Numerical Simulation Study of Diversion Gate Well Excavation and Support Scheme under Complex Geological Conditions

随着水利施工技术的发展，深竖井作为一种常见的地下结构，被广泛应用于调压、引水、通风等水利水电工程中。受恶劣地形和复杂地质的影响，在大直径且埋深大的竖井施工中，围岩的稳定性对于施工安全至关重要，需要对复杂地质深竖井施工过程的围岩和支护所产生的受力变形进行研究分析，以更好地确保围岩和支护的稳定性。本文以以色列克卡夫–哈亚邓抽水蓄能电站引水闸门井开挖支护结构工程为背景，采用现场监测和数值模拟结合的方法，对开挖支护引水闸门井时的支护参数以及施工开挖方案进行了数值模拟研究。通过设计正交试验，对不同灌注桩长度，灌注桩直径以及开外进尺三种因素进行参数敏感性分析，分析了10组不同支护方案下竖井开挖后围岩压力分布情况及其相应稳定性，发现在选取开挖支护方案为灌注桩直径1 m，开挖进尺2 m，灌注桩埋入深度35 m时，引水闸门井周边围岩及其支护结构的主应力值以及位移最小，说明该开挖施工方案最为合理，显著提高复杂地层下深竖井开挖的施工进度及安全，可为类似工程提供借鉴。With the development of water conservancy construction technology, deep shafts, as a common underground structure, are widely used in water conservancy and hydropower projects such as pressure regulation, water diversion, and ventilation. Affected by the harsh terrain and complex geology, the stability of the surrounding rock is very important for the construction safety of the large diameter and buried deep shaft, and it is necessary to study and analyze the stress deformation generated by the surrounding rock and support in the construction process of the complex geological deep shaft, so as to better ensure the stability of the surrounding rock and support. This article is based on the excavation and support structure project of the water intake gate shaft of the Israeli Kaff Hayadun pumped storage power station, using a combination of on-site monitoring and numerical simulation methods, Numerical simulation studies were carried out on the support parameters and construction excavation scheme during the excavation of the supporting diversion gate well. Through the design orthogonal test, the parameter sensitivity analysis of three factors, namely the length of the cast-in-place pile, the diameter of the cast-in-place pile and the footage outside the opening, analyzed the pressure distribution and corresponding stability of the surrounding rock after excavation of the shaft under 10 groups of different support schemes, and found that when the excavation support scheme was selected as the diameter of the cast-in-place pile was 1 m, the excavation footage was 2 m, and the burial depth of the cast-in-place pile was 35 m, the principal stress value and displacement of the surrounding rock and its supporting structure around the diversion gate well were the smallest, indicating that the excavation construction scheme was the most reasonable. It can significantly improve the construction progress and safety of deep shaft excavation under complex strata, which can provide reference for similar projects.