复合地层隧道围岩强度实时估算研究

隧道TBM开挖过程中经常会遇到复合岩层，在这种地质环境下，隧道掘进机（tunnel boring machine，简称TBM）开挖过程中的隧道围岩强度很难估计，隧道开挖掌子面和围岩容易发生坍塌。为了提高隧道掘进效率、预防事故发生，对开挖隧道围岩强度进行实时估算方面的研究很有必要。在重庆轨道九号线隧道TBM施工中，通过室内试验和现场实测数据发现，TBM推力F_N与岩石强度成正比、TBM扭矩推力比T/F_N（T为扭矩）与贯入度p^0.5成正比例关系。针对砂质泥岩、砂岩和灰岩组成的复合岩层，提出了一种利用现场实测推力F_N和扭矩T的值来快速估算开挖隧道围岩强度的方法，进一步对TBM实测数据进行线性拟合，从而得到估算公式中两个常数α₁、α₂的取值方法，并在10多个隧道实际工程中得到验证。结果表明，对于这种复合岩层地质环境，两个常数α₁、α₂的值与滚刀数量n和滚刀直径d相关。该研究成果为实时快速估算开挖隧道围岩强度提供了一种新的切实可行的思路，能提高隧道TBM施工的可靠性和安全性，具有重要的应用价值。

Real-time estimation of surrounding rock strength in composite strata tunnels

In TBM excavation, the composite rock strata are often encountered, in such a case, it is not easy to estimate surrounding rock strength during tunneling where the tunnel face and wall tend to collapse. For improvement of tunneling efficiency and disaster prevention, it is necessary to estimate surrounding rock strength in real time. Based on laboratory tests and field data in the construction of Chongqing Railway Line 9, it was found that the thrust F_N is proportional to rock strength, it was also found that the ratio of the torque force to thrust, T/F_N were proportional to p^0.5 (penetration p). In this study, for composite rock strata(including sandy mudstone, sandstone and limestone) surrounding tunnel, a method that can quickly estimate surrounding rock strength from thrust and torque measured in-site, was developed. The method can estimate rock strength in real time with two constants α₁, α₂ which can be obtained by linear fitting of the field data for TBM. The method had been already applied to more than ten tunnels. It was found that two constants were only related to the number of disc cutters n and cutter-head diameter d for this geological environment of composite rock strata. The results provide a more practical and feasible idea to estimate surrounding rock strength in real time, and also can improve the reliability and safety of tunnel TBM construction.