Safty Assessment And Analysis Of Xiaolangdi Desilting Tunnels

Safety assessment is important for tunnel to ensure the normal operation, and itaims to predict and find out the potential risk factors or harmful consequences in theengineering activities, so that we could formulate feasible methods and monitoreffectively the hazards in order to reduce incidence and loss of accidents and obtainthe optimal security. Xiaolangdi desilting tunnels first apply unbounded circularanchored prestressed concrete lining domestically. Lots of monitoring instrumentswere placed in the tunnels and have accumulated abundant data after a decade test ofvarious design water levels. This topic regards Xiaolangdi desilting tunnels as theresearch object, sums up and processes observational data in scientific and effectiveway, uses hydraulic tunnel safety assessment theory, assesses and analyzes the safetyof unbounded circular anchored prestressed concrete lining structure, studies thesafety performance of running status under different influencing factors, put forwardeffective ways to solve the engineering safety, and verifies the feasibility of safetyassessment in practical engineering so as to provide definite theory guidance andimportant resources for the safety assessment and analysis of similar projects in thefuture. The primary research content and conclusions are summarized as follows.(1) This paper describes comprehensively the project summary of Xiaolangdidesilting tunnels, mainly including the engineering geological and hydrologicalconditions, structure arrangement and observation instrument parameter information.(2) The safety of anchorage slot leakage in destiling tunnels is analyzed, and theproblem about prestressed anchor invalidation is reseached further. By using finiteelement method (FEM) to calculate, it finds out that the invalidation of first rootanchor in casting block is the most unfavorable. When the tunnels have excessivetensile stress, the lining concrete is likely to crack leading to leakage.(3) On the basis of observational data, the paper analyzes the operation condition ofdestiling tunnels, studies respectively the influence of temperature, water pressure andauthigenic volume deformation on strain of desilting tunnels lining, calculates theinfluence coefficient of strain, finds out the law of development on deformation, andfinally draws a conclusion that the the operation condition of destiling tunnels is safe.