围压环境爆破荷载作用下地下结构累积损伤动力响应特性研究

Aiming at frequent blasting construction characteristics of large equivalent rock in underground engineering, this research project will establish photoelectricity integrated test system, "3D model test system of underground engineering" under dynamic and static load combination function , surrounding rock and bolt-grouting body dynamic monitoring system in real time. Synthetically applied large scale similar model test, field test, numerical simulation and theory analysis, this project will put scientific research on dynamic damage of the surrounding rock and supporting structure under dynamic blasting loading. Based on parameters degradation characteristics of dynamics rock, described model of blasting cracks, blasting energy crushing criteria, this project will establish mechanics performance degradation of rock blasting stress wave owing to time-varying accumulation characteristics, it will obtain cumulative damage evolution rule of blasting stress wave under dynamic loading and unloading in the explosion source nearby and in the central of surrounding rock. By analyzing stress redistribution of the surrounding rock caused by blasting and excavation, the changing regularity of intense damage area, this project will build up the characteristic of damage and fracture mechanics under dynamic blasting loading and in rock loosing zone, the mechanical coupling effect of macroscopic phenomenological such as lithology, this project will reveal time-varying evolution process of surrounding rock in underground engineering under different confining pressures. Researched on physics damage, the stress corrosion and fatigue damage mechanism of anchor supporting structure under dynamic blasting loading, explored dynamic response rules of bolt supporting under dynamic blasting loading, it will search for effective ways to slow down degradation effects of the surrounding rock and supporting structure under dynamic blasting loading, this project will aim to build new technology to control surrounding rock stability under superimposed static and dynamic loading in underground engineering. Explored the blasting vibration energy dissipation rules caused by different factors such as the explosion sources and others, this project will obtain energy characteristics of blasting vibration wave and the dynamic respond characteristics of bolt-shotcrete supporting structure of surrounding rock under blasting vibration. This project will build up comprehensive safety criterion and instability criterion of surrounding rock supporting structure under blasting vibration in underground engineering. In the way of blasting optimization in underground engineering, parameters design of supporting structure and safety assessment of supporting structure under dynamic blasting loading, this project has important theoretical significance and guiding function in engineering practice.

针对地下工程频繁爆破施工特点，建立静动组合载荷作用的"地下工程三维模型试验系统"，运用模型试验、现场试验、数值模拟和理论分析，开展围压环境下地下结构的爆破荷载动态损伤破坏力学特性研究。基于岩体动力学参数劣化特性、爆破裂纹群描述模型、爆破能量破碎准则，分析围压环境下地下工程爆破开挖的围岩动态响应特征，从宏-细-微观不同尺度上获得爆破荷载作用下的围岩强度衰减规律及松动圈动态形成机理，揭示爆源近区、中区的爆破应力波加载、动态卸载的围岩损伤演化规律；研究爆破荷载的锚杆支护结构物理损伤、应力腐蚀、疲劳损伤机制，揭示静态应力场、动态应力场等多场耦合作用下爆破载荷的锚固体性能劣化累积效应；分析爆源和非爆源等不同影响因素的爆破振动能量特性、围岩锚固体的爆破振动动力响应特性，建立地下工程围岩锚固体爆破振动效应失稳准则。成果为地下结构的爆破、支护参数优化及围岩锚固体稳定性评价提供重要理论意义和工程指导价值。

针对地下工程爆破施工特点，运用模型试验、现场试验、数值模拟和理论分析，开展了围压环境下地下结构的爆破荷载动态损伤破坏力学特性研究。建立完善了围压作用下爆破荷载作用下数字光电高速摄影系统和地下结构三维模型实验系统，开创了爆破机理研究新方法。揭示了不同条件下爆炸应力应变场演化规律，利用小空孔的焦散斑特征得到了条形药包爆炸应力场主应力差的变化特征；获得了炮孔端部爆生裂纹、预制贯通裂纹的动态扩展规律，发现了群炮孔端部爆生裂纹的叠加效应；揭示了三维模型爆生裂纹扩展的动态演化规律，获得了爆生裂纹扩展形态、爆生裂纹面的多重分形特征，发现了反向起爆的炮孔底部“倒圆锥形”爆生裂纹的形成规律；揭示了爆破荷载对支护结构体的劣化机理，明确了爆炸应力波与锚固结构的相互作用规律，基于能量的频谱分析法及波势函数展开法，获得了巷道开挖和预应力的施加在锚固结构及周围岩体造成的应力状态，明确了分区锚杆动态应变的频谱分布特征；提出了多影响因素下的精确延时孔间及段别间的爆破延期计算方法，采用线性叠加法构造不同延期时间下的爆破叠加应力波形，给出了掏槽孔、非掏槽孔的孔间和段别延期时间，实现了爆破振动强度和破岩效果有效控制；获得了地表、隧道内及邻近隧道的地铁爆破振动传播规律，提出了地下工程爆破振动效应的围岩动力稳定性安全评价方法及安全判定标准，得到了建筑结构外部激励响应的爆破振动能量特征；构建了岩层精细化爆破技术，提出了分阶分段掏槽爆破及周边定向断裂控制爆破技术，实现高效安全精细化爆破。研究成果对地下工程岩体的爆破、支护参优化数和爆破荷载作用下的地下结构安全评价、长期稳定性预测具有重要的理论意义和工程指导价值。项目研究为同类条件爆破施工提供了典型案例和科学方法，在同类地下工程施工中具有重要借鉴意义和广阔推广应用前景。