Soil Displacement Research Articles

Extraction behavior of a modified suction caisson by reversely pumping water in layered soils

The suction caisson can be extracted for reuse by reversely pumping water after the decommissioning of offshore structures. Model tests were conducted to explore the modified suction caisson (MSC) extraction behavior by reversely pumping water. The results indicate that the MSC exhibits higher maximum over-pressure (MOP) but achieves smaller final extraction displacement (FED) in layered soils than in homogeneous soils. The MOP of the MSC in the clay over sand (t = 0.375, t is the ratio of the upper layer thickness to the total soil thickness) is 5.1, 7.6, and 4.5 times greater than that of the clay, sand, and sand over clay (t = 0.375), respectively. The FED of the MSC in the clay over sand (t = 0.375) is 71%, 60%, and 75% of the clay, sand, and sand over clay (t = 0.375), respectively. Furthermore, reversely pumping water into the internal caisson is better to achieve a higher FED in layered soils. In sand over clay, the MOP of the MSC decreases as t increases, while the FED initially decreases but then increases with t. In clay over sand, a specific upper clay thickness exists where the MSC results in the lowest FED.

Shaking Table Tests of Underground Substation Considering Soil–Structure–Equipment Interaction

ABSTRACTTo investigate the seismic dynamic response characteristics of underground substations, considering the interaction among soil, structure, and equipment, a model soil field shaking table test with a similarity ratio of 1:25 was conducted. Detailed analysis was conducted on the acceleration amplification factors, Fourier amplitude spectra, and displacements of soil, structure, and equipment during the experimental process. The experimental study revealed the following findings: It was concluded that the seismic excitation had a significant impact on the acceleration response of equipment near the edges of the structure, demonstrating an amplification effect. Both the acceleration amplification factors of the station structure and the site generally decreased with increasing input seismic intensity. As the seismic intensity increased, this decreasing trend gradually weakened. Additionally, the peak values of acceleration Fourier spectra often decrease with increasing burial depth. The examination of the postearthquake model system revealed the presence of surface cracks in the soil, which exhibited varying degrees of severity. These cracks were observed both parallel and perpendicular to the direction of excitation, with a significant concentration of soil fissures occurring directly above the structural elements.

Stochastic seismic performance of slopes reinforced by a combination of piles and anchor cables using the probability density evolution method

ABSTRACT A combination of piles and anchor cables effectively enhances the seismic stability of slopes. However, due to the uncertainty of earthquake and soil properties, the stochastic response of slopes reinforced with piles and anchor cables (SRPC) remains unclear. This study presents a framework for the stochastic analysis of the SRPC using the probability density evolution method. The soil deformation, natural frequency of the slope, and the load sharing ratios of piles and anchor cables were investigated. Additional analysis was also conducted to evaluate the effects of the time-history characteristics and randomness of earthquakes, and pile modulus on the stochastic response of the SRPC. The results indicate that combining piles and anchor cables significantly reduced the probability of large soil deformation and increased the natural frequency of slopes compared to that reinforced with either piles or cables. However, the soil displacement increased considerably as the dominant frequency of earthquakes approached the natural frequency of the SRPC. Therefore, the variability in frequency spectra should not be neglected when considering the randomness of earthquakes. Furthermore, the load sharing ratio of piles increased dynamically and was higher than that of cables. A higher pile modulus contributed to the enhanced effectiveness of piles in sustaining earthquake loads.

Slow‐to‐Fast Transition and Shear Localization in Accelerating Creep of Clayey Soil

AbstractAccelerating creep before catastrophic failure commonly follows a power‐law velocity‐acceleration relationship, with the exponent typically near 2 but often evolving from 1 to 2 at a certain point, indicating a dynamic transition. The underlying mechanisms, however, remain unclear. Here we investigate this transition by monitoring the slip displacement of clayey soil during fluid‐injection creep experiments. This transition is discontinuous in the first run but becomes continuous in the initially pre‐sheared sample. Using a regularized rate‐and‐state friction model, we explicitly examine the relationship between the exponent and the frictional properties of the soil. This model describes the dynamic transition, with the exponent evolving from 1 to 2 across a broad range of frictional parameters. Furthermore, by incorporating idealized shear localization processes, the model qualitatively reproduces the shear‐history‐dependent transition. Our study demonstrates that a combination of structural evolutions and frictional properties may explain slow and fast slips observed in various shear systems.

Numerical and parametric analyses of four unreinforced embankments on soft soils

The conventional method of estimating safety factors during various stages of construction remains prevalent for embankment stability analysis. This typically involves employing stability charts, equations, Limit Equilibrium Methods, and the Strength Reduction Method, with the Limit Equilibrium Method being the most conventional and widely adopted. Additionally, there is an increasing trend in leveraging results from instrumented embankments for performance and stability analyses, indirectly assessing parameters such as horizontal and vertical displacements, pore pressure, and soil displacement volumes. Despite the widespread acceptance of these traditional methods, many studies tend to evaluate results individually, overlooking the benefits of direct comparison for a more comprehensive analysis. This study employs a variety of methods and approaches to assess the stability of embankments under different geometries and soil conditions. The safety factors for various embankment configurations are estimated directly using two stability charts (O'Connor and Mitchell, 1977; Barnes, 1991), two stability equations (Huang, 2018; Sampa and Schorr, 2024), the Limit Equilibrium Method implemented in GeoSlope software, and the Strength Reduction Method in Abaqus and Plaxis. Conversely, the results of the soil deformability analysis are normalized for the purposes of indirect stability analysis, with the Abaqus software serving this purpose. Analyses were conducted on models featuring either a single material for both the embankment and the soil foundation or different materials for each. The elastoplastic model employing the Mohr-Coulomb failure criterion characterized the behavior of granular materials, while modified Cam-Clay models implemented in Abaqus described the behavior of soft soils. The analysis results focus on three key aspects: (i) comparison of safety factors, (ii) establishment of behavior patterns from stability and deformability analyses, and (iii) discussion of limitations, accuracies, and advantages of the assessed methods and approaches. Finally, a critical analysis addresses the impacts of varying criteria used in Abaqus and Plaxis software for determining safety factors based on the Strength Reduction Method concept.

Closure to “Load Response and Soil Displacement Field for a Vertically Loaded Strip Footing on Sand Underlain by a Stiff Base”

Closure to “Load Response and Soil Displacement Field for a Vertically Loaded Strip Footing on Sand Underlain by a Stiff Base”

Physical effects between the interaction of a Maxwell fluid and a uniform marine current on the mechanical response of a poroelastic soil

In this work, an analytical solution to the soil's dynamic response induced by the interaction between a long water wave and a viscoelastic mud is obtained. The system is divided into three regions: the upper layer is water, the middle layer is a viscoelastic mud, and the lower layer is a poroelastic soil. It is assumed that there is an horizontal marine current with uniform vertical profile. The water hydrodynamics is obtained under the assumption of a potential flow. In the mud region, which thickness is of the same order of magnitude as the water depth, the simplified Cauchy governing equations are solved, where the Maxwell rheological model is adopted. Because it is considered a viscoelastic mud at the mud–soil interface, the continuity of shear and vertical stresses is assumed. Increasing the mud thickness, the vertical stresses and the vertical displacements of the soil are also increased. It should be noted that increasing the mud viscoelasticy, represented by increasing values of the Deborah number, affects only the shear stresses and the horizontal soil displacements. It is identified that currents that are found in the same direction that the wave propagation induce larger liquefaction depth than those calculated for opposite currents. The present solution can serve, as a first approximation, to identify the effects of the wave–current interaction in the presence of a viscoelastic mud on the liquefaction depth.

Discussion of “Load Response and Soil Displacement Field for a Vertically Loaded Strip Footing on Sand Underlain by a Stiff Base”

Discussion of “Load Response and Soil Displacement Field for a Vertically Loaded Strip Footing on Sand Underlain by a Stiff Base”

Influence of the Soil Squeezing Effect on the Peripile Soil of Pre-Tensioned H-Type Prestressed Concrete Revetment Pile Construction Based on Field Tests

Pre-tensioned H-type prestressed concrete revetment piles are a newly developed product dedicated to the protection of river, lake, and sea bank embankments, and their cross-section is H-shaped. In this study, a field test of H-type pile soil’s squeezing effect is carried out based on the second phase project of the HujiaShen Line. Pore water pressure, soil displacement, and other parameters of the H-type pile-driving process are monitored in real time. The test results show the following: (1) The influence range of the excess pore water pressure caused by the soil squeezing effect in the horizontal direction is about 14–15D, and in the vertical direction, the pore water pressure within a depth range of about 7D below the pile bottom increases rapidly. Its dissipation rate is fast at first and then slows down, and it completely dissipates 20 days after piling. (2) The excess pore water pressure caused by the soil squeezing effect does not decrease linearly in the radial direction. The soil around the construction pile can be divided into four areas: A, B, C, and D. Among them, A and B belong to the plastic zone, and C and D belong to the elastic zone. (3) The horizontal displacement of the soil occurs within the depth range of 5D from the surface of the pile to the bottom of the pile at the piling location, and the radial influence range is about 8–12D. From a vertical perspective, the main horizontal displacement of the soil occurs in the long section of the pile driven into the soil, showing a “U”-shaped distribution. (4) The dividing point between the vertical displacement uplift and the settlement of the soil appears within the range of 2–3 m from the construction pile, that is, between 5 and 7D. Settlement occurs after the piling is completed, and the settlement rate is fast at first and then slows down. The final settlement of the soil is stable on the 20th day. This research and experiment provide a design reference for the engineering application of pre-tensioned H-type prestressed concrete bank protection piles.

Centrifuge model tests on pile groups under oblique pullout load for single point mooring system through transparent sand

Single point mooring systems anchored by pile groups have been widely applied to support floating offshore platforms. Centrifuge model tests on the pile group performance and soil displacement field were conducted using transparent sand. The pile group consisted of six piles connected by steel wires and divided into two groups. The two groups were symmetric in the x-direction, and the three piles in each group were symmetric in the y-direction. The influences of pile group arrangement and loading direction were investigated. With the increasing angle between adjacent piles in the same group (β), the pile group resistance for a given displacement increased under the x-direction load but decreased under the y-direction load. The difference in the pile load distribution increased with β, and the pile group resistance reduced significantly once one pile failed at β = 60°. The soil displacement field indicated that the overlap effect of the influence zone increased with the decreasing β, leading to a reduction in the pile group resistance at β = 30°. Therefore, the pile group arrangement with β equal to 45° was optimal in this study. Additionally, the pile group resistance improved as the loading direction changed from the x-direction to the y-direction.

Analytical Fragility Surfaces and Global Sensitivity Analysis of Buried Operating Steel Pipeline Under Seismic Loading

The structural integrity of buried pipelines is threatened by the effects of Permanent Ground Deformation (PGD), resulting from seismic-induced landslides and lateral spreading due to liquefaction, requiring accurate analysis of the system performance. Analytical fragility functions allow us to estimate the likelihood of seismic damage along the pipeline, supporting design engineers and network operators in prioritizing resource allocation for mitigative or remedial measures in spatially distributed lifeline systems. To efficiently and accurately evaluate the seismic fragility of a buried operating steel pipeline under longitudinal PGD, this study develops a new analytical model, accounting for the asymmetric pipeline behavior in tension and compression under varying operational loads. This validated model is further implemented within a fragility function calculation framework based on the Monte Carlo Simulation (MCS), allowing us to efficiently assess the probability of the pipeline exceeding the performance limit states, conditioned to the PGD demand. The evaluated fragility surfaces showed that the probability of the pipeline exceeding the performance criteria increases for larger soil displacements and lengths, as well as cover depths, because of the greater mobilized soil reaction counteracting the pipeline deformation. The performed Global Sensitivity Analysis (GSA) highlighted the influence of the PGD and soil–pipeline interaction parameters, as well as the effect of the service loads on structural performance, requiring proper consideration in pipeline system modeling and design. Overall, the proposed analytical fragility function calculation framework provides a useful methodology for effectively assessing the performance of operating pipelines under longitudinal PGD, quantifying the effect of the uncertain parameters impacting system response.

Lateral Effects of Jet Grouting on Surrounding Soil and Circular Diaphragm Walls

The installation of high-pressure jet grout piles induces significant lateral soil displacement, which can adversely affect nearby structures, such as diaphragm walls. Based on field tests, this study systematically analyzes the lateral displacement of soil caused by two distinct grouting techniques: the intelligent sensing super jet pile (SJT) technique and the Rodin jet pile (RJP) technique. Experimental results show that the SJT technique induces less disturbance to surrounding soil, with a maximum lateral displacement of approximately 6 mm at the closest inclinometer and an influence range limited to about 4 m. A theoretical model, based on passive pile theory, was developed to predict the lateral deflection of diaphragm walls due to adjacent jet grouting. Using a finite difference algorithm, bending moments on the walls were calculated and compared to measured data, showing a consistent correlation between predictions and observations. These findings are crucial for the design and construction of jet grout piles near sensitive structures, ensuring the safety and reliability of soil improvement practices and underground engineering.

Numerical analysis of soil reinforced by sand columns using different installation methods

This study involves a finite element numerical simulation of laboratory tests conducted on small-scale models. The tests involved the installation of columns using different techniques: without soil displacement and without column compaction (WR-NC), and without soil displacement but with column compaction (WR-WC). The reinforced soil masses were then subjected to a uniform 150 kPa load. A comparison between the numerical and experimental results showed excellent agreement, validating the simulation. Following this validation, a parametric analysis was carried out to examine the effects of the various parameters on the behavior of the reinforced soil masses. In the first method, three different column diameters were analyzed, focusing on the effects of diameter (area replacement ratio), column length, and geogrid containment benefits. In the second method, three levels of compaction pressure were applied during the column installation. The study evaluated the impact of column installation techniques on the behavior of the reinforced masses. The findings indicate that settlement reduction is proportional to the increase in area replacement ratio and column length. Additionally, confining the columns with geogrid was shown to be effective in further reducing settlements. The results also revealed that increasing compaction stress leads to greater radial expansion of the columns, which densifies and stiffens the surrounding soil, thereby reducing settlement. Overall, the study concludes that column installation techniques significantly influence the behavior of reinforced soil masses.

Modeling wheeled locomotion in granular media using 3D-RFT and sand deformation

Modeling the wheel-soil interaction of small-wheeled robots in granular media is important for robot design and control. A wide range of applications, from earthmoving for construction and farming vehicles to navigating rough terrain for Mars rovers, motivate the need for a model that can predict the force response of a wheel and the terrain shape afterward. More importantly, the speed, accuracy, and generality of the model should be considered for real-world applications. In this paper, we offer a straightforward sand deformation simulator to simulate the soil surface and integrate it with 3D-RFT in order to capture the soil motion caused by the wheel. The proposed method is able to: (1) estimate three-dimensional interaction forces of arbitrarily shaped wheels traveling in granular media; (2) simulate the soil displacement from the trajectory; and (3) perform the force calculation in real-time at 60 Hz.

Effect of periodic vibration-isolation piles on soil vibration in deep-buried tunnels of suburban railways.

This study aims to investigate the impact of isolation piles on soil vibrations in the environment surrounding suburban railways. Initially, a comprehensive numerical model of the train was established to simulate the wheel-rail interaction forces, which were then applied to a three-dimensional coupled track-soil model. The accuracy of the model was validated through comparison with measured data. The focus of the research is to analyze the vibration isolation effects of single-row, double-row, and triple-row piles, with particular attention to the influence of pile spacing in double-row piles on isolation effectiveness. The study found that the effectiveness of isolation piles in reducing soil vibration acceleration within a depth range of 0 m to 2 m decreases as the pile spacing increases. When the pile spacing reaches 2 times the pile radius, single-row piles exhibit the best vibration isolation effect. For reducing peak soil acceleration within a depth range of 4 m to 8 m, single-row piles are most effective when the pile spacing exceeds 1 times the pile radius. To attenuate peak soil acceleration at depths greater than 6 m, the pile spacing for single-row and double-row piles should be set at 0.5 times the pile radius, while triple-row piles should have a spacing of 1 times the pile radius. In terms of reducing peak soil velocity, single-row piles demonstrate better vibration isolation effects. To reduce peak velocity in soil at depths greater than 2 m, the pile spacing for single-row and double-row piles should be set at 0.5 times the pile radius, while triple-row piles should be spaced at 1 times the pile radius. For reducing peak soil displacement, single-row piles should be used, with optimal results achieved at a spacing of 1 times the pile radius.

Soil Displacement of Slurry Shield Tunnelling in Sandy Pebble Soil Based on Field Monitoring and Numerical Simulation

Due to its inherent advantages, shield tunnelling has become the primary construction method for urban tunnels, such as high-speed railway and metro tunnels. However, there are numerous technical challenges to shield tunnelling in complex geological conditions. Under the disturbance induced by shield tunnelling, sandy pebble soil is highly susceptible to ground loss and disturbance, which may subsequently lead to the risk of surface collapse. In this paper, large-diameter slurry shield tunnelling in sandy pebble soil is the engineering background. A combination of field monitoring and numerical simulation is employed to analyze tunnelling parameters, surface settlement, and deep soil horizontal displacement. The patterns of ground disturbance induced by shield tunnelling in sandy pebble soil are explored. The findings reveal that slurry pressure, shield thrust, and cutterhead torque exhibit a strong correlation during shield tunnelling. In silty clay sections, surface settlement values fluctuate significantly, while in sandy pebble soil, the settlement remains relatively stable. The longitudinal horizontal displacement of deep soil is significantly greater than the transverse horizontal displacement. In order to improve the surface settlement troughs obtained by numerical simulation, a cross-anisotropic constitutive model is used to account for the anisotropy of the soil. A sensitivity analysis of the cross-anisotropy parameter α was performed, revealing that as α increases, the maximum vertical displacement of the ground surface gradually decreases, but the rate of decrease slows down and tends to level off. Conversely, as the cross-anisotropy parameter α decreases, the width of the settlement trough narrows, improving the settlement trough profile.

Numerical tests on dynamic response of pile-supported reclaimed embankment for high-speed railway in saturated soft ground using soil–water coupling elastoplastic FEM

High-speed train (HST) running in the saturated soft ground induces significant vibration that may threaten the running safety and serviceability of high-speed railway (HSR). Extensive studies have been conducted on the dynamic responses of HSR, yet, the soil–water coupling and plastic behavior in the saturated soft ground are rarely considered, and thus the build-up of excess pore water pressure (EPWP) and displacement cannot be accurately calculated. In this study, 2D soil–water coupling elastoplastic FEM was employed to investigate HST induced vibration in the pile-supported embankment using FE code called DBLEAVES. Dynamic soil stress, EPWP, acceleration and displacement under different cases were numerically analyzed in detail. Numerical tests confirm that liquid phase in soft ground plays important influence on the dynamic responses that vertical acceleration and displacement will be overestimated while the horizontal acceleration and displacement as well as EPWP will be underestimated if soil–water coupling is not considered. Single-phase analysis also exaggerates the acceleration attenuation and underestimate the vibration amplification in soft ground. The existence of piles can induce significant soil arching effect in the embankment, the distributions of vertical acceleration and EPWP are partitioned sharply by the piles while vertical displacement in soft ground becomes more uniform along the depth direction within the pile reinforced area. The existence of piles also induces stronger vibration beneath the pile end so that larger EPWP is generated below the pile end than around the pile body. The main influence area due to HST vibration for pile-supported embankment is overall 20 m away from the centerline of HSR track, therefore, it is reasonable to improve the ground by properly increasing the number of pile within this area. When the number of pile is determined, increasing the length of pile or reducing the pile spacing are two effective ways to mitigate the dynamic response.

Analytical Solution to Estimate the Effect of Underlying Tunnel Excavations on the Existing Tunnel

ABSTRACTThe tunneling underlying inevitably leads to the displacement of adjacent soil, greatly influencing the deformation of the tunnel above. Most theoretical studies primarily concentrate on analyzing the mechanical equilibrium of individual tunnel sections, ignoring the energy generated by the system during tunnel deformation. Based on this, in view of the energy relationship, the overlying tunnel's deformation is simulated by using the Rayleigh–Ritz method. Further, its potential energy equation can be established based on the Vlasov foundation. The corresponding energy variational solution is solved according to the minimum potential energy principle, leading to an analytical solution for the shield tunneling‐induced overlying tunnel's response. The efficacy of the suggested method is verified by contrasting it with centrifuge experiments and field case studies derived from prior studies. Relative to the Winkler foundation model, which deviated from the suggested approach, the results derived from the suggested method show a closer correlation with the collected measurement data. Further parameter studies show that the vertical clearance and skew angle between two tunnels, the volume loss rate, and elastic modulus are significant factors affecting the tunnel behaviors due to tunneling underneath. The suggested theoretical model can be applied to forecast potential risks that an existing tunnel may encounter during the excavation of a new tunnel underlying in similar engineering projects.

Experimental and theoretical research on deformation monitoring of distributed piezoelectric inclinometer tube

To improve horizontal displacement monitoring in geotechnical engineering, researchers have focused on developing distributed, automated, and cost-effective inclinometers capable of long-term monitoring. However, existing technologies cannot fully satisfy these requirements. This study proposes a novel piezoelectric inclinometer tube that incorporates a sensor-enabled piezoelectric geocable (SPGC), which was mounted along the surfaces of three tubes made of different materials. The distributed strain along the inclinometer tube was measured using the impedance–strain effect of the SPGC, and a deflection curve was obtained. The results of the failure test showed that the piezoelectric inclinometer tube remained within its measurement range before breaking. Furthermore, the placement of the SPGC on the outer surface of the tube demonstrated superior monitoring effectiveness under bending deformation, providing qualitative insights into the deformation and fracture behavior of the tube. Loading and unloading tests demonstrated excellent reproducibility of strain in the piezoelectric inclinometer tube. Among the tested materials, the inclinometer tube made of acrylonitrile butadiene styrene exhibited acceptable elasticity, large bending displacement, and a high strain transfer rate, making it ideal for monitoring significant deformations in rock and soil. A linear calibration equation was established for the normalized impedance change–strain relationship of the piezoelectric inclinometer tube through calibration tests. Furthermore, a theoretical model was derived to convert the normalized impedance change to the deflection of the piezoelectric inclinometer tube using the finite difference method. Theoretical and experimental values were significantly consistent, with strain and deflection measurement accuracies of 10 με and 0.1 mm, respectively, and an average calculation error of less than 4%. These results are expected to improve the distributed monitoring of horizontal displacement in rock and soil.

Torsion of end-bearing pile foundations in layered anisotropic geomaterials

ABSTRACT An analysis for the torsional dynamic response of end-bearing pile foundations embedded in a layered transversely isotropic geomaterial (soil/rock) is presented. The deformation of the transversely isotropic soil or rock is described by the method of separation of variables. The elasticity theory for a viscoelastic medium with frequency independent hysteretic material damping, and the Extended Hamilton’s Principle are utilised to derive the differential equations describing pile and soil motions. The differential equations are solved analytically in an iterative algorithm. The accuracy of the analysis is verified with existing studies reported in the literature for pile foundations embedded in a homogeneous and layered soil deposit. The effect of the degree of anisotropy on the pile-soil response – dynamic pile-head stiffness, distribution of pile rotation and torque with depth, dimensionless soil displacement function for various values of pile slenderness and pile-soil stiffness ratios in a homogenous soil deposit is investigated. Design charts of static pile-head stiffness in a homogeneous soil deposit for a wide range of pile-soil stiffness and pile slenderness ratios, and degree of anisotropy are also reported. The effect of soil layering for a pile embedded in a two-layered soil deposit is also studied.