Research On The Deformation Of Adjacent Building Caused By Loess Foundation Pit Excavation And Dewatering

Currently, a large number of pits conducted in dense buildings. Deep foundation pit dewatering project in dense buildings can easily deform neighboring buildings, therefore,in the excavation pit precipitation process,deformation prediction of neighboring buildings is urgently to be strengthened. Especially for loess area, research on fluidsolid coupling of foundation pit excavation and dewatering should be reinfored, and study on the influence of different excavation depth on different neighboring buildings is insufficient. Thus, a lot of work has been done as followed.In this paper, the seepage and consolidation coupled were considered, FLAC3D was applied as numerical simulation software, the numerical analysis of loess precipitation model tests was conducted, theresults were comparedwith the test, and the fluid-solid coupling model was validated to be reasonable. On this basis, influences of only precipitation and precipitation-excavation of foundation pit on neighboring buildings were analyzed emphatically. The results concluded as followed:1) Through the numerical simulation of loess precipitation model test and resultant comparison. The method to construct model and the selection of parameters are verified to be reasonable; there is a uniformity among the pore water pressure, porosity and land subsidence, namely, both of porosity and land subsidence are great as the pore water pressure changes are big. Besides, changes in sedimentation loess soil always lags behind that of pore water pressure.2) In accordance with the method of precipitation model test numerical analysis, the existence of buildings with different base form and arrangement position was considered, and the influence of only precipitation foundation pit on the different buildings around. The results indicate that:(a) Precipitation of foundation pit has a great effect on the settlement of adjacent shallow foundation buildings, and has less effect on adjacent buildings with deep foundation, (b) Precipitation is be prone to cause the differential settlement of buildings, which has a large span along the direction of precipitation radius.3) On the basis of the foundation pit drainage model, a comprehensive analysis of the effect of precipitation-excavation of foundation pit on adjacent buildings, the results show that: (a) During the process of pit precipitation and excavation, the subsidence and tilt of shallow foundation increased with the increase of excavation depth, and maximized as the excavation depth was 1 to 2 times as the adjacent shallow foundation depth, (b) There is less influence on adjacent pile foundation in the process of pit precipitation and excavation, because the pile depth of sdjacent pile foundation building is bigger. When excavation depth got to or below a third of the adjacent pile foundation depth, the settlement of pile foundation increased with the increase of excavation depth, but the tilt of buildings with pile foundation kept small.4) With the increase of precipitation excavation depth of foundation pit, the horizontal displacement of foundation pitsupport structure increased, and the maximum horizontal displacement position gradually moved downward, besides, the postion of maximum horizontal displacement distance from the top of the foundation pit is about 1/3 of excavation depth eventually. In addition, both of the upheaval in the bottom of pit and surrounding ground settlement increased with the increase of excavation depth.