Due to the complex and changing geological conditions,engineering accidents occur frequently during the construc-tion in mixed-face ground. Therefore,more and more scholars from home and abroad have paid more attention to the study of mixed-face ground. However,there is no unified understanding about the concept of mixed-face ground at home and abroad. Firstly,based on the definition and classification of mixed-face ground,the paper summarizes the common types of mixed-face ground in engineering at home and abroad. According to different engineering orientation and considering scale characteristics, this paper makes a classification about mixed-face ground from lithology, fracture, strata, stratigraphic assemblages,hardness difference,rock strength and other characteristics, and proposes a systematic definition of mixed-face ground. Secondly, the characteristics of the geological conditions of the typical mixed-face ground are summarized,and the influence laws of the geo-logic structure distribution and stratigraphic lithology of mixed-face ground on its mechanical response are obtained. Finally,ac-cording to the research status quo of tunnel construction engineering practice and theory, this paper summarizes the interaction between TBM and surrounding rock mass,the construction parameters and structure optimization,disaster control and evaluation in the tunneling of mixed-face ground and the method of structure plane recognition and model reconstruction have been opti-mized. The results have important reference value for the study of mixed-face ground.%由于地质条件复杂多变,在复合地层施工时工程事故频发,因此,复合地层的研究得到越来越多国内外学者的关注.然而目前对复合地层的概念,国内外并没有形成统一的认识.首先根据前人对复合地层的定义和分类,总结了目前国内外工程中复合地层的常见类型,针对不同的工程定位,考虑尺度特征,从岩性、裂缝、地层、层间组合、硬度差异、岩石强度等角度对复合地层进行分类,并提出了一个相对系统的复合地层定义.其次,对典型复合地层地质条件特性进行总结,得出复合地层地质构造分布和地层岩性特征对复合地层工程力学响应的规律.最后,根据隧道工程施工实践与理论研究现状,从复合地层隧道开挖中TBM与围岩的相互响应、施工参数及结构优化、灾害控制与评价3个方面进行归纳,并提出了复合地层隧道围岩结构面识别和模型重建改进的方法.研究成果对研究复合地层具有重要的参考价值.
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