Lateral Soil Displacement Research Articles

Decoupled Analysis of a Multi-Layer Flexible Pipeline Buried in Clay Subjected to Large Lateral Soil Displacement

Multilayered flexible subsea pipelines may experience significant lateral movements due to manmade and environmental geohazards. These pipelines incorporate several structural and protective layers to resist different loads, and may require additional protection such as trenching, rock placement, or burial. In practice, simplifications are considered due to the complexities and uncertainties involved in the multi-layer pipe structure and the surrounding soil, compromising the pipe structure or the soil behavior. These simplifications are applied either on the pipe by assuming a rigid section or on the soil by representing it as elastic springs, which may result in inaccuracies. This study proposes a decoupled methodology combining the Coupled Eulerian–Lagrangian (CEL) model for soil displacement with a small-strain finite element analysis of the flexible pipe. This approach aims to accurately capture cross-sectional deformations and local stresses due to soil movement while maintaining reasonable computational effort. A parametric analysis was conducted to assess the impact of several variables on failure risk. The deformed cross-section was then used for a collapse analysis to determine critical loads at maximum operational depth. The study showed that modeling parameters such as soil strength and internal diameter might significantly influence pipe failure and the risk of collapse.

A Simplified Theoretical Method for Estimating the Effect of Capsule Grouting Expansion Technology on Controlling Pile Deformation

Deep excavation and shield tunneling processes often induce significant deformation in adjacent existing pile foundations, posing risks to the safety of superstructures. To address this issue, capsule grouting expansion technology has emerged as an efficient and economical technology to actively control pile deformation during such construction activities. This technology has been applied in some engineering projects aimed at safeguarding nearby buildings or facilities. However, theoretical research on capsule grouting expansion technology is limited and lags behind its practical engineering application. This paper proposed a simplified theoretical approach for estimating the effect of capsule grouting expansion technology on the deformation of neighboring pile foundations. Initially, virtual image technology was employed to obtain an analytical solution for the lateral displacement of soil resulting from the expansion of a cylindrical cavity with infinite height. The pile was considered as an Euler–Bernoulli beam on a Winkler foundation, allowing for the calculation of the loading response of the existing pile foundation. Utilizing the two-stage method, the theoretical analytical method of the lateral deformation of the pile shaft caused by capsule expansion was obtained. The reliability of the proposed theoretical method was verified by comparing the measured and calculated results. Further investigation into the controlling effect of the capsule grouting expansion technology on the deformation of the pile foundation was conducted through parametric analyses. These analyses encompass capsule radius, the distance between the capsule and pile foundation, the depth of the capsule, the length of the capsule, and the pile base constraints.

Consolidation behaviour of marine clay improvement by combined vacuum preloading with geotextile

ABSTRACT The traditional vacuum preloading method of prefabricated vertical drain (PVDs) has been widely used in practical engineering. However, the serious clogging effect around PVDs in the process of vacuum-preloading reinforcement can easily lead to a series of problems such as uneven settlement and large lateral displacement of soil after reinforcement, which seriously affects the application of PVDs in marine clay foundation treatment. In this paper, the effect of combined treatment of marine clay by geotextiles and PVDs on reducing the clogging effect around PVDs was studied by laboratory model experiment. The effects of geotextiles with different diameters and spacings on the surface settlement, excess pore water pressure and lateral displacement of the reinforced soil were analysed. The experimental results show that this method has obvious help on alleviating the above problems, thus providing a reference for the application of geotextile combined with vacuum preloading method to treat marine clay foundation in engineering practice.

Parametric Study of Lateral Load on Helical Pipe Piles in Clay

In the past decades, as the world has placed emphasis on green energy, solar energy has become a favorable option. Different piled foundations have been designed to strengthen the structure supporting the solar panels. These piled foundations include rectangular and circular hollow section piles, as well as H-shaped piles. With various environmental loadings, lateral soil displacement will be encountered when large solar panels are installed on the supporting structure at an inclined angle. Presently, helical pipe piles are widely used in solar farms as part of the supporting structure. In this paper, the pile–soil interaction of steel pipe piles and helical pipe piles with wind loads is analyzed using ABAQUS. The Finite Element Method (FEM) models are assessed with varying strength moduli and cohesions of clay. Further, this paper examines the pile soil system, considering different clay stiffnesses, including very soft, soft, firm, stiff, very stiff, and hard. It is found that the helical piles’ horizontal capacity increases with soil strength and Young’s modulus, but the capacity increment rate reacts differently. This study has a guiding effect on the construction of solar farms using the “tracker” solar system.

Large-scale Field Tests of the Performance of Geogrid-reinforced Piled Embankment over Soft Soil

When constructing superstructures on soft soils, geogrid-reinforced embankments and pile-supported embankments are used widely to improve the soft foundation and prevent issues including excessive settlements and large lateral displacements, so it is crucial to understand and evaluate their performance systematically. This study focuses on a case of piled embankments for a motor-racing circuit under construction in China. Two large-scale field tests of pile-supported embankments with and without reinforcement were carried out to investigate the effect of geosynthetic reinforcement on the improvement of embankments. During long-term monitoring, instruments in the test sites measured earth pressures, settlements, lateral displacements, and pore water pressures, and the performances of the reinforced or unreinforced embankments were examined. Test results from the two test sites under similar loading are compared, and it is concluded that the geosynthetic-reinforcement considerably influences the improvement of load transfer and diminishment of total and differential settlements. The lateral restraint provided by the geogrids also reduced the lateral soil displacement and the influence of subsoil depth. The smaller excessive pore water pressures in the site with reinforcement were associated with the enhanced load transfer due to the geogrids. This study provides an important reference for the design and construction of this circuit and other related projects.

Study on different reinforcement methods of inclined liquefiable site

The existing earthquake damage investigations indicate that the lateral spreading of site is more likely to occur in inclined liquefiable site under earthquake, therefore the way of foundation reinforcement is often adopted to reduce the lateral spreading phenomenon of inclined liquefiable site. In order to study the reinforcement principle of inclined liquefiable site by the two reinforcement methods of concrete pile and gravel pile, based on the verified numerical model of free field model, the model of concrete pile reinforcement and crushed rock pile reinforcement was established, the dynamic response and reinforcement effect of two different reinforcement methods in inclined liquefiable site were analyzed, and the effects of buried depth and pile diameter on the earthquake dynamic response and the effects of different reinforcement models are discussed. It is found that the concrete pile has a better reinforcement effect on inclined liquefiable site than gravel pile under the same buried depth and pile diameter. When the concrete pile is adopted to reinforce the inclined liquefiable site, the reinforcement effect is better when the concrete pile are embedded in dense sand layer at a certain depth; When adopting the gravel pile to reinforce inclined liquefiable sites, the effect is better when only clay and loose sand layer are reinforced, moreover, increasing the diameter of gravel piles greatly improves the reinforcement effect of inclined liquefiable sites. The pile group reinforcement model can greatly reduce the lateral displacement of site soil compared with the single pile reinforcement model.

Impact of Tunneling on Adjacent Piles Based on the Kerr Foundation Model Considering the Influence of Lateral Soil

The Kerr foundation model simulates the interaction between piles and soil. Considering the impact of lateral soil displacement on adjacent piles, the lateral displacement and bending moment of the adjacent piles caused by shield tunnel excavation are calculated in detail. Additionally, the reactions of groups of piles are obtained by focusing on the shielding effect of the piles on the soil displacement caused by shield tunnel excavation. The validity of the solutions is verified by comparing the calculated results with the boundary element program GEPAN. Additionally, adjacent pile lateral displacement and bending moment are compared, with and without considering lateral soil effects. Furthermore, this study investigates the influence of various factors, such as soil spring stiffness, pile–tunnel distance, ground loss ratio, and pile diameter on the pile group’s lateral displacement and bending moment. The research findings indicate that increasing the soil spring stiffness or the horizontal distance between the pile and tunnel can reduce the lateral displacement and the bending moment of the pile. On the other hand, as the ground loss ratio gradually increases, the pile lateral displacement and bending moment will also increase. However, when the diameter of the pile grows, the lateral displacement reduces, while the bending moment increases.

The impact of ‘T’-shaped furrow opener of no-tillage seeder on straw and soil based on discrete element method

In no-tillage planting systems, the ‘T’-shaped furrow opened by the furrow opener can effectively preserve soil moisture, ensuring that the seeds are consistently covered by the soil. Investigating the effects of different types of lateral blade on the ‘T’ -shaped furrow opened by the furrow opener is crucial. In this study, a discrete element method (DEM) model was established to simulate the interactions among the ‘T’- shaped furrow opener, straw, and soil. The rationality of the model was validated through soil bin experiments and simulation experiments, which involved multiple indicators, such as soil forward displacement, soil lateral displacement, straw forward displacement, draft force, and down force of the ‘T’- shaped furrow opener. During the exploration experiment, the influence of lateral blade shapes and working speeds on the performance of the ‘T’- shaped furrow opener was investigated. In the simulation, draft force, down force, soil displacement, and straw displacement were measured. The results indicated that both lateral blade shapes and working speeds, as well as their interaction, had significant effects on draft force, down force, soil displacement, and straw displacement. Different lateral blade shapes resulted in varied shapes of the ‘T’- shaped furrow opened by the furrow opener. Notably, the concave arc lateral blade had a disruptive effect on the soil below the surface and could induce secondary shear of the straw, enhancing the cutting efficiency of the straw. The simulation results are useful for selecting the lateral blade and evaluating the groove effect.

Dynamic and Static Analysis of Deep Excavation of Poligon Station in İzmir Metro Line

In this paper, the deep excavation stages of Poligon Station which is the located along the Üçyol–Fahrettin Altay subway line was modeled numerically. Although some parts of the metro line were constructed, some parts of metro line are currently under construction in İzmir. The Poligon Station is carried out with a surrounding diaphragm wall and top-down construction method. The foundation mat and four slabs of the station building are used as support elements. The excavation depth of the station is 18 meters. The soil properties of the numerical model were obtained engineering boreholes and laboratory tests. Lateral soil displacements were measured with inclinometers installed in the nearby soil layers. Displacements which were measured from inclinometers and obtained from numerical modeling were compared. Beside the static analysis, the Poligon station of the metro line was analyzed with a model earthquake. 16.12.1977 İzmir Earthquake (Ms=5.5, amax=0.21g) was used as a model earthquake for dynamic analyses. In addition, effects of changing the properties of the soil on computed results were numerically investigated using the software Plaxis.

Effects of different test methods on the seismic dynamic response in inclined liquefiable soil

According to horizontal liquefiable free-field shaking table test carried out by the research group, a finite element numerical model of horizontal liquefiable free-field is established based on OpenSees finite element platform, and the influence of the model box on dynamic response of soil is considered in this numerical model, and the reliability of numerical model is verified by comparing with the shaking table test results. The inclined liquefiable free-field finite element calculation model is established based on the horizontal numerical model, and three different numerical models of inclined shear box model, inclined soil in shear box model and inclined soil in rigid box model are established to simulate the different test methods adopted in the shaking table test. Through comparison, the dynamic response results of free-field soil calculated by three numerical models under the action of 0.3g Wenchuan earthquake Wolong wave are analyzed, and the influences of three different test methods on the calculation results are discussed, and the results showed that the response of the lateral displacement of soil by two test methods of inclined shear box and inclined soil in shear box have great differences, and the maximum difference value can reach 45%; the response obtained by the two test methods of inclined soil in rigid box and in layer shear box have more obvious differences in pore water pressure lateral displacement and acceleration of soil.

Inertial and kinematic interactions of bridge‐pile group subjected to liquefaction induced lateral spreading: Large‐scale shaking table experiments

AbstractThis paper investigates the seismic bridge‐pile‐soil system failure mechanisms due to liquefaction‐induced lateral spreading. Two large‐scale shaking table tests were performed on pile groups with and without bridges in sloped liquefiable soils overlain by soil crust. The systems were subjected to a weak earthquake signal (Tabas 0.05 g) and a strong earthquake signal (Tabas 0.3 g). Their responses were recorded in terms of excess pore pressure, acceleration, and displacement time histories. The piles seismic failure mode and mechanism are described based on the obtained results. In addition, the inertial and kinematic interaction effects on the piles’ deflection were evaluated. The results demonstrated that the bridge had no significant effect on the seismic response of the pile‐soil system under weak earthquakes. Meanwhile, the test model without a bridge experienced more significant soil lateral displacement, and the saturated sand exhibited dilatant behavior, and amplified the acceleration peak response during the strong earthquake. Moreover, the liquefaction‐induced lateral spreading moved the vulnerable position of the pile group bridge system from the pier bottom to the pile head, which changed the failure mode of the pile head. The results also revealed that, compared with weak earthquake excitation, the kinematic effect was significantly enhanced, and the inertia effect was weakened during strong earthquakes. Moreover, the pile curvature during both weak and strong earthquakes was inversely proportional to the bridge inertial load.

Assessment of post-liquefaction potential in soil displacement on irrigation canal reconstruction project in the Jono Oge and Lolu area, Central Sulawesi, Indonesia

A seismic event of magnitude 7.5 Mw took place in Central Sulawesi in September 2018, marking a significant occurrence in the geological hazard chronicles of Indonesia. The occurrence of liquefaction subsequent to the earthquake significantly damaged the water resource infrastructure in the Sigi Regency. This study aims to evaluate the possible soil displacement resulting from re-liquefaction events occurring in the main irrigation canals in the Jono Oge and Lolu regions. The study used semi-empirical and finite element analysis to compute the lateral displacement index and reconsolidation settlement within the designated study region. The examination of soil displacement is conducted under various groundwater level scenarios, utilizing the most recent soil investigation conducted in 2021. The findings of the study indicate that raising the groundwater level to -3.5 meters will result in significant soil and irrigation canal damage. In the future, it is suggested that limiting the groundwater level below -11 meters in the primary irrigation canal area might effectively mitigate soil lateral displacement and settlement.

Influence Law of Foundation Pit Excavation on Stress of Surrounding Tunnel Bolt

Due to the existence of a tunnel next to the foundation pit, the soil surrounding the foundation pit deforms into the foundation pit due to the excavation unloading during the process of foundation pit excavation, which causes the deformation of the tunnel. The supporting structure of the tunnel can ensure the deformation stability of the tunnel, so it is necessary to study the stress of the tunnel bolt supporting structure caused by the excavation of the foundation pit. In this paper, the numerical simulation method was adopted to study the influence of the distance between the foundation pit and tunnel and the width and depth of foundation pit excavation on the stress of the tunnel bolt, and the following results were obtained: (1) When the distance between the tunnel and the foundation pit changes, the axial force of the bolt changes accordingly. The axial force of the left bolt first increases and then decreases, and the largest axial force is located in the middle of the bolt. (2) With the increase in the excavation width of the foundation pit, the stress of the left bolt does not change much. For the left bolt, with the increase in excavation depth, the stress of the left bolt does not increase monotonically but shows a trend of increasing first and then decreasing. When the excavation depth exceeds a certain value, the influence of excavation depth on lateral soil displacement gradually decreases. With the increase in excavation depth, the axial force of the top bolt decreases first and then increases.

Large-scale shake table testing of pile group-bridge model in inclined liquefiable soils with overlying crusts

Large scale shaking table tests were performed to investigate the failure mechanism of pile group-bridge system subjected to liquefaction-induced lateral spreading. The tests comprised two cases: Case L which refers to a bridge model supported by a 2 × 2 pile group embedded into the inclined liquefiable soils with crusts; and case R which refers to the same bridge model fixed to a rigid foundation. The experimental details are provided and typical test results are elucidated. The failure mechanism of the pile group-bridge system under strong earthquakes is revealed. The results indicate that the lateral peak soil displacement profile has a linear distribution, while the lateral permanent displacement profile has a cosine distribution pattern. It was also found that the pile is prone to damage and bending failure both at its head and at the bottom of saturated sand where it is fixed into bearing stratum. For the pile group-bridge system, the liquefaction-induced lateral spreading causes the failure position to move from the pier bottom to the pile head. In addition, the pier bottom is more likely to experience damage under strong earthquakes in case R than in case L, while the opposite is true during weak earthquake excitation.

Critical support pressure of shield tunnel face in soft-hard mixed strata

Support pressure is a key factor to the stability of excavation face during shield tunneling, which further imposes a safety issue on surrounding buildings and facilities. However, several studies have been reported on critical support pressure in mixed strata regarding twin-tunnel excavation. This paper aims to obtain the critical support pressure based on minimizing the influence on the surrounding environment induced by shield tunneling in soft-hard mixed strata. A series of three-dimensional finite element models are established to analyze soil and lining responding with different support pressure caused by twin tunnels excavation. The results reveal that the ground surface settlement and lateral displacement of soil are sensitive to the change of support pressure, especially under clay-dominated conditions. Increasing support pressure slightly changes the lining movement and location of maximum stresses of the existing tunnel due to adjacent tunnel excavating. According to this study, the upper and the lower critical support pressures are 1.43 and 1.06 times of lateral earth stress at tunnel crown, respectively, which are also compared with the limit support pressure and measured results from a shield tunnel in the literature. The critical support pressure has great significance for the stability of the excavation face and minimizing the influence on the surrounding environment caused by shield tunnel excavation.

Analysis of the existing pile response induced by adjacent pile driving in undrained clay

An analytical method for quantitatively predicting the existing pile behavior induced by adjacent pile driving is of great engineering significance to evaluate the potential influence of adjacent pile penetration on existing piled buildings. In this paper, a simplified two-stage approach is employed to derive the vertical and lateral responses of the existing pile during adjacent pile installation. First, the free-field soil movement due to pile penetration is estimated by an improved source-sink imaging technique considering the existence of the top free surface. The validity and accuracy of this calculation approach are subsequently examined via comparison with published studies. Second, the shear-displacement method and improved Pasternak foundation model incorporating the impact of lateral soil displacement are introduced to investigate the pile-soil interaction. Moreover, based on the Randolph-Worth logarithmic attenuation function and Mindlin’s solution, the pile group response considering the shielding effect of piles is analyzed. Finally, the present solution for a single pile response is validated with the existing theoretical solution and the simulation solution, and extensive parameter studies are conducted to systematically discuss the variation of the behavior of the existing single pile and pile group.

A Large-Scale Model of Lateral Pressure on a Buried Pipeline in Medium Dense Sand

Modern countries utilise buried pipelines for the long-distance transportation of water, oil, and gas due to their efficiency and continuity of delivery to receiving locations. Due to soil movements such as landslides, excessive earth pressure imposed on buried pipelines causes damage and, consequently, leaking of liquids, gases or other harmful effluents into the soil, groundwater, and atmosphere. By using a large-scale physical model, the lateral pipeline–soil interaction in sandy soil was researched. This study investigated the stress distribution on a buried pipe induced by lateral soil displacement. The external forces on the buried pipe caused by the surrounding soil motion were measured using earth pressure cells installed in the active zone along the pipeline. Additionally, visual inspection of ground deformation patterns on the surface, including tensile cracks, above a shallow-buried pipeline subjected to lateral soil movement was reported. The results revealed that lateral soil movement has a potency effect on buried pipelines. The findings also indicated that the highest stresses occur at the unstable soil boundaries prior to reaching the soil’s peak strength. After observing the soil surface’s rupture, most of the stress increments were concentrated in the middle section of the pipe.

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.

Model test and analysis of soil displacement of cone-perforated column composite pipe pile under static pressure

In view of the fact that there is relatively little research on soil squeezing effe ct of conical-perforated column composite pipe pile, the lateral displacement and surfa ce uplift of conical-perforated column composite pipe pile after single pile is pressed i nto soil are observed by static pressure pile sinking method, and the change law of soil lateral displacement and surface uplift during pile sinking is analyzed. It is found that the lateral displacement increases with the increase of pipe pile driving depth, and whe n the pipe pile is fully penetrated, the soil lateral displacement ends, and the influence range of soil lateral displacement is 2 days.

Shaking table testing of two single piles of different stiffnesses subjected to liquefaction-induced lateral spreading

Lateral spreading is the main cause of pile foundation damage in liquefaction-prone areas during earthquakes. A soil profile in which a non-liquefied soil is on top of a liquefied soil is a critical design scenario. To investigate the influence of lateral spreading on pile responses in this type of soil profile, a shaking table test was performed on two single piles in the ground with a 2° slope. Considering different pile stiffnesses, an aluminum pile (Al pile) and a polypropylene pile (PP pile) were tested. The piles were embedded in multilayered soil comprising a clay layer sandwiched between dry sand above and saturated sand below it. The two piles had considerably different displacement and moment responses to an input motion based on a 1999 Taiwan Chi-Chi earthquake record. The experimental lateral spreading soil displacement profile approximated the cosine profile proposed by Tokimatsu and Asaka. Compared with the upper non-liquefied soil, the magnitude of the lateral spreading pressure of the liquefied soil was small. The experimental lateral spreading pressure from the non-liquefied soil layer was approximately 2.1 and 4.5 times Rankine's passive earth pressure for the PP and Al piles, respectively. The difference between the derived p-y curves of the Al and PP piles for the non-liquefied soil layer may have been due to the contribution of downhill soil reactions. To reflect the influence of pile stiffness, both the downhill and uphill p-y curves of the non-liquefied crust layer should be considered in lateral spreading analysis.