Numerical Parametric Studies on the Stress Distribution in Rocks around Underground Silo

Abstract

The underground silo was constructed as a facility for the disposal of low- and intermediate-level radioactive waste. It is divided into three parts: the upper-dome core, the lower-dome core, and the cylindrical-space core. Numerical parametric studies on the stress distribution occurring in the surrounding rocks around the underground silo are presented in this paper. It is assumed that the soil layer was distributed to a depth of −4.3 m from the ground level, the weathered rocks were distributed to a depth of −9.5 m from the bottom of the soil layer, and the rocks were distributed in the lower part of the weathered rocks. A 2D axial symmetric finite element model was considered for the numerical analysis of the underground silo. A 3D finite element model was used to verify the reliability of the 2D axial symmetric model. Finite element analysis was carried out under various ratios of in situ horizontal stress to vertical stress (Ko). The numerical results obtained through these analyses include detailed stress states in the p–q and octahedral planes at key locations of finite element models around an underground silo. Contours of safety factor distributions are also presented to evaluate the overall structural safety of the surrounding rock mass, which is the main supporting body of the underground silo.

Comparative Studies between Frequency Domain Analysis and Time Domain Analysis on Free-Field One-Dimensional Shear Wave Propagation

“…The first phase of the construction, which is the underground silo for LILW (Low-and Intermediate-Level radioactive Waste) disposal facilities with a 100,000 drum capacity, was completed in 2014 (see Figure 1) [2]. The facility in the first phase was constructed underground, 130 m below sea level consisting of six silos, 23.6 m in diameter and 50 m in height (see Figure 2) [3,4]. The engineered barrier system of the underground silo consisted of waste packages, disposal containers, backfills, and a concrete silo.…”

“…These earthquakes occurred in the area adjacent to WLDC, and the distances from the epicenter were 26 and 46 km, respectively. Therefore, interest in the stability of the underground silo increased significantly [4,10,11]. Although Korea has been recognized as a safe country for earthquakes, relatively large-scale earthquakes occurred in 2016 and 2017, respectively.…”

“…These earthquakes occurred in the area adjacent to WLDC, and the distances from the epicenter were 26 and 46 km, respectively. Therefore, interest in the stability of the underground silo increased significantly [4,10,11].…”