Papers by Keyword: Collapsibility

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Authors: Peng Ran Song, Chang Ming Wang
Abstract: Research the structure changes before and after collapsible experiment of loess microstructure. Using artificial preparation methods prepared different moisture samples of Liaoxi loess. Do collapsible test and Scanning electron microscope test with the prepared samples. According to Digital Terrain Model theory, three-dimensional porosities were calculated based on gray scale information from the SEM images extracted by MATLAB. The results are shown following as: the microstructure of loess samples is getting dense, the average number of pore of samples obviously increases and the pore area decreases after the sample is collapsed. The distribution before and after the collapsibility of gray value has certain regularity. The before one has double peaks, large distribution. The after one has single peak, concentrate distribution and meets normal distribution.
Authors: Li Wang, Yi Zhang
Abstract: The additive ZY, citric acid and ammonium chloride were used to modify sodium silicate and the influence of modified sodium silicate on the properties of molding sand has been investigated in this paper. The experimental results showed that the additives made the viscosity of sodium silicate increase and its surface tension reduce, the gel particle size of sodium silicate hardened by CO2 gas refine, leading to the strength at room temperature and the collapsibility of molding sand improved. The mechanism of sodium silicate modified by additives was also analyzed and it was concluded that the ZY was the best for modification of sodium silicate among experimental additives.
Authors: Quan Zhou Li, Xiao Qing Wu
Abstract: A novel water soluble core material composed of alumina, quartz sand, kaolin, gypsum powder and the solution of binders was prepared. The influence of different mass concentration of Polyethylene Glycol (PEG) binder solution and sodium silicate compounded (SS) binders solution on water soluble performance and compressive strength of the core materials was investigated, respectively. The results show that the compressive strength and solubility rate of the core materials, with the concentration of 30% of SS binders solution, are 1.023MPa and 0.24g/s respectively, which is satisfied for the requirements of Resin Transfer Molding (RTM) process completely.
Authors: Zhi Hong Nie, Kun Li, Jian Xia
Abstract: This paper has carried out soaking load test, routine soil test, X diffraction, scanning electron microscopy on coarse-grained soil in Gobi region, analyzed the coarse-grained soil collapsibility and explored the mechanism of collapsibility generation. The results showed that: the coarse-grained soil in Gobi region had a high degree of collapsibility; mineral composition, microstructure and salinity constituted the main internal reasons resulting in such phenomenon. In soaking conditions, the cementation strengthen between grains reduces, the structure is damaged under external force and the grain movement leads to greater settlement.
Authors: Xiao Ping Su
Abstract: The collapsibility of loess ground can directly affect the stability of the subgrade. Therefore, How to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation design in collapsible loess zone. Taking collapsible loess of the Liaoning Fuxin to Chaoyang highway as an example, the dispensing formula tests of cement were done. Mix cement in varying proportions with loess of different water content, then unconfined compression strengths of samples at four different ages were tested, and the relationship between improved soil strength and content of quick lime as well as ages was analyzed. The results indicate: 1) When the ages are certain, the strength of loess increases along with the mixture ratio increases, when the cement mixture ratio between 4%-14%, the scope of increases is quite obvious; 2) When the mixture ratio of specimens is certain, the intensity of test specimens increases along with the stadium increases, the intensity grows obviously in 28 days, and the growth rate is small in 28 to 90 days, the intensity will tend to be steady in the stadium of 90 days.
Authors: You Shou Zhang, Lu Xia, Jin Huang
Abstract: After reviewing deficiencies of organic foundry binders such as furan, phenolic resin, the author in this paper introduces a new inorganic binder which is colorless and tasteless and does not burn when contacted with liquid metal and has no smoke and other harmful materials to emit into atmosphere. In the paper, the hardening characteristic and properties of inorganic binder nobake and heat hardened sand such as tensile strength, humidity resistance, gas forming and collapsibility are investigated. Foundry trials were carried out to prove that the new binder meets practical requirements.
Authors: Hong Tao Niu
Abstract: Loess soils always have lower dry densities, open structures and joint fissures, and could exhibit a significant decrease in volume due to their collapse when wetted. These soils pose potential threat on structures built on them. When a tunnel built on such soils, the bearing capacity of tunnel foundation could not always meet requirements of structural stability, and therefore need some improvements. The improvements of collapsible loess foundation include cement compaction piles and root piles.
Authors: Xue Lang Wang, Yan Peng Zhu
Abstract: According to the formers' study of theory and experiment, to analyze the mechanical properties on compacting effect of lime compaction piles. The effects of collapsible loess reinforced by the lime pile have been analyzed. The theory of collapsible loess reinforced by lime pile has made useful exploration. Through the round hole expansion theory to lime piles under expansion compacting process, the elastic-plastic solution on compacting effect of lime compaction piles has been solved. The effective radius of expansion and the law of stress change between the piles can also be determined. Finally using the finite element method to verify the proposed method, and the results show that the proposed method is effective and can provide theoretical basis and guidance for the similar projects.
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