Study On Deformation Characteristics And Control Of Deep Foundation Pit Affected By Reverse Fault Fracture Zone

Based on a power tunnel engineering of JW-24 nodes（A foundation pit,fault fracture zone within the scope of influence）and JW-25 nodes（B of foundation pit,fault fracture zone scope）two qualification well foundation pit engineering as the background,the in-situ monitoring data and finite element numerical analysis and comprehensive comparison and analysis methods,the inverse fault fracture zone the influence of the deformation law of deep foundation pit project,At the same time,the actual effect of deformation control measures such as grouting reinforcement method and changing structural parameters is analyzed.Through Midas GTS NX finite element numerical simulation and data analysis software,combined with the actual monitoring data,comprehensive analysis of the impact of reverse fault fracture zone on the deformation characteristics of deep foundation pit,optimization of the foundation pit construction scheme.Studies on the impact of reverse fault fracture zone on deep foundation pit deformation are shown as follows:（1）The failure mechanism of the reverse fault fracture zone was studied,and two types of instability failure modes of deep foundation pit engineering in the reverse fault fracture zone were analyzed.Through the comparative analysis of the strata in the rupture zone of the reverse fault and other strata,it can be seen that the variation of dead weight stress in the rupture zone of the reverse fault is relatively small,and the variation of tectonic stress is obvious.The deformation form of retaining structure in the rupture zone of reverse fault is complex,which belongs to the combination form of cantilever deformation and parabolic deformation,and the variation form of surface subsidence belongs to groove subsidence.According to the data analysis of compression test and fast shear test provided by geological prospecting report,it can be seen that the cohesion and compression coefficient of rock strata in the fracture zone of reverse fault have obvious changes compared with other rock strata in the same region.（2）Midas GTS NX geotechnical analysis software and data processing software were used to compare the deformation differences between foundation pit A and foundation pit B under different working conditions.Through the analysis from four aspects: surface settlement form,displacement law of retaining structure,numerical change of axial force of internal support and uplift trend of pit bottom,The rupture zone of reverse fault has great influence on the maximum surface has great influence on the horizontal displacement field of δvm and rock and soil layers and the displacement of the pile body and pile top of the retaining structure.The curve changes of the retaining pile,inner support and surface settlement are analyzed by comparing the results of Midas GTS NX numerical simulation and actual monitoring.value and simulation value there is A certain difference,but the overall trend is the same,by Midas GTS NX geotechnical software of foundation pit is established model can be used to simulate the reverse fault fracture zone of deep foundation pit construction condition of regional.（3）The variation law of δvm of maximum surface subsidence,subsidence morphology,variation trend of horizontal strata displacement field and influence range of surface subsidence under the influence of reverse fault fracture zone are summarized.The horizontal displacement change rule of the retaining structure of foundation pit A was analyzed.The numerical simulation results show that the deformation of the envelope is affected by the spatial effect.By analyzing the deformation curve of the envelope,the deformation of the long axis side of the envelope is larger than that of the short axis side,consider the influence of spatial effect on the deformation of deep foundation pit,and compare and analyze the influence of material strength and structural thickness on the deformation of retaining structure.The variation law of the maximum heave at the bottom of pit a is studied,The thickness of grouting reinforcement in a certain range has a controlling effect on the heave of pit bottom.（4）By establishing a correlation model,the influence of fault fracture zone and foundation pit horizontal Angle of 0°,30°,45°,60° on the deformation of deep foundation pit was analyzed,and the influence law of reverse fault fracture zone Angle on the horizontal displacement of retaining structure was summarized.By simulating different grouting reinforcement ranges in the rupture zone of the reverse fault,the influence of grouting reinforcement ranges on the deformation law of deep foundation pit in the rupture zone of the reverse fault is studied.With the expansion of grouting scope in the rupture zone of the reverse fault,the control effect of grouting reinforcement measures on the surrounding surface subsidence deformation is more significant.The larger the area of grouting reinforcement is,the slower the horizontal displacement of the envelope decreases,and the weaker the control effect of grouting reinforcement measures on the deformation of the envelope.Figure [86] Table [13] Reference [63]...