考虑泥岩蠕变特性的富水隧洞施工控制研究

Study on Construction Control of Water-Rich Tunnels Based on the Creep Characteristics of Mudstone

摘要:

为探究在围岩蠕变作用下采用不同支护参数和施工方法对隧洞稳定性的影响,以新疆输水隧洞工程为背景,对现场取得的土样开展了三轴蠕变试验,用CVISC模型对试验结果进行泥岩蠕变参数拟合;利用FLAC 3D软件基于实际工况建立数值模型,优化支护参数;开展施工控制后的变形监测,验证数值模拟结果的有效性。结果表明:(1)泥岩变形包括施加荷载时产生的瞬时变形和随时间变化的蠕变变形,其中以蠕变变形为主;(2)泥岩蠕变参数拟合度较高,泥岩蠕变特性可通过CVISC模型表征;(3)模拟发现钢拱架布设间距为50 cm,C25混凝土喷层厚度为25 cm,锁脚锚杆打设长度为4.5 m,角度为60°时,能有效减小隧道变形,充分发挥支护结构作用;(4)现场优化施工后的监测数据验证了数值模拟结果的可靠性,证明该施工控制措施下隧洞是稳定的。

Abstract:

To investigate the influence of different supporting parameters and construction methods on the stability of tunnels under the action of surrounding rock creep, a triaxial creep experiment was carried out on soil samples obtained from the site of the Xinjiang water conveyance tunnel project, and the mudstone creep parameters were fitted using the CVISC model. FLAC 3D software was used to build a numerical model based on actual working conditions to optimize supporting parameters. Deformation monitoring after construction control was carried out to verify the validity of the numerical simulation results. The results show that: (1) Mudstone deformation includes instantaneous deformation and creep deformation over time, among which creep deformation is the dominant deformation. (2) Mudstone creep parameters exhibit a high degree of fitting accuracy, and the creep characteristics of mudstone can be characterized by the CVISC model. (3) When the spacing of steel arch frame is 50 cm, the thickness of C25 shotcrete is 25 cm, the length of lock bolt is 4.5 m, and the angle is 60°, tunnel deformation can be effectively reduced and the supporting structure can be fully utilized. (4) The monitoring data after optimizing the construction method on site verified the reliability of the numerical simulation results, proving that the tunnel was stable under the construction control measures and no supporting structure failure occurred.