Study On The Interaction Effect Of Blasting Excavation Of Deep Rock Foundation Pit And Adjacent Existing Foundation Pit

At present,the development and utilization of urban underground space is developing rapidly in China.Under such a great background,the environment of deep foundation pit excavation is increasingly complex,more and more engineering cases of two or more adjacent deep foundation pits are simultaneously or successively excavated are producing.The safety and stability of excavating pit and its adjacent foundation pit has become an important problem in its construction and construction process.In order to analyze the safety and stability of city rock deep foundation pit and its adjacent existing foundation pit in the process of blasting excavation,study the mutual influence between them,this article conducted the research on two pits' deformation characteristics and propagation law of blasting vibration wave along pits' slopes in the process of unloading excavation,based on methods of theoretical analysis,numerical simulation and field measurement.The specific content and results are as follows:Firstly,slope displacement of Jiasheng deep foundation pit and nearby existing foundation pit is monitored,then selected typical profile monitoring data is analyzed,so that changing regulation with the excavation depth of two foundation pits' slope displacement can be obtained.Secondly,the full dimension numerical simulation of the whole process of foundation pit excavation is carried out by using MIDAS/GTS software.To analyze the variation trend of two foundation pits' slope displacement with excavation depth,and compare it with field measured data,then interinfluence effect of two foundation pits can be summarized.Impacts of construction materials' loading on the safety of foundation pit are analyzed by applying simulated uniformly distributed load on the top of two foundation pits.So that safety and stability of foundation pits under the existing load conditions can be estimated.In the end,blasting vibration values of foundation pit excavation are monitored by installing monitoring instruments at the top of two foundation pits.The slope is divided into two regions by formula derivation and monitoring data fitting,so that the elevation range of the slope when the blasting vibration is amplified and attenuated can be obtained.Besides,the numerical simulation of blasting vibration wave's propagation law on the slope is carried out by using ANSYS/LS-DYNA software,thus elevation amplification effect of blasting vibration is further confirmed by comparing data of field monitoring and numerical simulation.