Foundation Soil Research Articles

A FEM‐DEM Coupling Analysis on Bearing Capacity of Sandy Soil Foundation Considering Fabric Anisotropy

ABSTRACTWith the acceleration of urbanization, the stability of the foundation is being more crucial to the performance and service of the superstructure. As our understanding of the factors influencing soil's physical and mechanical behavior deepens, it becomes increasingly challenging for traditional limit equilibrium and limit analysis methods to accurately consider the complex factors affecting foundation stability, such as initial fabric anisotropy caused by the particle morphology and geological deposition in sand. Although some scholars had used advanced constitutive models in the finite element method (FEM) to investigate the influence of initial fabric anisotropy on mechanical responses of foundations, this approach failed to reveal the microscopic information underlying the shear failure of sandy soil foundations. In this study, the influence of the initial fabric anisotropy of sandy soil on the ultimate bearing capacity and shear failure mode of shallow foundation is studied using the hierarchical FEM and discrete element method (DEM) coupling analysis method. Four representative volume elements (RVEs) with varying initial bedding plane angles are constructed in DEM for characterizing different initial fabric anisotropies, and the specific stress–strain information of DEM RVEs is directly passed into the corresponding Gauss points in FEM to replace the conventional constitutive model. Numerical results show that the initial fabric anisotropy affects the ultimate bearing capacity and shear failure mode of shallow foundations significantly, and the corresponding micromechanical behaviors at different local Gauss points have been explored, which advances our understanding of the micromechanisms underlying the progressive shear failure of sandy soil foundations significantly.

Laboratory experimental study on GESC combined with electroosmosis for ground improvement

To verify the effect of electrokinetic geosynthetics-encased stone columns combined with electroosmosis on soft soil foundation reinforcement, laboratory model experiments were conducted using stone columns (SC), geosynthetics-encased stone columns (GESC) with/without electroosmosis. The energy consumption coefficient and drainage rate of electroosmosis, the shear strength and water content distribution of soil, and deformation law of the pile section after static load tests at different depths were studied. Experimental results show the strength of soil around the pile increases after electroosmosis, enabling better support for the pile body, while the pile-soil stress ratio of the gravel pile is reduced and the side friction resistance is effectively exerted. Moreover, the expansion deformation distribution of the gravel pile in both the E-GESC and GESC configurations is basically the same, and the maximum radial deformation is less than that observed in the SC. Most of the deformation occurs within a range of 2 times the pile diameter below the boundary line of the wrapped section. The ultimate bearing capacity of the composite foundation formed by the electroosmosis with geosynthetics encased stone columns (E-GESC) method is 6.6 times that of the SC and 3.8 times that of the GESC, demonstrating a significantly enhanced reinforcement effect.

The modern state of the soil cover of the Transcarpathian lowland: diversity, properties and development dynamics of natural and anthropogenic soils

The regularities and peculiarities of the modern state of the soils of the floodplain complexes of the Transcarpathian lowland under the influence of natural and anthropogenic factors were investigated. Prognostic modeling of the dynamics of the further development of soils and soil cover in the region was carried out. It was established that a significant mosaic in space and dynamism characterize the soil cover of floodplains in time. Alluvial, semi-hydromorphic, and hydromorphic soils dominate the flood plains of Transcarpathian rivers. Alluvial soils were the dominant types in the pre-anthropogenic period. They develop in conditions of constant soil ground water level and periodic surface flooding by floodwaters. Alluvial sediment (silt) remains on the surface after the subsidence of flood waters and has a significant impact on the properties, morphology, lithology and fertility of soils. The high content of dusty ground particles in all variants of river silt ensures their rapid inclusion in the process of soil formation and contributes to the improvement of water-physical and physic-chemical properties of alluvial soils. First of all, alluvial soils significantly suffer from anthropogenic interference in the course of flood processes undergo critical changes in water-physical and physic-chemical properties. After the improve of melioration measures that regulate the flood regime in floodplains, significant areas of soil lose alluvial features and later develop as semi-hydromorphic or hygromorphic. Drainage melioration, depending on the further direction of soil-forming processes, can have completely different effects on soil properties. Therefore, it is necessary to approach melioration measures very carefully, foreseeing in advance all the consequences, which may occur on drained territories. The possible profit from the involvement to agricultural production of drained areas can be incomparably smaller, compared to the losses for maintaining the normal functioning of not only these areas, but also the territories adjacent to them. The secondary anthropogenic load is often imposed on the primary hydrotechnical and reclamation soil transformation due to the active agricultural use of drained floodplains. Depending on the duration and method of agricultural production, soils that were formed as alluvial acquire new properties, different from natural ones. Their soil density and soil hardness increase, the water-air regime is disrupted, and their physical and chemical properties change. Deeply drained and additionally changed by technical means, the soils of the hydromorphic range, after the abandonment of resource-consuming extensive production, are left for natural self-recovery, and the further course of soil restoration processes requires careful study and control by scientists. A mosaic natural-anthropogenic soil cover of the alluvial lowland was formed under the combined effect of natural and anthropogenic processes, so alluvial soils need the greatest protection and protection in fact. Such soils are part of unique floodplain complexes, the study, preservation and protection of which should be the primary focus of both scientists and environmentalists.

An Experimental Study on Industrial Concete Pile Foundation in Soft Soil: Comparison of Monolithic and Pile with Welded Joints

This study presents an experimental investigation into the industrial foundation piles. The research carried out employed both destructive and non-destructive testing methods to evaluate the concrete compressive strength and flexural strength capacity of the piles under monotonic loading. The Destructive Test (DT) involves a 28-day cylinder concrete compressive test, while the Non-Destructive Test (NDT) utilizes the Ultrasonic Pulse Velocity (UPV) and Rebound Hammer (RH) tests. The flexural strength test is conducted using a loading frame, and the results are compared to the GeoPIV-RG, which measures the displacement during the test. The experimental investigations provide insights into the behavior of pile joints when subjected to monotonic load in soft and loose soil. The results indicate a significant difference between the compressive strength obtained from the DT and NDT, with a ratio of 0.64-0.74. Furthermore, the failure occurred at the joints, rather than the welded area, with the ratio of the initial stiffness of the piles with joints to the monolithic pile being 0.15 for zig-zag welded and 0.30 for circular welded, and reaching an average value of 0.225. According to the GeoPIV-RG result, the displacement is similar to the flexural strength test result.

Long-Term Settlement Prediction for Over- Consolidated Soft Clay under Low Embankment

The long-term post-construction settlement of an embankment laid on a deep, soft soil foundation can give rise to a series of safety concerns and significant structural damage. The settlement is primarily attributed to the creep deformation of the soft soil following the removal of the surcharge load and the impact of traffic loads on the soft soil. In this study, a plan strain triaxial test was conducted to investigate the deformation of an undisturbed soft clay specimen subjected to static and cyclic loading. The results demonstrate that the volume creep and vertical creep are associated with the overconsolidation state of the soft soil. The Over-Consolidated Ratio (OCRq) of shear stress, can be used as a parameter to describe the state of overconsolidation of soft soil under spherical stress. Based on the vertical creep coefficient and considering the influence of stress history on the stress state of soft soil, a two-dimensional long-term settlement model under cyclic loading has been proposed.

Risks of the soil foundations stability losses of the Kyiv-Pechersk Lavra Dormition Cathedral due to the urban activities

Risks of the soil foundations stability losses of the Kyiv-Pechersk Lavra Dormition Cathedral due to the urban activities

Tracking Shaft Integrity of Jet Grouting Piles Injected in Soft Soil Layers Based on Sonic Integrity Test Method: A Case Study from Erdemli, Mersin Region, South Turkey

Many studies have focused on using the non-destructive testing (NDT) method to determine defects in piles. This paper presents an analytical approach that compares the obtained profiles with typical profiles to confirm the integrity of jet grouting column piles using the cast-in-situ Sonic Integrity Testing (SIT) method. In this context, grouting piles are being constructed within the scope of the under-foundation in Erdemli/Mersin Province, Turkey. SIT testing was performed on jet grouting piles by performing integrity tests on piles manufactured, which varied in length according to the field geology and the thickness of the soil layer. These pile tests are performed to determine changes that may occur in the pile's cross-section for various reasons. In the present study (in 2024) SIT was carried out on a total of 148 jet grout piles. In the SIT performed on the piles, at least six records were taken for each pile, the records were examined, and the evaluations and results were given graphically. The cross-sectional alterations and fractures that can be found in the pile cross-section as well as the subsurface soil condition are the outcomes of the integrity tests, and they have an immediate impact on carrying capacity. Based on the acquired data and comparisons with reference profiles, the 148 piles that were produced and examined at the site exhibit no discontinuities or flaws and are structurally intact. By utilizing this method, the necessity for costly on-site soil replacement or foundation handling will be avoided or prevented.

The Dynamic Soil–Foundation–Structure Interaction Problem in the Time Domain Using a Discrete Element Model

This study investigates the influence of the soil–structure interaction (SSI) on the seismic performance of structures, focusing on the effects of foundation size, soil type, and superstructure height. While the importance of SSI is well recognized, its impact on structural behavior under seismic loads remains uncertain, particularly in terms of whether it reduces or amplifies structural demands. A simplified dynamic model, incorporating both the mechanical behavior of the soil and structural responses, is developed and validated to analyze these effects. Using a discrete element approach and the 1940 El Centro earthquake for validation, the study quantitatively compares the response of soil-interacting structures to those with fixed bases. The numerical results show that larger foundation blocks (20 m × 20 m and 30 m × 30 m) increase the seismic response values across all soil types, causing the structure to behave more like a fixed-base system. In contrast, reducing the foundation size to 10 m × 10 m increases the flexibility of structures, particularly buildings built on soft soils, which affects the displacement and acceleration response spectra. Softer soils also increase natural vibration periods and extend the plateau region in regard to spectral acceleration. This study further finds that foundation thickness has a minimal impact on spectral displacement, but structures on soft soils show more than a 15% reduction in spectral displacement (SD) compared to those on hard soils, indicating a dampening effect. Additionally, increasing the building height from 7 to 21 m results in a more than 20% decrease in SD for superstructures with natural vibration periods exceeding 2.4 s, while taller buildings with longer natural vibration periods exhibit opposite trends. Structures built on soft soils experience larger foundation-level displacements, absorbing more seismic energy and reducing earthquake accelerations, which mitigates structural damage. These results highlight the importance of considering SSI effects in seismic design scenarios to achieve more accurate performance predictions.

Thermo-Mechanically Coupled Settlement and Temperature Response of a Composite Foundation in Complex Geological Conditions for Molten Salt Tank in Tower Solar Plants

The degradation of complex geological structures due to thermo-mechanical cycling results in a reduction in bearing capacity, which can readily induce engineering issues such as uneven settlement, cracking, and even the destabilization of the foundations of molten salt storage tanks. This study establishes a foundational model for a molten salt storage tank through the use of COMSOL Multiphysics and conducts a numerical simulation analysis to evaluate the settlement deformation and temperature distribution of the foundation under the influence of thermo-mechanical coupling. Concurrently, the research proposes two distinct design approaches for the tank’s foundational structure. A comparative analysis of the results indicates that the use of a pile raft foundation in conjunction with a traditional foundation mode results in a reduction of settlement at the center of the foundation’s top surface by 380.1 mm, while also decreasing the maximum effective stress in the steel ring wall by 240.7 MPa. The thermal effects impact a depth of 10 m in the foundation soil and an influence radius of 20 m. Additionally, the foundation soil exhibits optimal thermal insulation properties, resulting in minimal energy loss. These findings indicate that the pile raft foundation in conjunction with a traditional foundation mode displays remarkable adaptability to complex geological conditions, with both settlement and temperature distribution of the foundation maintained within acceptable limits.

Influence of Foundation–Soil–Foundation Interaction on the Dynamic Response of Offshore Wind Turbine Jackets Founded on Buckets

This study investigates the impact of soil–structure interaction (SSI) and foundation–soil–foundation interaction (FSFI) on the dynamic behaviour of jacket substructures founded on buckets for offshore wind turbines. A parametric analysis was conducted, focusing on critical load cases for conservative foundation design. Different load configurations were examined: collinear wind and wave (fluid–structure interaction) loads, along with misaligned configurations at 45° and 90°, to assess the impact of different loading directions. The dynamic response was evaluated through key structural parameters, including axial forces, shear forces, bending moments, and stresses on the jacket. Simulations employed the National Renewable Energy Laboratory (NREL) 5MW offshore wind turbine mounted on the OC4 project jacket founded on suction buckets. An additional optimised jacket design was also studied for comparison. An OpenFAST model incorporating SSI and FSFI considering a homogeneous soil profile was employed for the dynamic analysis. The results highlight the significant role of the FSFI on the dynamic behaviour of multi-supported jacket substructure, affecting the natural frequency, acceleration responses, and internal forces.

Service life evaluation of marine reinforced concrete structures in coastal soda residue soil subjected to chloride attack

In chloride salt environments, the corrosion of steel reinforcements due to chloride ions intrusion into concrete is the main cause of the durability failure of reinforced concrete structures (RCSs). The chloride content included in coastal soda residue soil (SRS) foundations with a high moisture content has been measured to be 2–3 times that of seawater, which seriously threatens the durability of RCSs built in the SRS environment. Compared with marine tidal environments, the influence of SRS corrosive environment with a high moisture content and high chloride ions content on the chloride ions transport behaviours and the service life for the marine RCSs remains unclear. Therefore, for this paper, an indoor experimental study on chloride ions intrusion into the marine concrete specimens in a coastal SRS environment was carried out. The concentration profiles and transport characteristics of chloride ions within concrete in a real SRS environment with a semi-buried zone (SBZ) and a fully buried zone (FBZ) and in a simulated salt solution (SSS) environment of SRS were revealed. The measured results of chloride transport in concrete specimens exposed to the marine tidal zone (MTZ) were used as the control group to quantify the differences in chloride transport behaviours between concrete buried in the coastal SRS environment and that in the MTZ (marine tidal zone). Chloride transport models of concrete in coastal SRS and MTZ (marine tidal zone) environments were built by means of the Fick's second law of diffusion. Taking a certain marine RCS as an example, the service lives of this structure in coastal SRS and MTZ (marine tidal zone) environments were evaluated via this paper’s proposed chloride transport models and then compared. Results indicated that the predicted service life of the RCS in the FBZ (fully buried zone) is the longest, followed by that in the MTZ (marine tidal zone), and that in the SBZ (semi-buried zone) is the shortest. The service lives of the marine RCSs in the FBZ (fully buried zone) and MTZ (marine tidal zone) were approximately 1.37 times and 2.76 times that of the SBZ (semi-buried zone), respectively.

Utilization of cement deep mixing pile for soft soil foundation: a malaysian case study

Cement deep mixing piles, as representatives of deep mixing technology, are mature and widely applied. However, effective application cases of cement deep mixing piles are relatively scarce in countries like Malaysia in Southeast Asia. In this paper, the application of cement deep mixing pile reinforcement in Malaysia is presented. Solidifying material was selected for deep mixing piles based on the soil conditions using unconfined compressive strength (UCS) tests. The relationship between the strength of deep mixing piles on-site and soil properties (type, organic matter content, and ion content) was analyzed. And a quality evaluation of the deep mixing piles in the project is conducted based on Kolmogorov-Smirnov (K-S) tests and relevant standards. Results show that fly ash cement is suitable as a solidifying agent for acidic soil layers containing organic matter in the local area. The strength of piles is significantly related to the soil condition. The UCS of cement mixing piles in silty clay and peat soils is smaller than clay. The overall correlation between organic matter content in the soil and UCS is negative, particularly when the organic matter content ranges from 10% to 14%, resulting in a significant drop in UCS. The bilateral significance probability is greater than 0.05 in K-S test, indicating that the UCS results in the projectconform to a normal distribution. Additionally, the evaluation of the overall quality of the mixing piles aligns with the requirements in the Japanese standard “Manual of Deep Mixing Construction Technology for Harbors and Airports” and the Chinese standard “Technical Code for Building Foundation Detection”.

Damage mechanism and energy evolution of frozen soil under coupled compression–shear impact loading

In cold region engineering, the impact of coupled compression–shear loading on frozen soil foundations is a critical issue that urgently needs to be addressed, as it often significantly reduces bearing capacity and can cause structural failures. Accurately characterizing the mechanical behavior of frozen soil under dynamic coupled compression–shear loading is essential for enhancing the safety and stability of cold region engineering projects. This study prepared four frozen-soil specimens with varying tilting angles to investigate failure mechanisms and energy evolution under coupled compression–shear impact loading. The impact-compression experiments were conducted on the specimens under different loading strain rates and temperature conditions using a split Hopkinson pressure bar. The results indicated that the strength of frozen soil was effectively enhanced by higher strain rates and lower temperatures, while it was reduced by increased tilting angle. The fracturing morphology of frozen soil was analyzed from both microscopic and macroscopic perspectives to reveal its failure mechanisms. To quantify the strength characteristics of the frozen soil under various loading conditions, damage variables were defined from an energy-based perspective and incorporated into the Zhu–Wang–Tang viscoelastic constitutive model. Hence, a dynamic constitutive model for frozen soil under coupled compression–shear loading was developed. The model's predictive capability was validated through comparisons with the experimental data, which revealed a high level of agreement. The results of this study provide practical insights into the failure mechanisms and construction design of frozen soil foundations under coupled compression–shear impact loading in cold region engineering.

Sustainable mitigation method for earthquake-induced liquefaction using gravel-tire chips mixture: an integrated approach

This study investigates the potential of using Gravel-Tire Chips Mixture (GTCM) drains to mitigate soil liquefaction during earthquakes through an integrated experimental and numerical approach. The experiments involved a controlled setup with three distinct scenarios, evaluating the effectiveness of GTCM drain configurations in controlling excess pore water pressure in foundation soils, thereby reducing liquefaction and building settlement under seismic loading. Numerical simulations were performed to complement the physical tests and provide deeper insights into soil-drain interactions during dynamic events. The experimental results showed that GTCM drains significantly reduced settlement, with a reduction of up to 40 times in cases where GTCM drains were used compared to unmitigated conditions. Additionally, the presence of GTCM drains was effective in dissipating excess pore water pressure, which is a primary cause of liquefaction. Numerical simulations confirmed the experimental findings, indicating minimal pore water pressure buildup and reduced deformation in soils reinforced with GTCM drains. This research demonstrates that GTCM drains provide a sustainable and effective method to mitigate liquefaction and reduce earthquake-induced structural damage. The findings emphasize the importance of strategic drain placement and highlight the environmental benefits of repurposing waste materials such as tires for geotechnical applications, offering a cost-effective solution for enhancing infrastructure resilience in earthquake-prone regions.

Analysis of bearing capacity of consolidated clay under the track load of deep-sea mining vehicle

Analysis of bearing capacity of seabed consolidation foundation is conducted. Two types of bearing capacity along the vertical and horizontal directions are derived. The stress distribution between tooth plates is analyzed using the slip line field theory, and the soil between the tooth plates is divided into wedge-shaped rigid zones, passive slip zones, and transition zones. The analysis results show that the ratio of tooth depth to tooth spacing significantly affects the formation pattern of the failure zone between the tooth plates. When the depth-to-spacing ratio is small, all three zones are present, while as the ratio gradually increases, the rigid wedge-shaped zone also increases, the transition zone becomes smaller, and the passive zone disappears. Therefore, it is advisable to arrange a smaller depth-to-spacing ratio to fully exploit the strength potential of the soil between the tooth plates. The results of the finite element method (FEM) analysis also show the existence of active and passive zones beneath the crawler tracks, and due to the combination of orthogonal loadings in the vertical and horizontal directions, there is a phenomenon of skewed stress bubbles in the foundation soil beneath and correctness of the derived bearing capacity of the foundation in this study.

Smart modeling of soil-foundation interaction using coupled mechanisms: a numerical framework for liquefaction risk mitigation

This study investigates the impact of nearby structures on the cyclic settlement mechanisms of shallow foundations in liquefiable soils using a numerical model based on Biot’s porous media theory. The model predicts excess pore water pressure and settlement by coupling equilibrium and continuity equations, solved using an implicit time integration scheme. Soil nonlinearity under cyclic loading is represented using generalized plasticity, boundary surfaces, and non-associated models. Three scenarios are simulated to study the effect of spacing between light and heavy foundations and variation in acceleration intensity. Results show that as spacing between foundations increases, lateral displacement and settlement decrease. Excess pore water pressure generation also decreases with increased foundation spacing. Soil just below the foundation exhibits maximum settlement, decreasing with depth. When input acceleration increases from 0.1 g to 0.15 g and 0.2 g, settlement increases by 40%–55% and 90%–110% respectively for both light and heavy foundations, regardless of spacing. Excess pore water pressure also increases sharply with higher acceleration intensity. The findings highlight the importance of considering foundation-soil-foundation interaction effects in liquefaction-prone urban settings and provide insights for designing resilient shallow foundations. The advanced numerical modeling approach offers engineers a more informed way to mitigate liquefaction risk and build safer, more durable structures in earthquake-prone areas.

Toward Smart Urban Management: Integrating Geographic Information Systems and Geology for Underground Bearing Capacity Prediction in Casablanca City, Morocco

To effectively manage the sustainable urban development of cities, it is crucial to quickly understand the geological and geotechnical attributes of the underground. Carrying out such studies entails significant investments and focused reconnaissance efforts, which might not align seamlessly with large-scale territorial planning initiatives within a city accommodating more than 3 million inhabitants, like Casablanca in Morocco. Additionally, various specific investigations have been conducted by municipal authorities in recent times. The primary aim of this study is to furnish city managers and planners with a tool for informed decision-making, enabling them to explore the geological and geotechnical properties of soil foundations using Geographic Information Systems (GISs) and geostatistics. This database, initially intended for utilization by developers and construction engineers, stands to economize a substantial amount of time and resources. During the urban planning of cities and prior to determining land usage (five- or seven-floor structures), comprehending the mechanical traits (bearing capacity, water levels, etc.) of the soil is crucial. To this end, geological and geotechnical maps, along with a collection of 100 surveys, were gathered and incorporated into a GIS system. These diverse data sources converged to reveal that the underlying composition of the surveyed area comprises silts, calcarenites, marls, graywackes, and siltstones. These formations are attributed to the Middle Cambrian and the Holocene epochs. The resultant geotechnical findings were integrated into the GIS and subjected to interpolation using ordinary kriging. This procedure yielded two distinct maps: one illustrating bearing capacity and the other depicting the substratum. The bearing capacity of the soil in the study zone is rated as moderate, fluctuating between two and four bars. The depth of the foundation remains relatively shallow, ranging from 0.8 m to 4.5 m. The outcomes are highly promising, affirming that the soil in Casablanca boasts commendable geotechnical attributes capable of enduring substantial loads and stresses. Consequently, redirecting future urban planning in the region toward vertical expansion seems judicious, safeguarding Casablanca’s remaining green spaces and the small agricultural belt. The results of this work help to better plan the urban development of the city of Casablanca in a smarter way, thus preserving space, agriculture, and the environment while promoting sustainability. In addition, the databases and maps created through this paper aim for a balanced financial management of city expenditures in urban planning.

Vibration Analysis of the Bow Bridge With and Without the Soil Foundation

Abstract. Earthquakes can impart the phenomenon of resonance, where the frequencies of seismic waves align with a bridge's natural frequency, causing amplification of vibrations that can lead to structural failures. Aiming to accurately predict potential vulnerabilities posed to the bridge when subjected to earthquakes, this research presents a vibration analysis of the Bow Bridge. Two models, which simulate the Bow Bridge with and without soil foundation, are conducted to investigate the bridges natural frequencies and mode shapes under soilless and soiled conditions. The research result shows that the average vibration frequency in a soiled environment is much lower than that in a non-soil environment, intuitively proving the mitigation of soil environment to bridges vibration frequencies. Based on the agreeable data output, this research demonstrates the feasibility of modeling in the prediction of practical construction.

A general solution of consolidation for a double-layer foundation soil induced by pre-excavation dewatering with bottom reinforcement considering delayed responses of water table

Precisely predicting soil deformation at each construction stage of foundation pit engineering is crucial for enhancing construction safety standards. However, the mechanics of ground settlement, both inside and outside foundation pits caused by pre-dewatering in an unconfined aquifer, remain unclear. Hence, this study proposes a semi-analytical solution that considers factors, such as soil stratification, pit bottom reinforcement, and unsteady pumping-induced flow in the unconfined aquifer, using finite Fourier transform and boundary transformation techniques. It verifies the acceptability of the proposed solution by comparing experimental and numerical results from COMSOL Multiphysics. A detailed parametric analysis is conducted to discuss how pit reinforcement parameters, specific yield, and soil stratification influence the behaviors of drawdown and deformation. The results indicated that increasing the reinforcement thickness at the pit bottom and reducing the permeability of the reinforcement layer can effectively mitigate soil deformation and drawdown. In contrast, the compression modulus of the reinforcement layer affects only the ultimate value of deformation. In addition, a larger specific yield significantly delays the rate of drawdown and deformation but does not impact their final values. For double-layer foundation soils, the final value of deformation and drawdown is reduced when the lower layer has higher permeability, resulting in less time for settlement completion. This study provides a theoretical reference for the engineering design of foundation pit projects.

Experimental investigation of cyclic responses of frozen soil under principal stress rotation induced by wave loads

Under the effect of wave loads, continuous and cyclic principal stress rotation (PSR) occurs, with constant principal stress values in foundation soil units. The stability of coastal engineering structures in permafrost regions is inevitably subjected to the persistent impact of wave loads, which poses a significant challenge to their durability. Consequently, a series of experimental studies were carried out using a frozen hollow cylinder apparatus (FHCA) to investigate the influence of crucial three-dimensional stress state parameters, including the coefficient of intermediate principal stress (b), mean principal stress (p), and principal stress rotation radius (R), on the deformation characteristics and dynamic property evolution of frozen soils. The results indicated that under continuous principal stress rotation, the mean principal stress p has a limited impact on the deformation behavior and mechanical property evolution of the frozen soil. In contrast, b and R significantly influence the mechanical properties of frozen soil. When b and R at low values, the continuous rotation of principal stress causes axial strain to develop positively, decreases the mechanical property parameter damping ratio, increases the elastic modulus, and densified the sample. However, with the increase in b and R beyond a threshold, the repeated principal stress rotation causes the axial strain to develop negatively, increases the damping ratio continuously, decreases elastic modulus, and leads to significant softening of the frozen soil with an increase in rotation cycles.