堆积体隧道围岩及支衬体系空间力学特性

Analysis of Spatial Mechanic Characteristics of Surrounding Rock and Support System for a Tunnel Constructed through Deposits

为研究堆积体隧道围岩和支衬体系受力空间变化规律,采用三维弹塑性有限元法模拟隧道施工过程,得到了洞室周边围岩和支护结构应力随掌子面开挖的变化过程。结果表明,隧道开挖对不同部位围岩扰动大小存在较大差异,扰动后拱部围岩应力强度较小,拱脚和边墙围岩应力强度最大,仰拱围岩应力波动较大但量值总体偏小;管棚在隧道开挖前后受力状态发生明显改变,支护和衬砌过程中有微小波动;拱部系统锚杆对于维持围岩临时稳定发挥了一定作用,但其作为永久支护对围岩长期稳定作用不大,锁脚锚杆在下台阶开挖以及隧道长期稳定方面均发挥了重要作用;初支拱部受拉、边墙和拱脚受压显著,其中拱腰、拱脚分别为拉、压控制性截面;与钢筋混凝土强度相比,二衬受力较小,具有较大的强度储备。

To research the force variation of surrounding rock and support system with space for a tunnel constructed through deposits, the process of tunnel construction is simulated by employing the three dimensional elasto-plastic finite element method, so stress of surrounding rock and supporting structures with the change of excavation process of tunnel face is acquired. Results show that. disturbances of surrounding rock for different parts is significantly different during excavation; stress intensity of surrounding rock in arched portion is less, while in arch foot and side wall is largest, and the volatility is larger but the quantity is small for inverted arch; stress states of pipe roof are changed obviously before and after tunnel excavation, and have small changes in supporting and lining process; system anchoring bolts of arch part have been contributing to maintain the temporary stability of surrounding rock, but it has little function to the long-term stability of surrounding rock as a permanent support- feet-lock bolt has played a critical role in the stage of excavation of lower part and long-term stability of tunnel structures. For stress of primary support, arch part is in tension, arch foot and side wall is under compression. The controlled section is at hance and arch foot. Compared with the strength of reinforced concrete, stress of secondary lining is less and has enough strength reserve.