路基刚度对冲击压实旧混凝土路面力学行为的影响分析

以冲击压实技术处理旧水泥混凝土路面的力学作用过程为对象,采用三维有限元方法,研究冲击压实施工中不同路基刚度条件下的旧路面结构及路基之受力、变形特征。分析路基刚度改变对旧面板破裂及路基受压效果的影响;探讨冲压荷载在板下路基中的传递规律及作用深度与路基刚度的关系等问题。数值分析表明:在冲压荷载作用下,板下路基在一定深度范围内承受三个方向的压应力,其数值与传力深度均随路基刚度增大而增大;路基刚度越小,板下路基的垂直压缩量越大,所受压应力越均匀,面板越易出现破裂;随着施工逐步进行,面板块度变小、路基刚度增大及土基所受压应力增大,这种在旧面板约束下的冲压作用正有益于不良路基实现先轻压后重压的逐步压实过程。所得结论与实际观察现象吻合。基于分析结果,提出的施工建议,将对冲击压实技术处理旧水泥混凝土路面具有一定的参考价值。

Influence of subgrade modulus on the mechanical behaviors of existing impact-compacted concrete pavement

Considering the mechanical process during the cracking and seating of existing concrete pavement by means of impact compaction in a rehabilitation project,the stress and deformation characteristics of the existing pavement structure and its subgrade were analyzed by using a three-dimensional finite element method.Several cases with different subgrade moduli of resilience were simulated in the FEM analyses and their mechanical influences on cracking of the slab and compacting of the soil subgrade are revealed.The relationships between the stress caused by impact load and the depth in soil subgrade were discussed.The scope of depth affected by impact load was explored for various subgrade moduli of resilience.The FEM analyses revealed several important features:(1) three dimensional compressive stresses exist in the affected scope of subgrade underneath the slab;(2)the scope and magnitude of the compressive stresses increase with the subgrade moduli;(3)the less the subgrade modulus,the more the vertical deformation and the stress are more uniform;(4)after the slab are cracked into smaller pieces,both the magnitudes of subgrade modulus and the compressive stress increase,which have positive effects on poor subgrades because of realization of first light then heavier compacting.