Study On Dynamic Characteristics Of Qiantang River Silt And Cement Mixing Soil

In this paper,the actual working conditions such as foundation pit excavation and support,foundation reinforcement and open-cut tunnel construction in the coastal area of the Qiantang River are taken as the research background,and the silt and ordinary Portland cement in the coastal area of the Qiantang River are taken as the research objects.The GDS-RCA electro-magnetic resonance column system is used to study the dynamic characteristics of silt and cement mixing soil in the Qiantang River under the surrounding dynamic action(construction dynamic load,traffic dynamic load,etc.).In this paper,the influence of confining pressure(soil depth),void ratio(soil compactness)and water content on the dynamic characteristic parameters of Qiantangjiang silt is studied.The research on the dynamic characteristic parameters of cement soil is carried out from four aspects:confining pressure,cement content,initial water content of sample preparation and curing age.The main research contents are as follows:(1)Through the resonant column test on silty soil along the Qiantang River,the variation law of soil stiffness with the increase and decrease of confining pressure,void ratio and water content was studied.It was pointed out that the influence of confining pressure on shear modulus was larger than that of void ratio.The change of shear modulus before and after loading and unloading was further explained,and the important role of reducing water content in improving soil stiffness was explained.(2)The variation of soil stiffness with confining pressure,cement content,initial moisture content of sample preparation and curing age was studied by resonance column test of silt-cement mixing soil in the coastal area of Qiantang River.The role of various factors in soil stiffness was evaluated,and the inference of the optimal economic applicable point of cement content(aw)and the optimal initial moisture content(w0)was proposed.(3)In the resonant column test,different excitation voltages were applied to simulate the variation of soil stiffness under various dynamic loads.The shear modulus G,shear modulus ratio G/Gmax and damping ratio D of silt and cement-mixed soil along the Qiantang River under different test conditions were studied.Based on the modified Hardin-Drnevich hyperbolic model,the empirical formulas of G/Gmax-? and D-y applicable to silty soil of Qiantang River are further verified and generalized.Figure[37]Table[12]Reference[82]...