Research On Deformation Properties And Affect Factors Of Subway Station Foundation Pit In Taiyuan Clayey Silt And Silty Clayareas

Clay with high-moisture and non-negligible creep may result in the increasing deformation of enclosure wall, even cause frequent engineering accidents. For the clay areas with high-moisture, the reasonable choices of supporting parameters and the results of soil creep influence on deformation are significant.The rules of foundation pit deformation and movement could give enlightenment on similar projects construction in the future.Taking Zhongxinjie station in the first excavation section of Line 2 as research background and by investigating the engineering geological conditions,numerical calculation and theoretical analysis, gray correlation analysis, this study explores the foundation pit deformation and movement rules in Taiyuan clayey silt and silty clay areas and corner effect, supporting parameters and the soil creep influence on deformation. At last the strength of the relationship between deformation and supporting parameters has been determined,influencing factors of primary and secondary relations have been obtained. On this basis, considering the construction process of the time effect on thedeformation of deep foundation pit, the thesis analyzes its deformation law from the perspective of technology and economy, and further puts forward the measures and methods to control the deformation of foundation pit. By the present study, the following discoveries has been made:(1)This study studies soil layer distribution and mechanical properties in this area where Rail Transit line 2 passes through and the place where Zhongxinjie station is located, and summarizes the effect of poor geologic conditions(high groundwater level, Seismic liquefaction, special soil) such as engineering difficulty increasing, ground stability weakening, intensity decreasing etc...(2)According to the research on the foundation pit deformation rules, this dissertation shows the causation of enclosure wall deformation, upheaval of the pit bottom and displacement of surrounding surface. Taking numerical calculation as measure, this thesis shows that enclosure wall shifts from triangle to cambered in its pattern with the advancement of engineering project, the deformation in the pit bottom is large at the center and small at the corner,surrounding surface turns to be fluted, corner effect is significant and the difference of deformation between pit corner and middle part of long side is large.(3)Based on numerical calculation and gray correlation analysis, this dissertation studies the relativity between supporting parameters and supporting effect. The results show correlation degree from high to low is enclosure wallinsertion ratio, enclosure wall thickness, steel pipe space, steel pipe thickness,prestressing value or steel pipe diameter.(4)By using Revised-CVISC model, the construction time in practice is equilibrated. On the base of analysis over the influence of soil creep on foundation pit deformation, the current study shows that soil creep has the greatest impact on the deformation of enclosure walls, upheaval of the pit bottom take second place, and then follow the deformation of surrounding surface. And further puts forward the measures and methods to control the deformation of foundation pit..