Construction Monitoring And Numerical Simulation Of Deep Excavation

Along with China’s economic developing,various municipal projects and construction project shave also been developing,deep foundation excavation is increasingconstantly. In engineering applications,deep excavation accidents occur frequently due to improper design and construction,resulting in a huge economic and life lost.So,it is necessary to conduct site monitoring and numerical simulation analysis todeep foundation excavation and ensure the safety and stability of deep foundation excavation.This paper take a deep foundation excavationin Hefei as the background,combining three methods of theoretical analysis, field monitoring and numerical simulation,study the laws of deformation、internal force and surrounding ground settlement of deep foundation pit support structureunder support scheme of “enclosure wall +inner support”combining theoretical analysis, field monitoring and numerical simulation,as reference and reference for practical engineering projects.The main research contents of this paper are as follows:(1)Analysis and research on the type of deep foundation pit structure, deformation mechanism, influencing factors, calculation theory and research status.(2)Taking the example of deep foundation pit engineering in Hefei as the background,determine the monitoring contents, monitoring points layout, monitoring scheme and implementation details of the deep foundationpit,organize the monitoring data of actual excavation engineering,analyze the laws of deformation、internal force and surrounding ground settlement of deep foundation pit support structure.(3)Establishfinite element of thefoundation pit excavation with finite element analysis software MIDAS/GTS,and conduct numerical simulation to deep foundation pit,then compare the simulation results with the monitoring results,it is found that the results agree well with each other and all in a stable and safe range.The results show: With the increase of excavation depth, the maximum lateral displacement value continued downward, the supporting structure displacement curve by linear approximation gradually transformed into a parabolic curve;In the early stage of foundation pit, the ground surface settlement is slow, the middle stage is accelerated, and the later stage is stable;Heave maximum occurs at the bottom of the middle, showing the distribution of "large middle and small on both sides";The inner supporting axial force increases gradually with the increase of the excavation depth of the foundation pit.(4)Based on the numerical model, make an intensive study of the influence of the shear strength parameters(cohesion and internal friction angle), wall thickness and embedded depth on the stability of supporting structure.The results show that the increase of soil shear strength, has a very good effect on deformation of retaining structure, but when added to a certain amount, the constraint effect is not obvious;The increase of enclosure wall thickness and the embedding depthis conducive to reduce the deformation of supporting structure,but when both of them reach a certain extent,the effect is limited and will also greatly increase the cost,So it is necessary to ensure the stability of the structure under the premise of saving cost.