Experiment Study On The Permeability Of Different Soils

Experts and scholars have achieved great research progress in water-earth pressure theory.Nowadays the calculating ways of estimating water and earth pressures separately and estimating water and earth together are extensively used,but the calculating way of estimating water and earth pressures separately is applied to the soil with large permeability coefficient and the calculating way of estimating water and earth together is applied to the soil with small permeability coefficient.The water-earth pressure calculating way of permeability coefficient of the soil between the mentioned two soils is controversial,meanwhile,the research of pore water pressure is rarely involved through model experiment.Hence,the research is carried out in terms of pore water pressure and water-earth pressure in the paper.The silt taken from Jingang road in Nanchang was regard as basic soil in the page.The six permeability coefficient experimental soils were collocated by adding different ratios of fine sand and bentonite into silt.When rigid retaining wall rotated about base in the situation of active displacement and passive displacement,water-earth pressure and pore water pressure of six permeability coefficient soils were measured.In the page the experimental water-earth pressure was compared with estimating water and earth pressures separately based on effective stress and total stress,estimating water and earth together based on total stress and the mixed calculating way proposed by Xu riqing.The model experiment was simulated by finite element software ABAQUS.The experimental results were compared with simulated results to verify the experimental degree of accuracy.The conclusions of the study include:(1)When the status of superficial soils transforms into active ultimate state,the displacement is 10mm~11mm in the situation of active displacement.When the status of superficial soils transforms into passive ultimate state,the displacement is 14mm~15mm in the situation of passive displacement.The status of deep soils is not ultimate state because the displacement of deep soils is too small.(2)Estimating water and earth pressures separately is suited to the soils added into 20%?10% and 5% fine sand,meanwhile,estimating water and earth together is more suited to the basic soil and soils added into 4% and 8% bentonite.(3)In the situation of active displacement,pore water pressure of the soils added into 20%?10% and 5% fine sand relatively stable,meantime,pore water pressure of the basic soil and soils added into 4% and 8% bentonite variates a lot with displacement of retaining wall largening.Pore water pressure gradually stabilizes at hydrostatic pressure.In the situation of passive displacement,Pore water pressure of the soils added into 20% and 10% fine sand rapidly increases maximum,with displacement of retaining wall largening,pore water pressure decreases slowly.Pore water pressure of the basic soil and soils added into 5% fine sand and 4%?8% bentonite also rapidly increases maximum and then rapidly decreases.Whereafter,negative excess pore pressure appears.With displacement of retaining wall largening,negative excess pore pressure is vanishing gradually and pore water pressure gradually stabilizes at hydrostatic pressure.(4)In the situation of active displacement,numerical simulation is less than experimental results.Compared with experimental results,the displacement of soils transforming into active ultimate state is greater.In the situation of passive displacement,numerical simulation is greater than experimental results.Compared with experimental results,the displacement of soils transforming into passive ultimate state is also greater.