic response model, such as soil migration during the press-in process of open caisson, is focused on. Through model tests of soil and caissons, the migration patterns of each part of the soil were carried out, and the mechanism underlying the stratigraphic response pattern was investigated. The three primary conclusions are as follows: 1) The bottom edge foot of caisson produces lateral extrusion on surrounding soil in the range of 10 cm (20%H) below, resulting in lateral movement of soil. 2) two kinds of plug, i.e., “wedged” and “unwedged” plugs exist, and the driven forces for the soil migration can be divided into three stages, i.e., caused by soil plug with active arch, by soil plug with passive arch and caused by soil squeezing effect. 3) there is a significant linear correlation between the soil plug changes, the horizontal movement of the deep soil body, and the displacement of the surface uplift. The soil plugging effect and squeezing effect are interacted and enhanced with each other. This study provides a new understanding of the stratigraphic response in the construction of press-in open caissons, and guides safety control of open caissons construction.

Field test study on soil squeezing effect of H-type prestressed concrete revetment pile

The pretensioned H-type prestressed concrete revetment pile is a new product specially developed for the protection of coastal dykes in rivers and lakes. Its cross section is H-shaped, and the H-type revetment pile is also a soil squeezing pile. The excess pore pressure and soil displacement caused by the soil squeezing effect of H-shaped piles are deeply analyzed. The influence range of excess pore water pressure is 14~15d, and the excess pore water pressure completely dissipates after 6d. The farther the vertical distance from the pile tip is, the less obvious the horizontal displacement is. In a row of piles. In the process, it will cause repeated uplift and settlement; However, after the erection, the law of vertical deformation is reflected in the near settlement and the far uplift.

An Experimental Study on the Microstructure Evolution of Soil under Lateral Consolidation Compression

Based on the lateral consolidation compression experiment of remolded soil simulating the effects of pile driving and soil squeezing, in this paper, the microstructures of soil with different degrees of lateral consolidation were investigated by a scanning electron microscope. Combined with Image-Pro Plus software to process data, parameters such as the equivalent diameter, porosity, circularity, directional frequency and fractal dimension of the soil microstructure were analyzed. The results demonstrate that the microstructure of the soil sample before consolidation was debris, aggregated particles and irregular flake aggregates. Following consolidation, the microstructure became a closed flake structure, where an obvious agglomeration phenomenon occurred. During the process of lateral consolidation compression, the large pore structure was more likely to be compressed and damaged, resulting in a decrease in the equivalent pore diameter and plane porosity, the approaching of circularity towards unity and an increase in the compaction and homogenization of soil with obvious directionality. Soil particles moved continuously under the action of consolidation compression to adjust the microstructure, and the fractal dimension gradually increased. Then, as consolidation compression continued, it gradually developed to a new equilibrium state, where the fractal dimension began to decrease and approach stability.

Dynamic Response Analysis of Pile Group Foundation of Super-Giant Sewage Treatment Structure on Hydraulic Fill Foundation

In this study, a 3D numerical model, considering the dynamic interaction between soil, pile foundation, and super structure, and the parameter analysis of internal force response of pile group foundation under differences seismic intensity, was established based on the Bangladesh sewage treatment plant project to investigate the dynamic response of pile group foundation of liquid-containing structures. The results show that the internal force of pile gradually increases with time, and the horizontal dynamic displacement peak value appears earlier under different seismic wave responses and seismic intensity. With the increase of seismic time history, the variation degree of dynamic impedance with frequency and impedance peak will increase. The pile group effect and single pile bearing capacity of foundation in hydraulic fill fine sand and silty clay were verified. By comparing numerical simulation and theoretical calculation, the results show that the pile group foundation exerts the soil squeezing effect after pile construction is completed, and the dynamic elastic modulus of the soil layer can be increased. Simultaneously, the soil layer will have a better integral stiffness. The pile group effect coefficient obtained by the solid perimeter method is most consistent with the numerical simulation method.

A New Spatial Deformation Measurement Method Using 3D Reconstruction Technology during Pile Penetration

Non-intrusive observation of the spatial deformation field of the soil has been a difficult problem for model test measurements. Based on the advantage that the visualization test method of transparent soil can observe the two-dimensional (2D) deformation inside the soil, this study proposes a new automatic tomographic scanning measuring device to observe the three-dimensional (3D) spatial soil deformation inside the transparent soil model. A series of 2D laser speckle images of different vertical cross sections before and after deformation were obtained, and an improved 3D reconstruction algorithm was used to reconstruct the 3D displacement field of soil after deformation. Different types of jacked-pile penetration model tests were carried out to investigate the spatial disturbance of the soil around the pile caused by the squeezing effect of the jacked-pile. The test results showed that the developed novel automatic tomographic scanning measuring device with the modified 3D reconstruction procedure could be an innovative tool in geotechnical physical model experiments. The model test results visually revealed the mechanism of the soil squeezing effect of jacked-piles with different pile head forms. Moreover, the spatial disturbance effect caused by different penetration stages was also discussed herein.

Spudcan-pile interaction in thick soft clay and soft clay overlying sand: A simplified numerical solution

A drilling jack-up is often deployed to perform drilling activities or well intervention at an existing fixed jacket platform. Depending on the clearance distance between the aft spudcan and the nearest pile, the installation of the spudcan may have an adverse effect on the platform pile which in turn could compromise the integrity of the jacket structure. This paper presents a simplified method for assessing the effect of spudcan installation on the pile foundation of a jacket platform in thick soft clay and soft clay overlying sand layers. Adopting a two-stage uncoupled approach, in which predetermined free-field lateral soil displacements are applied to a beam-column model with soil modelled using p-y curves, the soil displacements around a penetrating spudcan is estimated by an analytical solution derived from spherical cavity expansion theory. With appropriate consideration for the volume of soil displaced by the penetrating spudcan for the cases of thick soft clay and consideration for soil squeezing for soft clay overlying sand, the computed free-field lateral soil displacements are in fair agreement with the measured profiles in centrifuge tests and can be used in a beam-column model to estimate the induced bending moment in the pile in practice.The pile response to the free-field lateral soil displacements is assessed using a beam-column model incorporating p–y curves, considering the effect of soil remoulding caused by the installation of the spudcan where appropriate. A numerical model which considers the evolving lateral soil displacements due to the progressive advancement of the penetrating spudcan is also studied. The computed pile bending moment profiles are consistent with the measured profiles in the centrifuge tests and those computed by 3D large deformation finite element (LDFE) model. The proposed practical method is simple but yet effective to assess the influence of the installation of a spudcan foundation on an adjacent pile of a jacket platform in thick soft clay and soft clay overlying sand.

On the Influence of Pile Foundation Settlement of Existing High-Rise Buildings on the Surrounding Buildings

Pile foundation settlement is a kind of foundation form. In recent years, because of the increasing population and economic development in China, high-rise buildings have emerged in people’s vision. Due to the development of engineering construction, the type and technology of pile foundation, as well as the control and detection of the single pile and pile group have been greatly improved. In view of the influence of pile foundation settlement on the surrounding environment of high-rise buildings, this paper mainly studies from the angle of single pile settlement and pile group settlement. According to the construction method of pile foundation, the static pressure sinking pipe cast-in-place pile can produce soil squeezing effect in pile foundation construction. The experimental analysis was carried out. According to the engineering example, finite element numerical simulation is used to analyze the influence degree of pile foundation settlement on adjacent buildings with and without raft, and the feasibility and correctness of numerical simulation are analyzed by comparing the simulation results with the measured values. This paper mainly studies the influence of pile foundation settlement of high-rise buildings on surrounding buildings from the aspects of problems and solutions.

Numerical Analysis of Soil Squeezing Effect of Pipe Pile Construction in Deep Silt Site

This article is based on a pile foundation project in Wenzhou City, combined with construction site monitoring data, and established a finite element model to analyze the soil squeezing displacement caused by the construction of PHC pipe piles in deep silt sites, as well as the displacement of different sizes of digged holes on the surface impact. When the distance from the pile position to monitoring point is 35 times of the pile diameter, the field test results show that the horizontal displacement and velocity change of the soil caused by the pile foundation construction decrease with the buried depth, and the main influence range is within the buried depth of 0-14 m. Numerical simulation results show that: (1)without digged hole, the main influence range of the main soil squeezing displacement is about 8 times of pile diameter; (2)the larger the diameter of the digged hole, the smaller the displacement and the influence range of the affected soil on the surface; (3)The ground squeeze displacement caused by the pile construction attenuates in a power function with the distance from the pile position to the measuring point.

The Bearing Capacity Evaluations of a Spread Footing on Single Thick Stratum or Two-Layered Cohesive Soils

Nowadays many countries plan to increase the percentages of renewable energies by developing offshore wind power. Due to the large sizes of offshore foundations, such as spudcan footings of jack-up barges or pile anchors of wind turbines, the affected soil depth range caused by the foundation under loading can be relatively deep, so the affected range may include a single thick layer or stratified soils. This paper utilizes limit analysis and FLAC numerical simulation to investigate the bearing capacity of a footing on single thick stratum or two-layered cohesive soils. Under nature deposition condition, the undrained shear strength of most cohesive soil approximately increases linearly as the depth increases. The closed-form upper bound solutions of fully rough or fully smooth footings on thick cohesive soils are provided, for the purpose of fast evaluations in practical engineering, and the outcomes are within the results from the FLAC simulation and slip circle method. The problems of punch-through shear failure or soil squeezing could be critical for two-layered soils under some conditions, and the associated bearing factors and the failure mechanisms from different methods are demonstrated and discussed in the article.

Calculation of Soil Deformation Caused by Shield Tunneling through the Sludge Layer with Plastic Drainage Plates

Due to a lack of engineering experience, research on ground deformation during shield machine tunneling in sludge layers is limited, especially in areas with plastic drainage plates installed for ground stabilization. When the shield passes through this area, the shield cutterhead may be jammed by the drainage plates, resulting in excavation surface instability, excess ground deformation, and schedule delay. In this work, a Mindlin solution for ground deformation in such a layer is obtained, considering four factors: the frontal additional pressure generated by the shield cutterhead due to the soil squeezing effect, the uneven lateral friction between the shield shell and the soil, the frontal friction generated by the shield cutterhead when cutting through the drainage plate, and the shield machine restart after shutdown. The results show that the theoretical curve is in good agreement with the measured values. The maximum settlement was approximately 10 m behind the excavation surface, and the maximum uplift was approximately 5 m in front of the excavation surface. The most influential factor among all the studied factors was the additional pressure on the shield cutter, which accounted for approximately 56% of the maximum settlement and 60% of the maximum uplift. The soil settlement mainly occurred within 12 m on both sides of the tunnel axis. The maximum settlements at the different soil depths tested were all directly below the tunnel axis.

Model experiment study on the concrete pile soil squeezing effect on underground pipelines

A model experiment is carried out in this study by using plexiglass rod to simulate the concrete pile and PVC pipe to simulate the underground pipeline, in order to analyze the impact of concrete pile soil squeezing effect on the deformation of underground pipelines. The results show that the pipeline exhibits a strain softening phenomenon during the pile driving process when the pile-to-pipeline distance is relatively small, and the pipeline strain tends to stabilize when the pile-to-pipeline distance is relatively large. In general, as the pile driving process continues, the strain of the underground pipeline increases gradually; the deeper the pipeline, the larger the strain is. However, when the pile-to-pipeline distance is relatively large, the pipeline strain decreases with the increase of the buried depth; the larger the pile-to- pipeline distance, the smaller the strain is. This experiment has an important value in guiding the design and construction of pile foundation engineering projects in complex environments.

Model Test of Soil Squeezing effect of Jacked Pile Sinking in Sand Slope

Jacked pile sinking has many advantages in terms of construction, which is one of the commonly used piling methods. However, the jacked pile sinking has significant squeezing effect against the side slope, resulting in the stability of the slope being affected to a certain extent. This paper attempts to determine by model test the squeezing effect of jacked pile sinking in slope.

Large Deformation Modelling of Soil Squeezing and its Application to Spudcan in Clay with Interbedded Sand

Large Deformation Modelling of Soil Squeezing and its Application to Spudcan in Clay with Interbedded Sand

Field Tests of Cement Fly-Ash Steel-Slag Pile Composite Foundation

Abstract Steel slag is one of the main waste materials in the steelmaking process. As a result, a tremendous amount of steel slag is produced and deposited into storing yards every year. Recycling of the abandoned steel slag is of great environmental and economic value. This study investigates the usage of steel-slag concrete with fly ash as a kind of composite foundation pile material, which can be applied to multi-pile composition foundations for ground improvement involving different pile types. The micromorphology of the concrete, which uses steel slag as aggregate, is analyzed using scanning electron microscopy (SEM). The bearing characteristics of cement fly-ash steel-slag pile (CFS pile) composite foundations are investigated via field load tests, including settlement of the foundation base, horizontal displacement at different depths, distribution of vertical stress increase of the composite foundation, and stress increase of the soil around the pile hole. In addition, the effect of soil squeezing caused by the construction of a CFS pile is studied. To accomplish this, the variation in the increase in stress of the foundation at different distances in the horizontal direction is measured. The results suggest that the usage of steel slag as an aggregate can effectively satisfy the strength requirement of the pile. CFS pile composite foundations have the advantages of high bearing capacity, small settlement deformation, and limited horizontal deformation. This study demonstrates the potential usage of steel slag as aggregate in pile composite foundations, which can bring significant economic and environmental benefits.

Elastic solution to the squeezing displacement of spherical cavity expansion under nonaxisymmetric displacement boundary

Based on the current solution of the squeezing displacement due to cavity expansion in a semi-infinite soil layer, the horizontal surface and inclined slope displacement boundaries have been revised. The current analysis method is improved via the methods of coordinate transformation and superposition. Hereby a relatively simple solution to the soil compaction displacement field due to spherical cavity expansion is derived under nonaxisymmetric displacement boundaries, and the effects of the slope angle and the distance between the spherical cavity and the free boundary are analyzed. The results indicate that the inclination boundary condition has a significant influence on the squeezing displacement of both sides of the spherical cavity. With the increase of inclination, the influence of boundary inclination angle on the soil compaction displacement become more and more significant, and the larger the distance from spherical cavity position to the free boundary, the less significant effect on the soil squeezing displacement. This research may provide practical guidance for the design and construction of static piling on the adjacent slope and the issues related to cavity expansion.

Numerical Simulation of Soil Squeezing Effects of a Jacked Pipe Pile in Soft Foundation Soil and in Foundation Soil with an Underlying Gravel Layer

A three-dimensional finite-element analysis was carried out using ABAQUS to evaluate the squeezing effects of a prestressed high-strength concrete (PHC) pipe pile, including land upheaval, lateral soil displacement, and soil stress field with depth-varying during pile-sinking. Field data used in the analysis were obtained from the settlement building project in Hefei City, Anhui Province, China. In coastal areas of China, PHC pipe piles are normally used for reinforcement of soft foundation. The changes of displacement with the increase of soil depth and radial distance during pile-sinking are simulated for both soft foundation and soft clay with an underlying gravel layer. The numerical simulation results show that there is little difference in land upheaval with soil depth during pile-sinking, and the obvious land upheaval occurs within 0.8 m from the center of the pile. The lateral soil displacement is evident within the area of 1.0 m from the axis of the PHC, decreases with the increase of radial distance during pile-sinking, and becomes negligible beyond 4.0 m. The existence of the gravel layer helps reduce soil squeezing substantially, and the soil squeezing effects during pile-sinking have less influence on the surrounding area of foundation with a gravel layer than that in a soft foundation soil without gravel layer.

Design and Test of Self-Draining Pile

putting out a new pile type, that is, making the precast concrete pile with a vertical side channel and pouring the yellow sand, which lead to the pile had the self-draining function, reduce the soil squeezing effect of precast concrete pile construction in saturated soft clay, that is, the design principles and methods of self-draining pile. Indoor model test showed that the self-draining piles could reduce the pore water pressure, and its effect was obviously, its role is equivalent to sand wells, sand bags wells or plastic drain board, which meet the requirements of the construction technique.