半刚性基层表面裂缝影响因素

Influence factors on surface crack of semi-rigid base course

为了减缓半刚性基层表面收缩裂缝,应用有限元软件ABAQUS,通过建立8结点等参单元有限元模型,对影响半刚性基层表面裂缝产生的各因素进行了力学分析。计算结果表明:材料的温缩系数越大,对降温的敏感性就越强;材料的干缩系数越大,对失水率的敏感性就越强;基层表面裂缝尖端的应力强度因子与基层温缩系数、干缩系数和基层弹性模量呈线性增长关系。故在基层的设计和施工中,应减小混合料的温缩系数及干缩系数;在强度达到要求的情况下,结合料含量取低限;基层铺筑7d内应避免重车碾压,需加强洒水养生和保温、保湿等措施。

Focusing on the severity of semi-rigid base course shrinkage crack, a finite element analysis model of 8-node isoparametric elements was established, the mechanics analysis of the influence factors on surface crack was made by FEM(finite element method) software ABAQUS. Analysing results indicate that the greater the temperature shrinkage coefficient of material is, the stronger its sensitivity to temperature dropping isi the greater the dry shrinkage coefficient of material is, the stronger its sensitivity to the ratio of water loss is; the stress intensity factor(SIF) at the surface crack tip of base course has linear increase relation with the temperature shrinkage coefficient, dry shrinkage coefficient and base course modulus. So in the design and construction of semi-rigid base course, the temperature shrinkage coefficient and dry shrinkage coefficient must be reduced, and base course must be avoided rolling in 7 d of base spreading.