Analysis And Research On The Bearing Performance Of Rock-socketed Piles Under Different Geological Conditions Based On Self-balance Test

In recent years,with the development of economy,There are many tall,heavy and large buildings have been built in Guiyang.Pile foundation has been widely used in this process,especially rock-socketed pile.Guiyang area belongs to karst region.it has more complex geological structure and relatively rich lithology.There often has thin overburden upon the rock,which leads many buildings to choose their bearing layer over thick,undulating,broken or more broken rock.It improved the development of rock-socketed pile.However,as for the common rock in Guiyang area,how to exert the bearing characteristics of rock-socketed pile is still unclear.So,this paper selects four groups of common rock in Guiyang area to carry out self-balancing static load test,to analyze and study the bearing characteristics of rock-socketed piles under different geological conditions.There are main contents of this paper:?1?Introducing the research status at home and abroad and the purpose and significance of this paper?2?Introducing the common engineering geological condition and rock types in Guizhou;The basic conditions of several common rocks around Guiyang are introduced.?3?The methods of field test are briefly introduced,the working principle of self-balanced static load test is briefly introduced,and the load transfer mechanism of rock-socketed pile is introduced.?4?Introducing the physical and mechanical indexes of bedrock and the basic situation of pile test.According to the field test and test results under different geological conditions,the ultimate bearing capacity of pile foundation is calculated.According to the axial force distribution of each pile in the field test,the lateral friction resistance and end resistance of each pile are calculated respectively,and the distributions law is analyzed by the corresponding distribution curve.By comparing the magnitude and performance of pile lateral friction and pile end resistance under various geological conditions,calculating the ratio of the ultimate bearing capacity of the side of pile and the end of pile.Among them,the strongly weathered argillaceous limestone?0.133?>the medium weathered mud stone?0.097?>the medium weathered argillaceous dolomite?0.082?>the strongly weathered argillaceous dolomite?0.063?;Calculating and comparing the capacity of rock-socketed pile under three current Specification,It is concluded that the calculated value of the vertical ultimate bearing capacity of a single rock-socketed pile is not much different from the measured value,and most of them are safe.Considering the actual safety of the project and the similar geological conditions in Gui Yang area,it is suggested that calculate the bearing capacity of rock-socketed piles by using the calculation methods provided by these two specifications;In addition,about the four geological conditions in this paper,the calculation method adopted by the local standards of Gui Zhou province is closer to the measured value than the technical specification of construction pile foundation,and the relevant experienced parameters in the technical specification of construction pile foundation need to be further improved.?5?Introducing the finite element method and simulation software FLAC^3D.The field test is simulated by FLAC^3D,which is used to analyze the action of rock-socketed piles,and analyze the rationality and feasibility of the rock-socketed piles under self-balancing static load test.According to the test data recorded by the simulation software,the limit value of pile lateral friction resistance under each rock layer are calculated.Comparing the simulated value with standard value and the measured value to analyze the error causes,which is paid more attention in engineering practice.