Analysis And Application Of Double-row Piles With Different Stiffness And Length Combination In Deep Soft Soil Area Of Shantou

As a common supporting form in deep foundation pit engineering,double-row piles supporting structure is more and more widely used in foundation pit and slope supporting engineering,because there are many advantages,such as convenient construction,no needs of internal support,and saving construction time etc.However,the mechanism characteristics of double-row piles support structure are not very clear at present,especially in the application of irregular double-row piles supporting structure with different length and different stiffness in deep soft soil,and there are few research about this issue.Based on the retaining structure with double-row piles in deep soft soil area of Shantou engineering case,firstly,this paper proposes the double-row piles structure with different stiffness and different length in the deep soft soil area on the basis of the conventional double-row piles support structure;secondly,through the numerical simulation by Midas GTS NX finite element software,the influences of different parameters of length of the pile,stiffness of the pile,etc.,are analyzed to determine a reasonable combination mode;finally,the actual measured data is used for verification.The results show that through reasonable design optimization and comparative analysis,the proposed doublerow piles structure can not only meet the economic and reasonable requirements but also ensure the premises of safety.The results can provide a significant guideline for the application of irregular double-row piles support structure in deep soft soil in the future.The main work and research results of this paper are as follows:(1)This paper summarized the relevant research results of conventional and irregular double-row piles supporting structure at home and abroad.Moreover,the sources,assumptions,advantages and disadvantages of the calculation methods,and the rationality of their application were expounded.Finally,the idea that the support structures with different stiffness and different length can be adopted in the deep soft soil area was proposed.(2)Using the finite element software Midas GTS NX,the numerical model of the combined retaining structure with double-row piles of different stiffness and different length in the deep soft soil was established.Furthermore,the influences of different parameters of length of the pile,stiffness of the pile,stiffness of the linkage,passive area,soil parameters,overload,etc.,were studied and discussed.Based on the numerical results with different influence factors,their impacts on the stress and deformation of the retaining structure were summarized.According to the results,some reasonable suggestions were proposed for the design of doublerow pile supporting structure in deep soft soil.(3)Based on the successful cases of double-row piles supporting structure with different stiffness and different length in deep soft soil area of Shantou,the monitoring data and calculation results were compared and analyzed,which verified not only the rationality of the calculation model,but also the feasibility of the application of double-row piles supporting structure with different stiffness and different length in deep soft soil area.The combined double-row piles supporting structure could save the engineering cost compared to the conventional double-row piles supporting structure.(4)The matters need attention and destruction treatment plans during the design and construction process of the double-row piles support structure with different stiffness and different length in the deep soft soil area were proposed.