Xiao Ming, Yuan Qingteng, Zhao Binxin, Deng Liang
State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan, 430072, Hubei, China.
Sci Rep. 2023 Oct 8;13(1):16967. doi: 10.1038/s41598-023-44148-w.
The stability of the surrounding rock for the construction excavation and the reinforcement of the lining structure during operation in the water-rich area is a difficult problem for the design of high-head underground turnout pipes. Firstly, according to the mechanism of excavation load release and surrounding rock damage evolution, the seepage effect of excavation in the construction of the forked caves is coupled to the surrounding rock stress damage, and an iterative method of numerical simulation of the coupled mutual feedback effect of excavation surrounding rock stress and seepage is proposed. Then, based on the cracking characteristics of the high internal water pressure reinforced concrete turnpike lining, a numerical analysis method of the coupling interaction between lining cracking and internal water seepage is proposed by coupling internal water seepage to stress damage in the lining by cracking the forked pipe structure. Applying the aforementioned method to a forked pipe project, the results show that: during the construction period, there is a significant increase in the damage zone, stress, and displacement of the rock around the cavern after considering the coupled iterations; during the operation period, with the increase in internal water pressure, the lining structure accelerates cracking due to the external infiltration of internal water; after the internal water is applied, the surrounding rock bears the main internal water pressure and the reinforcement bears only part of the circumferential force. The method provides theoretical support for the analysis and calculation of the reinforcement of similar underground high-pressure tunnels for rock support and lining structures and has certain theoretical and engineering significance.
富水区高水头地下岔管施工开挖时围岩的稳定性以及运行期衬砌结构的加固是高水头地下岔管设计中的难题。首先，根据开挖荷载释放及围岩损伤演化机理，将岔洞施工开挖渗流效应与围岩应力损伤进行耦合，提出开挖围岩应力与渗流耦合互馈效应数值模拟的迭代方法。然后，基于高内水压力钢筋混凝土岔管衬砌开裂特性，通过岔管结构开裂将内水渗流与衬砌应力损伤进行耦合，提出衬砌开裂与内水渗流耦合相互作用的数值分析方法。将上述方法应用于某岔管工程，结果表明：施工期考虑耦合迭代后，洞室周边围岩损伤区、应力及位移有显著增大；运行期随着内水压力升高，衬砌结构因内水外渗加速开裂；施加内水后，围岩承担主要内水压力，钢筋仅承担部分环向力。该方法为类似地下高压隧洞围岩支护及衬砌结构加固分析计算提供了理论支撑，具有一定的理论和工程意义。
