路基容许不均匀沉降控制指标的理论分析

为了研究路基不均匀沉降的控制指标,利用数值计算的方法,研究路基不均匀沉降的沉降梯度对基层底部附加应力的影响;并基于双层弹性连续体系,求解不均匀沉降在半刚性基层底部产生的弯拉应力,最后利用麦克劳林展开式进行简化。研究结果表明:利用沉降梯度作为路基不均匀沉降的控制指标,具有一定的局限性;而沉降梯度与沉降距离的比值,即一阶梯度,与弯拉应力之间存在一一对应的关系,可作为容许不均匀沉降的控制指标。对于我国典型的半刚性路面结构来说,不考虑车辆荷载时,路基不均匀沉降的容许一阶梯度可取为0.000161m-1。

Theoretical analysis of evaluation index for allowable subgrade uneven settlement

In order to research the evaluation index of differential settlement, the finite element code was used to study the influence of settlement gradient on the additional stress of the base. Then the analytic solution of tensile stress at the bottom of semi-rigid base was obtained basing on the two layer of elastic continuous system, and the maclaurin expansion was adopted to simplify the analytic solution. Results showed that there were great limitations for using the settlement gradient to evaluate the allowable uneven settlement. But the first derivative settlement gradient, which was the ratio of settlement gradient to spread distance, had a well linear correspondence to the tensile stress. Therefore, the first derivative settlement gradient could be used as the key index to assess the allowable subgrade uneven settlement. For the typical semi-rigid base asphalt pavement structure, the allowable first derivative settlement gradient was 0.000161m-1, when the traffic loading was not considered.