粗粒土路堤填料路用性能及其循环动应力试验

Experimental on road performance and cyclic dynamic stress of coarse-grained soil subgrade

为了研究粗粒土路堤在动力荷载及雨水湿化作用下的路用性能,以粗粒土为研究对象,开展室内常规物理力学试验,分析压实度、干密度以及含水率对粗粒土填料回弹模量的影响;利用大型动三轴试验仪研究不同压实度和围压条件下轴载作用次数与动态回弹模量之间的关系,以压实度和含水率为条件变量对粗粒土试件进行永久变形试验,探讨循环动应力作用下粗粒土试件轴向累计轴向应变的发展规律。试验结果表明:压实度和含水率对粗粒土的物理力学特性影响较大,但对干密度影响较小;试件累计轴向应变随着压实度增大而减小,当压实度为90%时,试验前期累计轴向应变增加幅度较小,当累计轴载次数达到1 000时,累计轴向应变急剧增加;累计轴向应变随着含水率的增加而增大,并随着压实度的增大而减小;粗粒土随着轴载次数的增加经历了稳定、临界和破坏3种状态,其中压实度为90%的试件表现较为明显;粗粒土路堤填料的动弹性模量随着轴载次数的增加而减小,衰减速率逐渐减小,最终趋于平稳。

To determine the road performance of coarse-grained soil subgrade under a dynamic load and wet rain, coarse-grained soil was took as the research object, and the influence of the compaction degree, dry density, and moisture content on the modulus of resilience of coarse-grained soil was analyzed. This was based on conventional physical and mechanical laboratory experiments. At the same time, the relationship between the number of axial loads and the dynamic elastic modulus under different compaction degrees and confining pressures was studied using large dynamic triaxial apparatuses. Further, a permanent deformation test of coarse-grained soil specimens was carried out under the varying compaction degrees and moisture contents. In addition, the development rule for the axial cumulative strain of coarse-grained soil under cyclic dynamic stress was discussed. The results show that the degree of compaction and the moisture content have a significant influence on the physical and mechanical properties of coarse-grained soil, and the dry density has little influence. The cumulative axial strain decreases with an increase in the compaction degree. When the compaction degree is 90%, the cumulative axial strain increases slightly during the early stage of the test. Further, when the number of loads reaches 1 000, the cumulative axial strain increases sharply. The cumulative axial strain increases with the increase in moisture content and decreases with an increase in the degree of compaction. With an increase in load times, coarse-grained soil experiences three states, stability, criticality and destruction, of which 90% of the samples showed obvious compaction. The dynamic elastic modulus of the coarse grained subgrade filler increases with the number of axial loads, and the attenuation rate decreases gradually, finally tending toward stability. 4 tabs, 14 figs, 25 refs.