Study On The Influence Of Municipal Pipeline Water Gushing On The Stability Of Urban Shallow Buried Small Spacing Tunnels

With the rapid development of urbanization in China,a large number of people are concentrated in the first tier cities,and the agglomeration of big cities leads to the further squeeze of urban space.In order to alleviate the population pressure and the space pressure for the construction of municipal pipeline system,the development and utilization of urban underground space engineering has been booming,especially the urban traffic tunnel engineering.Due to the restriction of many factors,such as municipal pipeline and surrounding buildings,most of the urban traffic tunnel projects are designed as shallow buried small clear distance tunnels.In recent years,the types of municipal pipelines are becoming more and more diverse,and the structure is becoming more and more complex.At the same time,the municipal pipeline system of the city has been aging for a long time,which is in an unstable state.The construction disturbance further intensifies the municipal pipeline Instability leads to water inrush.In recent years,the collapse of the municipal pipeline caused by the burst of water and other accidents emerge in an endless stream,resulting in serious consequences.The problem of municipal pipeline water gushing has become one of the key problems restricting the rapid and safe development of urban traffic tunnels.In this thesis,based on the Yuhan Road small clear distance tunnel project of Jinan Shunhe viaduct South extension phase ? project,using theoretical analysis,laboratory test,numerical simulation and other research methods,the mechanism of tunnel instability caused by water inrush is studied.The theoretical prediction formula of the influence range of water inrush diffusion is put forward.The influences of the depth of the water gushing point,the location of the water gushing point and the soil properties on the tunnel construction and operation periods are studied.The critical criterion of tunnel instability caused by water inrush is put forward,and the mechanism of tunnel instability is revealed.The specific research results are as follows:(1)Based on the classification characteristics and layout rules of municipal pipelines,the main causes of water inrush of municipal pipelines are analyzed,and the main failure modes of pipelines are divided.On this basis,the failure modes of tunnel instability caused by water inrush are classified.(2)Based on the generalized Darcy's Law(capillary group theory),a time-based theoretical prediction formula for the influence range of water inrush and diffusion of municipal pipelines is proposed,which is verified by indoor physical simulation test and numerical calculation.The comparison between the test results and the theoretical prediction results verifies the accuracy and reliability of the theoretical prediction formula.(3)By using the finite difference numerical simulation software,the influence of the depth,location and soil properties of the water gushing point on the stability of the tunnel overburden is studied,and the instability rules of the tunnel overburden during the operation and construction periods are studied.The instability criteria and the critical failure conditions of the shallow tunnel with small clear distance are obtained.(4)The research results are applied to the reinforcement and treatment project of water inrush accident of small clear distance tunnel in Yuhan road.According to the different sensitive areas and different disaster treatment sections affected by water inrush accident,different reinforcement and treatment measures are put forward and good results are achieved.