道路行车荷载影响深度分析

Analysis of influence depth for roads induced by vehicle load

提出了黏弹性边界单元有限元模型,用以研究行车荷载在道路中的有效传播深度。通过与Lamb问题的解析解及连盐高速公路实测结果对比分析,验证了数值模型用于研究车辆荷载在道路中引起的动响应具有很好的精度。应用该方法探讨了行车速度、道路各结构层的回弹模量对动响应沿道路深度变化的影响。研究表明,用附加动应力大小作为行车荷载有效传播深度的控制标准不足以反映车辆荷载对道路沉降的影响。尤其对建于软土地基上的道路,建议以竖向动应变作为界定车辆荷载影响深度的控制标准为宜。分析表明,软土地基中行车荷载引起的动响应的影响深度一般在6～10m范围内,这对地基的设计处理和道路工后沉降的控制具有重要参考意义。

FEM with viscoelasitic boundary element was proposed to discuss the depth significantly influenced by vehicle load. This method is proved by Lamb＇s analytical solution and the field test of Lian-Yan expressway. Then,using this method,the effect of vehicle speed and resilient modulus of road structures on the variation of subgrade response at different depths was investigated. The results indicate that the dynamic stress is not enough to describe the settlement characteristics,especially in clay roadbed; and vertical dynamic strain is suggested to define the effective depth induced by traffic load. The depth is about 6-10 m in soft soil roadbed. It has important significance in design treatment of subgrade and controlling post-construction settlement.