Research On Evaluation Technology Of Impact Of Pipe Jacking Cable Tunnel Construction On Adjacent Structure

Soft clay is widely distributed in our country,especially in the eastern coastal areas of our country.The eastern coastal areas of my country are economically developed.With the increase of ground construction,in order to alleviate the pressure on the city,cables into the ground have become the main trend.Due to its special physical properties such as high water content,high compressibility,high sensitivity,low strength and low bearing capacity,soft clay has relatively high risks in the construction process of undercut or open-cut tunnels.Pipe construction has become one of the main construction methods for underground projects in soft clay soil areas.The pipe jacking tunnel construction process will inevitably have an impact on the surrounding stratum.During the pipe jacking tunnel construction process,the adjacent structures(ground buildings,underground pipelines)may lose their function or damage from time to time.However,taking too conservative measures during the pipe jacking construction process will greatly increase the economic cost.Therefore,it is particularly important to carry out the risk assessment of the impact of pipe jacking construction on adjacent structures.Based on this,this paper develops the risk database of the impact of pipe jacking construction on adjacent structures and the evaluation auxiliary system.The main work of this paper is as follows:(1)Consult a large number of pipe jacking construction risk assessment documents,establish a system framework for the impact assessment of pipe jacking construction on adjacent structures,and identify the risks of the pipe jacking adjacent construction project through the checklist method and the fault tree analysis method,and obtain the 20 main risks of the project factor.Choose the analytic hierarchy process to estimate the project risk.(2)Establish a risk database.The risk database mainly contains three modules:engineering risk information,numerical simulation results and engineering cases.The risk information related to the pipe jacking project is standardized and stored in the database;the pipe jacking construction process is numerically simulated by numerical simulation software.The main factors affecting the adjacent structure of the pipe jacking construction are the buried depth of the pipe jacking and the pipe jacking.The size,diameter of adjacent pipelines,clear distance between jacking and adjacent structures,and the spatial position relationship between jacking and adjacent pipelines,etc.The numerical simulation results are standardized and stored in the risk database;through consulting a large number of documents,more than 200 types of jacking are obtained Close the construction project case,standardize the project case,and store it in the risk database.(3)Regression analysis of numerical simulation results based on BP neural network theory,combined with fuzzy mathematics method and expert investigation method,explores the distribution law of the degree of membership of the probability of each risk factor.(4)When selecting the analytic hierarchy process for engineering risk estimation,the pairwise discriminant matrix of risk factors is mainly determined based on the single-factor sensitivity theory.The single-factor sensitivity analysis method is used to deal with the engineering risk factors dimensionlessly,and the sensitivity factor of each risk factor is obtained.Combined with the expert investigation method,the risk factor pairwise discriminant matrix is determined,and the matrix is processed by the eigenvalue method.The weight of each risk factor.(5)Combining the specific conditions of the water system network connection project in the Bohai New Area,the risk assessment of the project is carried out by the auxiliary system of pipe jacking construction on the adjacent structure impact risk assessment,and it is concluded that the construction risk of the project is at a medium risk level.