Study On Dredger Fill Foundation Treatment Method For Low Rise Prefabricated Light Steel Buildings

The reclamation of islands is an important way to alleviate the current shortage of land resources in the coastal areas.The dredger fill project in the reclamation Island project has poor engineering properties and needs reinforcement.At the same time,prefabricated light steel low rise building is the first choice of new buildings in Hainan Province and many places in China,which has the characteristics of green environmental protection,low cost and light weight.Combined with the above research background,this paper puts forward a dredger fill treatment method of insitu backfill,which is easy to obtain cushion materials in situ,and has good economy.Then two cushion materials are selected to carry out experimental research and theoretical calculation on the treatment effect of in-situ backfill method.Finally,the finite element analysis of the foundation treated by this method is carried out,which provides a reference for the cushion selection of in-situ backfill method Some valuable suggestions are put forward.The research work of this paper mainly includes the following aspects(1)The coconut shell fiber reinforced soil is selected as the cushion material of in-situ backfill method.The tensile property of coconut shell fiber is determined by tensile test.The shear strength parameters of coconut shell fiber reinforced soil are analyzed by direct shear test.The ultimate bearing capacity of coconut shell fiber reinforced soil cushion foundation is calculated by theoretical calculation method.The results show that the tensile strength of coconut shell fiber is high;the shear strength index of coconut shell fiber reinforced soil is good,and the optimal proportion of fiber length and content of reinforced soil are 5cm and 0.3%respectively;when it is used for prefabricated light steel low rise building foundation,the optimal proportion of coconut shell fiber reinforced soil cushion can greatly improve the foundation bearing capacity.(2)The miscellaneous fill near the dredger fill area is selected as the cushion material of the in-situ backfill method.The geotechnical classification name and basic physical properties of the miscellaneous fill are determined by laboratory test,and the treatment effect of the miscellaneous fill in-situ backfill method on the dredger fill foundation is determined by plate load test.The results show that the main component of the miscellaneous fill is red clay coarse sand,with good gradation and great bearing capacity potential;after the miscellaneous fill is treated by in-situ backfill method,the deformation modulus and bearing capacity characteristic value of the foundation are increased by more than 3 times.(3)Based on ABAQUS software,a three-dimensional finite element model is established to simulate the foundation treated by in-situ backfill method.The rationality of the model is verified by the test results and the common stress calculation formula of the foundation.Then the yield area of the foundation and the influence of different model parameters on the stress distribution and settlement of the foundation are analyzed by using the model.The results show that under the limit load,the depth and width of the yield area of the foundation concentrate within 1.5times and 2 times of the foundation width respectively;under the condition of load equal to 200 k Pa,different thickness width ratio,cushion elastic modulus,cushion cohesion,friction angle in the cushion,and foundation stiffness have significant effects on the stress distribution and settlement of the foundation,while the Poisson’s ratio of the cushion has significant effects Based on the test results and simulation results,the paper puts forward some suggestions on the cushion thickness and material selection of in-situ backfill method in practical engineering.