Risk Assessment Approach Study Of Surficial Building Damage Induced By Urban Utility Tunnel Shallow Buried Excavation

Urban utility tunnel is a kind of infrastructure used to ensure the urban operation,of which the constructing environment is inevitably under the surface of the city.It is a generally existent phenomenon that during the construction of urban utility tunnel,the tunnel will cross or be near to the residential buildings,which will be bound to have different impacts on the structures of those buildings.Although damages caused by urban engineering have brought huge costs to people's life and properties and it is also a key point concerned and researched by plenty of experts and scholars,there are still plenty of research gaps between building damage caused by underground construction and risk assessment of its relevant surface building.This paper studies the position relationship(including the distances and the angles)between the building and the urban utility tunnel,as well as the effects on building damage brought by geometric dimensioning through model experiments.During the course of the experiment,3D scanning technique was applied to monitor the settlement of the surface and the surface buildings,at the same time,Digital Image Correlation techniqu was employed to monitor the strains of building walls in order to obtain the damage strain of the building walls during the construction of the urban utility tunnel.This paper deduces the bending damage computational model of surface building based on the damage model of elastic deep beams buildings.The variable law of bending deformation rate of buildings in different geometric dimension under the construction of the urban utility tunnel is described.Prediction model of surface settlement under the construction of urban utility tunnel is built and the damage criterion of surface buildings in the impact region of excavation is obtained by analyzing the maximum tensile strains and maximum diagonal strains.At last,based on the results of experimental analysis and theoretical deduction,the comprehensive fuzzy level damage risk system considering various damage risk factors of the surface buildings,and the risk assessment method of the surface building damage induced by urban uility tunnel is applied to the risk analysis in the practical engineering.The main achievements of the paper are as follows.Firstly,model experiments are carried out on the basis of the construction method of urban utility tunnel in actual projects.Non-contacting damage deformation monitoring technologies are employed to study the damage differences of the surface buildings caused by different positions between the building and the utility tunnel and different geometric dimensioning.Based on the results,the paper discusses the damage mechanism of surface building caused by the construction of utility tunnel.Secondly,flexural deformation analysis model corresponding to the geometric dimensions(length,width and height)of the actual building is built.The proportion of bending deformation in total deformations triggered by building structural rigidity and geometric dimensioning is researched and compared with the classic deformation analysis model to verify the correctness and feasibility of the new model.Thirdly,this paper modified the three-dimensional model of surface settlement aroused by the construction of utility tunnel,Moreover,ultimate horizontal and diagonal strains of surface buildings in different positions generated during the construction stage of utility tunnel are used as the damage assessing criteria of surface buildings.A surface damage ranking of different positions is presented,a contour of building damage risk within the utility tunnel excavation influenced area is formedFinally,Based on the fuzzy analytic hierarchy process and the building damage factors studied in the model test,the Fuzzy hierarchy evaluation method for the damage risk of ground buildings induced by excavation of urban underground complex pipe corridor was established.