Based on large-scale triaxial tests of sandy gravel materials, the strength and deformation characteristics under loading/unloading conditions are analyzed. At the same time, the applicability of the hyperbolic constitutive model to sandy gravel is studied using experimental data. The results indicate that sandy gravel under low confining pressures (0.2 and 0.4 MPa) shows a weak softening trend; the higher the confining pressure, the more obvious the hardening tendency (0.6 and 0.8 MPa) and the greater the peak strength. During unloading tests, strain softening occurs, and the peak strength increases with increasing confining pressure. During loading tests, dilatancy appears when the confining pressure is low (0.2 MPa). With increasing confining pressure (0.4, 0.6, and 0.8 MPa), the dilatancy trend gradually weakens, and the cumulative volume tric strain increases, which reflects the relevance of the stress paths. Through research, it is found that the hyperbolic constitutive model has good applicability to sandy gravel soils, and the corresponding model parameters are obtained.

中文翻译：

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大尺寸加载/卸载三轴试验下砂砾土的本构模型

基于砂砾石材料的大型三轴试验，分析了其在加载/卸载条件下的强度和变形特性。同时，利用实验数据研究了双曲线本构模型对砂砾石的适用性。结果表明，砂砾石在低围压（0.2和0.4 MPa）下表现出较弱的软化趋势；围压越高，硬化趋势越明显（0.6 和0.8 MPa），峰值强度越大。在卸载试验期间，发生应变软化，峰值强度随着围压的增加而增加。在加载试验中，当围压较低（0.2 MPa）时出现剪胀。随着围压（0.4、0.6、0.8 MPa）的增加，剪胀趋势逐渐减弱，累积体积应变增加，这反映了应力路径的相关性。通过研究发现，双曲本构模型对砂砾土具有较好的适用性，得到了相应的模型参数。