Computers and Geotechnics最新文献

Methane hydrates, as a potential energy resource for the future, remain a considerable interest in the field of geo-energy and geo-resources. However, there is still a challenge to accurately characterize the coupled multiphysics during the entire exploitation process, specifically when involving sand production and sand control. In this study, an innovative semi-analytical model is developed to fully consider the coupled interactions between sand migration and multiphysics (seepage, temperature, hydrate dissociation, and mechanical behaviors) around a vertical production well. Furthermore, the mud cake formed near the screen is also taken into consideration. Meanwhile, the influence of reservoir deformation, hydrate dissociation, and hydraulic drag on sand production are taken into account in the current coupled multiphysics framework. Additionally, the effect of solid particle detachment on the mechanical properties of the formation and the effect of solid mass variation on the permeability and porosity of the reservoir, etc., are fully considered. As a step of validation, a good agreement is observed for gas production and sand production, between the presented solutions and field measurements. Based on the proposed solutions, depressurization-driven exploitation problems are analyzed for different cases, meanwhile, recommendations for engineering applications are presented from the perspectives of engineering safety, efficiency, and sustainability.

Near-fault regions are particularly vulnerable to seismic-induced landslides due to the intense energy pulses in near-fault ground motions (NFGMs). These pulses, shaped by terrain geometry and material properties, significantly influence seismic response and slope stability. This study investigates the impact of slope geometry on natural frequency and seismic response characteristics under both pulse-like ground motions (PLGMs) and non-pulse ground motions (non-PGMs). The results show that increasing slope height lowers natural frequency, making the slope more susceptible to resonance with seismic waves, thus amplifying ground motion and increasing instability. Similarly, steeper slopes also reduces the natural frequency, heightening instability by up to 0.17%. PLGMs generate seismic responses approximately 7% stronger than those induced by non-PLGMs. Furthermore, as the frequency of PLGMs rises, so does their destructive potential. Material analysis reveals that Rock Class A has a natural frequency 68% higher than Rock Class D, making it significantly resistant to seismic deformation. These insights are essential for designing more resilient slopes in seismic-prone regions.

The limit analysis incorporated with the random field theorem is an effective approach for the probabilistic analysis of geotechnical engineering stability. A failure mechanism for excavation stability analysis in spatially variable soil, which is combined with random field theory with rotational failure mechanism of excavation is proposed. Random distribution of soil shear strength parameters is readily generated with the proposed approach, thereby enabling efficient and accurate estimation of the failure probability of an excavation. Through an illustrative example, the feasibility of combining random field with rotational failure mechanism is verified. Through several practical engineering cases, the rationality of probability analysis results is verified. Parametric sensitivity analysis is performed with Monte Carlo method to investigate the effects of each factor on the failure probability of an excavation in spatially variable soil. The results show that the proposed failure mechanism of excavation in spatially variable soil provides the reasonable failure probability calculation results for engineering practices.

For tunnel, cavern, and shaft design, the inherent variability in a given rock mass domain makes accurately estimating rock mass quality and support requirements difficult. To capture the variability in rock mass properties when using the Q system, a methodology incorporating a statistical analysis of measured Q input parameters and Monte Carlo Simulation was developed to perform a probabilistic ground support design approach. Probability and cumulative density function curves were then developed using the mathematical program MATLAB to guide in estimating ground support based on all potential rock mass conditions. To illustrate the proposed approach, two hypothetical tunnels were designed based on real data from two previous projects. Finite Element Modelling was used to evaluate the suggested Q rock support performance in a range of rock conditions for one of the hypothetical excavations to validate the proposed approach. This method demonstrated that associating a range of potential ground conditions instead of a single deterministic value for each input parameter can provide a quantifiable measurement of uncertainty within a given rock mass domain. Additionally, the approach provides insight into the design criteria for ground support in underground excavations to potentially reduce overly conservative and costly recommendations.

It is known that rock cores drilled from high-stress environments experience a complex stress path. The induced tensile stresses within the cores may result in the formation of micro-cracks, potentially leading to incorrect estimation of their laboratory properties. In this research, the influence of coring stress path on damage formation and the consequent changes in the laboratory properties of intact rocks were investigated using a 2D numerical program based on the hybrid Finite-Discrete Element Method. For this purpose, two models with distinct grain geometries (triangular and Voronoi) were generated. They were initially calibrated against the laboratory properties of the undamaged Lac de Bonnet granite. The calibrated models were then subjected to a coring stress path to generate damage in the form of micro-cracks. The calibration process also involved the laboratory properties of damaged granite, focusing on capturing the nonlinearity in the stress–strain response due to crack closure during uniaxial loading. It was concluded that both models can effectively capture the formation and opening of micro-cracks during unloading, their closure during compressive loading, and the nonlinearity in the stress–strain response. However, the model with Voronoi grains more accurately represented the reduction in peak strength and Young’s modulus resulting from unloading-induced damage.

Understanding the in-situ behavior of rockfill materials through laboratory tests is challenging due to the influence of sample size. In this study, the discrete element method (DEM) is utilized to investigate the effects of sample size and boundary condition on the compressibility of rockfill materials at both macroscopic and microscopic scales. The results reveal that rockfill compressibility increases with sample size when rigid boundaries are applied, but no significant size effect is observed for periodic boundaries. Besides, the one-dimensional compression behavior of different initial packing varies with sample size under rigid boundaries, with the variance decreasing as size increases; however, this effect is negligible under periodic boundaries. Additionally, both the distribution uniformity of contact number and fabric anisotropy increase with increasing sample size under rigid boundary conditions. At a microscopic level, it can be observed that the sample size effect of granular materials is correlated to the coordination number per unit volume CN/(1 + e) for the considered particle shapes.