open access

https://hdl.handle.net/2115/40223

Effects of Strain Rate and Temperature on Bending Point Stress in Tangent Modulus Method

英語

Temperature

2009-05-13

Graduate School of Engineering, Hokkaido University

Proceedings of the 3rd International Workshop and Conference on Earth Resources Technology

116-123

3rd International Workshop and Conference on Earth Resources Technology "Stepping towards sustainable geo-resources utilization and development". 13-14 May 2009. Hokkaido University Conference Hall, Sapporo, Japan.

Precise measurement of in-situ stress is important in design of underground excavations. Tangent Modulus Method (TMM) is an oriented core based method for measurement of rock stress. Two cycles of uniaxial compressive loading are carried out for rock specimen. The stress-tangent modulus curve, based on the local slope of stress-axial strain curve in the first cycle, shows a bending point. Stress value at the bending point is regarded as the normal stress component of in-situ rock stress in the direction of rock specimen. Experiments were done to clarify the strain rate to be used in TMM and the effects of in-situ rock temperature on TMM. Kimachi sandstone specimens of length 60 mm were preloaded for one hour, simulating in-situ stress. The preloaded stress was then estimated by TMM. This experiment was repeated over a range of strain rates in both dry and saturated specimens. It was clarified that any strain rate between 0.0036 mm/min and 3.6 mm/min can be used. For investigating the effects of temperature, preloading was done in temperature controlled pure water for one hour, followed by TMM in air at room temperature. Between 40℃ and 80℃, temperature at preloading had no significant effect on the TMM stress.

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