基于环境和荷载的水泥稳定碎石抗裂评价系数试验研究

在分析现有半刚性基层抗裂评价指标的基础上,采用劈裂模型作为半刚性基层材料收缩开裂的评价模型,同时考虑干缩应变、温缩应变及行车荷载下基层层底拉应变,提出了抗裂评价系数作为水泥稳定碎石的评价指标。对6种级配水泥稳定碎石进行了劈裂和收缩试验,并用BISAR3.0计算了给定结构基层最大层底拉应变,进而比较了最大干缩应变、劈裂应变和抗裂评价系数3个抗裂指标。研究表明,采用抗裂评价系数能正确评价水泥稳定碎石的抗裂性能。采用控制关键筛孔通过百分率理论计算所得集料级配的抗裂性能优于富勒级配理论;超载对基层层底拉应变的不利影响显著。研究结果已在沪宁高速公路扩建工程中成功应用。

Experimental Research on Anti-crack Evaluation Coefficient of Cement-stabilized Macadam Based On Environment and Load

After analyzing existing anti-crack evaluation index of semi-rigid base,cleavage model was used to evaluate shrinkage cracking of semi-rigid base material.Considering the shrinkage strain,temperature shrinkage strain and tensile strain produced by traffic load,the anti-crack evaluation coefficient was put forward as the evaluation index of cement-stabilized macadam.Cleavage and shrinkage test were made for six kinds of gradation,and the max bottom tensile strain of base was calculated by BISRA 3.0.Then,three anti-crack evaluation indexes(the biggest dry shrinkage strain,splitting tensile strain and anti-crack evaluation coefficient) were compared through indoor tests.The research indicates that(1) using anti-crack evaluation coefficient can properly evaluate anti-crack performance of cement-stabilized macadam;(2) the cracking performance of gradation calculated by theory of controlling key sieve percentage is better than the cracking performance from Fuller gradation theory;(3) over loading has significant adverse impact on tensile strain at the bottom of base.The research results have been successfully used in extension engineering of Shanghai-Nanjing Expressway.