Soil Compression Research Articles

Track-bridge deformation relation and interaction of long-span railway suspension bridges subject to strike-slip faulting

During earthquakes, the long-span railway bridges crossing active faults are more vulnerable because of the combined effects of pulsed ground motions and surface dislocations. To study the track-bridge deformation and interaction of long-span railway suspension bridges crossing the strike-slip faults, the refined finite element model of a ballasted track-bridge-pile-soil coupled system was established using the nonlinear finite element software ANSYS/LS-DYNA. A detailed and systematic numerical simulation was conducted from the soil cracking and compression during the ground surface rupture, pile–soil interaction, and three-dimensional track constraints to track-bridge deformation relationships and interactions. One-dimensional wave propagation theory was employed to derive the ground motions on the bedrock according to ground surface-measured seismic records. The influences of the fault-crossing angle (FCA) and permanent ground rupture displacement (PGRD) on the seismic responses and track-bridge interaction were analysed by considering the pile–soil interaction and site response effect. A method for calculating the track curvature radius based on track deformation is presented to evaluate the running traffic conditions of the trains. Additionally, the stability of the ballast bed was estimated using the track-bridge relative displacement. The conclusions drawn can be applied in practical seismic design and train running safety assessment of long-span railway suspension bridges crossing the strike-slip faults.

Predicting clay compressibility for foundation design with high reliability and safety: A geotechnical engineering perspective using artificial neural network and five metaheuristic algorithms

This study aims at predicting clay compressibility (clay compressibility) for foundation design with unprecedented reliability and safety. To achieve this goal, we set forth several scientific objectives to enhance the accuracy of clay compressibility predictions and ensure the robustness of our models. Firstly, we explored an updated dataset comprising diverse clay types, focusing on the intricate relationship between clay compressibility and essential soil properties. By incorporating particle size distribution, the ratio between liquid limit (wLL) and plasticity index (PI), and the ratio between void ratio (eLL) and wLL, our objective was to gain a comprehensive understanding of clay behavior, facilitating more accurate predictions. Secondly, we employed Artificial Neural Networks (ANNs) as our primary modeling tool. ANNs, with their capacity to discern complex patterns within data, formed the foundation of our predictive model. Our scientific objective was to harness the power of ANNs to capture subtle relationships among input variables, thereby ensuring a robust foundation for clay compressibility predictions. To further refine our predictions, our third objective was to optimize the ANN model. We utilized five distinct metaheuristic algorithms—Bird Swarm Algorithm (BSA), Dragonfly Optimization (DO), Elephant Herding Optimization (EHO), Jaya Algorithm (JA), and Whale Optimization Algorithm (WOA). Our aim was to fine-tune the ANN model's parameters using these algorithms, capitalizing on their strengths to achieve superior predictive performance. Additionally, our study aimed to pioneer the development and evaluation of hybrid models for forecasting clay compressibility. By integrating the ANN model with the metaheuristic algorithms (BSA-ANN, DO-ANN, EHO-ANN, JA-ANN, and WOA-ANN), our objective was to create hybrid frameworks that synergistically combined the strengths of both approaches. We rigorously evaluated these hybrid models, ensuring their efficacy and reliability in practical engineering applications. Crucially, we validated our models through practical engineering scenarios. For this purpose, we prepared 30 new soil samples mirroring real-world conditions. Our objective was to apply the developed models to these samples, affirming their effectiveness and reliability in actual foundation design applications. In pursuit of identifying the most accurate and reliable predictive model, our final objective focused on the BSA-ANN model. Remarkably, this model demonstrated an exceptional accuracy of 99.8%. Our objective was to establish the BSA-ANN model as the preferred choice for practical engineering applications, ensuring high reliability and safety in foundation design.

Impact of remolded soil fabric on the volumetric deformation behavior of clayey soils

The volumetric deformation of clayey soils, leading to a reduction in the bearing capacity and serviceability of pavements and building structures, is a major concern during their design, construction, and maintenance. Several approaches are often followed to mitigate the volume expansion and concomitant damage, including removal and replacement, moisture treatment with appropriate compaction protocols, and chemical treatment. During these treatment processes, the in-situ fabric is altered as the natural undisturbed soils are remolded and compacted. Hence, it is crucial to understand the effect of remolding on the volumetric characteristics of clayey soils. To investigate this effect, coefficient of linear extensibility (COLE) tests were conducted on both natural and remolded soil samples. The objective was to evaluate the impact of soil fabric modification on volumetric characteristics such as suction compressibility index (γh) and soil water-retention characteristics, i.e., the soil–water characteristic curve (SWCC) of clayey soils. Our findings indicated that remolded soils had approximately 10% to 30 % higher γh-values than those of unaltered soils, which can be attributed to changes in porosity. Two distinct mechanistic models were developed using the packing theory concept to link the γh-value and SWCC of remolded and natural soils. Finally, an analysis was conducted to compare the potential vertical movement (PVM) of natural and remolded clay soils. This analysis revealed that the remolded soil fabric substantially increased the PVM values, particularly for high-plasticity clay soils. This effect should be considered when assessing the impact of treatment that requires remolding, which substantially alters the soil structure and fabric.

Dimensionless Parameters for Waveform Characterization of Acoustic Emission Signals: Application to Sedimentation and Soil Compression Experiments

Acoustic Emission (AE) is a non-destructive evaluation method that uses transient elastic waves produced by the sudden release of mechanical energy in a material or structure. This method generates multiple AE events during testing; therefore, it is important to develop parameters that capture the characteristics of each event (AE hit). The paper introduces new dimensionless parameters to characterize the waveform of AE signals: Earliness, Transitoriness, and Early Transitoriness. The study shows that these parameters provide an accurate description of AE waveforms, in some respects, better than traditional parameters, which makes them suitable for filtering with simple rules or in combination with machine-learning techniques. Two examples of the application of AE hit filtering from sedimentation and soil compression experiments are provided. In the sedimentation test analysis, the proposed parameters were used with K-means clustering to filter AE hits from outside the zone of interest and to calculate the rate of sedimentation. In the compression test of a sand sample under oedometric conditions, a simple filtering rule was applied to discriminate AE hits from unwanted sources and obtain a clear AE energy cumulative curve. In both cases, the dimensionless parameters have shown the capacity to discriminate between different AE sources and paths and the possibility of filtering hits from unwanted sources.

Analytical solutions for one-dimensional nonlinear large strain consolidation of soft soils with high compressibility under a multi-stage loading

At present, many achievements have been made in the analytical theory of large strain consolidation. However, the consideration of nonlinearity of compression and permeability is not yet sufficient. In this study, a large number of compressibility and permeability test data have been investigated to verify the advantages of log-log relationships in describing nonlinear characteristics of compressibility and permeability of soft soils under both large strain and small strain, and the variation range of parameters in log-log relationships are also presented. Also, based on the log-log relationships, a one-dimensional nonlinear large strain consolidation model of thin soft soil layer is established by considering excess pore pressure as a variable, and the analytical solutions of the consolidation model are obtained under three conditions, respectively. Then, the reliability of analytical solutions is verified by comparing with the results observed in the field and degenerate solution, respectively. Finally, the influence of loading method, final load, compressibility and permeability parameters on consolidation behavior are analyzed. This study provides theoretical supports for the calculation of nonlinear large strain consolidation of actual soft soil layer.

Influence of remediation by electrokinetic on the chemical and geotechnical properties of clayey soil contaminated by copper sulfate

The enhanced electrokinetic (EK) technique is an innovative approach and increasingly used in remediation of the fine-grained texture soils contaminated with different types of contaminant. In this study, the EK is enhanced by adding an intermediate compartment and using purging solutions at the electrode’s compartments. The natural clayey soil samples were obtained from Al-Ahadab oil field and artificially contaminated with two ratios of copper sulfate (66666.67 and 26666.67 mg/kg). The feasibility of using EK technique was evaluated by the efficiency of extracting copper from soil and the magnitude of recovery in the geotechnical properties of soil. The duration of remediation was continued for about 240-250 hours depending either on the continuity of electroosmosis flow or reach a constant rate of electrical current. The removal efficiency of copper from contaminated soil samples was ranged from 98.4% to 99.6%. The EK remediation technique proved a marginal impact on the specific gravity and Atterberg’s limits, but it has a significant effect on the shear strength parameters and compressibility of soil. Furthermore, the EK technique can be considered an efficient method for removing the low and high concentrations of copper sulfate from clayey soil of low permeability.

A One-Dimensional Nonlinear Consolidation Analysis of Double-Layered Soil with Continuous Drainage Boundary

Based on the soil nonlinearity assumptions proposed by Mesri, the one-dimensional nonlinear consolidation of double-layered soil is investigated. To better align with engineering reality, a continuous drainage boundary is introduced, bolstering the reliability of the derived solution through comparison against existing findings. Subsequently, the consolidation behavior of double-layered soil is analyzed for the soil permeability, compressibility, nonlinear parameters, and interface parameters. The outcomes elicit a positive correlation between the consolidation rate of the double-layered soil and both the ratio of permeability coefficient from the lower to upper soil layers and the value of the interface parameter. Furthermore, it is observed that a lower compressibility coefficient ratio between the lower and upper soil layers, along with a reduced ratio of compression index to penetration index, both contribute to an increased consolidation rate within the context of double-layered soil. The one-dimensional nonlinear consolidation of double-layered soil is intricate, intertwined with the relative permeability and compressibility of soil layers, and the influence of nonlinear parameters and drainage boundary configuration. Integrating these factors is crucial for analyzing the consolidation traits of double-layered soil, leading to a more precise portrayal of the consolidation behavior of coastal soft soils.

Nonlinear analysis for consolidation of soft soils improved by composite piles with stiff core and gravel shell

The implementation of composite piles has emerged as an appealing technology for reinforcing soft ground through fulfilling the requisite bearing capacity and facilitating consolidation. Nonetheless, previous investigations into the consolidation behavior of composite pile-improved ground have neglected the nonlinearity of soil compression and permeability. In this context, the logarithm models of e-lgσ and e-lgk are introduced to establish an analytical model for the nonlinear consolidation of composite ground with composite piles. Based on equal strain assumption and annular equivalent method, detailed solutions under four special loading schemes are then obtained. Additionally, a comprehensive analysis is conducted to assess the influence of various parameters on the nonlinear consolidation behavior of composite ground, and the feasibility of current model is verified by degenerations. The results show that ignoring the nonlinearity will lead to an overestimation of consolidation rate when the soil’s compression indices exceed the permeability indices. Moreover, the consolidation rate of composite ground is inversely proportional to σ¯u/σ¯s0′ and Cc/Ckh(v), while demonstrating a direct proportionality to Ksp, Ksg, and kg/kv0. However, σ¯u/σ¯s0′ mainly influences excess pore water pressure at the upper layer, and the influence of Cc/Ckv on the consolidation rate is limited and can even be ignored in comparison to Cc/Ckh. Finally, the proposed model is successfully applied to an engineering project in situ, where the obtained results exhibit a noteworthy agreement with the measured data.

Improving Characteristics of Clayey Soil Using Basalt Fibre, Construction and Demolition Waste and Calcium Carbide

When exposed to changes in moisture, highly compressible clay soils usually show the characteristic of swelling and shrinking and have very poor strength properties. The infrastructures standing on such soil produce fractures as a result of this feature, making the buildings unstable and liable to collapse. By enhancing the characteristics of clayey soils using soil stabilization can improve their engineering properties. The purpose of this paper tends to investigate the use of construction and demolition waste (C&D), basalt fibre (BF) and calcium carbide (CCR) for stabilization of highly compressible clayey soil. Several laboratory experiments including differential free swell (DFS), Atterberg limits, standard proctor and unconfined compressive strength (UCS) are conducted on soil alone and in combination with admixtures used. Based on UCS result,optimum percentages of C&D waste, basalt fibre and calcium carbide obtained were further tested for California bearing ratio (CBR). The findings show rising UCS and CBR values with addition of 21% C&D waste, 0.3% basalt fibre and 4% calcium carbide in combination to each other with clayey soil. The thickness for flexible pavement was developed using IITPAVE software for CBR values based on specifications of IRC: 37-2018. The software resultsrevealed a decrease in pavement thickness for all combinations ofcommercial vehicle daily counts of 1000, 3000, and 5000. When clayey soil is combined with C&D waste (21%), BF (0.3%), and CCR (4%) in combination, the greatest reductionin subgrade layer thickness and costis observed. This method not only improves the geotechnicalcharacteristics of the subgradelayer, aids in decreasing the thickness of the pavement, is highly cost-effective, and resolves the issue of disposal of C&D waste and environmental degradation due to CCR.

Stress-Strain State Assessment of Building Subfoundations Having Flexible Constructive Scheme in Irregular Soil Stratification

Introduction. One of the main problems in the operation of buildings and structures is possibility of their damage due to non-uniform deformation of subfoundation soil caused by the various natural and technogenic factors. To establish the possible character and degree of damage of the above-surface structures, it is necessary to calculate the value of subfoun- dation relative differential settlement at the level beneath the foundation bottom. The subfoundation settlement is calculated within the compressible soil thickness using the specific gravity values and soil deformation modulus. The increment of settlement is induced by the increase of vertical stresses in the massif and increase of soil deformability upon growth of moisture. The purpose of the study is to establish the dependence of the magnitude of the relative difference in settlement on the deformation properties of soils with uneven occurrence of layers in order to predict the nature of damage to above-ground structures.Materials and Methods. An example of subfoundation deformation calculations at the bottom level of the free-standing foundations of a building having flexible constructive scheme has been studied. A model of stratification of two heterogeneous geotechnical elements with a 1:4 boundary slope and differing physical and mechanical properties has been used. It has been assumed that one of the geotechnical elements has natural properties enabling the building foundations to rest on it without prior site preparation. Another geotechnical element has significantly worse properties. The calculations on determining the settlement have been made in accordance with the layer-wise summation methodology.Results. The regularity in alteration of the predicted settlement value depending on the ratio of firm and soft soils thickness in the irregular stratification has been established. It has been proven that the difference between the specific gravity values of the heterogeneous beds within 10 % does not affect the depth of compressible soil thickness if the calculation of settlement is made using the layer-wise summation methodology.Discussion and conclusions. The calculation results analysis of the subfoundation settlement of the equidistant column foundations was carried out, the engineering solution was proposed to ensure reliability per limit state groups.

Fireless Brick Making using Water Treatment Sewage Sludge with MICP Action

Bricks materials used in making the walls of building. Currently, brick making has new innovations. As in this study using water treatment sludge waste and bacillus subtilis bacteria. Sludge waste done with percentage of 20% and bacillus subtilis bacteria much as 6%. The process adding bacteria called the Microbially Induced Calcite Precipitation (MICP) process. The process to increase compressive strength clay soil. The purpose study to determine effect of Bacillus subtilis bacteria on the strength bricks using mud and the strength of bricks with bacterial reinforcement. The results showed the compressive strength did not the specifications, where value of the compressive strength of bricks in accordance with SNI 15-2094-2000 is 50 kg / cm². And results of compressive strength only amounted to 22.82 kg / cm² in the 28-day curing period. For compressive strength using mixture of bacteria produces highest strength value the 4-day culture period of 28.11 kg kg/cm².

Multivariate Statistical and Correlation Analysis between Acoustic and Geotechnical Variables in Soil Compression Tests Monitored by the Acoustic Emission Technique

In this research, a series of compression tests were carried out, under oedometric conditions, on sand samples prepared with different moisture contents. In these tests, in addition to the usual measurements of the stress and deformation of the sample, a series of acoustic emission sensors were used to monitor the parameters of the acoustic signals coming from inside the sample. This is a rather novel technique with great potential, but sometimes difficult to approach due to the large amount of acoustic emission data generated. In this paper, a correlation and regression analysis has been performed to quantify the correlations between the geotechnical variables and the parameters characterizing the acoustic emissions. The results presented open an interesting horizon of possibilities since, as it has been shown, it is possible to determine the values of the geotechnical properties from the acoustic variables, by means of the regression functions obtained for each type of soil or for each practical case. At the very least, this is a complementary tool in the determination of the mechanical properties of soils subjected to compression, although it could also be useful in those situations in which the monitoring of geotechnical variables describing the tenso-deformational behavior of the soil may be difficult or impossible.

Effect of saturation on dynamic characteristics of collapsible gypseous soil using cyclic triaxial testing

Studying the unsaturated gypseous soils behavior may lead to more understanding of the gypseous soil problems associated with unsaturation under the effect of the vertical vibrations. The purpose of this paper is to assess the suitability of unsaturated gypseous soil as a machine foundation soil. Moreover, such a purpose is considered beneficial in assessing appropriate methods for studying the characteristics and the behavior of unsaturated gypseous soils such as soil elastic modulus parameters, compressibility parameter, waves velocities, and amplitude axial strain for cyclic loading parameters under different with degree of saturation. The tests were performed for conditions 35% and 70% relative density of natural gypseous soil under 1.0 Hz and 2.0 Hz cyclic frequency at degrees of saturation (30%, 60%, and 80%), and fully saturated gypseous soil to investigate the gypseous soil behavior. It was found the values of the elastic modulus and wave velocities at degree of saturation 60% for different number of cycles and frequency increased with decrease of the strain and compressibility. Then, it began to decrease gradually at the saturation degree 80% and 100%, respectively. The best results based on strength consideration were obtained at 60% saturation, and the lowest strength was found when the soil was 100% saturated, for both load frequencies 1, and 2 Hz. The load frequency 1 Hz gave higher values than cyclic frequency 2 Hz of elastic modulus and wave velocities, while the number of cycles was less at the same time and for different degrees of saturation.

The Application of Machine Learning Techniques in Geotechnical Engineering: A Review and Comparison

With the development of data collection and storage capabilities in recent decades, abundant data have been accumulated in geotechnical engineering fields, providing opportunities for the usage of machine learning approaches. Thus, a rising number of scholars are adopting machine learning techniques to settle geotechnical issues. In this paper, the application of three popular machine learning algorithms, support vector machine (SVM), artificial neural network (ANN), and decision tree (DT), as well as other representative algorithms in geotechnical engineering, is reviewed. Meanwhile, the applicability of diverse machine learning algorithms in settling specific geotechnical engineering issues is compared. The main findings are as follows: ANN, SVM, and DT have been widely adopted to solve a variety of geotechnical engineering issues, such as the classification of soil and rock types, predicting the properties of geotechnical materials, etc. Based on the collected relevant research, the performance of random forest (RF) in sorting soil types and assessing landslide susceptibility is satisfying; SVM has high precision in classifying rock types and forecasting rock deformation; and backpropagation ANNs and Hopfield ANNs are recommended to forecast rock compressive strength and soil settlement, respectively.

Nonlinear response of laterally cyclic loaded pile in cohesionless soil based on conical strain wedge model

The response to environmental lateral cyclic loads is an important design consideration for offshore piles installed in sand. This paper proposes a novel conical strain wedge (CSW) model to simulate the pile-cohesionless soil interaction under lateral cyclic loads. The CSW model enhances the depiction of passive compression soil zone resistance and failure pattern compared to the conventional strain wedge (SW). The developed model is incorporated in a simplified and efficient method to calculate the nonlinear pile response to lateral cyclic loads. The performance of the developed theoretical model is validated by comparing its predictions with observations from several experimental studies reported in the literature. The validated CSW model and its solutions are then employed to elucidate the performance characteristics of the pile-soil system under cyclic loading. The results revealed that: (1) the degradation of soil stiffness is more pronounced at the onset of cyclic loading and the rate of increase in pile response due to degradation diminishes with the increase in the number of loading cycles; (2) as the cyclic load amplitude increases, the increase in pile displacement becomes increasingly severe; (3) the number of loading cycles has greater influence on the response of piles with lower flexural stiffness; and (4) the effect of soil shear strength on the pile displacement becomes significant as the number of loading cycles increases, whereas its effect on the pile maximum bending moment diminishes gradually.

Effect of the particle’s shape on the dynamic shear modulus and compressibility of diatomaceous soils

Diatomites are unicellular algae fossils that can be found worldwide. This paper studies the diatom's shape effect on diatomaceous soil mixtures' dynamic and compressibility properties. Physical characteristics of six diatomite samples with variable shapes and taxonomies are presented. Among these six samples, three diatomites of similar grain size distribution were mixed with kaolin, and the mechanical properties (i.e., shear modulus and damping ratio from small to large strains) were analysed. The results showed that diatom frustules increased the mixtures' compressibility and reduced the maximum shear modulus compared with pure kaolin samples. Moreover, the diatom's shape influenced the normalised shear modulus degradation curve and the damping ratio. Overall, the presence of diatomites reduces the energy dissipation capacity in soils. This research evidenced the importance of distinguishing the shape of diatom in soil mixtures when mechanical properties are analysed, a situation that has yet to be explored.

Remediation of Pb–Cd contaminated soil using coal bottom ash-based geopolymer and coir: Soil remodeling and mechanism

Stabilizing heavy metal-contaminated soil with solid waste-based materials is a sustainable approach. This study synthesized a coal bottom ash-based geopolymer and coir for the treatment of Cd- and Pb-contaminated soil. The results demonstrated that adding 10% geopolymer stabilized over 95% of Cd and Pb in contaminated soil, with the maximum compressive strength of soil reaching 634 kPa after curing. Geochemical model simulations revealed that Pb and Cd primarily converted to precipitated mineral forms (Cd4(OH)6SO4, Pb4(OH)6SO4, Litharge, and larnakite) when the system pH exceeded 5. From a mechanical perspective, the combination of coir and coal bottom ash-based geopolymers effectively solidified heavy metals while improving soil frost resistance, compression resistance, and shear resistance. The mineral recombination of coal bottom ash was successfully achieved, and it was prepared as an amorphous cementitious material. This study unveils the mechanism of geopolymer-cemented heavy metals and their structural strengthening, providing new technologies for addressing land resource pollution and realizing the green, sustainable, and clean reuse of industrial solid waste.

A case study on the variability of the coefficient of consolidation and its design reliability

The consolidation characteristics of cohesive soils are estimated using established relationships between the coefficient of consolidation (cv) and index tests, as well as laboratory oedometer tests. While the design cv is preferred from the field dissipation tests, the conversion from a horizontal to vertical value needs to be considered. A trial load was used to verify the consolidation parameters during a Queensland Road upgrade, which involved both road widening and raising of the existing embankments over compressible soils. Construction was done in 4 stages, and with preloading and surcharging in selected areas. Settlement monitoring and Asaoka plots were used to validate the design, and “moderately conservative” design values were adopted. This case study is used to show the large variability of the cv by the various test methods. While 99% of the site settlement was within the magnitude and time predicted during design, a 25 m length was not consistent with the data and performance of the rest of this site within the flood plain. The back-calculated cv was below the lowest test value and even data from nearby settlement plate monitoring from adjacent stages. In situ tests were located within 25m of this unconforming area and given that stratigraphy was consistent then the cv value adopted may not be representative. The lessons learnt show the various verification and validation process required to envelope risks, but all conditions with a “moderately conservative” design may not be covered.

A parametric study on deformation behaviour for design of braced excavation in soft clay

ABSTRACT Adequate prediction of surrounding ground movement during braced excavation is critically important as excessive soil movement damages adjacent structures. The magnitudes and patterns of ground movement and wall deflection largely depend on excavation parameters like thickness of diaphragm wall, wall embedment depth, strut locations and soil parameters such as soil strength, compressibility and creep parameter. In the present paper a thorough, parametric study has been conducted using finite element (FE) analysis to address the influence of various parameters on deformation characteristics of braced excavation in soft clayey deposits. The importance of correct estimation of soil parameters for braced excavation design is also documented. The analysis of typical braced excavations in soft clay is carried out using PLAXIS 2D software where soft soil creep constitutive model is used. On the basis of numerical study a handy design guideline is recommended. Further multivariate regression models are developed incorporating various important excavation parameters for the adequate prediction of maximum wall and ground displacement along with wall and ground surface deformation profile. Here large numbers of data reported in case histories and generated artificially from FE analysis are used for formation of regression equations. The proposed model is validated comparing results from literatures not used for the development of the model.

Numerical Evaluation of Drag Force on Integral Abutment Piles

Piles transmit structural loads through skin friction, end-bearing, or both to deeper and stronger soil layers. Surcharge loads, site grading, or dewatering activities induce downward movement in the soil that is adjacent to piles installed in a compressible soil layer. This movement causes negative skin friction stresses that act downward at the pile–soil interface, which causes an additional force denoted the drag force (Qn) that is applied to the pile, which results in a larger axial load in the pile shaft. The end-bearing force and positive skin friction that develops in the pile part within stable (incompressible) soil resist the applied loads [e.g., dead load (Qd) and Qn]. This paper aimed to evaluate Qn that was mobilized on driven H-piles that were installed in soft clay with three-dimensional (3D) nonlinear finite-element analysis. Two numerical models were validated against the field data from two instrumented H-piles, which were part of a three-span bridge (E-21) on Highway 418, Ontario, Canada. The calculated settlements and Qn agreed well with measured field data. The validated numerical models were employed to conduct a parametric analysis to investigate the location of the neutral plane (NP) at which the skin friction changed from negative to positive. In addition, the performance of the piles that were installed in small and large groups was investigated, which considered Qn and group effects. It was found that the group effect was negligible for piles that were installed in one row but were significant for piles that were installed in large groups. Finally, a group factor was proposed to calculate the drag force for piles in a group (Q(n)pile in group).