Research On Pile-soil Load Transfer Behavior And The Bearing Characteristics Of Self-balanced Method

In the design of foundation pile, the determination of the bearing capacity of a pile is very important. In actual projects identify the bearing capacity of a pile methods are:static load test, dynamic test, combining static and dynamic test. Traditional foundation pile static load test are heap load method and anchor pile method, these two methods has long been widely used in engineering, but its disadvantages are obvious:heap load method needs to install a huge heap load platform, also need to solve hundreds of even thousands of tons of load source, stack and transportation problems. Anchor pile method need to install the root anchor piles and big anti-power beam, not only the cost are expensive, time is long, and susceptible to the limitations of tonnage and site conditions, but also limited by tonnage and site conditions. Compared with the traditional static load test, advantages of self-balanced method are advanced technology, test automation, provincial, labor-saving, safe and reliable, not subject to site conditions and so on. Self-balanced method is a new bearing capacity of a pile test technology, Many of domestic and international studies show that self-balanced method could replace traditional static load test in practical engineering. Self-balanced method can obtain reliable data of the bearing capacity of foundation pile, judgment on its bearing capacity and guide the design of pile foundation.Self-balanced method has been applied in China and accumulated some experience, but how to use this method to determine the bearing capacity of pile still need to accumulate more experimental work and theoretical analysis. In the practical application of self-balanced method often encounter a variety of problems, and different construction factors have a greater influence to test results. Mainly display in the following aspects:determine the problem on two piles carrying the equilibrium point; determination of bearing capacity balance problems; self-balance method for engineering pile; construction factors on test results. Therefore field test of self-balanced method is very necessary, it has a very important significance for self-balanced method in the theoretical study and practical accumulation.In this paper according to the project of No.1bridge in Tianshui economic development zone, Described test principle and test methods of self-balanced method in detail, study on self-balanced method load boxes laying position, since self-balanced test results of the equivalent conversion and different on load transfer mechanism of self-balance method and traditional static load method, and the finite element numerical simulation for the field test and theory and equivalent conversion of data analysis. The research contents and main results of the article are as follows:(1) This paper summarized the basic principle of the balance test, test method and the main test device, and on the balance of the load test box embedded position are summarized. Since the balance method the test methods and traditional static load test in the load transfer mechanism has the very big difference, this paper on the test method of the balance when, under section of their respective pile load transfer mechanism, and with the traditional static load test of the pile at load transfer mechanism analysis.(2) In three of the pile foundation of the measured data collection and analysis on the basis of the test pile, and get under the Q～s curve segment, the pile shaft, pile side friction resistance to along the depth of distribution. Through the foundation pile in the selection of three from the balance testing that in2times the design load, on, under section pile deformation are smaller, and Q～s curve quite gentle, combining the converted Q～s curve gently and no turning section, there are certain that the bearing capacity of the surplus, through the test was checked every root pile bearing capacity of value.(3) According to the stress test of the pile foundation and data analysis, get pile body axial force, again conversion for pile resistance, can see3foundation piles of pile body along the breakdowns of the average side friction and bottom resistance has not yet fully, there are some surplus, through the test to determine the pile soil pile of each side friction and bottom resistance, for the region of similar projects in the future and provides reference for the design ofpile.(4) Combined with the field test, on the balance of the test process test are discussed in detail, and summarizes the implementation process of the field test of the key point. In the paper of the data line a detailed analysis on the balance test the experiment research has important reference value.(5) On the site since the balance on the basis of the research, the selection of the foundation pile S2fem simulation, simulated test and balance the pile top loading models under the load carrying characteristics. Through the analysis and comparison of data, more self-balanced method.this verify the reliability and accuracy of the transformation method.Finally, the paper summarizes the comprehensive work put forward, based on this topic remains to be further studied some problems.