静态预应力条件作用下岩板动态破坏行为试验研究

发布时间：2018-04-20 23:25

本文选题：岩石力学 + 预应力　；参考：《岩石力学与工程学报》2017年05期

【摘要】：深部岩石的动力破坏,是岩石力学研究的一个热点问题。为模拟深部岩石动态断裂情况,选取一种花岗岩制备带10 mm预制裂纹的板状试样,开展含预应力条件下的岩板动态破坏行为研究。试件尺寸为305 mm×305mm×10.5 mm岩板,在静态竖向预压的条件下,使用25 mm杆径的霍普金森压杆进行冲击试验。利用超高速摄影仪记录试样裂纹扩展的全过程,采用数字图像相关(DIC)技术分析试样的位移场及应变场,通过设置虚拟引伸计,获得预应力条件下岩板起裂时刻、裂纹长度、裂纹扩展速度及断裂韧性等动态断裂力学参量。研究结果显示:该岩板试件裂纹扩展速度可达到瑞利波速的0.57倍(~1000 m/s),验证了采用花岗岩岩板测试的优势。在特定预应力条件下,岩板的裂纹扩展速率与动态断裂韧性具有明显的率相关性;特定冲击速度条件下,随着静态预应力的增加,裂纹扩展速度受到抑制,破坏模式由单一裂纹扩展向多条微裂纹扩展等复杂模式转变,甚至出现止裂现象。当气枪冲击气压103.43 kPa、静态预应力30 MPa时,裂纹扩展速度降为452.4 m/s,属于低速裂纹扩展范围。
[Abstract]:The dynamic failure of deep rock is a hot issue in the study of rock mechanics. In order to simulate the dynamic fracture of deep rock, a type of granite is selected to prepare a plate specimen with 10 mm prefabricated cracks, and the dynamic failure behavior of the rock plate under the condition of prestressing is studied. The size of the specimen is 305 mm x 305mm x 10.5 mm rock plate, and the static vertical precondition is preformed. Under pressure conditions, the impact test was carried out with a Hopkinson pressure bar of 25 mm rod diameter. The whole process of crack propagation was recorded by ultra high speed photogrammetry. The displacement field and strain field of the specimen were analyzed by digital image correlation (DIC) technique. By setting a virtual extensometer, the cracking time, crack length and crack expansion under the prestress condition were obtained. The results show that the crack propagation velocity of the rock plate specimen can reach 0.57 times that of the Rayleigh wave velocity (~1000 m/s), which proves the advantages of the granite plate test. The rate of crack propagation velocity and the dynamic fracture toughness of the rock plate have a significant correlation with the dynamic fracture toughness under the specific prestress condition. With the increase of static prestress, the crack propagation velocity is restrained with the increase of static prestress, and the failure mode changes from the single crack propagation to the multiple micro crack propagation, even the stop crack phenomenon. When the air gun impact pressure is 103.43 kPa and the static prestress is 30 MPa, the crack propagation speed falls to 452.4 m/s, which belongs to the low speed. The range of crack growth.

【作者单位】：天津大学建筑工程学院;多伦多大学土木工程系;中国地震局地壳应力研究所;
【基金】：国家自然科学基金面上项目(51479131) 天津市自然科学基金项目(13JCYBJC40600,16JCQNJC07800)~~
【分类号】：TU458

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