Deformation Of An Expanded Deep Excavation In Loess And Its Neighbor Structure Responding Features

Deep foundation pit engineering is widely used in the construction of urban open cut tunnel and large-scale building underground structure.With the development of urbanization,the scale and depth of foundation pit engineering are also increased.The deformation characteristics of foundation pit and its influence on adjacent structures are concerned.In the design and construction control of foundation pit engineering,it is usually necessary to consider the influence of geotechnical engineering conditions,excavation depth of foundation pit,performance of retaining system,construction methods and procedures.For projects with long-term stagnation in the process of foundation pit construction,the influence of early construction status and construction interruption can not be ignored.Based on the results of field monitoring and numerical analysis,the deformation of loess foundation pit and the response characteristics of adjacent structures are analyzed.(1)On the basis of summarizing the deformation characteristics and main influencing factors of loess deep foundation pit,combined with the geotechnical engineering conditions,structural characteristics,construction process and the status quo of adjacent structures,the main factors affecting the deformation of retaining system and the supported soil in the process of foundation pit expansion are analyzed,and the basic characteristics of foundation pit deformation and adjacent structure response are given.(2)The field monitoring results show that in the process of foundation pit excavation,the deformation of retaining system and retaining soil and the response characteristics of adjacent structures are as follows: the maximum settlement of buildings occurs at the corner of adjacent foundation pit,and for the same building,the final settlement difference of each monitoring point is small,which will not produce differential settlement,and cause less damage to the building structure.(3)The results of field monitoring and numerical analysis show that,compared with the conventional continuous construction projects,the horizontal displacement of pile top of expanded excavation has experienced two rapid growth and slow change processes,that is,there are two sudden changes.The spatial effect of foundation pit excavation is not obvious,and the horizontal displacement curve of pile top is approximately "s" shape;(2)the settlement of pile top of slope protection pile is almost not affected by precipitation;(3)slope protection The horizontal displacement of the cantilever end of the pile is less than that of the middle part of the pile.