Abstract

The geological conditions of subsea tunnels are extremely complicated. When crossing faults, water inrush disasters are prone to occur under the combined action of seawater pressure, geological structure, and construction disturbance. An optimal combination weight-improved grey relational analysis (GRA) method is proposed here to evaluate the risk of water inrush in subsea tunnels through faults. Eight main factors are selected from fault zone properties, fault structure characteristics, engineering factors, and construction factors as risk assessment indexes, and the risk is divided into four levels. The subjective and objective weights are determined using the improved G₁-method and entropy weight method, and the optimal combination weight is calculated based on the minimum discriminant information principle and the Lagrange multiplier method. The improved GRA considering the evaluation criteria interval is used to determine the correlation degree of the water inrush risk level, and the maximum correlation degree criterion is adopted to judge the risk level. The method is applied to the Qingdao Jiaozhou Bay subsea tunnel to assess the water inrush risk crossing faults, and the assessment results are basically consistent with the actual engineering situation. This study provides a practical reference for the risk assessment of water inrush in subsea tunnels.

摘要

海底隧道的地质条件极其复杂。穿越断层时，在海水压力、地质构造和施工扰动的共同作用下，容易发生突水灾害。本文提出了一种优化组合权重改进灰色关联分析（GRA）方法来评估海底隧道通过断层的突水风险。选取断裂带性质、断裂结构特征、工程因素、施工因素8个主要因素作为风险评估指标，将风险分为四个等级。使用改进的 G _{1确定主观和客观权重}-方法和熵权法，根据最小判别信息原理和拉格朗日乘子法计算最优组合权值。考虑评价准则区间的改进GRA用于确定突水风险等级的相关度，并采用最大相关度准则来判断风险等级。将该方法应用于青岛胶州湾海底隧道对突水风险穿越断层进行评估，评估结果与实际工程情况基本一致。该研究为海底隧道突水风险评估提供了实践参考。