填土路基和桥涵下无重土地基承载力的分析

Analysis of Weightless Subsoil Bearing Capacity under Filled Subgrade and Bridge-Culvert

为了研究公路填土路基和桥涵构造物基础下无重土地基的破坏机理和极限承载力,把填土路基和桥涵构造物分别简化为柔性基础和粗糙底面的刚性基础,采用关联流动的Mohr-Coulomb内切圆屈服准则,通过增量加载的有限元方法,全程模拟了地基由初始的线弹性状态逐渐过渡到塑性流动的极限破坏状态的过程。通过对这二种类型基础下地基的计算结果的对比分析,并结合对照国内外模型试验成果,得出如下结论:桥涵构造物下地基较早进入临塑状态;填土路基地基承载力相对桥涵构造物地基承载力略有提高;桥涵构筑物基础下地基主动土压力滑动面明显要比填土路基下地基陡和深。

In order to study the destroy mechanism and ultimate bearing capacity of weightless subsoil under filled subgrade and bridge - culvert,they are simply regarded as flexible and rigid foundation with completely rough floor respectively ;Mohr -Coulomb ibside-tangent circle yield criterion and associated flow nile are adopted,the overall process gradually from elasticity to plasticity is modeled by elastoplastic FEM through load increment method. The computed results of these two sorts of foundation mentioned above are compared and integrated with some important results of model test, some significant conclusions can be obtained. That is： the plastic stage comes earlier in subsoil under bridge - culvert than that in filled subgrade. Compared with bridge - culvert, the filled subgrade may slightly increase subsoil bearing capacity. The slip surface of active earth pressure under bridge - culvert is steeper and deeper.