双线铁路隧道复合式衬砌优化研究

Study on Optimization of Composite Lining of Double-Track Haul Railway Tunnel

研究复合式衬砌的受力情况是复合式衬砌设计的基础,在实际工程中,复合式衬砌的设计方案通常以经验为主导,为了提出效益更佳的铁路双线隧道复合式衬砌设计方案,基于现场监测和数值模拟,改变喷混层厚度、格栅钢架型号和二衬厚度开展衬砌优化研究,通过分析改变以上设计参数对衬砌内力的影响来确定最优的设计方案。研究表明:(1)喷混层厚25 cm、格栅钢架H180、二衬拱腰和侧墙的厚度分别为40 cm和35 cm为该隧道的最优设计方案;(2)格栅钢架的轴力分布特征为“拱部最大、侧墙次之、仰拱较小”;(3)在改变格栅钢架型号并增加喷混层厚度后,格栅钢架承受的轴力下降了10%;(4)侧压力系数为0.8时,拱顶、拱腰和侧墙的内力分布较均匀,弯矩处于较低的水平;(5)减薄二衬厚度提高了衬砌的抗弯安全系数,验证了减薄层二衬5~15 cm优化方案的可行性。

The research on the stress of composite lining is the basis of the design of composite lining.In practical engineering,the design scheme of composite lining is usually dominated by experience.In order to put forward a better design scheme of composite lining for railway double-track tunnel,based on field monitoring and numerical simulation,the lining optimization research is carried out by changing the thickness of spray mixing layer,the type of grid steel frame and the thickness of secondary lining.The optimal design scheme is determined by analyzing the influence of changing the above design parameters on the internal force of lining.The research shows that:1)the optimal design scheme of the tunnel is 25 cm thick spray mixing layer,40 cm thick grid steel frame H180,and 35 cm thick secondary lining arch waist and side wall;2)The axial force distribution of the grid steel frame is characterized by'large arch,secondary side wall and small inverted arch';3)After changing the type of grid steel frame and increasing the thickness of mixing layer,the axial force borne by the grid steel frame decreases by 10%;4)When the lateral pressure coefficient is 0.8,the internal force distribution of vault,arch waist and side wall is uniform,and the bending moment is at a low level;5)Thinned secondary lining thickness increases the bending safety factor of the lining,and verifies the feasibility of the optimization scheme of thinned secondary lining 5~15 cm.