不同水因素影响下土石混填体承载力学特性研究

土石混填体如坝体或路堤必然受到复杂自然环境的影响,其竖向承载力学特性是工程建设关注的焦点。采用西南山区土石料按相似比理论制作级配良好的土石混填路堤模型,布设临近路堤中心线(“左列”)、加载板中心线(“中列”)和邻近路堤临空坡体(“右列”)的3列等间距土压力盒,使其分别处于初始环境状态(模型A)、降雨饱和环境状态(模型B)和干湿循环状态(模型C),采用分级加载程序进行模型承载试验和数值模拟。研究结果表明:模型A和模型C具有良好的结构性,p~s曲线有明显拐点,破坏有突发性,模型B荷载沉降关系曲线无拐点,相同荷载作用下模型C沉降量介于模型A和模型B之间;同层条件下加载板中心土压力比相邻土体大,“左”列约束大于“右”列使不同环境状态下土石混填路堤竖向应力扩散具有不对称性,“左”列土压力大于“右”列并随着路堤深度的增加而更加显著,临空侧坡体丧失承载特性加剧诱发应力扩散的不对称性。

Comparison between responses of reinforced and unreinforced embankments due to road widening

The objective of this work is to compare the responses of geosynthetically-reinforced embankment and unreinforced embankment due to road widening by using the centrifuge model tests and a two-dimensional(2D) finite element(FE) model. The measured and calculated responses of the embankment and foundation exposed to road widening include the settlement,horizontal displacement,pore water pressure,and shear stresses. It is found that the road widening changed the transverse slope of the original pavement surface resulting from the nonuniform settlements. The maximum horizontal movement is found to be located at the shoulder of the original embankment. Although the difference is small,it is clearly seen that the geosynthetic reinforcement reduces the nonuniform settlements and horizontal movements due to road widening. Thus the reinforcement reduces the potential of pavement cracking and increases the stability of the embankment on soft ground in road widening.