The Preliminary Study On Liquefaction Characteristics Of Hydraulic Fill Sands

Reclamation has become an important source of the development of land use in coastal region.With the seismic vibration intensified,artificial reclamation area is easy to liquefaction and the range of liquefaction is widely,which will be a serious threat for the buildings and the people's life and property safety of the coastal region.Thus,the dynamic liquefaction characteristics of hydraulic fill soils has becoming the focus of attention.The hydraulic fill soils called rinse fills too.It is deposited soil from the bottom sediment and river port by dredger mud pump and hydraulic fill through filling way,the hydraulic fill soils is usually mixed with sand and clay containing.The actual site of hydraulic fill soils,fill in the near distance,hydraulic fill soils composition,clay content is not the same,usually in the sand will form the clay lens,which resulted in the changes of soil drainage boundary conditions.Although a great deal of engineering construction has been carried out on this kind of mixed soil field,the study on the dynamic characteristics of this kind of hydraulic fill soils is still scarce,and the liquefaction mechanism of hydraulic fill soils is not clear.Based on the existing theories and methods at home and abroad,the dynamic characteristics and liquefaction mechanism of hydraulic fill soils are studied by using three axis test.The test samples taken from Guangzhou reclamation in Nansha District,to carry out this kind of hydraulic fill soils GDS three triaxial test.The anti-liquefaction strength of hydraulic fill soils with different sand content is determined by experiments.The test results show that the sand content in hydraulic fill soils has great influence on the parameters of Finn pore pressure model,and the pore water pressure model parameters of hydraulic fill soils Finn under different sand content are determined by experiments.The main conclusions are as follows:1Due to its different composition and particle content,hydraulic fill soils has a change in its anti-liquefaction strength.(1)By carrying out GDS dynamic three axis test of filling samples with different sand content,it is found that the anti-liquefaction strength of hydraulic fill soils decreases with the increase of sand content,and decreases greatly.When the sand content of hydraulic fill soils is greater than 60%,the anti-liquefaction strength of soil sample increases first and then decreases with the increase of sand content,and the liquefaction resistance is the lowest at a certain sand content.(2)The increase of pore water pressure ratio of hydraulic fill soils is larger at the initial stage of cyclic loading,then gradually reaches the initial liquefaction state amplitude and tends to be stable.In the course of loading,the ratio of pore pressure increases gradually,and tends to be stable at 0.95-1.00.The amplitude of pore pressure change is closely related to the sand content.With the increase of sand content,the amplitude of pore pressure ratio increases in the test process.(3)When the dynamic strain of the soil has reached the initial standard of liquefaction and the ratio of the pore to pore pressure has not reached,the dynamic strain is the main factor in liquefaction identification.(4)The samples under cyclic loading,the soil skeleton bear external load,sample loading soil particles gradually during compaction,the excess pore water pressure increases gradually,so more and more low strength soil,reach initial liquefaction condition.(5)With the increase of sand content in the soil,achieve the required initial liquefaction state failure vibration decreases and the results show that with the increase of the amount of sand soil liquefaction strength decreased,and decreased faster and faster.2Finn pore pressure model can better reflect the change of pore water pressure under cyclic loading.3Pore pressure model parameters required by Finn pore pressure model are obtained by consolidation test.The different components of the hydraulic fill soils Finn pore pressure model parameter influence,gives a different amount of sand blowing curves of pore pressure increment and volume strain increment for hydraulic fill soils fill,and provide a preliminary basis numerical analysis of liquefaction site.The above research results provide the measured data for the dynamic analysis of hydraulic fill soils site,and provide a preliminary reference for the analysis and evaluation of hydraulic fill soils site liquefaction.