双线重载铁路隧道基底结构受力特性现场激振试验研究

Field Test Research with Vibration Exciter on Mechanical Characteristics of Foundation Structure of Double-track Heavy-haul Railway Tunnel

依托于张唐线双线重载铁路隧道——付营子隧道现场试验,在Ⅴ级围岩条件下利用大型激振设备不同频率和配重块组合模拟了25、27、30t轴重的重载列车作用。根据光纤光栅传感器采集时程曲线提取的静压力和瞬时动压力幅值,针对基底不同结构层表面上不同测点的接触压力横向和竖向分布规律进行研究。结果表明:双线重载铁路隧道基底结构通车前静压力分布基本对称,重载列车荷载作用下,因仅半幅受到重载荷载影响,其动力响应明显于普通客运线路使基底结构受力不平衡易发生失稳。在重载线路中心、轨道位置和客运线路轨道3条监测线上各结构层表面动压力竖向衰减规律类似,均可拟合为三次多项式用于类似工程的设计和受力预测。

Based on the large scale excitation test in Fuyingzi tunnel of Zhangjiakou Tangshan double track heavy haul railway, this paper simulated the dynamic response of heavy haul trains of three axle loads of 25 t, 27 t and 30 t with the different frequencies of large scale exciting equipment and counterweight blocks under the condition of Grade V surrounding rock. According to the amplitude of static pressure and instantaneous dynam ic pressure extracted from the time history curve collected by the fiber grating sensor, the horizontal and vertical distribution of the contact pressure of different measuring points on the surface of the base of different structure layers was studied. The results show that the static pressure distribution of the base structure of the double track heavy haul railway tunnel was generally symmetrical before the railway was put into operation. Under the load of heavy load train, because the left track （the right track is used for passenger train） of the tunnel is affected by heavy load, the dynamic response is more obvious than the passenger train track and will cause the unbalanced load of the base structure. In the three on line monitoring lines including the center of heavy haul railway, right rail of heavy haul track and passenger train track, the vertical attenuation of dynamic pressure on each structural layer is similar, which can be fitted to similar engineering design and stress prediction.