Analysis And Research On Design Theory Of Retaining Structure With Double-row Pile

At present in the reclamation, two problems in the face of the deep foundationpit：One is the soft soil, the other is highly permeable aquifer. Deep foundation pitsupport and stopping the water must be unified considering，many past supportmethods are not suitable for soft soil and strong permeable aquifer. In addition,because the inner support lead to complexity in large span in foundation pit，In theproject, the double cantilever retaining piles supporting water system is more andmore used in the design of deep foundation pit.The main research contents in this paper include theory:(1)The calculationmethod and model of elastic foundation beam.(2)The spatial effect of earth pressure.(3)The deformation coordination role of crown beam.(4)Distribution of soil pressureon the pile.(5)Calculation model of double-row pile theory.(6)Before and after theretaining structure with double-row piles and piles of quantitative proportion.(7)Common pile types and characteristics of double-row piles. Combined withengineering cases, the Bank of Jinzhou deep foundation pit are analyzed, includingthe simulation of excavation and analysis of effect of supporting simulation andstructural parameters of the properties of deep foundation pit, obtained the followingconclusions:(1)In the front row pile quantity, through theoretical calculation and derivation,can draw the minimum number of back row pile, has certain directive significance tosave the engineering cost.(2)The front row piles and the back pile under positive moment size isapproximately the same, the size of the front pile negative moment was significantlygreater than that of back pile, front row pile retaining effect is the main structure.Double-row piles is a top-down from the pressure to pull over process.(3)The row spacing of double row pile supporting system of great influence,row spacing is too small of double-row pile is equivalent to a single row pilesupporting system; row spacing is too large structure system is equivalent to the pileanchor bracing system, the back row piles with cap beam equivalent to anchor role, reasonable spacing in the range of3～5times the pile diameter.(4)The reasonable pile length and contact the strength of the beam to reduce thestructural displacement and inner force distribution is of great help, but beyond acertain threshold, increasing the pile length and the contact stiffness is meaningless.For the pile diameter is1.2m supporting pile: reasonable pile length is21m~23m, theembedded depth of at least3.5m, main rib section of reasonable reinforcement ratiofor2%~3%.