基于修正[BQ]值的软岩隧道挤压变形预测

Squeezing prediction of tunnel in soft rocks based on modified [BQ]

高地应力条件下,深埋隧道破碎围岩容易发生挤压大变形。挤压变形量的预测对于工程的设计与施工至关重要。经验预测方法因其形式简单、使用方便得到广泛应用,现有隧道挤压变形预测的经验法具有以下特点:(1)考虑的影响因素较少,多数仅能对挤压变形进行分级,无法给出挤压变形量;(2)现有经验变形预测方法多基于围岩Q分级系统,不能直接应用于国内的BQ分级系统。因此,基于对国内外100多条隧道变形监测数据的分析,提出一种新的适用于国内岩体基本质量指标修正值[BQ]的挤压变形预测方法。该方法综合考虑了隧道埋深、跨度、围岩强度应力比、地下水、岩体结构面等影响岩体挤压变形的多种因素。通过与多条大变形隧道监测结果的对比分析,验证了预测方法的合理性,研究成果对高地应力软岩隧道确定支护强度及提前采取超前加固措施具有十分重要的指导作用。

Soft rocks around deep-buried tunnels under high geo-stress conditions are prone to emerging large deformation. Nowadays,the prediction of squeezing deformation is a significant problem during the design and construction of practical engineering.The existing empirical prediction methods of squeezing tunnels are widely used due to its simplicity and convenience, while they also have many limitations,e.g.most of they can only classify the squeezing degree but can't predict the exact deformation with considering on a few influencing factors,they were developed based on foreign Q system and not applicable for the BQ system of China.Therefore,a new empirical method,that are available for BQ system,is proposed based on more than 100 deformation monitoring data of squeezing tunnels.The method could synthetically take many factors into account,such as tunnel depth,span,ratio of rock strength stress and initial stress,groundwater and structure surface of rock.The proposed method is verified through comparison and analysis of monitoring results of several tunnels with large deformation,and plays a very important guiding role in determining the strength of the support and applying advance reinforcement measures.