加温三轴试验中砂岩的微裂纹与横波速度

RELATIONSHIP BETWEEN S WAVE VELOCITIES AND MACROCRACKS IN SANDSTONE DURING THE HEATING TRIAXIAL TEST

通过对砂岩进行加温三轴试验，分析了超声波速度与应力的关系。根据实验结果，提出了一种以横波速度最大值评价砂岩试件微裂纹开始产生时的应力值的方法，即横波速度峰值点及其后波速减小现象说明载荷下的砂岩产生了新的微裂纹。Ｓ波速度峰值点的应力值大小，随砂岩的孔隙度和粘土含量的不同而不同。致密砂岩是大于破裂强度的５５％ 出现Ｓ波速度峰值，而疏松砂岩在大于破裂强度的７０％

The relationship between wave velocity and stress in the sandstone during the heating triaxial tests was studied with MTS815 servo control test machine. Based on the analysis of the test results, a new criterion for the stress value of stress induced microcracks is presented with the peak value of the S wave velocity. The appearance that the S wave velocity peak value and the velocity began to decrease illustrates new microcracks were produced in the sandstone test sample. When new stress induced microcracks present, the stress values are different, along with it, the clay content and porosity are not alike. The peak value of the S wave velocity appears when the fracture strength of the tight sandstone is >55%, and that of the S wave velocity appears when the fracture strength of the loose sandstone is >70%. The new stress induced microcracks were determined by the peak value of the S wave velocity means and can be extended in test of solid material.