地下工程开挖面空间效应特征研究及应用

Study of spatial effect of excavation face for underground facility and its application

地下工程开挖面对围岩变形具有约束作用,在该约束作用下开挖面表现出显著的空间效应。通过开展地下工程开挖面空间效应现场试验,获得了开挖面空间效应特征。根据现场试验结果,提出了描述开挖面空间效应的双曲正切函数经验公式。利用上述经验公式,开展了洞室围岩稳定性控制研究,获得了不同预警等级条件下拱顶沉降值控制标准。研究发现,对某特定断面,空间效应最显著时并非开挖面透过该断面时;地下工程围岩稳定性越差,开挖面空间约束效应越不明显;若采用常规先开挖再监测的方法,不能监测到围岩全部位移,从而影响参数反分析的准确性;利用开挖面空间效应原理可以获得地围岩稳定性位移控制标准。研究结果为深入了解地下工程空间效应和开展地下工程稳定性控制提供了借鉴和参考。

The deformation of rock mass around underground facility is confined by excavation face. Under the confinement, the spatial effect of excavation face is remarkable. Field test was performed to investigate the characteristics of the spatial effect of excavation face. An empirical hyperbolic tangent formula is proposed to describe the spatial effect. The stability of an underground cavern was analyzed using the proposed empirical formula. It is shown from this study that for a certain section, the spatial effect is not the most remarkable when the excavation face is passing the section. For rock mass of low quality, the spatial effect is less significant than that of high quality. The total displacement could not be obtained using the conventional monitoring method, which takes influence on back analysis of mechanical parameters of rock mass. The standard for stability control could be obtained using the principle of spatial effect. This study will benefit the understanding of the spatial effect and provide the reference for the stability control of underground facility.