Analysis of Structural Characteristics of Underground Cavern Group by Simulating All Cavern Excavation

Abstract

The traditional Three-dimensional (3D) model for stability analysis of a large underground cavern group only includes the main powerhouse, the main transformer chamber, the tailrace surge tank, the main electrical wire hall, and part of the diversion tunnel and tailwater tunnel. Other caverns excavation are not taken into consideration, which is inconsistent with the actual project. In this study, a 3D Finite Element Method (FEM) model, including all the cavities, and a 3D simplified model containing only part of the cavities were established based on the actual underground cavern group project. We study the structural characteristics of the cavern group during excavation via 3D nonlinear FEM. At the same time, three numerical calculation schemes are designed for comparison. The results show that the simulated distributions of the stress field, deformation field, and plastic zone of the two numerical models are similar, but the magnitudes of the 3D FEM model, which considers all caverns are generally higher than the simplified model. The difference between the two simulated horizontal displacements of the main powerhouse reaches 53.72%. Therefore, from the perspective of engineering safety and actual construction, it is advisable to adopt the 3D FEM model, including all the cavities, when conducting a simulation analysis of the underground cavern group.

An Analysis of Two Case Studies on the Construction of Underground Caverns-A Focus on the Tiantai Pumped Storage Station

“…To facilitate comprehension of this process, we briefly introduce the relevant basics here. Formula (4) describes the rock mass yield surface in the stress space according to the Hoek-Brown strength criterion, while formulas (5) to (7) detail the H-B parameters.…”

“…[5] Ma H et al (2023) have considered three factors that affect the stability of surrounding rock: excavation sequence, excavation method and support measures. [6] Hu et al (2022) have applied a method of back analysis to be utilized for the interpretation of field measurements in monitoring the stability of tunnels. [7] However, these researchers have not considered the beam crane and rock support during construction, and these problems have been addressed in this paper.…”

“…[6] Hu et al (2022) have applied a method of back analysis to be utilized for the interpretation of field measurements in monitoring the stability of tunnels. [7] However, these researchers have not considered the beam crane and rock support during construction, and these problems have been addressed in this paper.…”