黄土连拱隧道施工方案优化分析

Analysis on Optiming Construction Scheme for Loess Double Arch Tunnel

为了优化双连拱隧道的施工方案,依托山西某黄土连拱隧道,利用ANSYS建立数值模型并导入FLAC3D中,模拟了三导洞法和台阶法的开挖,分析了两种施工方案下连拱隧道的拱顶沉降、地表沉降规律,拱顶和中隔墙大主应力变化以及压力拱范围,结果发现:台阶法施工该连拱隧道的拱顶沉降、地表沉降、应力影响范围比三导洞法小,台阶法施工连拱隧道使得中隔墙的偏应力条件较早得到纠正,形成了较好的受力体系。最终台阶法(三导洞法)形成的拱顶、中隔墙上部围岩压力拱为1.0D(1. 5D)范围,台阶法施工对围岩的扰动范围也更小。因此,为保证该隧道的整体稳定性,建议本隧道采用台阶法施工。

In order to optimize the construction scheme of double arch tunnel, a loess double arch tunnel located in Shanxi is referred. The ANSYS model is imported into FLAC3D software, and then the excavation of three-pilot drift method and benching tunnelling method is simulated by using FLAC3D software. The law of vault and ground settlement, maximum principal stress variation of vault and middle wall and the range of pressure arch are analyzed in two construction schemes. The research indicates that the vault and ground settlement and influence range of stress about benching tunnelling method construction is smaller than that of three-pilot drift method construction. The partial stress conditions of the middle wall have been corrected earlier by benching tunnelling method construction of the double arch tunnel, and a better stress system has been formed. Finally, the surrounding rock pressure arch which is caused by the benching tunnelling method （three- pilot drift method） acting on the vault and upper middle wall is 1.0D （1.5D）. The disturbance range of surrounding rock is smaller by benching tunnelling method. Therefore, in order to ensure the overall stability of the tunnel, it is suggested that the tunnel should be constructed by benching tunnelling method.