既有铁路隧道受下穿引水隧洞近接施工影响预测

Closely Constructing Influence Forecast of Hydraulic Tunnel Under-Cross Existing Railway Tunnel

结合云南省盐津县白水江3级电站引水隧洞下穿内昆铁路手扒岩隧道的实际情况,采用三维数值模拟计算,对既有铁路隧道受下穿引水隧洞施工的影响和铁路隧道结构安全对策进行了研究。结果表明:引水隧洞施工对铁路隧道产生影响的范围与掘进方向有关,靠近铁路隧道侧为2D(D为引水隧洞的开挖洞径),远离铁路隧道侧为4.5D;铁路隧道纵向受影响范围为6.5D,横向受影响范围为3D。引水隧洞近接施工时,铁路隧道将发生类似扭转的变形,需在铁路隧道受影响范围内对隧道底板沉降、衬砌变形、衬砌横/纵向受力和两隧道交叉点的竖向振动速度进行监测,并对钢轨采用扣轨处理等措施,以确保铁路隧道结构及列车运行的安全。

This paper gives an analysis of the influence which under-cross hydraulic tunnel construction imposed on the existing railway tunnel and discusses the security countermeasure for existing railway tunnel＇s structure. Using three-dimensional numerical modeling methods associated with the practical situation of Shoupayan tunnel on Neijiang--Kunming railway which was under-crossed by Baishuijiang 3-level power station hydraulic tunnel in Yanjin county of Yunnan province. The results indicate that the hydraulic tunnel construction circle which affects the existing railway tunnel has relation with the driving direction. The circle is 2D （D stands for the excavation diameter of the hydraulic tunnel） adjacent to the existing railway tunnel, while it is 4. 5D away from the tunnel. The inflection area of the existing tunnel is 6.5D in longitudinal direction and 3D in transversal direction. When closely constructing the hydraulic tunnel, deformation such as twist rotation will occur in railway tunnel. Monitoring of railway tunnel baseboard settlement, lining distortion, lining transversal/vertical force and vertical vibration velocity at the two tunnels crossover point in the influence circle of existing railway tunnel must be carried out. In addition, the rail should be reinforced by clasp in order to ensure the safety for existing tunnel structure and train operation.