A thermal stress loading technique for large-sized hot dry rock mechanical tests

Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering. In traditional mechanical loading,stresses on large-sized specimens are achieved by large host frames and hydraulic pumps, which could lead to great investment. Low-cost testing machines clearly always have great appeal. In this study, a new approach is proposed using thermal expansion stress to load rock specimens, which may be particularly suitable for tests of deep hot dry rock with high temperatures. This is a different technical route from traditional mechanical loading through hydraulic pressure. For the rock mechanics test system of hot dry rock that already has an investment in heating systems, this technology may reduce the cost of the loading subsystem by fully utilizing the temperature changes. This paper presents the basic principle and a typical design of this technical solution. Preliminary feasibility analysis is then conducted based on numerical simulations. Although some technical details still need to be resolved, the feasibility of this loading approach has been preliminarily confirmed.