Abstract

The replacement depth of black cotton soil (BCS) was investigated to control the cracking of the highway embankment. With the help of the user subroutines Abaqus, the FEM model of the highway embankment on BCS was constructed. The change of major principal stress within the highway embankment due to the water losing shrinkage of BCS was simulated. The results indicate the tensile stress caused by shrinkage of BCS extends gradually to the inner side of the embankment along the slope surface, finally reaches the threshold and results in the cracking of highway embankment. There is a critical value of BCS depth and its replacement depth, respectively. Beyond this value, the cracking of embankment is mainly controlled by the shrinkage of BCS outside the subgrade. The weight of earth filling can restrain the embankment cracking caused by shrinkage of BCS. To control the cracking of high-filled highway embankment on deep BCS, the top 1.2 m of BCS should be replaced. For low-filled highway embankment, the replacement depth of shallow BCS should be greater than 0.8 m, while that of deep BCS should not be less than 1.2 m, moreover, measures such as slope protection should also be used.

摘要

研究了黑棉土（BCS）的置换深度，以控制公路路基的开裂。在用户子程序Abaqus的帮助下，在BCS上构建了高速公路路基的有限元模型。模拟了BCS失水收缩引起的公路路基主应力变化。结果表明，BCS收缩引起的拉应力沿坡面逐渐向路堤内侧延伸，最终达到临界值，导致公路路基开裂。BCS深度及其替换深度分别有一个临界值。超过此值，路基开裂主要受路基外BCS收缩控制。填土重量可以抑制BCS收缩引起的路堤开裂。为控制深BCS高填公路路基开裂，应更换BCS顶部1.2m。对于低填方公路路基，浅BCS更换深度应大于0.8m，深BCS不应小于1.2m，并应采取护坡等措施。