超大跨度扁平地下洞室变形控制标准研究

Deformation Control Standards for Super-Large-Span Flat Underground Cavern

为解决目前超大跨度扁平地下洞室(跨度大于50 m)变形控制尚无明确规范的问题,基于某工程实例,采用理论解析与数值模拟相结合的方法,对大跨洞室变形控制标准进行研究。以围岩应变作为岩体强度指标评判大跨洞室稳定性,建立洞室拱顶沉降量S与围岩极限应变ε的关系,并提出以"沉降跨度比"作为大跨洞室沉降变形控制指标,给出适用于各施工阶段的变形控制标准,并建立变形控制标准分级管理办法。研究结果表明:1)大跨洞室沉降变形允许值与洞室几何形状、围岩强度特性相关;2)结合本工程大跨洞室"分部开挖-预留岩柱"的开挖方案,洞室变形主要发生在大跨洞室阶段。

There is no relevant normative guidance for the construction deformation control of the super-large-span flat underground cavern with a span greater than 50 m. Therefore, the theoretical analysis and numerical simulation methods are used to study the deformation control standards for large-span caverns based on an actual project. To assess the stability of a large-span cavern, the surrounding rock strain is used as a rock mass strength index. The settlement-span ratio is proposed as the deformation control standard, and a correlation between cavern crown settlement S and rock mass ultimate strain ε is proposed. Furthermore, the deformation control standards applicable to each excavation stage are proposed, and the classification management method for deformation control standards is developed. The results show the following:(1) The allowable settlement deformation of a large-span cavern is related to the geometry of the cavern and the strength characteristics of surrounding rocks.(2) Regarding the excavation scheme of partial excavation and reserved rock pillar for the case study of the large-span cavern, the deformation of the cavern mainly occurs in the large-span cavern stage.