高水头抽水蓄能电站的引水隧洞围岩往往存在渗透破坏或失稳问题。针对川西某高水头抽水蓄能电站,在工程关键位置开展水压致裂法地应力和高压压水试验。通过实测应力统计分析,结合围岩地质条件,对该电站的不同洞段应力场分布特征展开研究,发现应力量值主要随埋深变化,但受地质条件的局部差异影响,在引水洞和地下厂房区呈现出分异性,应力方位受河谷地形影响较大,整体上与下库河谷走向趋近。综合枢纽布置、优势结构面走向、最大地应力方位等因素,提出了厂房轴线布置方案。基于岩体渗透性试验统计,开展高压引水隧洞围岩的渗透稳定性和抗水力劈裂能力分析,根据相关判据,对不同洞段的围岩衬砌方案的制定提供了针对性建议。

The surrounding rock of water diversion tunnels in high-head pumped storage power stations often suffers from seepage failure or instability. Focusing on a high-head pumped storage power station in western Sichuan, in-situ stress measurements by hydraulic fracturing method and high-pressure water injection tests were conducted at key locations in the project. Through statistical analysis of measured stress and combined with geological conditions of surrounding rock, the stress field distribution characteristics of different tunnel sections of the power station are studied. The stress value mainly varies with burial depth, but is affected by local differences in geological conditions, showing differentiation in the diversion tunnel and underground powerhouse area. The stress direction is greatly affected by the terrain of the valley, and overall it tends to be closer to the direction of the lower reservoir valley. Considering factors such as the overall layout of the hub, the orientation of dominant structural planes, and the direction of maximum in-situ stress, a reasonable plan for the layout of the powerhouse axis were proposed. Based on the statistics of rock mass permeability test, the permeability stability and hydraulic jacking resistance ability of surrounding rock of high-pressure diversion tunnel are evaluated. According to the relevant criteria, targeted suggestions have been provided for the surrounding rock lining schemes of different tunnel sections.