Brace Characteristics In Deep Excavation And Analysis Of The Impact On The Surrounding Tunnels

Foundation pit engineering has obvious environmental effects,and the excavation of foundation pit has a greater impact on the surrounding environment,at the same time,the foundation pit engineering itself is also very complex.With the continuous advancement of urbanization and urban construction,all kinds of high-rise buildings have emerged.At the same time,urban land resources have become more and more tense,and many foundation pit projects have to be carried out in a complex environment.This article takes a foundation pit project in Foshan as the starting point,with on-site monitoring as the focus,organizes and analyzes on-site monitoring data,studies the deformation characteristics of the support in the deep foundation pit and the impact on the surrounding environment,and uses numerical simulation as an auxiliary means.Restore the original environment of the foundation pit to a certain extent,compare and analyze the obtained numerical simulation results with the on-site monitoring results to verify the rationality of the numerical model and the correctness of the laws obtained from the monitoring results.Therefore,on this basis,predict the deformation,stress characteristics and impact on the surrounding environment of similar foundation pit projects,and provide a predictive method to ensure the safety of the foundation pit and the overall stability of the surrounding environment.The main conclusions of this paper are as follows:(1)Through the analysis of the monitoring results of the foundation pit,the horizontal displacement of the retaining structure of the foundation pit is proportional to the depth of the foundation pit.As the depth of the foundation pit increases,the horizontal displacement of the retaining structure continues to decrease.The depth-displacement curve is in the shape of an "inverted triangle",and the long side of the foundation pit is obviously affected by the excavation of the foundation pit.The middle position of the long side of the foundation pit is the position with the largest horizontal displacement of the whole area.At the same time,the displacement of the corner position of the foundation pit It is often small,so the corner position of the foundation pit has a certain degree of restriction effect on the horizontal displacement of the foundation pit retaining structure.(2)The axial force of the support in the foundation pit is affected by the change in the displacement of the retaining structure of the foundation pit.Since the horizontal displacement of the retaining structure of the foundation pit shows a trend of "large displacement from the upper part and gradually decreasing downwards",the axial force of the inner supporting structure also increases with the support.The position moves down and lowers in steps.(3)Through the analysis of the on-site monitoring results,it is found that the main factor affecting the settlement value of the surrounding buildings and the ground is the distance from the edge of the foundation pit to the building or the ground.The distance is within 40 m.When the distance doubles,the settlement value is relative to the near point.Decrease by 14%.At the same time,the long side of the foundation pit has a higher settlement amount on the ground and surrounding buildings than the short side,and the long side direction is more obviously affected by the excavation of the foundation pit.The excavation of the foundation pit has the most impact on the settlement of the middle part of the long side of the foundation pit.obvious.(4)Based on comprehensive monitoring data and numerical model analysis,the deformation of the subway tunnel adjacent to the foundation pit is mainly concentrated on the side near the foundation pit in the middle of the section.The deformation of the pit enclosure structure is interrelated,and the characteristics of the tunnel can be derived from the deformation of the foundation pit.