围岩-初支结合体的动力学特性试验

Experimental Investigation on the Dynamic Mechanical Properties of the Combination of Surrounding Rock and Primary Support

隧道工程施工中,隧道围岩与支护易受爆炸冲击、开挖扰动等复杂载荷影响,其结构稳定性是工程设计的重要参考依据.采用砂岩和砂浆制作初支与围岩结合体试样,基于大直径霍普金森实验系统进行冲击试验,研究冲击荷载下结合体的变形与破坏特征,分析初支和围岩的径向厚度及其比例特征对结合体破坏模式的影响机理.结果表明:砂浆的厚度对结合体的应力应变及破坏特征影响显著;由于砂浆的影响,应力-时间曲线表现出“双峰特性”,且当砂浆与砂岩厚度一致时,试样的第二应力峰值明显增大;冲击载荷下,裂纹首先在砂岩与砂浆交界面处产生,而后向四周扩散,导致试件形成宏观拉伸破坏.该研究对隧道工程的结构设计及优化具有重要的参考价值.

In tunnel construction engineering,the surrounding rock and primary support are usually exposed to the complex loadings,such as explosion impact and excavation disturbance.The structural stability is an important reference for engineering designing.The sandstone and mortar are used to prepare the equal proportion specimens of primary support and surrounding rock in this paper.The dynamic tests are carried out by using variable diameter Hopkinson experimental system.The dynamic properties and failure characteristics of the combination structure under impact loads are studied.The influence of the radial thickness of the primary support and surrounding rock on the failure mode of the combination are analyzed.Results show that the thickness of mortar has a significant effect on the stress-strain and failure characteristics of the combination.The stress-time curves show bimodal characteristics because of the existence the mortar,and while the thickness of mortar and sandstone is consistent,the second peak of the stress increases significantly.The cracks firstly occurr in the interface between sandstone and mortar,and then spread around the specimen causing macroscopic tensile failure further.The research shows an importantly referential significance for the designing and the optimizing of tunnel engineering.