Papers by Keyword: Loess

Abstract: Engineers and researchers pay close attention to high-filled embankment project with loess as its main filler. In order to study its characteristics and settlement rules, a series of laboratory tests on the fillers and in situ observation based on the actual project located in the east central of Taiyuan were made. These work resulted in some settlement curves for the each soil layer. Then some basic physical properties of loess were get at the same time. Observation results were analyzed and the influence of different factors on the settlement curves were discussed.After considering various factors,effective construction suggestions were raised to control the dry density and moisture content in order to decrease the settlement of embankment and improve the quality of the construction.

Abstract: With the development of in the western area, transportation infrastructure meets more and more tunnels covered by loess soil. During the excavation of these tunnels, special geological problems are inevitably encountered when through the loess-rock interface. With regard to these problems, the present paper establishes a three-dimensional numerical model by finite different software Flac 3D. Based on this model, the up-down excavation processes of the tunnel through loess-rock interface are simulated.

Abstract: This paper introduced to the low viscous loess liquefaction problem by acid modification method. The liquefaction test showed that after the modification, the modified loess’s pore water pressures is very smaller then unmodified samples under 50-65Kpa dynamic stress. The modified loess almost no stress reduced after the liquefaction test. It showed that the method can effectively reduce low viscous loess liquefaction potential, and enhance the loess strength.

Abstract: Under the effect of periodic cycle load, the frozen soil exists hysteretic characteristics. According to the research, the five parameters which are the residual strain , the numerical of short axis to long axis of the hysteretic curve , the slope of the hysteretic curve long axis k, the distance of adjacent hysteretic curve center point d and the area surrounded by hysteretic curve S are used to quantitatively represent the morphological characteristics of the hysteretic curve. The hysteretic curve of frozen soil is not a standard ellipse. Its morphological characteristics relate to the initial loading position. The morphological characteristics of the hysteretic curve of different soil affected by frequency, confining pressure and dynamic stress amplitude are different.

Abstract: Natural foundation in loess areas is collapsible; however, composite foundation with rammed soil-cement pile can be used to meet the load requirements of the building. Immersion-compression test and field static loading test were carried out to measure the treatment effect. The test results showed that: the collapsible of loess foundation can be eliminated by treatment with rammed soil-cement pile when the loading pressure is between 200 to 500 kPa. Engineering properties of the foundation soil between piles are improved. The parameters improve more obvious with the pile spacing getting smaller. The bearing capacity of composite foundation increased to 291 kPa, compared with natural loess foundation. The research results can be applied to design and construction of compacted soil cement pile composite foundation in loess area.

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.

Abstract: In order to reduce the cost of backfilling materials in north-west mining area, the feasibility of making the loess as backfilling material in coal mine was discussed in this paper, an orthogonal experiment were conducted and the ratio of backfilling material is gained by author. The experiment was based on the material as main material: loess with fly ash, auxiliary material:cement with lime and other additive agent. According to the mechanism of alkali excitation on the potential activity of the fly ash , a four levels and five factors experiment was conducted by using the orthogonal principle, to analyze the influence of various factors on the main indicators of material specimen, the new material ratio that meet the requirements of backfilling is obtained. Experimental results indicate that: it's feasible to make the loess with fly ash as filling material in coal mine, the appropriate slurry concentration is 60% ~ 65% and the optimal range of the weight ratio of loess with fly ash is 1:1.5~1:3, the optimal range of the weight ratio of auxiliary materials with solid material is 30%~33% and 5%～7% of additive dosage respectively, the appropriate curing time is 28 days.

Abstract: Typical loess areas of Shanxi test section as the basis, through on-site tests, the paper presents the relationship between filed CBR, compaction,moisture content and on-site bearing plate modulus. Through laboratory experiments, the paper examines the variation of resilient modulus and CBR in different water content and degree of compaction conditions. The correlation between site and interior strength indicators was analyzed and the result shows that indicators tested in laboratory have good correlation while indicators tested in field have poor correlation. Key words: loess; rebound modules; CBR; moisture content;compaction; correlation

Abstract: The paper describes the mineralogical and petrographic examinations and testing of the mechanical properties of loess and the experimental adobe bricks. The tested material corresponds to a common loess, which was traditionally used in clay buildings in the region. Due both to its composition and mechanical properties it was found to be applicable as a rammed earth building material, and was later used for building a replica of a traditional Moravian folk house at the open-air museum in Strážnice, Czech Republic. The research is part of a cultural heritage documentation and preservation project.

Abstract: Drucker-Prager Creep Model is introduced, and the Viscoelasto-Plastic Model with Double Yield Surface is detailed deduced. Parameters of loess in China West are discussed in detail during construction of underground warehouse. Those two creep models are applied to pit excavation during construction of underground warehouse. The results calculated show that the displacements calculated according to Viscoelasto-Plastic Model with Double Yield Surface is bigger than those according to Drucker-Prager Creep Model. Those ways uesd may provide reference to engineering practice.