重载铁路隧道基底结构的动压力响应

Dynamic Pressure Response of Foundation Base Structure in Heavy Haul Railway Tunnel

以晋中南重载铁路太行山隧道为工程依托,研究轴重为27t的重载列车以80km·h-1的速度经过时隧道基底结构的动压力响应。分别采用有限元模拟和现场实测方法得到动压力典型时程曲线,分析隧道基底各位置处动压力的横向及竖向分布规律。结果表明:隧道左右侧的动压力基本对称分布,线路中心线处动压力受到重载列车动荷载影响更大;动压力在填充层内的实际衰减程度大于理论分析,仰拱上表面左右侧沟底部实测动压力大于线路中心线处,而仰拱上下表面动压力横向分布规律相反;动压力竖向传递过程分为快速和缓慢衰减2个阶段,分别位于道床与仰拱填充层内和仰拱内,但在缓慢衰减阶段,线路中心线处的动压力幅值出现一定程度的增长,而平均值仍为衰减。由此可知,隧道的仰拱极易出现大变形而形成裂缝,并且易发生侧沟外挤等病害。

Based on Taihangshan tunnel project on Jinzhongnan heavy haul railway, the dynamic pressure response in foundation base structure when heavy haul train with the axle load of 27 t passing tunnel at the speed of 80 km· h-1 was studied. Finite element simulation and field measurement method was adopted respectively to obtain the typical time-history curve of dynamic pressure. The distribution of horizontal and vertical dynamic pressure at each position of tunnel foundation base was analyzed. Results show that the dynamic pressure distribution on the left and right sides of tunnel is almost symmetrical, and the dynamic pressure distribution at track center line is more affected by the dynamic load of heavy haul train. The actual attenuation of the dynamic pressure in filling layer is greater than that of theoretical analysis. The measured dynamic pressure on the left and right side ditches of inverted arch upper surface is greater than that of track center line, and the lateral distribution of the dynamic pressure on the upper and lower surfaces of inverted arch is the opposite. The transmission of vertical dynamic pressure is divided into two stages including the rapid attenuation stage located in ballast bed and invert filling layer while the slow attenuation stage located in invert arch. In slow attenuation stage, the amplitude of the dynamic pressure at track center line appears growth to a certain degree, while the average value still shows attenuation. Thus, it is clear that the inverted arch of tunnel is prone to large deformation and cracks, and easy to appear the displacement of side ditch and other diseases.