Foundation Soil Research Articles

Effect of Rubber Scrap Tire Pads on the Behavior of Partially Connected Pile Raft Foundation System Subjected to Dynamic Loading

A partially tied piled foundation raft where both horizontal and vertical movements will be tamed. Interfacing RSTP changes are in structural dynamics and the way the forces are distributed. Nevertheless, the overall seismic behavior of this type of foundation in medium dry sand soil links to the pile raft foundation system with partial structural connection has not been studied adequately. To fill this gap we experimentally tested ten pile and group pile layouts in the laboratory in order to explore the interaction of the cushion layer with piles at different spacing. These tests concern the displacement mechanism of the raft foundation and the stressing change of the RSTP layers that occur during earthquakes. The results showed that using RSTP layers helps to minimize the variations in displacement between patterns with connected piles and those with disconnected piles when subjected to shaking loads. The pattern 1DR6cm showed a high settlement reduction ratio compared with 1DR2cm. Pattern 2C2D appeared less reduction in the vertical displacement. More significant displacements and rotating behavior anticipate lateral shaking due to reduce the number of connected piles for pattern 1C4D compare with pattern 4C1D. The pattern 3C6DHR2cm decreased the vertical displacement by 48.4% using one layer of RSTP. Using three layers of RSTP contributes to reducing the displacement by 36.4%. The number of the piles in a connection condition with the piled raft and the cushion thickness belongings on the strain deformation values.

A study of bacteria producing carbonic anhydrase enzyme for CaCO3 precipitation and soil biocementation

We study the carbonic anhydrase (CA) pathway using autochthonous CA-producing bacteria as a means of inducing calcite precipitation, which acts as a biocement to improve the engineering soil properties. Forty different microbial strains producing CA were isolated from the foundation soil of a railway embankment in Prickwillow, UK. Three of the best CA-producing strains were selected and identified by DNA sequencing as Bacillus licheniformis, Bacillus toyonensis and Bacillus pumilus with CA activity values respectively of 1.79 U/ml, 1.42 U/ml and 1.55 U/ml. To optimise the treatments, we investigated the effect of pH, temperature, zinc co-factor and cementation solution molarity on the growth and CA activity and bioprecipitates, with CO2 added in the form of bicarbonate. Scanning electron microscope (SEM) analysis of the bioprecipitates showed that these had characteristic morphologies of calcite and vaterite crystals. The formation of calcite was further corroborated by FT-IR and Raman analysis of bioprecipitates. The precultured bacteria were injected into the fine-grained soil together with cementation solution. Unconfined compressive strength in treated soil increased up to 1 MPa, and its calcium carbonate content increased by 2.78%. This, as well as the stability of the treated soil upon water immersion, proved the biocementation of the fine-grained soil. These findings suggest the potential of employing the CA biocementation route for soil stabilisation pending further development of the technique.

Laboratory test study on deterioration process of cement soil piles in radial direction in marine soft soil foundation

The deep mixing method is a commonly used foundation treatment technology for marine soft soil sites. Due to the long-term corrosion of seawater ions, the deterioration of cement soil pile in-site is inevitable. Revealing and predicting the development trend of cement soil can provide data support for the durability evaluation of marine engineering. The existing research on the deterioration development trend of cement soil neglects the influence of different stress states along the length direction of the pile on the deterioration. This study developed a tester that can simulate the deterioration of solidified soil in the stress state of natural foundations. A rapid prediction method for the deterioration depth of cement soil considering the influence of seawater pressure is established. The research concept has certain reference significance for research on the prediction of the deterioration depth for solidified soil in similar corrosive environments.

Study of the Pore Water Pressure Development Characteristics of PHC Pipe Piles in Soft Soil Foundations

When constructing hollow prestressed high-strength concrete (PHC) pipe piles in soft soil foundations, the generation and dissipation of pore water pressure can induce negative friction on the pile. This phenomenon increases the settlement of the pile foundation and, in severe cases, can lead to pile deflection and flotation. To further investigate the development characteristics of pore water pressure during PHC hollow pipe pile driving in soft soil, this study combined existing theories and numerical models to analyze the generation and influence areas of pore water pressure. Field tests were conducted at three different sites: an untreated site, a surcharge preloading site, and a site treated with cement mixing piles and well dewatering. These tests monitored and analyzed the horizontal and vertical development and behavior of pore water pressure during pile driving at each site. The results indicate that during the pile driving process, when the horizontal distance from the pile center is 3d and 9d, the peak values of the excess pore water pressure in the site treated with cement mixing piles and well dewatering are 117 kPa and 100 kPa. After pile driving is completed, they decrease to 50 kPa and 48 kPa, respectively. The peak values of excess pore water pressure in the surcharge preloading site are 122 kPa and 97 kPa, and after pile driving, they decreased to 80 kPa and 21 kPa, respectively. The peak values of excess pore water pressure in untreated sites are 140 kPa and 121 kPa; after pile driving, they decreased to 82 kPa and 60 kPa, respectively. Pore water pressure increases with the depth of pile driving and decreases with distance from the pile driving location. The peak pore water pressure and dissipation rate during construction were found to be higher at the untreated site compared to the other two sites. Therefore, during pile sinking in soft soil foundations, dewatering and driving drainage boards are effective methods for reducing pore water pressure and accelerating its dissipation. These findings provide a theoretical basis and technical support for ensuring the safety of engineering constructions.

Simplified Tunnel–Soil Model Based on Thin-Layer Method–Volume Method–Perfectly Matched Layer Method

In order to analyze the ground vibration responses induced by the dynamic loads in a tunnel, this paper proposes a new simplified tunnel–soil model. Specifically, based on the basic theory of the thin-layer method (TLM), the basic solution of three-dimensional layered foundation soil displacement was derived in the cylindrical coordinate system. The perfectly matched layer (PML) boundary condition was applied to the TLM. Subsequently, a tunnel–soil dynamic interaction analysis model was established using the volume method (VM) in conjunction with the TLM-PML method. The displacement frequency response function of the foundation soil around the tunnel foundation was derived. Finally, a ground vibration test under an impact load in a tunnel was carried out. The test and calculated results were compared. The comparison results show that the ground vibration acceleration response values within 25 m from the load are similar. Compared with the test results, the theoretical calculation results exhibit a decreasing trend in the range of 40–80 Hz between 25 and 60 m, with the maximum reduction being approximately one order of magnitude. In addition, the experimental comparison demonstrates that the model can be used to analyze the ground vibrations caused by underground loads.

Comprehensive crashworthiness simulation analysis of a large aircraft fuselage barrel section in various crash scenarios

To utilize computational techniques in investigate and evaluate the crashworthiness of typical fuselage section of a large transport aircraft in various crash scenarios, the finite element model of fuselage section was modeled and validated based on the vertical drop test of fuselage section at 6.02 m/s. The crash simulation analysis in various crash scenarios (such as concrete ground, soft soil grounds and water) were further conducted based on the validated model of fuselage section, and the crash response characteristics (deformation and failure mode, acceleration response and occupant injury risk, energy-absorbing characteristics) were analyzed and compared. The results show that the finite element model can accurately simulate the unrolling failure mode (three plastic hinges failure mode) of fuselage section and the failure of the connections of cargo floor crossbeams and fuselage frames, and it is in good agreement with the test results in terms of impact velocity and acceleration response. In the case of various soft soil grounds impact scenarios, the partial impact energy is absorbed by the soft soil ground, resulting in slightly different failure modes of fuselage section and a reduction in the peak acceleration. The water-entry impact failure mode of fuselage section is consistent with the rigid ground impact failure mode, the overall deformation degree of fuselage section decreases, but the degree of bending and upturning of fuselage frames increases with the increasing of the water-entry impact velocities The safety of occupants can be effectively protected in the soft soil ground and water-entry impact scenarios. The unrolling failure mode of fuselage section can be changed to the flattening failure mode (multiple plastic hinges failure mode) through the reasonable design to avoid the rupture of cargo floor crossbeams, and the more crash energy can be absorbed due to the production of more plastic hinges for the flattening failure mode, and the crashworthiness of fuselage section can be significantly improved.

Stress-strain state of building structures taking into account possible local failure of the element

The issue of choosing a structural design and material for supporting structures is an important technical and economic task at the stage of developing a design solution. It depends on a number of factors: consequence class of the structure, reliability of the design solution, savings in basic building materials. The publication provides a classification of design schemes and types of load-bearing structures used in the corresponding solutions. The disadvantages and advantages of using prefabricated and monolithic structures for the installation and subsequent operation of the structural scheme of buildings and structures are considered. Modern design requirements include ensuring the ability of a damaged structure to adapt to new conditions while continuing to function while ensuring the integrity of human life, property and equipment. New conditions mean the consequences of the occurrence of a certain emergency situation, accompanied by weakening or overloading of the load-bearing structures of a structure or soil foundation: a change in the structural design, a combination of new existing loads and a redistribution of internal forces. The publication reflects the results of assessing the redistribution of the stress-strain state of the elements of the “base - foundations - load-bearing structures” system as a result of the implementation of a hypothetical emergency situation with the exclusion of the load-bearing structure from operation. The case of the collapse of one of the vertical load-bearing elements (local failure of the pylon) of an underground floor, which can be used as a dual-use structure, is considered. Calculations for the stability of the structure against progressive collapse were carried out by numerical modeling in the LIRA SAPR-2019 software using a quasi-static calculation and the method of direct integration of dynamics over time. It has been demonstrated that the method of numerical modeling the joint work of a building with a soil base affects the results of a calculation of the progressive collapse of the building frame. The influence of local collapse of a vertical load-bearing element on the redistribution of stresses and strains in the foundation structures of a building section is assessed. The load on the piles under the pylons around the element removed under the local failure scenario is expected to increase by 15...25%.

NUMERICAL STUDIES OF THE DISTRIBUTION CAPACITY AND DEFORMABILITY OF THE SPATIAL MODEL OF THE SOIL BASE IN THE FORM OF A LINEAR-DEFORMED LAYER

The article analyses the existing approaches to modelling the interaction between a structure and a soil foundation, which consider the joint deformation of the soil and the structure. The “base-foundation-structure” models can be created in one-dimensional, two-dimensional, or three-dimensional space. Each of these models has its own set of boundary conditions and calculation methodology The advantages and disadvantages of each model, during application in engineering calculations, are presented. The purpose of research is to substantiate the methodology for assigning the geometric parameters of a three-dimensional model of a soil foundation, represented as a linearly deformed layer of finite resolution, for adequate modelling of interaction in the "base- foundation-structure" system. A finite-element model of the interaction between the soil base and the slab foundation was built using the modern SCAD software package. The modelling was performed in three dimensions. The soil base is represented by volumetric finite elements with constant deformation characteristics. The foundation is modelled by plate finite elements In context of this research, the slab model of the foundation was assumed to be rigid to neglect stress redistribution in the above-ground part of the building. Based on the analysis of modern approaches to the assignment of geometric parameters to the model of the soil base represented by a continuous linearly deformed layer with finite overall dimensions, which is created in a three-dimensional problem statement, it was shown that today there is no single approach to modelling such a “base-foundation-structure” system. Numerical studies of the effect of rigid horizontal constraints in the plan on the stress-strain state of a uniformly loaded rigid foundation interacting with a linearly deformed layer (compressible thickness) of finite distribution capacity were carried out using the SCAD program. Based on the analysis of the results of numerical calculations for a three-dimensional problem, the minimum allowable sizes in terms of the model of a linearly deformed layer of finite distribution capacity, which considers the distribution of compressive stresses along the depth at an angle of α = 25º to the vertical from the edges of the loaded foundation, are substantiated. At the same time, the overall size of the model in the plan according to the distribution angle α = 25º has practically no effect on the average settlement and maximum moment forces of the foundation compared to the angle α = 45º. Keywords: slab foundation, soil foundation, linear-deformed model, distribution angle, stress-strain state.

A Bibliometric Analysis Of Geotextile As Underground Filtration In Subsurface Drainage Towards Slope Stability Using Vosviewer

Geotextile is a geosynthetics tool in civil engineering that addresses geotechnical issues. As an alternative employed in dealing with the soil foundation, geotextiles serve functions such as separation, filtration, drainage, reinforcement, stabilization, protection, and a combination of these functions. This study aimed to systematically map the scientific research outcomes on slope stabilization and geotextiles using a quantitative review method known as bibliometric analysis. Bibliometric analysis is a widely used and robust method for investigating and analyzing extensive scientific data sets. This approach allows us to unravel the evolutionary intricacies within a particular field and illuminate emerging areas. With the help of Publish or Perish, the data sourced from the Crossref database will be analyzed using VOSviewer software. The results indicated that the most document publications occurred in 2023, with 74 journals published that year. The findings revealed a significant focus on slope reinforcement among researchers, as evident in the 810 articles published from 2000 to 2023. Of these, 54% consisted of papers published in journal articles. In summary, this research provides a quantitative examination of trends and future directions in this research field, serving as a valuable resource for researchers. Also, this paper will serve as a valuable reference for acquiring insights into the available techniques and procedures for conducting studies utilizing bibliometric analysis.

Effect of tunnel-building separation distance on the dynamic soil-structure interaction response

Understanding how buried structures respond to cyclic loading is crucial for designing earthquake-resistant underground infrastructure. The complexity of the dynamic response of these underground structures is accentuated when accounting for their interaction with adjacent buildings. This study focuses on the impact of the lateral distance between a shallow rectangular tunnel and an adjacent residential structure on dynamic soil-structure interaction, employing two dynamic centrifuge tests. Particle Image Velocimetry technique was adopted to observe the developed mechanisms of liquefied soil deformation, tunnel uplift, and foundation settlement. Results show the pronounced effects on soil deformation above the tunnel crown with a reduction in the tunnel-building separation distance. The distribution of excess pore pressure along the tunnel lining will be presented. Tunnel manifested additional lateral movement and reduced uplift when the adjacent building was in close proximity. A decrease in the tunnel-building distance contributed to a reduction of building rotation, primarily due to the significant mitigation of non-uniform settlement under the footing. Overall, the soil deformation mechanism around the tunnel and the building will be shown to change depending on the separation distance between them.

Derivation and Application of Analytical Coupling Loss Coefficient by Transfer Function in Soil–Building Vibration

Vibrations generated by railways may undergo amplification or reduction while traversing the foundations, floors, and spans of adjacent structures. This fluctuation in the vibration intensity, identified as a building’s coupling loss, is commonly considered in vibration forecasts through the utilization of universal frequency-independent adjustment parameters. This article employs a theoretical analytical approach to investigate the propagation characteristics of Rayleigh waves in elastic foundation soil, as well as the variations at the contact surface of buildings’ foundations. Analytical expressions for the coupling loss coefficient are derived to explore the displacement transfer relationship in the soil–structure interaction. To accurately and efficiently analyze the proposed buildings and site, the entire vibration propagation system is decoupled into substructure systems for independent analytical calculations. Theoretical analytical methods are utilized to obtain the displacement transfer functions between the soil and the structures through the refraction and transmission of waves. From a theoretical perspective, a thorough understanding of the interaction between soil and buildings is achieved. The influence of various variables related to railways and foundations on the building responses is analyzed. By comparing with measured data, the correctness of the analytical form of the coupling loss coefficient is validated, filling a gap in the literature due to the lack of analytical research on displacement transfer losses in soil–structure interactions.

Numerical analysis of soil arching effect in piles-reinforced airport foundation

The soil arching effect is the key mechanism for load transfer in pile-supported reinforced road (runway) foundations. To investigate the formation and evolution process of soil arching effect in the whole process of embankment filling and soft soil foundation consolidation, a three-dimensional hydro-mechanical coupled numerical model of pre-fabricated high-strength concrete (PHC) pile-reinforced soft soil runway foundation was established based on the foundation treatment project in Pudong Airport. The laws of variation of soil settlement, pore water pressure and pile soil stress were analysed, and the influence of pile spacing was considered. These data from both numerical simulation and field test indicate the soil arching effect in the foundation reinforced by PHC piles and preliminarily reveal the evolution of soil arching in the process of embankment filling and soft soil foundation consolidation. The preliminary results encourage the authors to continue this research to investigate the evolution of soil arching under aircraft dynamic loads through adding a more suitable constitutive model or subroutine in this numerical model.

Influence of Surcharge and Foundation Soil on the Seismic Stability of Helical Soil-Nail Walls

Influence of Surcharge and Foundation Soil on the Seismic Stability of Helical Soil-Nail Walls

Stabilization of Fibrous Peat Soils with Addition Palm Shell Ash Waste

South Sumatra Province has a peat area of 1.4 million Ha. The distribution of peat soil in Ogan Ilir is 23,687.91 Ha. Peat soil has a low bearing capacity. This research aims to explain the effect of stabilization on peat soil characteristics. Peat soil samples were taken using the Block Sampling method. The research locations are Parit Village and Lorok Village, Ogan Ilir Regency. Peat soil needs better properties and is unsuitable for foundation soil for civil construction. To overcome this, one method of soil improvement is required, namely the chemical stabilization method: changing the chemical properties of the soil by adding a mixture. The mixture used is palm shell ash waste with variations of 0%, 10%, 15%, 20%, 25%. Soil properties (physical and chemical), SEM, EDS, PTS, and CBR tests were carried out to determine the effect of this mixture. Soil properties test results: water content () in Parit Village 226.39%, and Lorok Village 252.39%. The fiber content (FC) test results for Parit Village were 25.18% and for Lorok Village 28.01%. Peat soil is classified as fibrous peat soil. The CBR value for Parit Village was 4.60%, and Lorok Village was 4.16%. The results of the immersion CBR test showed that Parit Village had a curing period of 7 days, a variation of 5%, namely 4.68%. Look Village obtained the most outstanding results: a curing period of 14 days, a variation of 25%, and 4.76%. The CBR value obtained in this study is 3%-5% (average) when used for subgrade strength with compaction conditions depending on the road category.

A new method for predicting consolidation settlements of soft ground based on monitoring results

Excessive settlement or differential settlement of subgrade will lead to the deterioration of line operational conditions, the reduction of passenger comfort, and even endanger the safety of traffic. Therefore, it is of great significance to study the settlement prediction of subgrade. In order to predict the settlement of foundation under the next level of loading earlier during the embankment construction process, a new method of predicting settlement of soft soil subgrade is proposed. Firstly, based on monitoring results of soft soil foundation, the consolidation parameters of soil layer are back-calculated according to the three-point method. Then, combined with the theory of the consolidation degree of graded loading, the formula that can predict settlement under different loading conditions are derived. Eventually, the practical application of the method is verified by the prediction and comparative analysis of measured settlements based on engineering examples. The result of research shows that the method can predict the foundation settlement after loading during construction of engineering fill. This method has obvious advantages over the traditional curve fitting method and can guide the actual engineering construction.

Analysis of the Dynamic Behavior of Multi-Layered Soil Grounds

The ground consists of many layers of soil with different properties. The propagation speed and path of seismic waves are affected by different soil layers. It is necessary to understand that layered soil exhibits different dynamic behaviors and responses under the action of seismic waves. This study utilized weathered soil and silica sand as materials to create multi-layered soil conditions with varying degrees of compaction. By conducting a 1 g shaking-table test on multi-layered soil, the interactions and influences between different soil layers under different earthquake conditions were observed. The approach of our numerical analysis aimed to complement the experimental results and provide an in-depth understanding of the dynamic behavior of multi-layered soil surfaces during seismic events. The acceleration results achieved with the ABAQUS and DEEPSOIL models for multi-layered soil were in good agreement with the experimental results. By comparing the stress–strain curves, the deformation mechanisms under different constitutive models in the numerical analysis were studied. The results of this study show that the amplification effect of seismic waves is related to the number of soil layers and the degree of compaction of the soil layers. This indicates that multi-layered soil ground and the behavior of the soil layers play an important role in the propagation and impact of seismic waves, and this amplification effect is of great significance in the design of actual seismic disaster risk assessments.

Comparative Analysis of Performance of Mat Foundations in Non-liquefiable and Liquefiable Soil

Comparative Analysis of Performance of Mat Foundations in Non-liquefiable and Liquefiable Soil

Assessment of thermal stability and application of engineering solutions to preserve the degrading road embankment near Hudson Bay Coast, Canada

There are 14 northern communities in Nunavik, the Arctic region of Quebec province, Canada. Transportation infrastructure plays a vital role in the social and economic development of these localities. The thawing of permafrost compromises the stability of northern transportation infrastructure. Harsh Arctic climate conditions limit the installation of effective monitoring systems to assess infrastructure stability. In Akulivik, the access road connects the Akulivik airport and the village of Akulivik. There is no monitoring to observe the thermal condition of the permafrost foundation of the access road, hindering the capacity to perform preventive maintenance activities, especially in the context of observed climate warming in Nunavik. This paper describes a project aiming at the assessment of the stability of the access road using a new approach and proposes adaptation solutions to stabilize the road, based on design tools recently developed. Particular attention was paid to the foundation soil under the side slope where relatively rapid permafrost degradation was occurring due to accumulated snow. The results indicate a positive thermal gradient of 0.29 °C/m under the side slope and a near-zero thermal gradient under the centerline. Projected climate warming was also considered to further investigate the thermal condition, providing a safety margin for the design of promising adaptation solutions. These results assist government agencies in evaluating the thermal conditions of underlying permafrost and deploying potential adaptation solutions in Akulivik.

Experimental Study on Influencing Factors of Mixing Solidification Strength of Marine Soft Soil

It is a common problem that the soft soil solidified strength by mixing is low. In order to search for the sensitive factors that affect the solidified strength, a certain marine soft soil is taken as an object, four influencing factors, such as solidified material and its dosage, mixing uniformity, water-cement ratio and curing environment, were selected for experimental study, the results show that: (1) the effect of the curing material and its content on the curing strength is obvious: the curing agent of HR soft clay is 183-212% of the cement curing strength, and the curing strength of the same kind of curing material with 20% is 25-44% higher than that of 15%. 2 mixing uniformity has a significant effect on the curing strength: the curing strength of slurry and soft soil after mixing for 1 minute is very different, and the average strength is only 10% of the full mixing strength. The average strength of the three-minute-agitation was 49-50% of the full-agitation strength, while the average strength of the six-minute-agitation strength was 92-93% of the full-agitation strength. 3 the effect of water-cement ratio on the curing strength is obvious: the curing strength decreases by 24-47% when the water-cement ratio is 1.0 vs 0.6, and by 75-80% when the water-cement ratio is 3.0 vs 0.6. 4 curing environment has obvious influence on curing strength: compared with standard curing condition, curing strength of low temperature curing condition is reduced by 52-57%. This study has important guiding significance for soft soil foundation treatment and solidified soil based on soft soil.

Gravity wharf failure mechanism and safety analysis considering the wave-structure-soft-soil-foundation interaction

The soft soil foundations of gravity wharves are subject to the wharf weight and wave forces, and the deterioration of the wharf soil foundation strength under such cyclic loading affects the structural safety of gravity wharves. This study investigated the weakening characteristics of soft soil strength. Undrained triaxial tests were conducted on undisturbed saturated soft soil specimens under isotropic consolidation conditions, and a dynamic finite element model of the wave–gravity-structure–soft-soil-foundation interaction was established. The results indicated that the shear modulus of the soil was related to the effective confining pressure and shear strain; this relationship was fitted using the Van Genuchten equation. As the internal friction angle of the soft-soil foundation decreased, its stability decreased nonlinearly, the strength decreased, and the sliding failure surface expanded. Simply increasing the riprap layer thickness had a limited effect on the overall wharf stability. These findings will guide the design of gravity wharves with foundations on soft soils in port areas that are subjected to intense wave actions.