Abstract
In order to study the influence of environmental factors on creep properties of deep shale, a series of creep tests of deep black shales are performed under different environmental conditions, including stress deviation, temperature, and chemical pH value. The influence of these conditions on creep properties of deep shale is studied. The results show that the creep and creep rate of shale will grow with the increase of temperature, stress difference, and acidity-alkalinity. We get nonlinear creep model of deep shale when pH = 4 and T = 30°C. The critical stress difference of deep shale is no larger than 31.04 MPa when the chemical pH value is 4 and the temperature is 30°C. By scanning shale after corrosion, we know that the effects of chemical pH value on the creep characteristics are mainly determined by the feldspar dissolution and corrosion caused by chemical action. Our work has important theoretical significance and practical value for evaluating rock engineering stability.
Highlights
Deformation and failure of the underground engineering in Shandong Tangkou Coal Mine showed that the engineering was mainly located in shale and mudstone area. e overburden of surrounding rocks is under the influence of gravity and coupled with the complex geological environment by the threat of high ground temperature, high pressure, and groundwater erosion, which produce rheological phenomena as time increases
To study the chemical corrosion e ects on the creep properties, each sample was immersed in the chemical solution of the same volume and the pH value of 4, 7, or 10 (Table 1), which was tightly sealed
Test equipment is the triaxial creep test machine, which was jointly developed by Qingdao University of Science and Technology and Lear Ltd. of Yantai in Shandong (Figure 2). e axial loading system is composed of a common tension and compression test machine used in the course of mechanics of materials, which is the axial force source equipment of the test machine. e triaxial environmental chamber is a core unit of the triaxial creep test machine
Summary
Deformation and failure of the underground engineering in Shandong Tangkou Coal Mine showed that the engineering was mainly located in shale and mudstone area. e overburden of surrounding rocks is under the influence of gravity and coupled with the complex geological environment by the threat of high ground temperature, high pressure, and groundwater erosion, which produce rheological phenomena as time increases. Erefore, study of the in uence of stress di erence, temperature, and chemical corrosion on creep characteristics of deep shale can provide theoretical guidance and technical approach for the support design, disaster prediction, safety assessment, and long-term maintenance of deep mines under complex environment in this area. It can be used as a reference for other underground tunnels, undersea tunnels, and deep roadways in other areas. By simulating di erent conditions of stress deviation, temperature, and chemical corrosion, we carry out laboratory experiments of creep characteristics of deep shale and nd the creep behaviors under various environmental factors
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