Sedimentation Control Composite Pile Foundation Of Traits

As a new philosophy of using piles as settlement controller, piled raft foundation provides an economical foundation option for circumstances where the performance of shallow foundation doesn't satisfy the design requirement. As limited cognitive level , civil engineers still use traditional methods to design piled raft foundation. However some engineers begin to analyse the pile-soil-raft interaction recently. This paper gives some research on the analysis of piled raft foundation subjected to vertical loadings.For the pile foundation on the soft soil, settlement control is the design key. The general design requires that loads are born entirely by piles, regretting the bearing capacity of soil between the piles. Based on the former researches, the Balanced Settlement Optimum Design Method is presented in this paper. According to this method, the differential settlement can be better reduced by adjusting the rigidity of both the foundation soil and the piles. Meanwhile, the average settlement and the whole bearing capacity all satisfy the code request, and the cost of foundation can also be reduced. The main contents and conclutions are as the followings:1. By getting conclutions from the former studies on the settlement of composite pile foundation, a new method, settlement calculation under cooperation of pile and soil, has been brought forward which is more simple and more practical.2. The numerical simulation are carried through to analyze the composite pile foundation under the circular raft. By adjusting several main factors such as pile length, pile space and soil elastic modulus in the finite-element model, a conclusion can be drew that pile length adjusted method and central locating piles combining with soil elastic modulus modulation method are two effective ways to reduce the differential settlement of composite pile foundation. Beside, this analysis process also gives out the common non-linear design method of pile-raft foundation which aims to reduce the differential settlement to zero.3.After giving the idiographic concept of differential settlement, this paper anasys the mechanism of cooperation among the structure on the ground and basis and foundation, at the mean time, put forward the optimized methods which can adjust the differential settlement of the composite pile foundation. When the design demands have been achieved, we will do our best to adjust the differential settlement and save the project cost.4. Combining with the actual settlement data of pile raft foundation from engineering, its pile length variation design is simulated by finite-element method.Beside, the finite-element model of central locating piles combining with soil elastic modulus modulation method is simulated, proving that the Balanced Settlement Optimum Design Method discussed in this paper can effectively control even remove the differential settlement. The results of numerical simulation shows that not only the differential settlement is completely controlled, but also the number of piles is reduced greatly comparing to the general pile foundation design in order to save the foundation constructing cost. Thus, the purpose of the Balanced Settlement Optimum Design Method has achieved.