Study On Vertical Bearing Capacity Of Jacked-in Pipe Pile In Songhua River Floodplain Areas

Jacked-in pipe pile is widely used in practical projects with the merits of vibrationlessness, noiselessness and low cost of supervising the entire process.If the bearing capacity of a single pile is determined based on the empirical formula of the current design code,generally it will much lower than that by static load text.This inevitably led to the low bearing capacity of single pile,the result is a waste of project cost,the jacked-in pipe pile can not reflect the economy.In Songhua River floodplain areas,designers department can only learn experience and relevant technical regulations from Guangdong Province when designing jacked-in pipe pile.Basic theoretic research on jacked-in pipe pile is obviously lagged behind engineering practice because there is no technical regulations of design and construction suitable for this region.Firstly,in the paper,based on the analysis of soil plugging effect and soil compaction effect,it illustrated that soil plugging effect and soil compaction effect is the main reason for the enhancement of the vertical bearing capacity of a single jacked-in pipe pile.Secondly,based on theoretical analysis,the paper statistics and analysis the data of the static load test results of 15 typical jacked-in pipe pile in Songhua river floodplain areas.After removed secondary factors,it found a number of laws when a pile tip into the bearing stratum depth and the impact of bearing stratum thickness under the pile tip to vertical ultimate bearing capacity of single standard value.The paper also modifies the tandard value of ultimate end resistance with sandy soil as the bearing layer for precast piles,which is specified in the〈Technical Code for Pile foundation〉(JGJ94-94).Moreover,it proposes the calculation of parameters for Songhua river floodplain areas and verify the revised standard tip limit resistance Standard value to the applicability of jacked-in pipe pile.Finally,the paper based on the main consideration in the ratio between length and diameter of pile and considers some projects of jacked-in pile in Songhua river floodplain areas. It quantitatively analyzes the regional estimated empirical formula of final pressure and the standard value of vertical ultimate bearing capacity of single pile,and compares the empirical formula to other regions.It find out the characteristics of this region.