Research On Deformation Of Deep Foundation Pit Diaphragm Wall Retaining Structures Based On The Time-space Effect

With the enhancement of the national economy and rapid development of economic construction,the process of urbanization is also accelerating.After the1990s,as the depth of high-rise building pit and underground engineering is large,deep foundation construction is becoming one of the city’s main geotechnical engineering.Today,the foundation pit engineering also has some new features.For example,the increasing depth and width,pit density becomes more dense,appear more support method,excavation engineering geological condition becomes worse,especially in large-scale deep soft soil area it appears more important during the construction.In addition,the excavation process of foundation pit is closely related with time and space.How to consider the deep foundation pit deformation under the influence of the space-time effect becomes very important.This article discussed the deformation of underground continuous wall envelope during in the process of deep excavation based on the time-space effect theory and incremental principle method.Firstly,the article preliminary introduced and analyzed the types of pit deformation and some influencing factors.The deformation is broadly divided into three types:pit foreign soil deformation,envelope distortion and pit uplift deformation. Summary of the main factors include design factors,construction factors and geological factors.Then it pointed out the influence and their impact on the excavation retaining structure deformation effect based on the theory of time-space effects.Secondly,academician Liu Jian-hang proposed the time-space effect theory by considering the level of time and space effects on excavation and design.The horizontal resistance coefficient of soil related to the time,space,geological conditions and reinforcement conditions etc. It is a function of excavation time,space,formation soil conditions,reinforcement conditions,environmental conditions,etc.That is able to reflect the effect of time and space effect during excavation.On this basis,the paper divide the deformation envelope into two parts.One part is calculated according to the geological conditions of the deformation parameter and the other one is to consider the impact of time-space effect.The sum of two parts is the total amount of deformation of retaining structure.Compared deformation values calculated with measured values,conclusions can be got.Through detailed calculations and analyzes about a excavation deformation examples. We found that the total amount of deformation when considering the impact of time-space effects and deformation increments every step of the conditions,that is more in line with the actual situation when comparing with the measured values.In addition,we can see that the greater distance from the location of the excavation section,the smaller impact of time and space effects during excavation.Thus it can be seen that the time and space effect is mainly affected the area excavation section,the influence trend is gradually reduced at both ends.