Analysis Of Space-time Effect Of Deep Foundation Pit Deformation In Soil-rock Composite Stratum

In the excavation process of foundation pit engineering,it will inevitably have a certain disturbance to the surrounding soil,and cause the deformation of foundation pit and the uneven settlement of the surrounding surface.It will cause the surrounding buildings and underground pipelines to deform and even destroy,which will seriously cause engineering accidents and even casualties.At present,the deformation caused by deep foundation pit excavation at home and abroad pays more attention to soft soil area,but less research on deep foundation pit excavation in soil-rock complex area.Therefore,based on the deep foundation pit engineering of a subway station on Urumqi Line 1,this paper studies the characteristics and rules of the space-time effect of the deep foundation pit deformation in the soil-rock composite stratum and carry out the following tasks:Firstly,this paper studies and summarizes the research status of deep foundation pit deformation and space-time effect at home and abroad,understands the research history and current progress in this direction,and puts forward the main contents and four expected objectives of its own research.Secondly,the mechanism of space-time effect of deep foundation pit deformation is analyzed theoretically,and the main influencing factors of foundation pit deformation are summarized.Thirdly,taking the Metro Station of Urumqi Line 1 as the engineering background,aiming at the monitoring data,focusing on the deep foundation pit surface settlement and the deformation characteristics of the retaining structure,the law is analyzed.The temporal and spatial effects of deep foundation pit deformation in soil and rock composite strata are studied.Then,using Midas GTS NX finite element software is used to calculate and simulate the excavation of deep foundation pit,and the process of excavation is analyzed.The generated displacement cloud diagram can vividly describe the dynamic evolution process of foundation pit deformation.It is possible to study the space-time effect characteristics of deep foundation pit deformation directly and compare the simulation results with the field monitoring data to verify the rationality of the calculation model.Finally,in order to reduce the deformation of deep foundation pit in soil-rock composite stratum by using the theory of space-time effect,the influence of supporting and non-supporting of foundation pit,the influence of trench excavation and non-trench excavation on the deformation of foundation pit are studied andanalyzed.According to the research results,several control measures based on space-time effect theory to control the deformation of deep foundation pit are put forward.The final research shows that the deformation of deep foundation pit in soil-rock composite stratum has obvious space-time effect,and the deformation of foundation pit can be restrained by making use of the space-time effect reasonably,and the construction cost can be reduced effectively,and the safety of construction can be improved.The rationality provides a good safety guarantee for the design and construction of deep foundation pit engineering.