半刚性基层材料硬化阶段的湿度应力

Moisture Stresses of Semirigid Base at Hardening Stage During Construction

摘要:

针对半刚性基层材料施工硬化阶段因湿度变化引起的开裂问题，采用弹性地基梁力学模型，讨论了干缩应变、地基反应模量、地基水平摩擦阻力系数等因素对湿度干缩应力、湿度翘曲应力的影响.分析结果表明，湿度干缩应力系数随水平摩擦阻力的增大呈S型曲线增加，最终收敛于1；而湿度翘曲应力系数是相对刚度半径（即梁长与刚度半径比值）的函数，随着相对梁长的增大略超过1后趋近于1.最后，计算了常用水泥掺量下水泥稳定碎石在施工硬化阶段的湿度应力，依据开裂判据，硬化阶段水泥稳定碎石基层很容易产生早期开裂.

关键词:道路工程; 干缩应变; 湿度梯度; 干缩应力; 翘曲应力

Abstract:

In terms of semirigid base cracks induced by moisture change at hardening stage during construction, the shrinkage stress and curling stress were discussed in related to the factors of dry shrinkage strain, horizontal friction stiffness and vertical reaction modulus by using an elastic foundation beam model. The results show that the shrinkage stress ratio grows with increase of the horizontal friction stiffness in “S” trend and gradually converges to 1; whereas the curling stress ratio is the function of L/r (the ratio of the length and stiffness of the beam radius) with increase of L/r，firstly grows up and slightly exceeds 1 then comes down to 1. In the end, the moisture stresses for a group of cement stabilized aggregate with ordinary cement content are calculated, based on the crack criterion, it is easily judged that the premature cracking on cement stabilized aggregate base would be induced at hardening stage.

Key words:road engineering; dry shrinkage strain; moisture gradient; shrinkage stress; curling stress