Geotechnical Engineering Problems Research Articles

Undrained response of fibre reinforced expansive soil subjected to cyclic loading

The evaluation of dynamic soil characteristics is a crucial task in understanding the geotechnical engineering problems associated with dynamic loads. Most of the investigations concentrated on non-expansive materials, and there is a dearth of information on the dynamic performance of fibre reinforced expansive soil. This research paper presents the experimental soundings on unreinforced and reinforced expansive soil with randomly distributed polypropylene fibre with varying confining pressures under cyclic loading. Furthermore, to understand the micro structural behavior of the fibre reinforced soil, samples are examined under SEM analysis after being subjected to cyclic loading. Quantitative analysis of soil micro pores was done through image processing. In addition, the study also included the presentation of maximum shear modulus, a modulus reduction curve and a pore pressure variation curve. Experimental results indicate that, the addition of fibres caused an improvement in the dynamic shear modulus and damping ratio with a rise in confining pressure. Inclusion of fibres reduces the permanent strain. The change of dynamic shear modulus and damping ratio over shear strain amplitude and the dynamic shear stress–strain curves were analyzed under different confining pressures. From the SEM analysis, fibre reinforced soil has a fabric with large packets of soil particles. Moreover, the presence of fibres enhanced pore distribution and diminished considerable amount of voids. The results of image processing shown the area porosity of unreinforced soil is 25.3% and that for 1% of fibre reinforced soil is 6.9%. This shows the enhancement of the interface effect of soil reinforced with fibre, which strengthens the soil and integrity.

A novel peridynamic solution for modelling saturated soil-pore fluid interaction in liquefaction analysis

Saturated soil-pore fluid interaction under earthquake shaking can cause extensive damages to critical infrastructure systems. As such, accurate modeling of saturated soil-pore fluid interaction and its consequences (e.g., seismically-induced large deformation) are of particular importance for liquefaction analysis. Peridynamics (PD) has emerged as an effective method for solving large deformation problems by overcoming the disadvantage of finite element method caused by mesh dependency. However, the PD has not been extended to model soil-pore fluid interaction, limiting its application in liquefaction analysis. To bridge this gap, a novel solution strategy is presented for modeling soil-pore fluid interaction (i.e., the u-p equations herein) in liquefaction analysis of saturated granular soils, based on a hybrid PD (HPD) method recently proposed by the authors and co-workers. An explicit-explicit method is used to solve the coupled u-p equations. Liquefiable soil on level and sloped ground are analyzed and compared with experimental data and finite element simulations to validate availability and efficiency of the method, demonstrating the method to be effective in solving the soil-pore fluid equations and applicable to a broad range of geotechnical earthquake engineering problems associated with liquefaction.

Framework of a performance-based design for liquefaction resistance

Seismic liquefaction hazards remain a very challenging problem in geotechnical earthquake engineering and are one of the most important aspects currently to update the framework of the liquefaction resistance design from a performance-based perspective. In this paper, by investigating the characteristics of the seismic liquefaction hazard, as well as integrating the existing performance-based earthquake engineering (PBDEE) and advanced risk management theory, the connotation and key points of performance-based liquefaction hazard governance are proposed, and the framework of a performance-based design for liquefaction resistance (PBDLR) is constructed according to the technical system construction rules. The results indicate that the liquefaction hazard has its own characteristics in terms of the hitting target, hazard scale, occurrence mechanism, chain effect, treatment technology, and uncertainty of the influencing factors. Its technical system of hazard governance requires special consideration. The presented PBDLR integrates the advantages of both the advanced risk management theory and the existing performance-based earthquake engineering technology system, and the elements and structure consider the sociality of the target, the integrity of the function, the hierarchy of the composition, and the linkage of the elements and the completeness of the technology. The PBDLR takes the liquefaction hazard governance objective as the primary factor and performance analysis as the technical main body of the framework, and it is equipped with several new elements matching the characteristics of the liquefaction hazard and the requirements for the technical development of an anti-liquefaction design. The PBDLR presented in this paper can provide guidance and a reference for future research and technical development in liquefaction hazard governance.

A Novel Approach Proposal for Estimation of Ultimate Pile Bearing Capacity Based on Pile Loading Test Data

Determining the ultimate bearing capacity of piled foundations has been one of the most important problems in geotechnical engineering. It has been observed that the pile loading test evaluation methods based on the mathematical model give values far away from the failure load, even in piles that have reached the failure state. For this reason, it is aimed at developing a new mathematical pile loading test evaluation method based on the load-settlement curve. It has been thought that the main problem with the pile loading test evaluation methods based on other mathematical models giving values far from the failure load is that the methods iterate excessively. The new method proposed in the study was developed by taking this situation into account. The performance of the proposed new method was investigated using eight pile loading tests conducted in various provinces of Turkey. In order to verify the reliability of the newly developed method, the study was completed by applying multiple comparison tests with other methods in the literature (theoretical methods, finite element analysis methods, and pile loading test evaluation methods). According to the applied analysis of variance, it was concluded that the proposed new method remained within the 95% confidence interval and was usable.

A dynamic large-deformation particle finite element method for geotechnical applications based on Abaqus

In this paper, the application of Abaqus-based particle finite element method (PFEM) is extended from static to dynamic large deformation. The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion. Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy. The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error. The procedures of the proposed Abaqus-based dynamic PFEM (Abaqus-DPFEM) analysis and its implementation in Abaqus are detailed. The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples. The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.

Study on Utilization of Biopolymer in Liner

Abstract: Biogeotechnology is a branch of Geotechnical Engineering that deals with the application of biotransformation, biogrouting and mineral precipitation (MICP) to geotechnical engineering problems. Soil capping is a technology to curb the interaction between a waste body and the ground surface. A final cover system in landfill capping play a major role in intercepting rainwater infiltration and percolation of surface water into the subsurface waste dumped area. In order to minimize the water infiltration through different barrier layers such as single liner system, single composite liner system and double liner system in cover system are recommended. A single composite liner system comprises of two barrier (made up of different material), placed over one another to provide beneficial effect whereas the single and double liner system consists of same material to attain the effect. The present study deals with the action of sea weed in the form of powder (produced by the cell wall) in the layer of soil capping which intercept the rainwater intrusion in liner. The results obtained from the hydraulic conductivity of different treated soils indicate that the effect of single liner system is equivalent to single composite liner system. It has been observed that the addition of sea weed powder causes dissociation of hydroxyl groups attached to silicon in silica sheets with increase in optimum water content. Thus the addition of sea weed powder decreases the infiltration rate by clogging the soil layers.

SPH approach for stability analysis of soil slope with variable permeabilities

A simulation framework based on meshless method has become an alternative numerical tool to model many deformation problems in geotechnical engineering. Large deformations in the failure zone can alter porosity, permeability etc., which in turn can affect the process of the failure. In this paper, a two-phase model in the framework of Smooth Particle Hydrodynamics (SPH) is introduced to model the interaction between water and soil through drag forces according to Darcy’s law. Changes in soil porosity and associated permeability are automatically adjusted within this framework. Firstly, two different problems i.e., flow through porous media and fluidized bed problem, are investigated to examine the suitability, and stability of the proposed SPH method. Then, the stability analysis of a soil slope under different water level conditions is performed with the strength reduction technique, and the groundwater effect of the slope is simulated. It is found that owing to the negative impact of seepage on soil slope, the horizontal displacement of the slope can be significantly larger. Afterwards, the influence of the variable permeabilities on the slope failure is investigated. The simulation results show that the change in permeability has a slight effect on the slope. Although the calculated safety factor does not change, the sliding distance differs by about 10%. The initial porosity has a large negative influence on the stability of the slope. The developed SPH model has been shown to be a valuable and effective tool for modelling complex problems that are challenging to be addressed with traditional approaches.

A Systematic Review of Machine Learning Techniques and Applications in Soil Improvement Using Green Materials

According to an extensive evaluation of published studies, there is a shortage of research on systematic literature reviews related to machine learning prediction techniques and methodologies in soil improvement using green materials. A literature review suggests that machine learning algorithms are effective at predicting various soil characteristics, including compressive strength, deformations, bearing capacity, California bearing ratio, compaction performance, stress–strain behavior, geotextile pullout strength behavior, and soil classification. The current study aims to comprehensively evaluate recent breakthroughs in machine learning algorithms for soil improvement using a systematic procedure known as PRISMA and meta-analysis. Relevant databases, including Web of Science, ScienceDirect, IEEE, and SCOPUS, were utilized, and the chosen papers were categorized based on: the approach and method employed, year of publication, authors, journals and conferences, research goals, findings and results, and solution and modeling. The review results will advance the understanding of civil and geotechnical designers and practitioners in integrating data for most geotechnical engineering problems. Additionally, the approaches covered in this research will assist geotechnical practitioners in understanding the strengths and weaknesses of artificial intelligence algorithms compared to other traditional mathematical modeling techniques.

Numerical investigation of displacement pile installation in silica sand

The penetration of deep foundations into sand is a classic geotechnical engineering problem that carries not yet fully understood aspects of the soil-pile interaction. The complexity of rigorous numerical and experimental studies of these foundations is well-stated in the literature. Extensive measurements of the properties of the soil that surrounds the pile are difficult to obtain experimentally. In this paper, the analysis of the installation of closed-ended, displacement piles in two silica sands is undertaken. Centrifuge tests from the literature on loose and dense dry sand samples are employed for validation of the numerical models, based on the Arbitrary Lagrangian-Eulerian (ALE) method. To capture the constitutive behaviour of the sand, the hypoplastic constitutive law with intergranular strain is adopted. After successful validation, an investigation on the variation of the initial conditions of the soil mass surrounding the pile during its installation is undertaken, and their influence on the tip resistance, the radial stresses, and the void ratio at the target penetration depths are identified. This paper illustrates the effect of cone apex angle on the state of sand after installation. Flat-ended piles tend to create clear zones of dilated material around the shaft.

RPIM-RITSS Method for Large Deformation Analysis Using ABAQUS

In the standard Lagrangian finite-element framework, the “remeshing and interpolation technique with the small strain” (RITSS) method has been applied increasingly in geotechnical engineering. However, the mapping algorithm of the RITSS method suffers from either the onerous division of unique element, such as the modified unique element divisional method, or frequent mapping of the stress and other information between integration points and nodes, resulting in the loss of precision, such as superconvergent patch recovery (SPR) and recovery by equilibration of patches. In this study, within the original RITSS, the radial point interpolation method (RPIM) mapping algorithm is implemented to improve accuracy and convenience. The RPIM-RITSS method is integrated into the ABAQUS (6.14) commercial software package. With a master Python script, the whole analysis process is performed automatically and continuously without any intervention from the user. The efficiency and robustness of the RPIM-RITSS method are verified through three numerical examples: penetration of the strip footing, the pullout and the rotation of the anchor plate, and deep penetration of the T-Bar. Consequently, the RPIM-RITSS method is an alternative, powerful, and easily extensible way to tackle large deformation problems in geotechnical engineering.

Clayshale stabilization using active natural lime to increase the shear strength of soil

Clayshale not used in construction because it is easily weathered when exposed to air and water to reduce the soil shear strength. As a result, this decline can cause geotechnical engineering problems, and clayshale needs stabilization. This study aims to determine the shear strength of clayshale by adding variations of 5%, 8%, and 11% lime. Tests carried out to obtain soil parameters include soil index and engineering properties. Based on laboratory tests, the original clayshale soil has a 33.2% liquid limit, a 6,1% plasticity limit, and a 27,1% plasticity index. Hence, clayshale soils belong to the CL(clay-low plasticity) category based on the USCS. Adding lime variations can increase the specific gravity and the optimum moisture content of the clayshale soils. Still, it can reduce the dry unit weight and the plasticity index value on clayshale soils. The triaxial test on the original clayshale soil sample obtained a cohesion(c) value of 0.20kg/cm2 and friction angle(f) of 6.38°. In contrast, the values of c and f occurred the highest increase from the original clayshale soil with the addition of 8% lime, so lime can be used as an alternative in soil stabilization because it can increase the shear strength of the soil.

A hyper parameterized artificial neural network approach for prediction of the factor of safety against liquefaction

Soil liquefaction during earthquakes is a complex geotechnical engineering problem. Although various analytical approaches exist for predicting liquefaction risk, their limitations have led researchers to explore using artificial intelligence and machine learning methods. Machine learning has the potential to significantly improve the ability to predict soil liquefaction and mitigate the associated risks. This study proposes a hyper parameterized artificial neural network architecture using random search, grid search, and Bayesian optimization algorithms to predict the factor of safety against liquefaction. The performances of hyper parameterized machine learning algorithms, including artificial neural networks (ANN), decision trees (DT), random forest (RF), and support vector regression (SVR), were compared. Statistical tests show that the proposed ANN outperformed the others with a determination coefficient of 0.99 at a 95% significance level. Hyperparameter optimization significantly improved learning performance with up to a 48% reduction in RMSE scores. The proposed method was compared with previous studies, and performance results confirmed its effectiveness and generalization ability. In conclusion, this study highlights the potential of machine learning algorithms for predicting soil liquefaction and emphasizes the importance of hyperparameter optimization for improving model performance. The findings of this study have practical implications for improving liquefaction risk assessment and mitigating the associated hazards.

Deep Neural Network Analysis on Uplift Resistance of Plastic Greenhouses for Sustainable Agriculture

In this study, we attempted to find an alternative method to identify and efficiently predict the interaction between the soil and basic structure of plastic greenhouses for sustainable agriculture. The interaction between the foundation structure of the plastic greenhouse and the soil appears as uplift resistance. We first measured the uplift resistance by using various artificial neural networks. The data required by the model were obtained through laboratory experiments, and a deep neural network (DNN) was employed to improve the model performance. We proposed a new deep learning structure called DNN-T that has the advantage of stabilizing neural circuits by suppressing feedback by using the concept of biological interneurons. The DNN-T was trained using driving data for four scenarios. The upward resistance of the DNN-T according to the training conditions showed a high correlation (r = 0.90), and the error decreased when the input conditions of the training data were varied. DNN-Ts mimicking interneurons can contribute to solving various nonlinear problems in geotechnical engineering. We believe that our DNN-T model can be used to determine the uplift resistance of solid and continuous pipe foundations, effectively reducing the need for time-consuming and extensive testing.

Assessment of the liquefaction potential of the Arifiye (Sakarya) region with multidisciplinary geoscience approaches in the GIS environment

The severity of damage under building load during an earthquake, one of the most critical geophysical and geotechnical engineering problems, varies according to soil types. Therefore, the liquefaction problem constitutes an essential phenomenon, especially for the settlements located on alluvial units in high seismicity regions. This study used standard penetration test (SPT), and share wave velocity (Vs) based approaches to evaluate the liquefiability in the Arifiye region in the North Anatolian Fault Zone (NAFZ) with 40 drillings and 35 seismic measurements considering the Izmit (Mw: 7.4) and Mudurnu (Mw: 7.0) earthquake scenarios. In this context, three different approaches (Liquefaction potential index (LPI), Ishihara boundary curve (IB), and Ishihara-inspired index (LPIISH)) were employed. The maps from these assessments were prepared in the Geographic Information System (GIS) environment. It was determined for the study area that the lakeside and northern part of the NAFZ linearity, which has a very shallow groundwater table and low Vs values, are vulnerable to liquefaction hazards for all approaches. On the contrary, the south part of the NAFZ linearity is defined as non-liquefiable. Although the Vs and SPT-based LPI maps considerably overlapped, some differences in LPI values emphasized the importance of integrated use of the geophysical and geotechnical methods. Hence, liquefaction analysis with different approaches will enable it to operate according to the most cautious situation in risk management.

Coupling Numerical Analysis Method for Primary and Secondary Consolidation of Soft Soil Foundation

Soft clay is widely distributed in our country, and this type of soil usually has the character of large compressibility and poor permeability, so the foundation composed mainly of soft clay is prone to primary and secondary consolidation coupling settlement deformation after the completion of construction. In this paper, secondary consolidation deformation is redefined in the improved time logarithmic coordinate system, and the calculation formula of secondary consolidation deformation is given. Then an extended unified hardening model is introduced, and by applying this model, the effect of time can be transformed to the increment of equivalent stress. The numerical governing equations are established in combination with the seepage consolidation theory. Thus the coupling analysis of primary and secondary consolidation of soft clay foundation can be realized. By means of a finite element case analysis and verification of subgrade construction and post-construction deformation, it is found that the effective calculation of primary and secondary consolidation deformation can be accomplished smoothly based on the extended unified hardening model, and meanwhile the permeability coefficient and secondary consolidation parameters are able to effectively control the primary consolidation deformation and secondary consolidation deformation of soft clay foundation. The research is valuable to develope the prediction method of soft clay foundation deformation and improve the prediction accuracy of soft clay foundation deformation in engineering, and it is of great significance to solve complex geotechnical engineering problems.

Evolutionary polynomial regression improved by regularization methods.

Evolutionary polynomial regression (EPR) is a data mining tool that has been widely used in solving various geotechnical engineering problems. The fitness function is the core of EPR. However, overfitting may still occur in EPR, and this issue may cause the testing dataset not to perform effectively. Improvement of the EPR fitness function through L1 and L2 regularization methods is critical to avoid overfitting and enhance good generalization. First, the appropriate values of the regularization parameter λ of the L1 regularization method (L1RM) and L2 regularization method (L2RM) are determined by comparing the test data sets. Then, the EPR with a classical fitness function is compared with that of L1 or L2 regularization methods to evaluate their abilities in developing regression and producing accurate predictions. The results show that the fitness function combined with the regularization method could improve the EPR. However, L1RM performs better in prediction than L2RM. Improvement of EPR using L1RM could solve problems associated with construction constitutive models or could be used for prediction in geotechnical engineering.

Effects of dynamic changes of desiccation cracks on preferential flow: experimental investigation and numerical modeling

Abstract. Preferential flow induced by desiccation cracks (PF-DC) has been proven to be an important hydrological effect that could cause various geotechnical engineering and ecological environment problems. Investigation on the PF-DC remains a great challenge due to the soil shrinking–swelling behavior. This work presents an experimental and numerical study of the PF-DC considering the dynamic changes of desiccation cracks. A soil column test was conducted under wetting–drying cycles to investigate the dynamic changes of desiccation cracks and their hydrological response. The ratios between the crack area and soil matrix area (crack ratio), crack aperture and depth were measured. The soil water content, matrix suction and water drainage were monitored. A new dynamic dual-permeability preferential flow model (DPMDy) was developed, which includes physically consistent functions in describing the variation of both porosity and hydraulic conductivity in crack and matrix domains. Its performance was compared to the single-domain model (SDM) and rigid dual-permeability model (DPM) with fixed crack ratio and hydraulic conductivity. The experimental results showed that the maximum crack ratio and aperture decreased when the evaporation intensity was excessively raised. The self-closure phenomenon of cracks and increased surficial water content was observed during low-evaporation periods. The simulation results showed that the matrix evaporation modeled by the DPMDy is lower than that of the SDM and DPM, but its crack evaporation is the highest. Compared to the DPM, the DPMDy simulated a faster pressure head building-up process in the crack domain and higher water exchange rates from the crack to the matrix domain during rainfall. Using a fixed crack ratio in the DPM, whether it is the maximum or the average value from the experiment data, will overestimate the infiltration fluxes of PF-DC but underestimate its contribution to the matrix domain. In conclusion, the DPMDy better described the underlying physics involving crack evolution and hydrological response with respect to the SDM and DPM. Further improvement of the DPMDy should focus on the hysteresis effect of the soil water retention curve and soil deformation during wetting–drying cycles.

Application of Tempe Cell to Measure Soil Water Characteristic Curve along with Geotechnical Properties of Oil Sands Tailings

The traditional Tempe cell can be used to adequately determine the soil water characteristic curve (SWCC) for soils that do not undergo significant volume change as matric suction is increased, such as coarse-grained material such as sand with a low air entry value (AEV) (<500 kPa). When soils undergo substantial volume change as soil suction increases, such as fine-grained silts, clays, and oil sands tailings material, the soils need to be tested with distinctly different methods involving two apparatuses when using the Tempe cell. A single-step Tempe cell technique was developed and tested to measure the geotechnical and unsaturated properties of oil sands tailings samples. A series of nine Tempe cells were simultaneously used to measure the geotechnical and unsaturated soil properties of untreated fluid fine tailings (FFT) and treated flocculated centrifuged tailings (FCT). The results of the single-step Tempe cell technique provide several useful engineering functions relating matric suction to water content (SWCC), void ratio (volume change), solids content, and undrained shear strength. Both the traditional and single-step Tempe cell techniques yield comparable SWCC results, but the single-step Tempe cell yields result about three times faster than the traditional Tempe cell. The geotechnical results indicate that both the solids content and undrained shear strength of the FCT are greater than those of the untreated FFT and this indicates that flocculation and centrifugation increase solids content and undrained shear strength of the treated samples. Furthermore, the results indicate that the FFT starts at higher fine void ratio than the FCT and loses more water (volume change) at matric suctions lower than 7 kPa. Beyond 7 kPa, the compressions of both samples become the same. The single-step Tempe cell technique is, however, labor-intensive. The number of Tempe cell can be reduced to six depending on the starting load of the test. The use of the single-step Tempe cell technique in providing fast estimates of SWCC and geotechnical properties for oil sands tailings will be attractive to practitioners who intend to incorporate matric suction in oil sands geotechnical engineering problems.

Seismic fragility analysis of free-spanning submarine pipelines incorporating soil spatial variability in soil-pipe interaction and offshore motion propagation

Geotechnical engineering problems are always faced with various sources of uncertainty, especially the uncertainties of soil properties. This paper presents the seismic fragility analysis of free-spanning submarine pipelines (FSSPs) with consideration of soil spatial variability. Firstly, the two-dimensional random field theory is employed to account for the spatial distribution characteristics of soil properties, and the levels of spatial variability are shifted by changing the autocorrelation lengths. Then, based on the generated random field data, the finite element (FE) models of the soil-pipe system are established and the offshore spatial motions applied to pipelines are stochastically synthesized. Meanwhile, the impacts of soil spatial variability on the soil-pipe interaction and offshore motion propagation are investigated. Next, the probabilistic seismic demand models of FSSPs are derived via dynamic analyses and statistical regression, and the seismic fragility curves are generated. The influence of soil spatial variability on the seismic performance of FSSPs is examined by comparing the fragility curves between the random-field and random-variable cases. Finally, a fast assessment method for the ultimate bearing capacity is proposed to simply incorporate soil spatial variability in the seismic performance estimation of FSSPs. Numerical results highlight the necessity of incorporating soil spatial variability in seismic fragility analysis of FSSPs. The proposed assessment method can provide a great convenience for designers and engineers to obtain the accurate ultimate bearing capacity of FSSPs or other underground structures in the preliminary stage of seismic design.

Experimental study on mechanical properties and failure behaviours of new materials for modeling rock bridges

Rock bridges control the stability of rock slopes with intermittent joints. To better understand the evolution of water-induced damage in rock bridges, we developed new, water-sensitive similar materials and investigated their physical, mechanical, and hydraulic properties. The reasonable proportions of the material components required to simulate a rock bridge were systematically determined based on deformation failure modes, shear creep characteristics, deterioration degree, and the brittleness characteristics after water-rock interaction. Sensitivity analysis and contribution rates were used to characterize the effects of different influencing factors on the mechanical properties of similar materials. We found that one similar material specimen, SM-24, exhibited the analogous characteristics of natural rock bridge in shear creep behavior, crack propagation, and ruptured surfaces. Such similar material for modeling rock bridges has the following mechanical characteristics: reproducing the volume-expansion point, showing high deterioration degree and specific brittle failure characteristics after water-rock interaction, and reproducing the identifiable precursor of accelerated creep and stepped fracture morphology subjected to shear creep loading. The bone-binder ratio dominated mechanical properties of similar materials, while physical and hydraulic properties depended mainly on the bentonite content. These findings provide guidelines for reliably producing similar materials that meet the requirements of different geomechanical model tests in solving geotechnical engineering problems considering the water-rock interactions.