Experimental Study on the Fracture Toughness of Granite Affected by Coupled Mechanical-Thermo

Abstract Hot dry rock geothermal energy is deep geological energy. Its ability to resist fracture an important basis for effective reconstruction and scientific evaluation of the stability reservoirs. typically buried deeply, reservoir often in a high-temperature high stress environment. There have been limited studies conducted on effect different three-dimensional temperature granite toughness. Thereby, herein experimental study heat treatment under external loads temperatures. The variation toughness with pressure studied using three-point bending mechanics experiment, scanning electron microscope (SEM) observation, acoustic wave velocity measurement. results show that joint influence 25 MPa deviator 200 °C temperature, Mode I, Mixed mode (I + II), II nonlinear change trend decreasing increasing. Among three modes, range I not more than 10% which significant. Contrarily, degradation mechanical properties caused by action II) predominant. maximum reduced 22%, whereas 18%. However, compression causes slight enhancement properties, wherein increased 12%. Furthermore, granite’s tensile, shear, composite (tensile shear) coordinated temperatures loads. This may be due small effect, similar early loading stage uniaxial compression. External thermal damage occur along compaction pore cracks. These mechanisms dominant positions varied coupling conditions, resulting either or weakening granite. this are conducive gaining in-depth understanding law exploration hot reconstruction.