Advanced Materials Research Vols. 838-841

Abstract: To the question of reclaimed land of low hills, gentle slope and gully of Lanzhou City, including the compaction way of backfill site with loess and physical parameters of test, the paper discusses the main factors affecting the soil compaction, and put forward suitable compaction method of backfill site with loess. By analysing a large number of soil physical parameters experimental data, the paper gives empirical value to estimate the compaction coefficient and water content base on the quality of the sample or D-value of the quality. This article also discusses the relationship between the compaction curves and backfill ground on the same field or different. For the compaction of backfill site with loess and the parameters of the test in other city, it provides the reference.

Abstract: Peat soil, (peat and peat soil) has high organic matter content, large void ratio, high natural water content, low shear strength, compressibility, strong characteristics, is a kind of special soil is very weak. But with the development of national economy, the peat soil and engineering construction is more and more close, especially for Kunming area, huge number of peat soil. So the way is very necessary to strengthen the peat soil.Based on typical engineering geological characteristics of peat soil in Kunming region, by adding fly ash, cement to verify the superiority to improve the performance of peat soil strength. Dissolution method is used to determine the degree of reaction of fly ash, peat soil is studied in the degree of reaction of fly ash and admixture, the relationship between parameters such as age, and the correlation model was established;

Abstract: California bearing ratio (CBR) test was carried out, CBR changing laws of different graded crushed rocks were analyzed, an aggregate gradation on the base of port was put forward, and its performances were verified through laboratory test. Test result shows that the main skeleton structure composed of the aggregate with diameter 19mm-4.75 mm has interlocked force, and the optimal mass fraction is 90%~65%. The aggregates with diameter 4.75mm-0.075mm have the effects of filling the void of main skeleton structure, whose optimal mass fraction is 10%-35%.And the optimal mass fraction of the aggregate with diameter 19mm-9.5 mm is 25%.When the optimum proportion of coarse aggregate to middle aggregate is 25:40, the CBR value of coarse-middle-fine combined aggregate reaches the highest point, and is more than 158.97%, and the ratio reached 377%. On this basis, the optimal aggregate gradation of graded broken stone is reference on design and construction of graded crushed rock on the base of port.

Abstract: The paper presents the development of a similar material to simulate the soft rock type in engineering, especially the time-depending behavior. The iron, barite and cement are selected to be the aggregate and the solution of rosin is selected as the glue. To improve the plasticity and rheology behavior, chlorinated paraffin was added, too. Laboratory test was carried by construct the specimens using a mould. The uniaxial complex modulus test and indirect tensile strength test were performed to obtain the basic mechanical behavior. And the rheology test was carried by a self-developed rheology test machine to research on the time-depending behavior. By laboratory test, the influence of the each component on the mechanical behavior was determined. Results show that the effects of component ratio and solution thickness on the material mechanical behavior. The rheology behavior was especially well simulated by the similar material developed.

Abstract: Traditional design of structural members is considered less collision effects, so it may be possible to cause damage due to impact loads. In view of this, impact-resistant performance of the composite protective measures proposed in the early time was analyzed. In the process of the numerical simulation, the observed reinforced concrete beams fixed at both ends with four different measures including the unprotected, the rigid protective, the flexible protective and the composite protective one were considered separately. Protective effects of the different measures were compared and analyzed by observing the strain, the velocity, the acceleration and the impact force of the target beam. Numerical results show that the composite protective system works best. The composite protective layer of the beam can suppress the impact response effectively.

Abstract: Oxytetracline (OTC) is a widely-used antibiotic, which could transport into aqueous and soil systems. The coexistence of heavy metals, such as copper (II) [Cu (II)], may change the adsorption behaviors of OTC onto soils. This study investigated the simultaneous adsorption behaviors of OTC Cu (II) onto loess soil, which is ubiquitous in the northwest of China. The kinetics experiments were conducted in single and binary systems for OTC and Cu, and the results showed that the kinetics data of both OTC and Cu could be well fitted by the pseudo-second-model model. The co-adsorption might increase the adsorption rate of both OTC and Cu. However, the effects of the complexation of OTC and Cu (II) on their adsorption amounts onto loess soil were quite different. The presence of Cu (II) could increase the uptake of OTC from pH 3.0 to 10.0. By contrast, the coexistence of OTC would decrease the uptake of Cu (II), especially at pH > 5.0. Hence, it is proposed that the migration of OTC might be slowed down by the coexistence of Cu (II), whereas the transportation of Cu (II) would be accelerated by the presence of OTC.

Abstract: This paper discusses the relationship between shear strength of soil-root composite and root content of different plant species. The direct shear test of root - soil composite was made by grass and shrub plants -- alfalfa, Indigofera amblyatha, cynodon dactylon and purple soil .That how plant root system can improve the soil shear strength was analyzed. The results show that the shear strength of reinforced soil is increased. When the same plant root-soil composite is under the same root content, the shear strength is enhanced with the increase of normal stress. The peak value of shear strength appears in 0.4 - 0.5g per 60 cubic centimeter.

Abstract: To study the microscopic mechanism of stress-induced anisotropy for coarse-grained soil, with PFC(particle flow code) numerical simulation method, many planar biaxial test samples composed of regular disk particles or irregular clump particles were prepared, different initial stress states were given, and equal stress increment was applied on different directions. Then, initial elastic modulus and stress-induced anisotropy property were got, and analysis of its microscopic mechanism of stress-induced anisotropy was given. Results shows, the stress-induced anisotropy of coarse-grained soil occurs under the interaction of internal irregular microscopic structure and external non-isotropic stress.

Abstract: Expansive soil mixed with a certain amount of lime in the post-isostatic pressing, as measured through the oedometer specimen expansion and contraction coefficient changes. Test divided load and no-load charge plus two groups, drawn economically reasonable dosage of lime for building design and construction to provide evidence.

Abstract: In order to study the effect of spatial uncertainty of soil parameter in unsaturated zone on contaminant migration, Permeability coefficient was chosen as a typical soil parameter to be researched. Bayesian method was used to deal with permeability coefficients and Monte-Carlo method was used to simulate spatial uncertainty of permeability coefficients. Numerical model of HYDRUS-1D was used to simulate the contaminant migration in the unsaturated zone taking spatial uncertainty of permeability coefficient into account. And Cl^-was chosen as the contamination. The result was that: The distribution of contamination concentration presented a significant uncertainty, and compared with the case of ignoring spatial uncertainty of permeability coefficients in unsaturated zone, it is closer to the actual situation. Meanwhile, a suggestion about the value of initial concentration in numerical simulation of groundwater is given combining the results.