Research On Mechanism Of Cooperative Work Of Socketed Piles And Entrust-pillar Transfer Foundation Beam

In recent years, rapid-developing economy led to increasing shortage of buildinglands. Underground cavity and some existed structures requires minimum centerdistance of piles. That leads to a difficult construction of caps and we need to reduce thecost. Therefore in the multi-storey frame structure entrust-pillar transfer foundationbeam supported on the rock-socketed pile on the situation has occurred.Superstructurescan be set on foundation beams by pillars, and loads from foundation beams can betransmitted to rock-socketed piles. Though there are some advantages of foundationbeams supported by pillars, its disadvantages cannot be ignored. Nowadays, based onconversion beams supported pillars, designing foundation beams supported pillarsconsidered piles as frame-supporting pillars, while actual mechanical characteristics ofpiles differ from frame-supporting pillars. Frame-supporting pillars mainly bear verticalloads transmitted from superstructures without lateral restraints, while piles bear verticalloads, as well as constraints of soils around. Deflection occurs in foundation beamsunder large loads from pillars and that leads to supporting force if soil layer underfoundation beams is fine. When considering the interaction of the beam on the wall, theproblem is further complicated. Thus, impacts of supporting force and lateral force onthe stress performance of the system is worthy of being studied when rock-socketedpiles and column supporting foundation beams are in cooperative work.There exists a large number of researches about entrust-pillar transfer beam androck-socketed piles, but few were about cooperative work of rock-socketed piles andfoundation beams supported by pillars. Based on the theory, performance of cooperativework of rock-socketed piles and foundation beams supported by pillars androck-socketed piles in one construction site in Chongqing, an analysis on reasons andmain factors was conducted by comparing conversion beams supported by pillars in thispaper. Mechanical performance of foundation beams supported by pillars androck-socketed piles was obtained and suggestions to design were proposed.Main works in this paper are as follows:①Experiments. Based on a construction of entrust-pillar transfer foundationbeam and rock-socketed piles in Chongqing, data in different construction stagesmeasured by reinforcement meters buried in foundation beams supported by pillars androck-socketed piles were processed. Internal force on key sections was calculated and compared with working performance of conversion beams supported by pillars. Further,mechanism of rock-socketed piles and foundation beams supported by pillars’cooperative work was concluded.②Numerical Simulation. A numerical model similar to actual situation wasmodeled in ANSYS by some rock and soil parameters acquired from one foundationconstruction in Chongqing. Internal force on sections of rock-socketed piles andfoundation beams supported by pillars under different loads was computed and bycomparing with values from SATWE and ANSYS, test values, some conclusions inChapter3were verified.③Influence factors. According to mechanism of cooperative work ofrock-socketed piles and entrust-pillar transfer foundation beam and combined withactual performance in rock-socketed piles and foundation beams’ construction, anumerical analysis on the impacts of overlaying soil, rock-socketed depth and basementon cooperative work performance was conducted to supply suggestions to design.Through experiments and numerical analysis, actual stress values on importantsections in socketed piles and entrust-pillar transfer foundation beam are smaller thancomputed values, so design nowadays is conservative. Therefore, the current design hasoptimized space.