Da Zhi Wu

Study on the Diffusion Properties of Heavy Metal Copper Ion in Silty Clay

The silty clay samples from Xiasha zone, Hangzhou city, are put into the reaction tank, which is specially made to investigate the diffusion characteristics of heavy metal copper ion. The silty clay is compacted, and then the solution with concentration of copper sulfate is 1762mg/L are added into one end of the tank. After laid for a time, several soil samples are cut from different positions in the tank, the adsorption contents of copper ion are tested. Experimental results show that the adsorption contents of copper ion in the silty clay decreases with the increase of the diffusion and movement distance. Besides, the relationship between the adsorption contents of copper ion and the diffusion and movement distance can be formulated as an exponential function.

Study on the Settlement of Soft Soil Subgrade with a Crust Layer

By using the finite element method, the settlement of soft soil subgrade with a crust layer has been investigated. To find the influence of thickness of the crust layer on the settlement, four different thicknesses, which are 0.0m, 1.5m, 3.5m and 5.5m, are selected. Besides, the settlement during the construction and post construction are also analyzed. It is found that the crust layer can reduce the settlement and uneven settlement of subgrade effectively. Besides, the settlement of the subgrade decreases with the increase of the thickness of crust layer. Moreover, with the increase of time, the uneven settlement of the pavement increases gradually. And when the time is up to a certain degree, the uneven settlement tends to be stable.

Study on the Shear Strength Properties of the Silt in Hangzhou, China

To investigate the shear strength properties of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the cohesion force varies from 20.8 to 28.3kPa, and the internal friction angle varies from 12.3 to 31.8degree. Finally, the properties of the shear strength are studied, and find that the relationship between the shear stress and the shear strain is conformity with the strain hardening curve, and the relationship between the shear strength and the vertical pressure applied on the soil samples is linear, and agrees with the Coulombs law.

Study on the Geotechnical Engineering Properties of Polluted Soil

To investigate the geotechnical engineering properties of polluted soil, ten soil samples are collected from Anqing copper ore, Anhui Province, China. The geotechnical engineering parameters of the polluted soil are measured in the soil mechanics laboratory. Tests results show that the natural density varies from 1.56 to 2.04t/m3, the moisture content varies from 15.36% to 27.87%, the modulus of the compression varies from 1.27 to 8.10MPa, the cohesion force varies from 32 to 210kPa, and the internal friction angle varies from 25.4 to 57.9 degree. Finally, the properties of the shear strength and the compression are studied, and find that the compressibility of the polluted soil is very big, and the relationship between shear strength and the normal pressure conforms to the law of Coulomb.

Study on the Compressibility of the Silt in Hangzhou, China

To investigate the compressibility of the silt, three soil samples are collected from Xiasha zone, Hangzhou, Zhejiang Province, China. The geotechnical engineering parameters of the silt soil are measured in the soil mechanics laboratory. Tests results show that the uniformity coefficient of the silt is 13.6, the natural density is 1.96t/m3, the moisture content is 17.0%, the plasticity index is 9.4, the compression coefficient varies from 0.06 to 0.40MPa-1, and the compression index varies from 0.015 to 0.108. Finally, the properties of the compression are studied, and find that the compressibility of the silt soil is very large, and the relationship between the initial void ratio and the logarithm pressure is linear.

Study on the Treatment Technology of Polluted Soil with Heavy Metal

The main ways of soil polluted by heavy metal are analyzed, and the technical methods of treating the polluted soil have been put forward. The research results show that physical rehabilitation, cement solidification and plant-remediation are main technologies to treat the polluted soil. The research results can be used for provided reference in actual projects.

Study on the Diffusion Properties of Heavy Metal Copper Ion in Sandy Soil in Hangzhou, China

The diffusion properties of heavy metal copper ion are studied on sandy soil from Xiasha zone, Hangzhou city, China. The sandy soil is put into the large scale reaction tank in the laboratory, then compacted layer, and made to reach the degree of the natural density. The solution with concentration of copper sulfate is added into one end of the reaction tank, then the solution of the copper ion will diffuse into the sandy soil in the self-weight stress. Based on the adsorption content of the copper ion in the sandy, the diffusion regularity of the copper ion in the sandy soil is studied by the analytic test in the laboratory, and the diffusion mechanism of the copper ion is analyzed. Experimental results show that the adsorption contents of the copper ion in the sandy soil decreases with the increasement of the diffusion and the movement distance. Besides, the relationship between the adsorption contents of the heavy metal copper ion in the sandy soil and the diffusion and the movement distance can be formulated as an exponential function.

Experimental Study on the Permeability of Fresh Municipal Solid Waste

Basing on traditional constant head permeability test with large scale specimen, the permeability of municipal solid waste has been studied. The municipal solid waste material is divided into three parts: the material that is easy to be biodegraded, reinforced material that is difficult to be biodegraded and the incompressible solid waste material. Two different proportions of these three parts, which are 50%, 15%, 35% and 65%, 10%, 25% are selected. A series of laboratory tests have been performed for different initial void ratios, and the initial void ratios are 2.5, 3.0 and 3.5, respectively. Testing results show that the initial void ratio and the content of the organic matter are the main influence factors on the permeability coefficient of the municipal solid waste. Besides, the coefficient of permeability decreases with the decreasement of the initial void ratio of the municipal solid waste. Furthermore, when the proportion of the three parts is 65%, 10% and 25%, the coefficient of permeability varies from 7.8×10-4 to 3.72×10-3 centimeter per second, and when the proportion of three parts is 50%, 15% and 35%, the coefficient of permeability varies from 1.08×10-3 to 6.67×10-3 centimeter per second.

Study on the Properties of Natural Shear Strength for Municipal Solid Waste

The Properties of natural shear strength for municipal solid waste are studied by applying a new developed direct shear testing instrument. The municipal solid waste is divided into three parts: incompressible solid waste, reinforced material that is difficult to be biodegraded and the material that is easy to be biodegraded. The properties of these three parts are 15%, 5% and 80%, respectively. A series of laboratory tests have been conducted for different initial void ratio, and different pressure applied on the test specimen. The testing results show that the initial void ratio is a key factor for the natural shear strength of the municipal solid waste, the relationship between the shear stress and the shear strain is a strain hardening curve, the shear stress gradually increases with the shear strain. Besides, the natural shear strength shows a linear relationship to the pressure applied on the test specimen, and it is in accordance with the law of coulomb. According to the fitted lines, the shear strength parameters are obtained. The cohesion varies from 4.7 to 12.6kPa, and the internal friction angle varies from 14.5 to 18.3 degree for the shear strain is equal to 5%. When the shear strain is equal to 20%, the cohesion varies from 8.5 to 17.2kPa, and the internal friction angle varies from 25.5 to 30.7 degree.

The Duncan-Chang Model Parameters for Municipal Solid Waste

By theoretical analysis and laboratory test, the model parameters of Duncan-Chang for municipal solid waste have been studied. To obtain the mechanical parameters, a new simple and practical method has been established. Research results show that the damage ratio is 0.6, parameter n is about 1.05, parameter F varies between 0 and 0.1, and parameter G varies between 0.3 and 0.4. Besides, the relationship between parameter k and the initial void ratio is linear, and the slope of the line is 5.0.