Fig 1.
The conventional triaxial deviatoric stress‒strain curves [50].
Fig 2.
Schematic diagram of the definition of RUd.
Fig 3.
Method of determining RUd thresholds.
Fig 4.
Threshold values for energy dissipation degree at different confining pressures and the curve between Up d and σ3.
Table 1.
The threshold values of energy dissipation degree RUd and dissipation energy density Up d.
Fig 5.
Schematic diagram of the criterion for dividing EDZs based on RUd.
Fig 6.
Fitting of the energy dissipation degree–axial strain relationship curves at different confining pressures.
Table 2.
The relevant fitting coefficients.
Fig 7.
Curves of the coefficients A1, A2, A3 and A4 versus the confining pressure σ3.
Table 3.
The relevant fitting coefficients.
Fig 8.
(A) Overall model and calculation scope, (B) excavation sequence, and (C) 3D model of the underground caverns of Shuangjiangkou Hydropower Station.
Table 4.
The parameters for numerical simulations of the rock mass of the Shuangjiangkou Hydropower Station.
Fig 9.
Characteristics of EDZs in surrounding rock of the underground caverns of Shuangjiangkou Hydropower Station.
Fig 10.
Method of classifying the EDZs of surrounding rock mass according to the variation of wave velocity.
Fig 11.
EDZs in the surrounding rock in the 0+070.00 m section of the main powerhouse with the depth of borehole.
Fig 12.
EDZs in the surrounding rock in the 0+100.00 m section of the main powerhouse with the depth of borehole.
Fig 13.
Distribution characteristics of the EDZs of surrounding rock in 0+070.00 m section of the main powerhouse: (A) based on RUd thresholds and (B) based on wave velocity.
Table 5.
Distance from the EDZ boundary to the borehole entrance in the 0+070.00 m section and 0+100.00 m section of the main powerhouse based on RUd thresholds and wave velocity.
Fig 14.
Distribution characteristics of the EDZs of surrounding rock in 0+100.00 m section of the main powerhouse: (A) based on RUd thresholds and (B) based on wave velocity.
Fig 15.
The conventional triaxial test data and associated curves for brittle sandstone [59].
Table 6.
The threshold values of energy dissipation degree RUd for brittle sandstone.