Numerical Simulation Analysis Of The Composite Supporting Structure Of Double-row-piles And Anchor

In recent years,with the development of economy and society,people are always yearning for high-rise buildings,super high-rise buildings and all kinds of out of gauge complex structure forms,making the structure’s requirement for underground engineering higher and higher,the excavation depth and the area gradually increased,at the same time because of complex underground space structure forms,construction and various underground facilities,such as big underground parking lot,underground commercial street,large subway station,complexity the excavation and foundation support technology is also rising.Therefore,how to design,construct and monitor foundation engineering problems reasonably and safely has become an important topic.At present,the form of excavation diversification of the composite supporting structure of double-row piles and anchor integrated the structure of double row piles and pile anchor supporting system’s traditional advantages,especially in the face of the surrounding environment for engineering and hydrogeological conditions,and complex subway station with the deformation control requirements are particularly stringent in,have development great potential.Although there are many successful cases in the actual project,the research of deep load mechanism is not enough,especially the form of earth pressure and the interaction between soil and pile.For the composite supporting structure of double-row piles and anchor system,the influence of various factors,especially the location of anchor,the length of anchor bolt,the size of prestressed anchor,and the number of anchor bars on the structure’s stress and deformation need further discussion and further research.Therefore,this paper studiesthe composite supporting structure of double-row piles and anchor,and the main contents and conclusions are as follows:1.The three-dimensional numerical model of the composite supporting structure of double-row-piles and anchor was established by MIDAS/GTS to analyze the deformation of the composite supporting structure of double-row-piles and anchor of the internal force,the basic characteristics are analyzed and compared,and the results show that compared with the simple structure of double row pile front and rear row pile bending moment of pile horizontal displacement amplitude and the amplitude decreased significantly,the prestressed anchor added to better improve the ability of structure to resist lateral displacement;in addition,the bending moment of front and rear piles is more close,and the reinforcement design is more conducive because of the prestressed anchor.2.At the same time,it focuses on the influence of the depth of anchor,the length of anchor,the size of prestressed force,the number of anchor vertical rows and the lateral rows.The following main understandings and conclusions are obtained:With the depth of anchor position decreases,the horizontal displacement of the front row pile with anchor pile composite structure decreases continuously,reaching the corresponding simple double front row pile displacement amplitude position minimum,and then increased slightly;then the row pile horizontal displacement does not change significantly.At the same time,the bending moment amplitude of the pile body is minimized at the position of the moment of the bending moment of the front row pile of the corresponding simple double row pile structure.With the increasing force of prestressed anchor,the displacement of pile body and the bending moment of pile body in front and rear piles are decreasing,and it is basically linear decreasing.For the composite supporting structure of double-row piles and anchor,by increasing the number of anchor rows,the bending moment and horizontal displacement of the front and rear row piles can be reduced,and the reduction is greater than other factors.At the same time,the anchor is applied simultaneously at the position of the amplitude of bending moment and the position of the horizontal displacement amplitude at the same time,and the effect is better.With the increase of the length of anchor pile,horizontal displacement amplitude of the overall downward trend,but when the length reaches about 3 times the depth of foundation pit tends to be stable,so in the actual engineering design,considering the internal force,deformation,considering the economic and convenient construction principle,general 2-3 times the depth of foundation pit is appropriate.For the composite supporting structure of double-row-piles and anchor,through the combination of the different effects of the factors,especially the optimal combination,can make the pile depth before and after each horizontal displacement decreases,displacement amplitude decreases by up to 45%,at the same time front and rear pile bending moment was also decreased,the amplitude of bending moment decreases by up to 37%.In addition,because of decrease of the spacing of lateral anchor the decrease of the bending moment and deformation is also very obvious.3.At last,compared with the results of numerical simulation and theoretical design of the composite supporting structure of double-row-piles and anchor,the reasonableness of the results is proved.