荷载条件下原状膨胀土浸水膨胀变形试验研究

摘要

The effects of moisture content and overlying load for the expansion of typical undisturbed expansive soil of the second line of Lanzhou-Xinjiang railway were studied through grading soaking under different load conditions with the thickness of 2 cm.The test results show that the expansion time history curve of undisturbed expansive soil shows a steplike growth curve.The expansion amounts show a sharp expansion stage,an outer convex curve and a linear slow expansion stage with time variation in a certain moisture content.The overlying load would have a restraining effect for expansion of undisturbed expansive soil.The larger the load is,the smaller the expansion is.The smaller the load is,the larger the load is.The saturated moisture content of expansive soil is gradually decreased with the increase of the overlying load when the expansion is stable in the end.Under a certain overlying load,the moisture content and the expansion of undisturbed expansive soil are in good logarithmic relationship.And then the formula parameters are fitted according to different overlying load.A model for calculating the expansion of undisturbed expansive soil under the coupling action of moisture content and overlying load is established.The calculated results agree well with the measured data.%以兰新铁路第二双线一处典型原状膨胀土为研究对象,进行厚度为2 cm的原状膨胀土在不同荷载条件下的分级浸水膨胀变形试验,以研究含水率和上覆荷载对原状膨胀土膨胀量的影响.试验结果表明:原状膨胀土的膨胀时程曲线呈阶梯型增长,且在某一含水率下的膨胀量随时间变化呈现出直线剧烈膨胀阶段、外凸弧线减速阶段和直线缓慢膨胀阶段;上覆荷载对膨胀量起抑制作用,上覆荷载越大,膨胀土的膨胀量越小,上覆荷载越小,膨胀土的膨胀量越大,且膨胀土最终达到膨胀稳定时的饱和含水率随上覆荷载的增大在逐渐减小;在上覆荷载一定的情况下,含水率和原状膨胀土的膨胀量呈良好的对数关系,再依据不同上覆荷载对公式参数进行拟合,建立了含水率和上覆荷载耦合作用下原状膨胀土膨胀量计算模型,模型计算结果与实测数据吻合较好.