Determination of Optimal Support Timing for Pumped Storage Power Station Tunnels Based on Displacement Release Rate

The optimal timing of support is difficult to determine due to the excavation of the tunnel.This paper proposes a method for determining the optimal support timing of pumped storage power station tunnels based on the displacement release rate, using the indicator of the distance between the support and the palm face as a judgment of the support timing, and when the excavation load release rate reaches a certain value during the excavation process, the peripheral rock displacement increment will have a steep increase in the point of the excavation load release rate to reach the time of the excavation load release rate to determine the time of the optimal timing of the initial support. This method can maximize the self-supporting capacity of the surrounding rock and minimize the support load. Three-dimensional modeling simulation is used to apply this method as an example.