| Taking the first phase of the underground comprehensive pipe gallery project in xuwei new district,lianyungang city,as an engineering example,this paper conducts an in-depth study on the key construction technologies of the comprehensive pipe gallery deep foundation pit by combining the construction of the pipe gallery deep foundation pit,numerical simulation and on-site monitoring.The main contents include:(1)Based on the comprehensive engineering background and engineering geological conditions,the paper puts forward the type of pipeline corridor section applicable to the coastal silt formation,studies the technical key points of different pipeline corridors,and puts forward the principle of pipeline corridor under different working conditions.(2)Based on the engineering case of the standard section of the comprehensive pipe corridor foundation pit in xi ’an section,a plane strain model was established,and numerical simulation studies were carried out on four working conditions,namely,steel sheet pile support,borehole pile support,square pile support and slope excavation.The results show that steel sheet pile supporting in the standard section of the pipe gallery foundation pit can meet the deformation requirements of the foundation pit.There are major safety risks in the river reach,so the use of borehole pile support can effectively limit the deformation of the foundation pit and reduce the risk level.The foundation pit at intersection section has the influence of space effect.Adopting the square pile with greater stiffness to support the foundation pit and improve the overall support stiffness of the foundation pit will be more conducive to control the deformation of the foundation pit and reduce the impact on the surrounding environment.(3)Taking the case of foundation pit engineering at the intersection of environmental protection road no.The results show that the cross sections of two support sections which are parallel to the direction of the axis of the foundation pit can be optimized,and the cost can be saved while the support strength is satisfied.At the same time,the second and third vertical support in the project can be optimized and steel support can be used instead.(4)Combined with the geological conditions of the foundation pit project and the characteristics of the support structure,a targeted on-site monitoring scheme for the foundation pit was developed,with emphasis on monitoring.The main test items include the horizontal displacement of pile body,settlement of pile body and settlement of ground points on both sides of foundation pit.Through field measurement,the results show that each test item is less than the warning value needed to ensure the safety of foundation pit,which further verifies the feasibility of the scheme. |
