Soil desiccation cracks and crack networks significantly influence the mechanical properties of soils. Accurate modeling and prediction of crack development are essential for both laboratory research and practical applications in geotechnical engineering and environmental science. In this study, a Desiccation Crack Simulation Program (DCSP) was developed on the MATLAB platform to simulate the evolution of soil desiccation cracks. Based on comprehensive statistical analyses of crack network images from previous studies and detailed observations of crack propagation, we propose a stochastic crack network generation model informed by geometric parameters and crack development processes. The model encompasses five key steps: (1) selection of crack initiation points, (2) crack propagation and intersection, (3) termination of crack growth, (4) secondary crack generation, and (5) final network formation. Key parameters include crack step size, randomized propagation direction, number of initial development points, and crack attraction distance. The DCSP enables both the rapid generation of random crack networks and the prediction of partially developed networks. The program was validated using two soil types, Xiashu soil and Pukou soil, demonstrating its effectiveness in simulating crack evolution. Prediction accuracy improves as crack network develops, highlighting the model's potential for predicting soil desiccation crack patterns.

Soil desiccation cracking, a natural phenomenon involving the complex interaction of multi-physical fields, significantly weakens the mechanical and hydraulic properties of soil, potentially leading to natural hazards. This study proposes a coupled thermo-hygro-mechanical peridynamic (PD) model to investigate the mechanical responses and fracture behaviors in saturated soils due to moisture evaporation and heat transfer. Specifically, the temperature-dependent moisture diffusion and moisture-dependent heat conduction equations are nonlocally reformulated using peridynamic differential operators (PDDO). The constitutive model incorporates the spatial attenuation of nonlocal interactions and the effects of moisture and temperature in the bond-based peridynamic framework. Utilizing a hybrid explicit-implicit solution strategy, the model can effectively capture soil strip detachment, cracking, and curling. The model is also employed to explore moisture transmission mechanisms, evaluate the effects of temperature and thickness on crack morphology, and reveal the relationship between stress, strain evolution, and crack propagation. Furthermore, the model incorporates the reference evapotranspiration formula, which can account for environmental factors such as solar radiation, ambient temperature, relative humidity, and wind speed. Therefore, this expands the scope of model applicability and enables the simulation of soil desiccation cracking under natural conditions.

This study investigates the role of polypropylene fibers (PFs) in mitigating the combined effects of wet-dry (W-D) cycles and vibration event (VE), such as earthquake or machine vibrations, on the desiccation cracking and mechanical behavior of clay through model tests. A comprehensive experimental program was conducted using compacted clayey soil specimens, treated with various PF percentages (i.e., 0.2 %, 0.4 %, 0.6 %, and 0.8 %) and untreated (i.e., 0 % PF). These specimens were subjected to multiple W-D cycles, with their behavior documented through cinematography. Desiccation cracking and mechanical responses were evaluated after each W-D cycle and subsequent VE. Results indicated that surface cracking, quantified by morphology and crack parameters i.e., crack surface ratio (Rsc), total crack length (Ltc), and crack line density (Dcl), increased with progressive W-D cycles. Higher PF content in soil significantly reduced desiccation cracking across all W-D phases, attributable to the enhanced tensile strength and stress mitigation provided by the fibers. Following VE, surface crack and fragmentation visibility decreased due to the shaking effects, as indicated by reductions in Rsc and Dcl. However, Ltc increased slightly, suggesting either crack persistence or lengthening. Higher PF content resulted in a more substantial reduction in Rsc and Dcl and a reduced increase in Ltc after VE. W-D cycles led to increased cone index (CI) values, reflecting enhanced compactness due to shrinkage which enhances with PF content showing improved soil resistance to loading. Meanwhile, VE reduced CI values following W-D cycles, particularly in nearsurface layers, PF content mitigates this reduction, demonstrating that PF contributes to a more stable soil matrix. Also, PF content decreased the soil deformation under W-D cycles and subsequent VE.

Soil tensile strength is a critical parameter governing the initiation and propagation of tensile cracking. This study proposes an eco-friendly approach to improve the tensile behavior and crack resistance of clayey soils. To validate the feasibility and efficacy of the proposed approach, direct tensile tests were employed to determine the tensile strength of the compacted soil with different W-OH treatment concentrations and water contents. Desiccation tests were also performed to evaluate the effectiveness of W-OH treatment in enhancing soil tensile cracking resistance. During this period, the effects of W-OH treatment concentration and water content on tensile properties, soil suction and microstructure were investigated. The tensile tests reveal that W-OH treatment has a significant impact on the tensile strength and failure mode of the soil, which not only effectively enhances the tensile strength and failure displacement, but also changes the brittle failure behavior into a more ductile quasi-brittle failure behavior. The suction measurements and mercury intrusion porosimetry (MIP) tests show that W-OH treatment can slightly reduce soil suction by affecting skeleton structure and increasing macropores. Combined with the microstructural analysis, it becomes evident that the significant improvement in soil tensile behavior through W-OH treatment is mainly attributed to the W-OH gel's ability to provide additional binding force for bridging and encapsulating the soil particles. Moreover, desiccation tests demonstrate that W-OH treatment can significantly reduce or even inhibit the formation of soil tensile cracking. With the increase of W-OH treatment concentration, the surface crack ratio and total crack length are significantly reduced. This study enhances a fundamental understanding of eco-polymer impacts on soil mechanical properties and provides valuable insight into their potential application for improving soil crack resistance. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

This study presents an inverse method integrating the digital image correlation (DIC) and finite element modeling (FEM) to characterize the shrinkage and fracture of desiccating bentonite clay, considered a buffer material in engineered barrier systems for nuclear waste repositories. Rheology tests were conducted to measure elastic moduli of bentonite at various moisture contents, and a restrained ring test was designed and conducted to induce shrinkage followed by crack initiation and propagation due to the soil desiccation process. Due to the complex nature of characterizing multiphysical fracture parameters, especially for materials undergoing desiccation cracking, an inverse method was employed. The full -field displacement of the desiccating bentonite, captured by DIC, was used to calculate shrinkage-induced stresses. A boundary value problem representing the test conditions was modeled through the finite element method incorporated with cohesive zone elements to simulate the shrinkage-induced cracking. The moisture-dependent shrinkage and fracture parameters of bentonite were inversely characterized through an optimization process, where material parameters in FEM were iteratively calibrated to ensure that the simulated full -field displacements before the onset of cracking and subsequent crack dimensions agreed well with the experiment. The novel experimental-computational method can identify evolving material characteristics subjected to complex hygro-mechanical conditions with fracture damage.

Desiccation cracks have an important effect on engineering mechanical properties of clayey soil. This paper investigated the soil desiccation cracking behavior response to various compaction states. We performed desiccation tests on soil specimens with different compaction water contents and dry densities in a constant temperature chamber. The evolution of typical crack parameters during drying, as well as the crack width distribution after drying, was monitored and quantitatively analysed using image processing methods. The findings reveal that the cracking water content where soil cracking occurs decreases with increasing compaction water content or initial dry density. An increase in either compaction water content or initial dry density is correlated with a decreasing trend in surface crack ratio. Meanwhile, average crack width and total crack length exhibit similar variations. The microstructure of soil compacted at various compaction states plays a critical role in its cracking behavior. It should be noted that soil specimens at high compaction water contents or high dry densities may still develop some cracks with wide widths, despite having low average crack widths and surface crack ratios. This strongly affects the permeability of the soil.