高速铁路采空区群桩受力机理数值模拟

对高速铁路采空区桥梁群桩基础的受力机理研究,目前还非常少见。以合肥至福州高速铁路官山底特大桥采空区群桩基础为原型,通过数值模拟获得群桩受力规律。研究表明:随着荷载增大,桩上部轴力变化明显,桩身轴力沿深度逐渐减小,在采空巷道内桩身轴力不变,所有桩均为端承摩擦桩;桩侧摩阻力沿桩身先增大后减小,整个桩的侧摩阻力分布重心下移,穿过采空区的桩侧摩阻力分布重心比未穿越采空区的桩下移深度略深;承台下中部的桩间土应力要大于承台边角位置的桩间土应力,随着荷载增大,桩间土应力增长速率小于桩顶应力,桩身开始承担更多荷载。

Numerical Simulation on Mechanical Mechanism of Pile-Group Foundation of High-speed Railway in Goaf Area

The aim of this paper was to study the mechanical mechanism of bridge pile-group foundation of high-speed railway in goaf area,while a study of this kind still remains very rare at present. In this paper,the pile-group foundation of Guanshandi super-major bridge on Hefei-Fuzhou high-speed railway was taken as the example,and then the mechanical behavior of the pile-group foundation was revealed by the use of numerical simulation. The research result shows:( a) With the increasing of load,the pileshaft axial force obviously changes at the upper part of the pile,gradually decreases along the pile shaft towards the bottom,and remains the same within the range of goaf roadway; all the piles are of endbearing friction pile.(b) The pile side friction increases at first and then decreases along the pile shaft, and the distribution centroid of the pile side friction of the whole pile lowers down; the distribution centroid of the pile side friction of the piles passing through the goaf area is deeper than that of piles not passing through the goaf area.(c) The soil stress between piles below the bearing platform at the center place is larger than that at the edge places; and with the increasing of load,the increment rate of soil stress between piles is slower than that of pile top stress,that is to say,the pile top begins to bear a larger proportion of load.