The ability to predict the soil mechanical parameters swiftly is critical for off-road vehicle mobility. This paper introduces a novel interpretation methodology for determining critical soil mechanical parameters by impact penetration tests, enabling rapid and remote assessment of terramechanics properties. Initially, the method employs the Mohr-Coulomb constitutive model and the Coupled Eulerian-Lagrangian (CEL) finite element method to generate a dataset of soil impact penetration resistance and acceleration responses. Subsequently, a Radial Basis Function (RBF) neural network is employed as a surrogate model and integrated with the Nondominated Sorting Genetic Algorithm II (NSGA-II) to accurately interpret parameters such as density, cohesion, internal friction angle, elastic modulus, and Poisson's ratio. Experimental validation using sand and silty clay from Yangbaijing, Tibet, confirmed the accuracy and robustness of the method. The results indicate that the mean absolute percentage error for interpreted values was below 25%, with relative errors for some key parameters even below 10%. Furthermore, each single-condition calculation was completed on a standard computer in less than one minute. Comparative analyses with other algorithms, including MIGA and POS, demonstrated the superior performance of NSGA-II in avoiding local optima. The proposed interpretation framework offers a rapid, reliable, and remote solution for identifying the soil mechanical properties. Its potential applications range from disaster mitigation and emergency response operations to extraterrestrial soil exploration and other scenarios where in-situ investigations are challenging.

To address the challenges of extraction difficulties and penetration risks associated with traditional spudcan jackup platforms, a new jack-up platform featuring a pile-leg mat foundation is proposed. The horizontal bearing capacity of hybrid foundations under the influence of dynamic loads is a critical factor that requires close attention. This research numerically examined the dynamic response of a hybrid foundation to horizontal cyclic loading on a sandy seabed. A user-defined subroutine was employed to incorporate the Cyclic Mobility (CM) model within Abaqus, facilitating the analysis of sand response under different densities. The horizontal cyclic bearing capacities of the foundation were investigated considering the effects of different loading conditions, sand density, and pile-leg penetration depth. Simulation results indicate that the cyclic loading amplitude, frequency, and load mode significantly influence the generation of soil excess pore water pressure (EPWP), subsequently affecting foundation displacement and unloading stiffness. Under cyclic loading, the loose sandy seabed shows the most pronounced fluctuations in EPWP and effective stress, leading to surface soil liquefaction. While surface soil in medium-dense and dense sand conditions remains non-liquefied, their effective stress still varies significantly. Increasing the pile-leg penetration depth enhances the foundation's horizontal bearing capacity while affecting its vertical bearing capacity slightly.

Understanding the mechanical properties of continental submarine slopes is critical for the assessment of geo-marine slope stability hazards. This paper presents the first detailed geomechanical study on sediment profiles associated with a geologically recent sliding event at the Goliath submarine complex offshore southern Israel. Sediment samples were extracted from similar to 5-m-long piston cores collected from three representative sites: on the recent slide headscar (PHS3), the adjacent undisturbed slope seafloor (PSL4), and at the dextral tail-depositional lobe (PTL3). The investigation included Gamma-ray and CT scanning, sediment phase measurement, laboratory T-bar penetration, and vane shear testing. The evaluated properties for the three sites are the undrained shear strength, over-consolidation ratio, soil sensitivity, water content, and density. The experimental results show a strong correlation between the findings of the various investigation tools regarding the original soil condition before sliding, the slide scar location, the degradation in properties of the disturbed soil, and the post-slide deposited soil properties. Despite the variation in properties among the different sites, the paper presents a prediction model for the soil strength in the Goliath slide area. Beyond the geomechanical characterization, the analysis of the test results highlights two unique findings: (1) evidence of a long-term strength softening phenomenon in the post-slide period, and (2) insights into the transition of geomechanical properties with depth within the slide scar.

Mining leads to soil degradation and land subsidence, resulting in decreased soil quality. However, there are limited studies on the detailed effects of mining activities on soil properties, particularly in western aeolian sand. This study, therefore, quantitatively assessed the aeolian sandy soil disturbance induced by mining activities in the contiguous regions of Shanxi, Shaanxi, and Inner Mongolia. The following soil physical quality indices were measured in the pre (May 2015), mid (October 2015), and postmining period (April 2016), such as the soil water content (SWC), particle size (PS), soil penetration (SP), and soil saturated hydraulic conductivity (SSHC). The results showed that mining activities brought irreversible effects on soil structures. In the pre-mining period, land subsidence broke up large soil particles, destroying soil structure, leading to decreased PS (218.33 vs. 194.36 mu m), SP (4615.56 vs. 2631.95 kPa), and subsequently decreased SSHC (1.12 vs. 0.99 cm/min). Rainfall during the midmining period exacerbated this fragmentation. Thereafter, low temperatures and humidity caused the soil to freeze, allowing the small soil particles to merge into larger ones. Meanwhile, the natural re-sedimentation, subsidence, and heavy mechanical crushing in the post-mining period increased PS and SP. The SSHC hence increased to 1.21 cm/min. Furthermore, the evaluation of soil indices from different stress zones showed that the external pulling stress zone always had a higher SSHC than the neutral zone in any mining period, possibly due to the presence of large cracks and high SWC. This study contributes to the understanding of the impact of mining activities on soil physical qualities, providing a theoretical basis and quantitative guidance for the surface damage caused by coal mining in the aeolian sandy area in Western China.

Soil liquefaction is a major contributor to earthquake damage. Evaluating the potential for liquefaction by conventional experimental or empirical methods is both time-intensive and laborious. Utilizing a machine learning model capable of precisely forecasting liquefaction potential might diminish the time, effort, and expenses involved. This research introduces an innovative predictive model created in three phases. Initially, correlation analysis determines essential elements affecting liquefaction. Secondly, predictions are produced using Convolutional Neural Networks (CNN) and Deep Belief Networks (DBN), verified by K-fold cross-validation to guarantee resilience. Third, Ant Colony Optimization (ACO) improves outcomes by increasing convergence efficiency and circumventing local minima. The suggested EC + ACO model substantially surpassed leading approaches, such as SVM-GWO, RF-GWO, and Ensemble Classifier-GA, attaining a very low False Negative Rate (FNR) of 2.00 % when trained on 90 % of the data. A thorough performance evaluation shown that the model achieved a cost value of 1.133 % by the 40th iteration, exceeding the performance of other models such SVMGWO (1.412 %), RF-GWO (1.305 %), and Biogeography Optimized-Based ANFIS (1.7439 %). The model exhibited significant improvements in convergence behavior, with a steady decline in cost values, especially between the 20th and 50th iterations. Additional validation using empirical data from the Tohoku-oki, Great East Japan earthquake substantiated the EC + ACO model's enhanced accuracy and dependability in mirroring observed results. These findings underscore the model's resilience and efficacy, providing a dependable method for forecasting soil liquefaction and mitigating its seismic effects.

A coupled electrothermal damage theory model for pipelines is proposed to assess the failure behavior of buried pipelines under lightning strikes. This article considers local thermal nonequilibrium (LTNE) conditions in the soil-water porous medium and the nonlinear characteristics of lightning functions. The calculation results show that the proposed theoretical model has better applicability and accuracy compared with previous models. Parametric analysis shows that under lightning conditions of Im = 20 kA and T1/T2 = 1.2/50 mu s, the maximum local temperature of the soil around the pipeline can reach 2160 K, leading to pipeline breakdown. Metal pipelines are shown to be more effective in conducting charges, which alters the electric field distribution in the soil and impacts the formation of plasma channels. The half-peak value of the lightning waveform has a significant impact on pipeline breakdown, and its increase will increase the risk of pipeline breakdown gradually. When considering LTNE conditions, the change in the pipeline surface temperature becomes more pronounced. Under 8/30 and 8/40 mu s lightning waveforms, the pipeline surface temperature is approximately 150 and 550 K higher, respectively, compared with the thermal equilibrium conditions. The thermal conductivity and porosity of backfill soil can also affect the thermal damage of lightning-struck pipelines. With clay filling, the highest pipeline surface temperature can reach 2590 K, while with fine sand and coarse sand, it is 1980 and 1510 K, respectively. The pipeline lightning disaster model proposed in this article has engineering significance for the investigation of pipeline lightning failure and disaster prevention mechanisms.

The suction foundation (SF) has significant resistance reduction effect due to the seepage effect under the suction-assisted penetration. Seepage is an important factor in resistance reduction. In this paper, the model experiments and numerical simulation method were employed to analyze the resistance of suction-assisted penetration in sand. By analyzing the mechanism of resistance reduction, a suction foundation for enhancing seepage (SFES) has been proposed. The SFES was installed the degradable material inside the SF. The size of the degradable materials is smaller than the inner diameter of the foundation. During suction-assisted penetration, water suddenly contracts inside the foundation, resulting in a decrease in excess pore pressure on the inner side of the foundation and ultimately reducing installation resistance. The coefficient of evaluating the change of penetration resistance under seepage action was put forward. The results had shown that the pore water pressure of the sandy soil near foundation wall was reduced by the sudden contraction during the suction-assisted penetration, which was more conducive to resistance reduction. Under the same penetration depth, the inner resistance of the SFES change coefficient was 8.4 %-25.9 % smaller than that of SF. When the relative penetration depth h/D >= 0.25, the area of piping (4 >= 1) region within SFES was smaller than that of SF. As h/D = 0.9, the area of piping (4 >= 1) region within SFES producing piping was 27.9 % less than SF. The SFES had more advantages in the suction-assisted penetration.

Most natural soils exhibit a certain degree of soil structure which, in general, leads to increased strength and stiffness properties. However, the mechanical characterization of these soils based on conventional laboratory testing proves difficult in many cases due to sample disturbance. The present work aims to characterize the microstructure of a postglacial, normally consolidated, fine-grained deposit in Seekirchen, Austria, adopting in situ testing, laboratory testing on high-quality samples, and numerical analysis. The latter involves recalculating in situ piezocone penetration tests (CPTu) using an advanced constitutive model for structured soil. In contrast to existing in situ interpretation methods, the results of the numerical study, the mineralogical and hydrochemical testing, as well as the oedometer and bender element testing on undisturbed and reconstituted samples suggest that the soil is characterized by a significant amount of structure. It is demonstrated that the difference in shear wave velocity measured in situ and through bender element testing on reconstituted samples can be used as an indicator for soil structure. Ignoring the effects of structure may lead to inaccurate parameter determination for advanced constitutive models, which are subsequently employed to solve complex boundary value problems in geotechnical practice. As a consequence, the prediction of expected displacement may not be reliable.

Accurately predicting pile penetration in marine soft clays is crucial for effective construction, load-bearing design, and maintenance of offshore pile foundations. A semi-analytical solution employing the combined expansion-shearing method (CESM) is introduced to model pile penetration in soft clays. This method innovatively simplifies the Pile penetration into undrained cavity expansion and vertical shearing. Using the S-CLAY1S model, which incorporates the anisotropy and structure of natural soft clays, an exact semi-analytical solution was developed to describe soil behavior around the pile under undrained vertical shearing, expanding upon existing undrained cavity expansion solutions. The accuracy and innovation of the CESM were validated through the results of field tests and finite element simulations. Additionally, a comprehensive parametric study highlighted the significant impact of soil's initial structure and stress state on pile penetration response. The study findings strongly align with theoretical calculations, field Measurements, and numerical simulations. Compared to the conventional cavity expansion method, CESM excels in resolving soil stresses at the pile shaft, albeit with a slight limitation in evaluating excess pore water pressure of soils at the pile shaft. The proposed solution considers the fundamental properties of soft clays, including their anisotropy and structural behavior, while incorporating the vertical shearing experienced by the soil during pile installation, thereby providing a simplified yet precise theoretical framework for addressing pile penetration challenges.

This study investigates the pore water pressure (PWP) behavior of soil around large-diameter open-ended thin- walled piles (LOTPs) during impact driving using a large deformation finite-element method. A comparative analysis of the PWP accumulation curves of the soil inside, outside, and below the LOTP tips with different diameters and wall thicknesses during impact driving is conducted under the same hammering solution. The PWP development is dependent on the absolute distance from the pile surface to the location of the soil and the dimensions of the LOTP. The excess pore water pressure (EPWP) accumulates and gradually dissipates, and its level decreases with increasing pile diameter. However, a negative excess pore water pressure (Ne-EPWP) is identified during hammering. Based on the above findings and analyses, a PWP prediction equation for LOTP during driving is proposed, and the predicted curves are compared with the numerical results. The influence of PWP accumulation after penetration of 2d (d is the LOTP internal diameter) does not increase significantly. This equation can provide the initial distribution field of PWP in saturated clay for LOTPs, thereby facilitating pile drivability analyses.