岩石动静组合加载力学特性研究

 根据深部岩石力学研究的需要，在分析深部开挖中岩石受力特点的基础上，提出岩石动静组合加载问题。通过对多载荷凿岩机、INSTRON系统、SHPB装置的不断改进和尝试，研制出中高应变率段岩石动静组合加载试验系统，该系统可实现岩石轴向静压0～200 MPa、围压0～200 MPa和冲击动载0～500 MPa的同时加载。基于新研制的试验系统，对岩石在不同动静组合加载下的强度特性、破碎规律及吸能效率进行研究。结果表明：冲击动载一定，轴向静压从0增大到其单轴静压强度70%时，岩石的组合加载强度大于其纯静载强度或纯动载强度。轴向静压不变，随着冲击动载的增大，岩石的组合加载强度逐渐增大，表现出率相关性。动静组合加载下，岩石的破坏呈拉伸破裂模式，岩石的破碎块度在冲击动载或轴向静压增大时都向细粒端发展。岩石的吸能率随着动静组合加载的不同而不同，通过选择合适的动静组合加载，可使岩石的吸能率最大。

STUDY OF ROCK MECHANICAL CHARACTERISTICS UNDER COUPLED STATIC AND DYNAMIC LOADS

In consideration of the research requirements from rock mechanics at depth，the stress states of rock in deep-level projects is analyzed；and then the research topic of rock under coupled static and dynamic loads is brought forward. After exploration on multi-load drilling machine，INSTRON system and SHPB device，a new testing system is constructed，where rock specimen deforms and fails at medium to high strain rate. With the system，rock can be loaded with 0–200 MPa axial static pressure，0–200 MPa confining pressure and 0–500 MPa impact loading respectively or simultaneously. Tests for rock strength，fragmentation behavior and energy absorption with different coupling loads show that，with the same impact loading，rock strength is greater than its individual static or dynamic strength if the axial pressure is less than 70% of its static compression strength. With the same axial pressure，rock strength under coupling loads increases with the increase of impact loading owing to the strain rate effect. Under coupled static and dynamic loads，rock breaks with tensile failure mode. As for the particle-size distribution of fragments，the percentage of small particles increases with higher axial pressure or impact loading. The energy absorption ratio varies with coupling loads. With proper combination of static and dynamic loads，the maximum energy absorption ratio can be obtained.