Experimental Study On The (Triaxial) Static And Dynamic Properties Of Saturated Yellow River Silt For Road Use

Infrastructure construction in the Yellow River Basin is a hot development direction in the future.There is a huge demand in subgrade fillers for the construction of the expressway along the Yellow River.The Yellow River is rich in silt resources.Using the Yellow River silt as subgrade filler is not only conducive to solving the siltation problem of the Yellow River silt,but also can meet the huge filler demand for the constructed expressway along the Yellow River.In order to promote the popularization and application of the Yellow River silt in the expressway subgrade along the Yellow River,as well as meet the design and safety evaluation needs of the Yellow River silt subgrade,it is necessary to carry out systematic experimental research on its geotechnical properties to provide theoretical and data support.In this paper,the Yellow River silt of a typical reach in Zhengzhou is selected to carry out laboratory soil tests,static and dynamic triaxial loading test under isotropic consolidation and undrained conditions.The basic physical and mechanical properties,as well as the static and dynamic characteristics based on triaxial tests are studied.The main research results are as follows:(1)Through particle analysis test,specific gravity test,compaction test,minimum dry density test,joint determination test of liquid-plastic limit and California Bearing Ratio(CBR)test,the basic physical and mechanical indexes such as particle gradating,specific gravity,optimum moisture content,maximum dry density,minimum dry density,liquid plastic limit and CBR of the Yellow River silt are measured,which verifies that the Yellow River silt meets the basic performance requirements according to the subgrade design and construction specifications.(2)By the loading mode of stress control,a static triaxial shear test under undrained condition is carried out.The effects of confining pressure,relative density and loading rate on the strength,deformation and pore water pressure variation of the saturated Yellow River silt are studied.The undrained shear strength of Yellow River silt under different loading conditions is obtained.And the hyperbolic function model describing the stress-strain relationship of the Yellow River silt is determined.(3)The dynamic triaxial test was carried out to study the dynamic shear modulus and damping ratio of the saturated Yellow River silt.The effects of confining pressure,relative density and loading frequency are taken into account.The mathematical relation between the damping ratio and dynamic shear modulus of the Yellow River silt is established.And the prediction model for the dynamic shear modulus and damping ratio of the Yellow River silt is determined.(4)In order to study the liquefaction characteristics of the Yellow River silt,the dynamic triaxial test on the saturated Yellow River silt is carried out.The effects of confining pressure,relative density,cyclic stress ratio and loading frequency are considered,the dynamic characteristics such as dynamic pore water pressure,dynamic stress,dynamic strain,liquefaction times and dynamic strength of the Yellow River silt under different loading conditions are systematically studied.The liquefaction mechanism of the Yellow River silt under dynamic load is analyzed.And the instability failure criterion of the Yellow River silt in the process of liquefaction is proposed.Finally,a prediction model of pore water pressure for the Yellow River silt is established.(5)In order to simulate the influence of practical traffic load,the half sinusoidal load is adopted to carry out a series of long-term dynamic triaxial tests on the saturated Yellow River silt.The effects of confining pressure,relative density,cyclic stress ratio and loading frequency are considered.The cumulative strain and rebound strain of the Yellow River silt under different loading conditions are investigated.The dynamic strength for the plastic failure of the Yellow River silt is obtained.And the prediction model of the cumulative strain for the Yellow River silt is established.Based on the above mentioned prediction model and the layered summation method,a method for predicting the settlement of the Yellow River silt subgrade under long-term traffic load is proposed.