引汉济渭秦岭隧洞开挖期围岩稳定性数值分析

Numerical Analysis of Surrounding Rock Stability During Excavation of Qinling Tunnel from Hanjiang River to Weihe River

隧洞岩体的稳定性分析是保证施工期和运行期安全稳定的重要研究课题,隧洞围岩稳定中地应力因素有着十分重要的作用,基于引汉济渭秦岭引水隧洞二衬混凝土开裂洞段典型断面的应力实测结果与地形地质构造条件,运用FLAC3D软件模拟地下隧洞工程的施工开挖。结果显示,洞周围岩总体处于受压状态,主压应力一般为8~38 MPa,在拱顶与右侧拱肩、拱墙与底板交汇处有一定程度的压应力集中,压应力为28~38 MPa。隧洞顶拱位移总体上为5~20 mm,两侧边墙朝临空面方向的位移总体上为5~35 mm,底板回弹变形总体上为5~25 mm,位移较大处在Ⅳ类围岩中,断层f处尤其突出。隧洞开挖后产生了一定范围的塑性区,以剪切破坏为主,塑性区主要在Ⅳ类围岩中,深度3~4 m;靠近断层区域塑性区进一步向断层延伸,局部塑性区深度达6 m。

The stability analysis of tunnel rock mass is an important research topic to ensure the safety and stability of the construction period and operation period.The in-situ stress factor plays a very important role in the stability of tunnel surrounding rock.Based on the stress measurement results of the typical section of the second lining concrete cracking tunnel section of the water diversion tunnel from Hanjiang to Weihe and the geological and topographical conditions,this paper used the FLAC3 D software is used to simulate the excavation of underground tunnel.The results show that the surrounding rock around the tunnel is generally in a state of compression,and the main compressive stress is generally between 8 MPa and 38 MPa.There is a certain degree of compressive stress concentration at the intersection of the vault and the right spandrel,the arch wall and the bottom plate,with the magnitude of 28 MPa to 38 MPa.The displacement of the tunnel top arch is generally between 5 and 20 mm;the displacement of the side walls on both sides towards the free face is generally between 5 and 35 mm;the rebound deformation of the bottom plate is generally between 5 and 25 mm;the larger displacement occurs in class IV surrounding rock,especially at fault F.After the tunnel excavation,a certain range of plastic zone is produced,which is mainly shear failure.The plastic zone mainly appears in class IV surrounding rock,and the depth is within 3-4 m;in the area near the fault,the plastic zone further extends to the fault,and the depth of local plastic zone reaches to 6 m.