考虑岩土试样软弱夹层特性的三轴剪切数值仿真实验设计OA

[Objective]Engineering practice in the South-to-North Water Diversion Project in China has shown that,in certain expansive soil regions,the presence of numerous unevenly distributed weak interlayers or fissures within foundation soils significantly reduces soil strength.This reduction in strength is a direct cause of landslides that occur during the excavation of canal slopes in expansive soil areas.However,obtaining intact soil specimens with weak interlayers,controlled dip angles,and controlled penetration rates remains extremely challenging.Such specimens are rare,and their preparation typically requires specialized molds and equipment.The preparation process is complex,exhibits poor reproducibility,and fails to satisfy the requirements of conventional laboratory geotechnical testing.To overcome these limitations,this study develops a triaxial shear simulation experiment incorporating weak interlayers by integrating Rhino modeling software with the FLAC3D numerical calculation platform.[Methods]First,triaxial shear numerical simulations were performed on expansive soil specimens containing weak interlayers with a fissure penetration rate of λ=100%and a fissure dip angle of θ=45°.The resulting stress-strain curves and peak strength values were compared with data obtained from laboratory triaxial shear tests to validate the numerical model.After validation,Rhino modeling software was used to construct a series of triaxial shear specimen models with varying weak interlayer characteristics,including fissure penetration rates λ ranging from 0%to 100%and fissure dip angles θ ranging from 0° to 70°.These models were then imported into FLAC3D,where triaxial shear simulation experiments were conducted to systematically investigate the influence of fissure penetration rate λ and fissure dip angle θ on the strength behavior of fissured expansive soil with weak interlayers.Finally,a mathematical model was established to describe the relationship between soil strength and the characteristic parameters λ and θ.The predictive performance of this model was evaluated by comparing it with numerical simulation results.[Results]The simulation results demonstrate the following:(1)The stress-strain curves obtained from numerical simulations closely agree with those from laboratory triaxial shear tests,with deviations in peak strength not exceeding 5%.(2)When the fissure dip angle satisfies θ≤45°+φ/2,the strength of fissured expansive soil with weak interlayers decreases in a hyperbolic manner as both the fissure penetration rate λ and dip angle θ increase,reaching a minimum at θ=45°+φ/2.(3)The proposed mathematical model accurately captures the strength variation of fissured expansive soil with weak interlayers,with an average relative error of approximately 1.1%compared with numerical simulation results under different confining pressures.[Conclusions]By integrating Rhino modeling with the FLAC3D numerical calculation platform,a robust triaxial shear numerical simulation framework for geotechnical specimens containing weak interlayers is established.This approach effectively overcomes practical engineering constraints associated with in-situ soil sampling,including difficulties in obtaining specimens with consistent fissure penetration rates and dip angles and the limited availability of intact samples.The developed mathematical model reliably describes the relationship between the strength of fissured expansive soil with weak interlayers and key controlling parameters,such as fissure dip angle and penetration rate.These findings further enhance the understanding of the mechanical behavior and strength characteristics of expansive soils containing weak interlayers,providing valuable reference for geotechnical design and stability assessment.