多次应力波作用下P-CCNBD岩样动态断裂的能量耗散特性研究

Experimental study on energy dissipation of dynamic fracture characteristics of P-CCNBD rock specimens under multiple stress waves

为了研究多次应力波作用下岩石的动态断裂破坏规律,采用直径100 mm的分离式霍普金森压杆径向加载直径为160 mm的含预制裂纹人字形切槽巴西圆盘大理岩试样,分别采用裂纹扩展计和普通应变片测定试样裂尖的起裂和扩展过程,分析试样破坏过程中的动态断裂规律和能量耗散特性。结果表明:在0.13 MPa的子弹发射压力下,出现了试样被多次应力波作用形成破坏的试验现象;入射能、反射能和耗散能均随着作用次数的增加而逐渐减小,但是试样的总耗散能却随作用次数的增加而增大;试样的能量耗散率和动态断裂韧度都随作用次数的增大而减小,并且满足近似的线性关系,这有助于理解多次应力波作用下岩石的动态断裂机制。

In order to investigate the dynamic fracturing characteristics of rock under the loading of multiple stress waves,some marble specimens of 160 mm in diameter being pre-cracked chevron notched Brazilian disc（P-CCNBD） were tested diametrically by using the split Hopkinson pressure bar（SHPB） of 100 mm in diameter. The crack initiation and expansion process of specimens were measured with the crack propagation gauge and strain gauge. The dynamic fracturing and energy dissipation characteristics of specimens were analyzed. The results show that P-CCNBD specimens were fractured under loading of multiple stress waves due to 0.13 MPa impact pressure. The energy dissipation in the process of failure under a single stress wave and multiple stress waves were analyzed. The incident energy,reflected energy and dissipative energy of P-CCNBD specimens were reduced with the increasing of the loading times,but the total dissipation energy of P-CCNBD specimens increased with the increasing of loading times. Both the rate of energy dissipation and the dynamic fracture toughness of P-CCNBD specimens decreased with the increasing of loading times and satisfied the linear relationship approximately. Which helps to understand the dynamic fracture mechanism of rock under loading of multiple stress waves.