温度与荷载对砂岩动态力学性能及裂纹的影响

为研究在不同温度与荷载下砂岩的动态力学性能,运用了SHPB实验仪器及配套高温环境箱分别在25(常温)、100、200、300、400、500、600、700℃下对砂岩进行3种不同荷载(0.3、0.5、0.7 MPa)动态压缩实验,并结合SEM设备对高温应力作用下砂岩内部裂纹进行分析。结果表明:当冲击荷载增大时,砂岩所能承受的动态压缩强度显著提高;当所处温度一定时,其破裂情况也随荷载的增大而加剧;当冲击气压一定时,随着温度升高,砂岩的峰值应力表现出平缓、上升、下降的变化趋势,最终在700℃时达到最小值。在应力与常温作用下,试件会先以应力作用影响为主,出现单条裂纹,当温度升高至300℃以上,单条裂纹会有所延伸并形成多条裂纹,出现二次开裂。

Effect of temperature and load on dynamic mechanical properties and cracks of sandstone

To study the dynamic mechanical properties of sandstone under different temperatures and loads, three different load(0.3,0.5,0.7 MPa)dynamic compression experiments were carried out on sandstone at 25(normal temperature),100,200,300,400,500,600,700 ℃ by using SHPB experimental instruments and supporting high temperature environmental boxes, respectively, and the internal cracks of sandstone under high temperature stress were analyzed in combination with the SEM equipment. The results show that when the impact load increases, the dynamic compressive strength of sandstone increases significantly, and when the temperature is fixed, the rupture condition increases with the load. When the impact air pressur is fixed with the temperature rises, the peak stress of sandstone should be force shows a gentle, rising, decreasing trend of change, and finally reaches the minimum at 700 ℃. Under the action of stress and normal temperature, the main effect of stress is the single crack. As the temperature rises to more than 300 ℃, a single crack will extend and form multiple cracks, and secondary cracking will occur.