Analysis On Excessive Deformation During Deep Foundation Excavation In Soft Soil Area

For a foundation pit, if the deformation is excessive, not only the safety of the pititself will decline, but also surrounding buildings, roads and underground pipelineswill be cracking damage due to uneven settlement and their normal function will beaffected, which have negative social impact. Therefore, it is important to analyze theoccurrence mechanism and control measures of excessive deformation to protect thesurrounding environment of foundation pit.On the basis of the summary on the characteristics, mechanism and influentialfactors of the excavation deformation, excessive deformation due to excavation isstudied by using the finite analysis method and the main conclusions are as follows:(1) When the deformation of retaining wall is excessive, the distribution ofground displacement corresponsive to different deformation mode of retaining wall donot change. The areas of angle strain and horizontal strain corresponsive to cantileverdeformation mode both increase. The areas of angle strain and horizontal straincorresponsive to kick-in, convex, composite deformation modes do not increase, butthe compressive strain area reduces, the tensile strain area increases. For theincreasing rate of angle strain and horizontal strain, the convex deformation mode islargest, the kick-in and composite deformation modes are less, and the cantileverdeformation mode is smallest.(2) When the foundation is excessive excavation, the embedded depth of retainingwall is inadequate and the distance between the last support and the bottom offoundation pit is too large, thus leading to excessive deformation of foundation pit.When the foundation is excessive excavation, the deformation of foundation pit ismore sensitive to the change of excavation depth, excavation range and excavationposition.(3) When the foundation is excessive excavation, the appropriate increase ofstiffness of retaining structure can be useful to control the deformation of foundationpit and improve the stability of foundation pit, but too large increase is less useful.When the foundation is excessive excavation, reinforcement the bottom soil offoundation pit is the most effective measure to control excessive deformation and toimprove foundation stability. (5) To control excessive deformation of foundation pit, it is not only necessary tocontrol the occurrence of local excessive deformation, but also necessary to improvethe ability that the foundation pit resists continuous excessive deformation, namelythe deformation redundancy of foundation pit.For the convex foundation pit,reinforced wale will be needed to improve the horizontal continuity of retaining walland improve the deformation redundancy of foundation pit.