Abstract
In deep mining and excavation of tunnels with high geothermal, the surrounding rock is not only subjected to high ground stress but also subjected to high temperature. Temperature will change mechanical characteristics and energy storage capacity of rocks, as well as increase the destructiveness and randomness of rockburst. To reveal the mechanism of high-temperature strain burst in deep rock, the rockburst tests from uniaxial compression to three-dimensional compression were reviewed, and the research results of the minimum principal stress rapid unloading, true-triaxial loading with one free face, and dynamic disturbance triggered pre-heated granite rockburst simulation tests were focused on. According to the occurrence state of country rock for deep high-temperature and stress state in the whole process during excavation, six development directions for high-temperature strain rockburst simulation tests were proposed: (1) constructing the damage constitutive models of high-temperature rocks according to linear energy dissipation law; (2) developing the true triaxial rockburst simulation testing system accomplishing the function of “real-time high temperature + unloading + dynamic disturbance”; (3) considering the true triaxial rockburst simulation test after microwave irradiation; (4) developing the real-time high-temperature rockburst simulation testing device for large-size specimens and internal unloading; (5) focusing on the energy actuating mechanism for deep high-temperature rock failure via rockburst simulation tests; and (6) implementing the three-dimensional rockburst simulation test on the basis of deep in situ coring.
Highlights
Rockburst is an engineering geological disaster on account of deep rock excavating [1,2,3,4,5,6], which will cause great harm to the safety of personnel and equipment
The Gaoligong mountain tunnel, the longest railway tunnel in China, has the characteristics of high geothermal, high seismic intensity, and high ground stress; its maximum buried depth is 1155 m, the groundwater temperature is as high as 102°C, and rockburst disasters occur frequently [13]; the Sangzhuling tunnel, which belongs to China’s Sichuan-Tibet Railway, has a temperature of 89°C in surrounding rock, the number of rockburst can reach more than 90,000 times and the length of the rockburst section accounts for 55% of the total length [14,15,16]
AEF was used to quantitatively characterize the rockburst proneness of pre-heated granite specimens under various temperatures, as shown in the consistency between the evaluation results and the actual failure severity was compared of specimens, and it was found that the statistical results ME and discrimination results AEF of pre-heated granite at different temperatures had a good correspondence relationship (Figure 8). e results illustrated that AEF can precisely and quantitatively characterize the rockburst proneness of preheated granites at different temperatures. e discriminant results were as follows in order of temperature: 300°C (317.9 kJ/m3), 100°C (264.1 kJ/m3), 20°C (260.6 kJ/m3), 500°C (245.5 kJ/m3), and 700°C (158.9 kJ/m3); the rockburst proneness of pre-heated granites at 300°C was the highest
Summary
Rockburst is an engineering geological disaster on account of deep rock excavating [1,2,3,4,5,6], which will cause great harm to the safety of personnel and equipment. E above triaxial compression tests well reproduce the rockburst failure phenomenon of hard rock after preheating, whereas there is still a certain difference from the actual situation (real-time high-temperature) of the deep surrounding rock For this reason, the occurrence environment of the deep surrounding rock, as well as stress characteristics of the whole process during excavation, must be taken into consideration before the high-temperature rockburst simulation test. The occurrence environment of the deep surrounding rock, as well as stress characteristics of the whole process during excavation, must be taken into consideration before the high-temperature rockburst simulation test On this basis, the development of a mechanical testing machine meeting the requirements of “real-time hightemperature + unloading + dynamic disturbance” can better reveal the mechanism of strain burst in deep high-temperature rocks.
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