公路新建和扩建全过程力学响应数值分析

Numerical Analysis of Mechanical Response for Road Constructing and Widening

考虑公路扩建工程中新、老路修建历史的差异,建立了软土地区公路新建和扩建全过程力学响应分析的平面非线性有限元模型。对新、老路软基未加固和搅拌桩加固的4种地基加固方式下新、老路面对差异沉降的力学响应进行了数值模拟分析。计算结果表明,拓宽前老路基顶面沉降呈"盆形"分布。新路基荷载下老路中心处发生回弹。老路软基搅拌桩加固时老路基顶面沉降由"盆形"分布逐渐发展为"倒钟形"分布。新、老路软基均未加固时面层顶部的最大水平拉应力最大,新、老路软基均搅拌桩加固时面层顶部的最大水平拉应力最小。老路软基搅拌桩加固时新路面层顶部受拉,其余3种地基加固方式下新路面层顶部受压。

Considering significant difference in construction sequence for existing highway and widening one,a nonlinear plane strain finite element model is established to simulate their mechanical responses to constructing and widening. The numerical analysis is performed to obtain surface settlement of old and new subgrades and stress in pavement structures under different ground improvement conditions. The results show that surface settlement curve of old subgrade is of ＂basin shape＂before widening,it changes gradually into ＂reverse bell shape＂with increase of height of new subgrade when the soft soil below old subgrade is improved by soil-cement mixing piles. The maximum horizontal tensile stress in upper layer of surface course is the biggest when the soft ground is not improved,and it will be the smallest when the soft soils below old and new subgrades are improved by soil-cement mixing piles. The horizontal stress on top of surface course on new subgrade is tensile stress when the soft soil below old subgrade is improved by soil-cement mixing piles,and it will be compressive stress under other three ground improvement conditions.