Risk Assessment Of Tunnel Water Inrush Based On Fuzzy Analytic Hierarchy Process

In recent years,due to the rapid development of underground space construction,the scale,quantity and construction speed of underground projects have increased sharply,the geological conditions faced by underground engineering construction have become increasingly complex,and the frequency and intensity of water inrush disasters have become increasingly high.The tunnel water inrush disaster is affected by factors such as ground stress distribution,rock mass strength,groundwater seepage characteristics,excavation section size,excavation method and excavation speed.There are still deficiencies in research,especially for developing countries with limited experimental conditions and field detection conditions,it is urgent to carry out research on the prediction and assessment of tunnel water inrush disasters based on their own conditions,and to propose innovative risk assessment methods to ensure underground engineering stability and long-term safe operation.This thesis takes the water inrush disaster assessment of the water diversion tunnel of the Neelum-Jhelum hydropower station in Pakistan as the engineering background,systematically analyzes and constructs the water inrush disaster index set and evaluation framework,proposes a water inrush disaster prevention and control decision support system,and carries out system comparison and field application.The following research results were obtained:(1)Comprehensive water inrush risk assessment can effectively improve the safety of tunnel construction and prolong the operating life of the tunnel.This thesis firstly analyzes and describes the inherent meaning and necessary factors of water inrush risk assessment.The analysis shows that timely and effective water inrush disaster assessment is of great significance to avoid and control disasters and ensure long-term safe operation of tunnel projects.(2)Water inrush risk assessment is one of the typical multi-criteria decision-making problems which makes it difficult for decision-makers to make correct decisions in a complex multi-criteria environment.Evaluation index methods are an effective means of overcoming complexity through multiple decision-making processes.Based on it,this thesis proposes an evaluation index method for water inrush disaster prevention and control in tunnels,which provides technical support for water inrush disaster assessment and prediction,and improves the sensitivity of water inrush risk assessment.(3)Using the fuzzy set theory,the water inrush indicators are quantified and analyzed,and the weights of the indicators are determined using the fuzzy analytic hierarchy process(FAHP),and a regional model with Pakistan as the application background of water inrush disaster prediction is constructed.By deriving the water inrush enhancement indicators(6 main indicators,35 evaluation indicators),a water inrush disaster assessment framework is established,and the framework of factors affecting water inrush is built into the evaluation index system to consider the impact of different application environments.(4)Among all water inrush factors,hydrogeological index is the most important factor causing water inrush,followed by unfavorable geological factors and construction factors.This means that if the impact of these indicators is reduced,future water inrush problems can be avoided or minimized.Hydrogeological indicators and geological structure indicators account for a relatively high proportion and should be regarded as key improvement indicators.After these aspects,construction factors,aquifuge index and dynamic feedback must be considered,followed by engineering geological indicators.From the analysis of each sub-indicator,it can be seen that in order to achieve the goal of long-term safe tunnel water inrush disaster prevention and control,it is necessary to strengthen the understanding of water inrush disasters and risk assessment methods,and take measures such as grouting,bolting,working face precipitation,and hole exploration.Prevention and support technologies such as advanced drainage,drainage fabrics,and barbed wire can effectively reduce the risk of water inrush through appropriate risk assessment and appropriate auxiliary technologies.This study improves the accuracy of water inrush disaster assessment in tunnels,puts forward the key points and countermeasures of water inrush disaster prevention and control in terms of theory and engineering construction management,deepens the understanding of tunnel water inrush disaster assessment,and has a better understanding of test methods and on-site detection methods.The water inrush disaster faced in tunnel construction in less developed countries provides a simple and easy evaluation and prediction method and approach.There are 24 figures,06 tables,and 113 references in the thesis.