ABSTRACT
To explore the characteristics and mechanism of compression deformation of the top arch of deep-buried caverns, the displacement analysis method is used to analyze the compression deformation characteristics, and the elastoplastic theory is adopted to qualitatively analyze the shrinkage deformation driving mechanism. Furthermore, the characteristics of the prestressing load and their relationship with surrounding rock deformation in the shrinkage deformation zone are discussed. Research results show that the surrounding rock deformation presents significant spatial differentiation characteristics in the top arch. The deep part of the upstream side of the top arch produces shrinkage strain, and the distribution range along the axis of the plant is proportional to the depth. The shrinkage strain is concentrated in the range of 10.0m, and the magnitude decreases with increasing depth. The redistribution of stress caused by the excavation causes the deep layer of the top arch to produce an arch effect zone. The deep surrounding rock of the top arch on the upstream side is located at the “arch abutment”, and its force is loaded along the radial direction of the top arch, resulting in shrinkage and deformation; the top arch on the downstream side is an unloading relaxation zone. The shrinkage deformation zone is related to the size of the cavern. As the excavation progresses to the deep part, the shrinkage strain of the relatively shallow surrounding rock weakens and even turns into tensile strain. The anchor cable prestress has significant stage characteristics. The empty bearing period verifies the compression deformation of the surrounding rock in the deep part of the top arch. When the range of the contraction zone exceeds the reinforcement depth of the anchor cable, the prestress is close to the locked value, and the steel strand only bears the pretension load, showing low or empty load.
