Analysis And Study On Behavior Of Ram-compacted Piles With Bearing Base Composite Foundation

With the rapid development of economic construction and engineering construction, formed a lot of old building structures of construction waste. And ram-compacted piles with bearing base in construction process by ramming construction waste in order to reinforce the soft foundation. Using ram-compacted piles with bearing base can not only reduce the cost of the construction waste processing, and through to soil compaction in construction process, can improve the soil parameters so as to improve the bearing capacity of foundation. With the continuous development of the technology of composite foundation, the ram-compacted piles with bearing base as reinforcement for Composite Foundation began to be used in engineering practice. Ram-compacted piles with bearing base composite foundation is composed of soil and the Ram-compacted piles with bearing base to bear load, but its research far later in engineering practice, so it is necessary to do further research on behavior of Ram-compacted piles with Composite Bearing Base Composite Foundation. This paper first summarizes the ram-compacted piles with bearing base and composite foundation bearing capacity and settlement calculation method, analyzes the load transfer rule and the failure form of the ram-compacted piles with bearing base and composite foundation. Respectively discusses the method of load transfer method, elastic theory method, shear displacement method of three kinds of research method of composite foundation pile-soil cooperative work and its advantages and disadvantages, and mainly introduces the numerical simulation method used in this paper. In this paper, ABAQUS software for specific ram-compacted piles with bearing base composite foundation works to establish a two-dimensional finite element model of the calculated and experimental values were compared to prove the rationality of the finite element model. And the application of the finite element model to analyze the effect of load, cushion, pile length, pile diameter, bearing base diameter and other factors on the ram-compacted piles with bearing base composite foundation. Get the following conclusion: Not only is there the friction effect between Ram-compacted piles with Composite Bearing Base and soil in the Composite Foundation and compacting effect, the presence of neutral point of pile-soil cooperative work, and load, cushion, pile length, pile diameter, bearing base diameter and other factors have effect on its; With the increase of the depth of pile soil stress between piles is gradually reduced, the pile length of 15% ~ 30% reaches a minimum, Then as the increase of the depth of pile soil stress between piles is gradually increasing; and along pile depth direction vector ram-compacted piles with bearing base stress becomes larger and larger, and in the pile body length of 15% to 30% of its maximum value, then along pile depth direction and its value decreased gradually; When the upper part of the rigid foundation, the Ram-compacted piles with Composite Bearing Base composite foundation under piercing damage may occur, when the cushion adjustment ability is insufficient, and the bottom is difficult to pierce, load is large, the Ram-compacted piles with Composite Bearing Base composite foundation has a possibility of pile body of shear failure; The diameters of the bearing base great influence on the bearing capacity of the ram-compacted piles with bearing base composite foundation, and when the bearing base diameter increased to more than 1.25 times the diameter of the original model of bearing base, displacement is decreased obviously, ram-compacted piles with bearing base composite foundation bearing capacity significantly increased; Ram-compacted piles with bearing base composite foundation bearing capacity increases according to the growth of pile length, depending on the pile diameter increases and becomes larger; Cushion as part of the ram-compacted piles with bearing base composite foundation, can adjust pile-soil cooperative work, increasing the modulus of the cushion can increase the stress ratio of pile and soil, increasing the thickness of the cushion can effectively reduce the stress of pile and soil, cushion thickness increase in the original model of thickness of one times, the ram-compacted piles with bearing base composite foundation bearing capacity increase obviously, but too big cushion thickness makes settlement increase, pile effect cannot be fully embody, the design should select suitable cushion thickness.