Study On The Influence Of Deep Foundation Excavation Construction Of A Subway Station In Kunming On The Deformation Of Adjacent Over-Serviced Foundation Pits

In the main urban area of Kunming,which mostly belongs to the soft soil area of the river and lake phase,with the continuous improvement of its urban carrying capacity,the continuous investment in the construction of urban rail transportation and the accelerated modernization of the city,a large number of underground stations and building foundation pit projects have appeared.Some of these pits have been put aside for a long time,forming pits that are overdue for service,and even two adjacent pit works have emerged,posing a great threat to the safety of the adjacent works.In order to ensure that the two adjacent foundation pit projects are in a safe state during excavation and construction,and to reduce unnecessary loss of life and property,it is important to carry out mutual influence analysis and research on the deformation of adjacent foundation pit projects.In view of this,this paper relies on the "Safety Analysis and Assessment of an Overdue Pit" project located in Wuhua District,Kunming,to carry out a study on the influence of an overdue pit on the north side of the study area on the deformation of the adjacent 9.7m deep foundation pit of the metro station on the south side,in order to ensure the safety of the two pits during the excavation of the deep foundation pit of the metro station.The thesis research mainly has the following contents and understanding:(1)Through the data collection of the two pits in the study area,the site investigation and the collation and analysis of the engineering geological conditions,and then combined with the testing data of the support structure of the overdue pit and the monitoring data of the two pits,a qualitative analysis of the safety of the two pits themselves was carried out to further obtain the deformation of the two pits and the relationship of their mutual influence.(2)Two methods were used to verify the reliability of the numerical simulation method.The same idealised model was verified and compared with the normative calculation method using the numerical simulation method;the deformation monitoring data of the two pits in the study area and the calculation results of the three-dimensional numerical simulation were compared and analysed to verify the reliability of the numerical simulation method.(3)Using the numerical simulation method,the sensitivity of soil parameters in the influence of foundation excavation and support deformation in soft soil areas was studied,and the sensitivity was concluded as internal friction angle > Poisson’s ratio > cut-line stiffness > cohesion.(4)Numerical simulation was used to analyse and study the overall deformation of the excavation,support and stoppage of the two adjacent foundation pits to further determine the mutual influence relationship between the two pits and derive the deformation and safety of the two pits under the effect of mutual influence.In summary,through data collection,site investigation,theoretical analysis and numerical simulation,this paper analyses and studies the construction deformation of two adjacent pits in the study area,and concludes that the deformation form of the two pits,the mutual influence relationship exists between the two pits,the amount of influence deformation is within the controllable range,and the two pits are in a safe state during the excavation of the deep foundation pit of the metro station.