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在川西地区,由砂砾石与黏土颗粒构成的混合土路基经常会发生沉降变形问题。对于交通荷载作用下土体中的累积变形,可通过建立循环荷载作用下的动本构模型进行描述。在边界面弹塑性理论的框架内,综合考虑崩坡积混合土非饱和状态和细颗粒含量两大主要影响因素,结合能比较真实描述非饱和土体湿陷性能的LC(loading-collapse)屈服曲线,同时基于可移动映射中心的映射准则,采用经典的修正剑桥模型作为塑性势方程,构建了混合土的非饱和动本构模型,其参数可通过拟合或常规试验获得。通过与试验结果进行对比,该模型不仅可以较好地反映非饱和混合土在静载和循环荷载下的力学特性,而且能够真实地预测土体在加、卸载过程中的滞回特性。其结果可为川西混合土路基沉降变形预测提供理论依据。
In the western Sichuan area, the subsidence and deformation of mixed soil subgrade composed of gravel and clay particles often occur. For the cumulative deformation in soil under traffic load, it can be described by establishing the dynamic constitutive model under cyclic loading. In the framework of elastic-plastic theory of boundary surface, two main influencing factors of non-saturated state and fine particle content of landslide-soil mixed soil are comprehensively considered. Combining LC-loading-collapse, which can describe the collapsibility of unsaturated soil more seriously, Based on the mapping criterion of movable map center, the classical modified Cambridge model is used as the plastic potential equation to construct the unsaturated dynamic constitutive model of mixed soil, whose parameters can be obtained through fitting or routine experiments. Compared with the experimental results, this model not only can reflect the mechanical properties of unsaturated mixed soil under static and cyclic loading well, but also can predict the hysteretic behavior of soil during loading and unloading. The results can provide a theoretical basis for the settlement deformation prediction of the mixed-soil subgrade in western Sichuan.