半刚性基层拱胀现象的力学分析

采用材料力学中的压杆失稳理论和弹性力学中的薄板压曲理论对半刚性基层由温度变化引起的拱胀问题进行分析。计算出了半刚性基层不发生拱胀破坏的临界应力,将临界应力与其温度应力相比较,可以判断施工完成时半刚性基层是否会发生拱胀。对影响温度应力大小的技术指标进行了分析,给出这些指标在施工中的建议值。研究结果表明:两种方法分析计算的结果是一致的,但用压杆失稳理论进行分析偏安全。为避免半刚性基层产生拱胀破坏,在实际施工中,应该尽量避免半刚性基层在冬季施工以减小整个施工过程中温差;施工单位不宜追求高强度而增加水泥剂量而导致基层材料的回弹模量值过高;应该尽量采用膨胀系数较小的骨架密实型基层混合料。

Mechanical Analysis of Vaulted Expansion of Semi-rigid Base

Vaulted expansion of semi-rigid base caused by thermal stress was analyzed with the theory of buckling of columns in mechanics of materials and the theory of elastic plates in mechanics of elasticity.Whether vaulted expansion of semi-rigid base will happens was judged by comparing the thermal stress and critical stress calculated with the two theories respectively.Several technical parameters which influence the thermal stress were analyzed and suitable values of them in construction were recommended.The result indicates that,the calculation results are coincident,however result computed with the theory of buckling of column is prone to be more conservative;in order to avoid the failure caused by vaulted expansion in semi-rigid base,construction in winter should be avoid;the difference in temperature during construction should be as low as possible;it is improper for contractors to pursue the excessive high elastic module for semi-rigid base by increasing the content proportion of cement;materials with dense structure of skeleton which has low expansion coefficient should be adopted for semi-rigid base.