Validation of a New Elastoplastic Constitutive Model Dedicated to the Cyclic Behaviour of Brittle Rock Materials

Abstract

Old mines or caverns may be used as reservoirs for fuel/gas storage or in the context of large scale energy storage. In the first case, oil or gas is stored on annual basis. In the second case pressure due to water or compressed air varies on a daily basis or even faster. In both cases a cyclic loading on the cavern's/mine's walls must be considered for the design. The complexity of rockwork geometries or coupling with water flow requires finite element modelling and then a suitable constitutive law for the rock behaviour modelling. This paper presents and validates the formulation of a new constitutive law able to represent the inherently cyclic behaviour of rocks at low confinement. The main features of the behaviour evidenced by experiments in the literature depict a progressive degradation and strain of the material with the number of cycles. A constitutive law based on a boundary surface concept is developed. It represents the brittle failure of the material as well as its progressive degradation. Kinematic hardening of the yield surface allows the modelling of cycles. Isotropic softening on the cohesion variable leads to the progressive degradation of the rock strength. A limit surface is introduced and has a lower opening than the bounding surface. This surface describes the peak strength of the material and allows the modelling of a brittle behaviour. In addition a fatigue limit is introduced such that no cohesion degradation occurs if the stress state lies inside this surface. The model is validated against three different rock materials and types of experi-

Constitutive model of rock triaxial damage based on the rock strength statistics

“…The slope is the zero according to the peak-point method (Cerfontaine et al, 2017;Gu et al, 2018;Liu and Zhu, 2018;Wang and Li, 2007;Zhu, 2017) at the peak point of stress-strain curve, and we can obtain from equation 29r…”

Anisotropic fatigue behaviour of interbeded marble subjected to uniaxial cyclic compressive loads

“…Wang et al proposed a bounding surface method to predict the cyclic stress‐strain relations for soft rock. Cerfontaine et al proposed a new elastoplastic constitutive model to investigate the fatigue behaviour of a brittle rock, and the model was validated by Lorano marble under triaxial cyclic loading testing. Liu et al proposed a damage constitutive model for intermittent jointed rocks under cyclic loading, and the experimental results prove the reliability of the model for the cyclic stress‐strain curves and the fatigue deformation modulus.…”

Underground Pumped-Storage Hydropower (UPSH) at the Martelange Mine (Belgium): Underground Reservoir Hydraulics

“…A detailed evolution of the water levels in the complex underground reservoir(s) needs to be predicted for feasibility analysis, as the continuous shifting of water level in response to discharge variations during the pump/discharge cycles will affect the head difference between the upper and lower reservoirs and possibly the turbomachinery operation. Water level variations are also needed to assess the structural stability of the system [28]. The water level variation and the energy efficiency of the UPSH plant are particularly affected by the geometry and the aeration conditions of the underground reservoir [23,24].…”