Deformation Control Standards for the Crown Arch of Large Underground Caverns Considering Uneven Deformation

In response to the lack of clear and available specifications for controlling rock mass deformation in large underground caverns, a study was conducted to establish standards for controlling the deformation of the cavern crown arch region. The study utilized the rock mass ultimate strain as an indicator to quantify the degree of rock extrusion and assess cavern stability. Various empirical formulas for calculating the rock mass ultimate strain were compared in detail, and robust and comprehensive formulas were selected. A geometric calculation model for the deformation of the underground cavern crown arch was established considering uneven deformation. A theoretical analytical method was employed to derive a relationship between the displacement of feature points on the crown arch and the rock mass ultimate strain. Accordingly, the deformation control standard for the crown arch in underground caverns was established, along with a hierarchical management mechanism. The engineering case study indicates the following: (1) the theoretical analytical method provides an innovative way to establish deformation control standards for a large underground cavern crown arch. (2) The allowable deformation value of the crown arch is closely related to the dimensions of the cavern profile and the surrounding rock mass strength properties. (3) The proposed deformation control standard for the crown arch has significant engineering implications in controlling crown arch deformations and evaluating the surrounding rock stability in caverns. A detailed comparison was conducted to select more robust and comprehensive empirical formulas for calculating the ultimate strain of a rock mass.Theoretical analytical methods were employed to derive and establish deformation control standards for a large underground cavern crown arch.A hierarchical management mechanism was developed for the proposed deformation control standard.The application of the proposed control standard in an engineering case demonstrates its potential engineering value.

Automated summary

This study establishes standards for controlling the deformation of the crown arch region in large underground caverns. The study compares various empirical formulas for calculating the ultimate strain of a rock mass and selects robust and comprehensive formulas. A geometric calculation model for the deformation of the underground cavern crown arch is established, considering uneven deformation. Theoretical analytical methods are used to derive a relationship between the displacement of feature points on the crown arch and the rock mass ultimate strain. The proposed deformation control standard has significant engineering implications in controlling crown arch deformations and evaluating the surrounding rock stability in caverns, as demonstrated by an engineering case study.