动静载荷下巷道围岩裂纹扩展规律的试验研究

为了研究动静载荷耦合作用下巷道围岩裂纹的扩展规律,将PMMA材料加工成含有单裂纹的试件,利用爆炸加载动态焦散线测试系统进行了巷道围岩裂纹扩展规律的试验.研究表明,预制裂纹的扩展位移、试件损伤度以及试验围压之间存在密切联系:扩展位移与试件损伤度呈负相关的关系;损伤度随围压的增大呈现先增大后减小的变化规律;不同围压条件下,预制裂纹在等量爆炸载荷作用下均出现扩展和止裂交替变化的现象,但预制裂纹扩展位移随着围压的增大呈先减小后增大的变化规律,在0MPa围压下扩展位移有最大值30.84mm,在0.4MPa时扩展位移有最小值10.98mm.裂纹端部扩展速度与能量释放率关系较为密切:能量释放率增大时,扩展速度会相应增大;预制裂纹扩展速度减小后,受应力波影响,裂纹端部积累能量,能量释放率又会相应增大.

The experimental research on the propagation laws of cracks in roadway surrounding rock subjected to static-dynamic load

In order to study the propagation law of the crack in surrounding rock subjected to static dynamic load, the poly methyl methacrylate (PMMA) are used to make specimens containing a single prefabricated crack and dynamic caustics experimental system with explosion load is used to conduct experimental research on the propagation laws of crack in roadway surrounding rock. Study has showed that there exists close relation among the extension displacement of the prefabricated crack, the damage degree of the specimen and confined pressure around the specimen. There is a negative correlation relationship between the extension displacement and the damage degree, which is closely associated with the confined pressure, presenting a rule of increasing firstly and decreasing later as the increasing of confined pressure. Changing the confined pressure around the specimen and keeping the explosion condition unchanged in the study, the prefabricated cracks all appear the phenomenon of alternative variation between extension and arresting, but the value of extension displacement reaches a maximum of 30.84 mm and a minimum of 10.98 mm when the value of confined pressure is 0 MPa and 0.4 MPa respectively, presenting a trend of decreasing firstly and increasing later as the increasing of confined pressure. There exists a close relation between energy release rate around the crack tip and propagation speed of the crack. When energy release rate increases, the propagation speed will increase then, but when the propagation speed decreases, energy accumulation occurs around the tip induced by the explosion stress wave, resulting in energy release rate increasing.