真三维高地应力条件下高边墙洞室劈裂破坏机理与支护控制方法研究

Field observations show that a lot of vertical or near vertical parallel splitting cracks often appear in the high side wall cavern in high geostress area during excavation of cavern.True 3D geomechanical model test of similar material for excavation unloading and excavation supporting of the high side wall cavern will be conducted to simulate the forming process of splitting failure under 3D high geostress condition. To explore the derivation, initiation, propagation and coalescence failure process of splitting cracks and the supporting effect of system bolts and prestressed anchor cables on splitting failure. To find out the mechanical cause and the production condition of splitting failure. To understand the formation mechanism of splitting failure and the anchoring mechanism of system bolts and cables.Based on the revealed splitting failure mechanism and the supporting mechanism for splitting failure by the geological mechanical model test, the splitting failure criterion and the toughening mechanical model and the supporting energy criterion preventing the splitting failure will be established through the theoretical research. The supporting control method for splitting failure will be put forward. The theory method system analyzing the splitting failure mechanism and supporting control technology for high side wall cavern will be formed. The research results of the project will provide important theoretical basis and technical support for the safe, economic and efficient development construction of national large scale underground engineering.

现场观测表明：高地应力地区的水电站地下厂房在开挖卸荷过程中常常会在厂房洞室的高边墙部位出现大量垂直向或近似垂直向的平行劈裂裂缝。项目针对高边墙洞室开挖出现的劈裂破坏现象，拟通过真三维高地应力条件下高边墙洞室开挖卸荷和开挖支护相似材料三维地质力学模型试验，真实模拟洞室劈裂破坏的形成过程；探索劈裂裂缝的衍生、起裂、扩展与贯通破坏过程以及系统锚杆和预应力锚索对劈裂破坏的支护锚固效应；探明劈裂破坏的力学成因与产生条件；弄清劈裂破坏的形成机理以及锚杆、锚索对劈裂破坏的锚固作用机理。在依托模型试验揭示的洞室劈裂破坏机理与支护作用机理的基础上，通过理论研究建立洞室的劈裂破坏准则、增韧止裂力学模型和防裂支护能量判据，提出针对洞室劈裂破坏的支护控制方法，形成高边墙洞室劈裂破坏分析与支护控制的理论方法体系。项目研究成果可为我国安全、经济与高效地进行大型地下工程开发建设提供重要的理论依据与技术支持。

随着国民经济的快速发展，我国对资源和能源的需求急剧增加，许多在建和规划中的地下厂房、跨流域调水工程和引水隧洞不断进入地下深部。随着地下工程开挖深度的显著增加，深部岩体工程中出现了一系列新的特征科学现象，其中高边墙洞室的劈裂破坏是高地应力条件下因洞室开挖卸荷形成的一种特殊工程破坏现象，该现象已成为影响深部洞室施工安全和长期运行稳定的重要因素，已引起国内外专家学者的普遍关注，并已成为深部工程领域研究的热点和难点科学技术问题。项目以瀑布沟水电站地下主厂房高边墙洞室为研究工程背景，开展了高地应力条件下高边墙洞室施工开挖与支护控制真三维地质力学模型试验，全景真实再现高边墙洞室劈裂破坏的产生过程，首次发现高边墙洞室径向位移和应力呈现振荡衰减变化规律，阐明了高边墙洞室劈裂破坏的产生条件与影响因素，弄清了劈裂破坏的岩锚支护作用机理，建立了劈裂破坏弹塑性损伤软化模型、劈裂破坏能量损伤准则和劈裂破坏岩锚支护力学模型，开发了劈裂破坏计算分析程序，系统揭示了高边墙洞室劈裂破坏的力学成因与产生机制，构建了高边墙洞室劈裂破坏与支护控制的理论分析方法。项目研究成果可为水电、交通、矿山和国防工程领域深部洞室工程施工与运行安全提供重要理论支撑。