In-situ stress field inversion and hydraulic fracturing resistance analysis of Daye Pumped Storage Power Station in Hubei Province

To investigate the in-situ stress field of underground engineering under deep burial and complex multi-lithology geological conditions, taking the Daye Pumped Storage Power Station in Hubei Province as an example, this study analyzed the distribution of the in-situ stress field and the hydraulic fracturing resistance of tunnel surrounding rocks. Comprehensive in-situ stress tests were carried out on-site using the hydraulic fracturing method and the strain relief method two methods to obtain key parameters such as principal stress magnitudes and azimuths. By integrating the comprehensive test results with geological condition inversion, the spatial in-situ stress field was derived, and the stress distribution law along the axis of the water conveyance line was systematically analyzed. Furthermore, based on the inversion results, the layout of the axis of the underground cavern group was evaluated, with special emphasis on analyzing the hydraulic fracturing resistance performance of the area along the axis of the water conveyance line. The results showed that: in the area of the underground cavern group, the maximum horizontal principal stress ranged from 10.4 MPa to 11.3 MPa, and the minimum horizontal principal stress ranged from 7.7 MPa to 8.1 MPa, belonging to a medium-low stress level. The stress differentiation at rock stratum boundaries was relatively obvious. The direction of the maximum horizontal principal stress intersected the axis direction of the underground cavern group at a small to medium angle, which was favorable for the stability of surrounding rocks. The safety factors against hydraulic fracturing of all sections of the water diversion tunnel exceeded 1.1, meeting the requirements for hydraulic fracturing resistance, and the ordinary reinforced concrete lining scheme could be adopted.