长深隧洞突涌水危险性等级指标及评价方法

长距离、大埋深已成为未来隧洞工程的新特点，其中突涌水问题是制约此类工程开挖进度的关键因素之一。陕西省引汉济渭秦岭输水隧洞越岭段长81.8 km，最大埋深2 000 m，地质构造复杂，因此以该工程为背景研究长深隧洞突涌水灾害等级评价问题具有重要的科学价值和实用价值。在分析大量地下洞室突涌水灾害的基础上，针对长深隧洞突涌水的孕灾环境，遴选了地层岩性、岩层产状、不良地质、地表汇流条件、隧洞底部水头压力、可溶岩与非可溶岩接触带、层面（间）节理裂隙与地表河流规模结合度7大指标，采用打分法描述指标致灾因子的致灾程度，构建了长深隧洞突涌水灾害危险性等级评价指标体系，运用模糊层次分析法构建指标间的判断矩阵，用最大特征根法求取每个指标的权值，通过对评级层建立云模型，使综合评价等级的隶属度更加客观，形成了一种长深隧洞突涌水灾害危险性等级评价方法；并建立了突涌水危险性等级与单点最大突涌水量范围之间的对应关系，可在初期设计阶段预测突涌水量范围。结果表明：秦岭隧洞已开挖段（约60 km）突涌水危险性评价结果与实发突涌水情况吻合性较好，验证了长深隧洞突涌水灾害危险性等级指标及评价方法的可靠性，对秦岭隧洞未贯通（约20 km）突涌水危险性进行评价，为有效预防突涌水灾害发生奠定了基础。

Risk Rating Index and Evaluation Method for Water Inrush in Long-deep Tunnels

Long distance and deep burial have become features of future tunnel projects, and water inrush is one of important factors that influencing the speed of excavation advancement. The Qinling water conveyance tunnel of the Hanjiang-to-Weihe River Valley Water Diversion Project is approximately 81.8 km long with a maximum depth of 2 000 m, and the geological structure is complex. The risk evaluation of the inrush water hazard is therefore of great scientific and practical value. Based on the analysis of a large number of inrush water disasters in underground caverns, the characteristics of inrush water in long and deep (long-deep) tunnels were studied. A method of evaluating the hazard level of water inrush in long-deep tunnels was established. Formation lithology, orientation of bedrock, unfavorable geology, surface confluence conditions, head pressure at the bottom of the tunnel, contact zone of soluble and insoluble rocks, and combination degree of interlayer (interlaminar) fissures and surface rivers were selected as seven risk rating indexes of water inrush hazard in a index system for long-deep tunnels. A scoring method was used to quantify the degree of disaster of the index factors. An analytic hierarchy process (AHP) method was used to construct the judgment matrix between the indexes. The weight of each index was obtained by the maximum eigenvalue method. Applying a cloud model to the rating made the synthetic attribute measurement of rating more objective. The corresponding relationship between the risk level of the water inrush and range of single-point maximum volumes of water inrush was established. From this, the range of water inrush volumes could be predicted on the basis of the risk assessment in the early stages of design. The results are in good agreement with the actual situation in the excavated section of the Qinling tunnel (approximately 60 km long), which shows that the method of rating the risk of the water inrush hazard is reliable. Evaluation of the risk of water inrush for the non-excavated section of the Qinling tunnel (approximately 20 km long) can provide a foundation for effective prevention of water inrush.