车辆荷载作用下双层路基层间动应力响应试验研究

Tests for interlayer dynamic stress response of a two-layer roadbed under vehicle load

针对层状路基土的动力响应与稳定性评价问题,以某双层路基为工程背景,利用现场实测数据,揭示出硬、软土层界面处存在动应力突变现象,并给出了动应力突变系数;根据室内模型试验数据,以动应力突变系数为试验指标,采用极差分析法对主要影响因素进行了排序;借助动三轴试验获得硬、软土体的临界动应力,推导得出两种土体的动应力水平关联性系数,并提出一种评价路基长期稳定性的"概率区域"方法。研究表明:路基运营后期,硬、软土层压缩模量之比将取代硬壳层厚度,成为影响层间响应的首要因素;埋置较深的下卧软土层是控制路基稳定性的关键层。

Aiming at dynamic response and stability evaluation problems of layered subgrade, based on an actual two-layer roadbed project, the phenomenon of dynamic stress mutation at hard-soft soil layers, interface was revealed with field measurement data, and a coefficient of dynamic stress mutation （CDSM）was obtained. According to the data of laboratory model tests, the main factors affecting CDSM were ranked with the range analysis method. In virtue of hard and soft soils, critical dynamic stress obtained with the dynamic triaxial tests, the relevance coefficient between two soils, dynamic stress levels was deduced, and a “probability area” method was proposed to evaluate the long-term subgrade stability. The results showed that the ratio between two soils,compression moduli is the primary factor affecting inter-layer dynamic stress response in stead of the thickness of hard crust layer, and the soft soil layer embedded at deeper location is the key layer to control subgrade stability.