The Test Research On Vertical Bearing Mechanism And Application Of Rock-socketed Pile

Rock-socketed pile is an important type of the pile foundation. It has high bearingcapacity, small settlement, weak pile group effect, and simple construction. So it is widelyused in the engineering of bridge, port and construction. But because of rock-socketed pile’sfoundation has difficulty in destructive test. Theoretically, it has some questions which needto be further researched in constitutive model of soil, constitutive model of rock andquantitative study on deformation mechanism of pile and the pile and soil. In respect ofdesign, specification method is still based on half theoretical and half experience calculationformula to determine the vertical bearing capacity of rock-socketed pile, And the difference ofbearing capacity computing of rock-socketed pile is big in different nations industry and areastandard. In-situ test is the most direct and the effective method for the study of rock-socketedpiles. This paper uses field test and numerical simulation methods to study the verticalbearing mechanism of rock-socketed pile. The concrete work includes:(1). According to sorting the existing experimental data, the rock-socketed pile’s loadtransfer law under vertical load is described, and rock-socketed pile’s effect of bearingperformance by pile modulus ratio, the ratio of length to diameter, embedment ratio, holecleaning condition are analyzed. Rock-socketed pile’s vertical bearing capacity is composedof side resistance of the soil cover, side resistance of the rock and tip resistance. The designallowable value of the rock-socketed pile’s vertical bearing capacity is confirmed by thestrength of pile material, the vertical displacement of pile top, rock and soil resistance and soon according to the research of the pile frictional resistance, rock friction pile and the pile tipresistance.(2) The AASHTO LRFD Bridge Construction Specifications、British standard Code ofpractice for Foundations:BS8004-1986、French bridge specification、ENV1997—1-Eurocode7and Chinese Standards are introduced. The characteristic of the standard in different nationsand industries and the problem of the quantitative estimation of rock-socketed pile’s bearingcapacity are analyzed.(3). Which I participated in the design of Nanjing metro line three viaduct as engineeringbackground, according to the requirements of the design in the field using the balance methodto carry on the static load test of piles were taken, through three spot test pile data analysis,that axial force distribution of pile, pile side resistance distribution, finally the single pilevertical ultimate bearing capacity is determined. The method of the numerical simulation ofself balance and static load test of traditional is used in the metro line three in Nanjing by MIDAS/GTS. The GTS analysis is verified feasibly compared the result of numericalsimulation and the field test data.(4) The rule of the rock-socketed pile bearing capacity is used in the engineeringconstruction by GTS simulation in the design of metro line three in Nanjing and the bridgedesign of Zambia. Such as the pile foundation (d=1.2m and d=1.5m) of the metro line threeand the pile foundation (d=1.8m) of the bridge design of Zambia. Thereby verifying thereliability of the pile foundation design values.