巨跨超扁平地下洞库建设方法及实践

为探讨巨跨超扁平地下洞库勘察设计和施工运营过程中的关键技术难题，采用文献调研、理论分析和实践验证相结合的方法，对巨跨超扁平洞库洞室稳定机制、关键性地质参数及其评价体系、定量化设计方法、施工工艺工法以及监控技术进行研究。得出： 1）通过及时、主动的支护体系有序调整围岩承载力是巨跨超扁平地下洞库成洞的关键。2）巨跨超扁平地下洞库围岩稳定性评价方法必须考虑尺寸效应，结构面产状、地应力、跨度、高跨比、摩擦角是影响围岩稳定性的显著因素。3）喷+锚+网柔性支护体系是合适的，宜采用“以数值计算为主，类似大跨经验为参考，施工监测动态反馈调整”相结合的综合设计方法。4）采用预留双岩柱支撑开挖方法是合理的。5）应采用多种手段对结构及围岩应力场和位移场进行监控量测，可采用“以收敛和沉降指标为主，围岩内部位移指标相结合”的综合判断方法，评判施工及运营过程中围岩的稳定性和结构的安全性。

Construction Techniques and Application of Giant Span Flat Underground Caverns

Cavern stabilizing mechanism, key geological parameters and their corresponding evaluation system, quantitative design method, construction techniques, and monitoring methods of a giant span flat underground cavern are analyzed through literature investigation, theoretical analysis, and application verification. Conclusions drawn from the study are as follows: (1) A timely and active support system, which can warm up and recover the bearing capacity of surrounding rocks, is key to a giant span flat underground cavern construction. (2) The size effect must be considered in the surrounding rock stability evaluation system of a giant span flat underground cavern. The structural surface occurrence, geostress, span, height span ratio, and friction angle are also equally important for the cavern. (3) Spraying + anchoring + a flexible support system is feasible, and it is recommended to adopt a comprehensive design method combining numerical calculation, construction experience of similar projects, and monitoring measurement. (4) Reserved double rock column support method is rational. (5) The stress and displacement fields of surrounding rocks and structures should be monitored using various methods. A comprehensive identification method that regards the convergence and settlements as key indices while considering internal surrounding rock displacement is proposed to evaluate the stability of surrounding rocks and structures during the construction and operation phases of giant span flat underground caverns.