Abstract

With the development of society and the economy, the scale of underground cavern engineering is becoming increasingly larger. Unfortunately, underground cavern disasters such as roof collapse and rockburst occur frequently. Many studies have shown that the collapse of underground caverns is closely related to joints, which restricts the development of underground space and threatens the safety of underground engineering. Based on laboratory tests, this paper first explored the mechanical properties and acoustic emission (AE) evolution characteristics of jointed rock caverns in different positions, while the stress and crack distribution of the cavern were analysed theoretically. Second, based on the acoustic emission characteristics, the damage characteristics and safety damage threshold value of jointed rock caverns were analysed. The results show that the joint position has a great influence on the overall bearing capacity of jointed caverns, and the most influential joint position is at the arch foot of the rock cavern. Joint position affects the AE evolution and damage development processes of rock mass cavern samples, the existence of joints will reduce the intensity of acoustic emission, compared with the intact rock sample. The cavern is shown to be destroyed mainly along the joints. Moreover, tension cracks are mainly concentrated at the top and bottom of the cavern, and shear cracks are mainly concentrated at cavern foot. Tension cracks and shear cracks appeared at the cavern shoulder. The crack distribution around the cavern is closely related to the joint positions and stress concentration factor. Based on the ratio of pre-peak stress to peak stress, the damage threshold values of the intact rock mass cavern and jointed rock cavern are set as 0.1–0.2 and 0.1–0.4, respectively. The research results of this paper have importance for the safety and operation of underground engineering.

Article Highlights

• Explored the influence of different joint positions on the strength and AE characteristics of rock caverns.

• The influence of different joint positions on the damage evolution of rock caverns was analysed.

• Proposed damage threshold and corresponding stress threshold.

中文翻译：

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基于声发射的节理洞室损伤特性及安全损伤阈值试验研究

摘要

随着社会和经济的发展，地下洞室工程的规模越来越大。不幸的是，顶板坍塌、岩爆等地下洞室灾害频繁发生。许多研究表明，地下洞室的坍塌与节理关系密切，制约着地下空间的开发，威胁着地下工程的安全。本文在室内试验的基础上，首先探讨了节理岩洞不同位置的力学特性和声发射(AE)演化特征，同时从理论上分析了洞室的应力和裂缝分布。其次，基于声发射特性，分析了节理岩洞的损伤特征和安全损伤阈值。结果表明，节理位置对节理洞室整体承载力影响较大，其中影响最大的节段位置为岩洞拱脚处。节理位置影响岩体洞室样品声发射演化和损伤发展过程，与完整岩样相比，节理的存在会降低声发射强度。洞穴显示主要沿关节被破坏。此外，拉裂缝主要集中在洞顶和洞底，剪切裂缝主要集中在洞脚。洞肩出现拉裂缝和剪裂缝。洞室周围的裂缝分布与节点位置和应力集中因子密切相关。根据峰值前应力与峰值应力的比值，完整岩体溶洞和节理岩溶洞的损伤阈值分别设置为0.1-0.2和0.1-0.4。本文的研究成果对地下工程的安全和运行具有重要意义。

文章亮点

• 探讨了不同节理位置对岩洞强度和声发射特性的影响。

• 分析了不同节理位置对岩洞损伤演化的影响。

• 建议的损伤阈值和相应的应力阈值。