The Numerical Analysis Of Stress Properties Of Reinforced Mixing Pile (MC Pile)

The reinforced mixing pile is a new kind of composite pile, which is composed of cement-soil ring and reinforced concrete core. It is used in soft ground engineering. The project practice proof, this pile has stable and reliable quality, the bearing capacity high, the construction cost low, the construction craft simple and the environment pollution little and so on the merits. This article will adopt the method of theory analysis combined with practical engineering to research on stress properties of the reinforced mixing pile (MC pile). The main work has the following several aspects:(1)Combined with a real project in Yangzhou city, using ABAQUS finite element software to simulate, and analyze stress properties of the reinforced mixing pile (MC pile). Then compare results with the project monitoring data. The finite element simulation results show that:the pile along with soil sank together. The displacement of pile top is biggest and pile tip is smallest. The core pile takes most of the load. Compared with QS curve which is got by static loading experiment, the simulation results are slightly less than testing data in numerically, but the trend is consistent. To further illustrate the applicability of the finite element method in engineering application.(2)Using ABAQUS finite element software to establish a reinforced mixing pile (MC pile) of finite element model. Respectively analysis the mechanical characteristics of equal core pile and long core pile when the properties of the pile endpoint soil are different. The simulation results show that: ①In the vertical load, compared with the cement pile, the load which is borne by the core pile is larger. And the load transfers modes are:concrete core pile→cement pile→pile around soil→pile endpoint soil.②Whether it is long core pile or equal pile, when the pile end soil is hard soil, the side resistance is rising. It proofs that the side resistance has not reached the limit, and it can continue to play. It is beneficial to improve the ultimate bearing capacity of the pile; when the pile end soil is soft soil, the side resistance rises slowly at first, and then it decreased. It is indicated that the decline of the side resistance will make the ultimate bearing capacity of the single pile fall. And when the pile end soil is hard soil, the side resistance is bigger than it when the pile end soil is soft soil. So when the pile end soil is hard soil, the bearing capacity of the reinforced mixing pile (MC pile) is more than bearing capacity when the pile end soil is soft soil. But in the same load, when the pile end soil is hard soil, the settlement of the reinforced mixing pile (MC pile) is smaller than settlement when the pile end soil is soft soil.(3)With long core pile as the research object, discuss the influence of different factors on the bearing capacity of the reinforced mixing pile (MC pile). The results show that: ① The bearing capacity of the reinforced mixing pile (MC pile) is increased with increase of the rate of cross section core content. When the cross section of the core content increases from 0.111 to 0.444, the ultimate bearing capacity of the reinforced mixing pile (MC pile) increases 73.82%. ②For the long core pile, the longer the concrete core piles, the bigger bearing capacity of the reinforced mixing pile (MC pile). When the length of the core content increases from 9m to 10m, the ultimate bearing capacity of the reinforced mixing pile (MC pile) increases 16.06%.③The bearing capacity of the reinforced mixing pile (MC pile) is increased with the increase of elastic modulus of concrete core pile. When the elastic modulus of concrete core pile increases 1×104MPa, the ultimate bearing capacity of the reinforced mixing pile (MC pile) of an average increase of 46.88kN.④The more elastic modulus of soil-cement piles, the greater bearing capacity of the reinforced mixing pile (MC pile). When the elastic modulus of cement-soil pile increases 50MPa, the ultimate bearing capacity of the reinforced mixing pile (MC pile) of an average increase of 81kN.