Applied Mechanics and Materials Vols. 90-93

Abstract: The height of “two belts” for overburden distortion and failure in mining workface is very important to coal mine safety production. The height results can be gained through mine geophysical method. The geological model of 32 coal seam in 33 mining field of one mine in Huaibei is selected in the article. The model system of coal mining is formed through the technique of the indoor similar simulation, and the union test system of the bore-laneway resistivity method and seismic wave CT method is found. Through simulating mining process of workface, the distribution of the resistivity and wave velocity in the top rock of detecting field is tested and analyzed. The understanding of development regularity for the distortion and failure of top rock during mining of coal seam is obtained, and it can provide correct guidance parameters for practical production in mine. The results of integrated simulation show that the bore-laneway detecting system can give clear resistivity reaction of distortion and failure, and the seismic wave CT method can provide complete velocity distribution of rock development. The integrated system has high resolution for distortion of the top rock, and can give correct height of “two belts”. The simulating achievement is coincided with the practical detection in mine, and it is helpful to renewal and develops the theory and practice of testing technique of overburden failure in mine.

Abstract: According to the analysis of the landslide monitoring data, it is revealed that the amount of the cumulative displacement of the landslide depends on the monitoring cycle. And the trajectory curve of monitoring point has the fractal characteristics. The fractal dimension of the landslide internal points’ movement direction is various with the landslide development, which is decreased from the generation to the deformation and then to the damage. Meanwhile, based on the fractal boxing counting theorem, the program in Matlab is created to calculate the box dimension of the curve. Take a reviving landslide in Three-Gorge as an example, the fractal dimensions of the surface GPS monitoring points’ trajectory curves from 2007 to 2009 are obtained, and the dimension of each point is close to 1. The result indicates that this landslide is in the plastic deformation stage. It is the same with the landslide actual deformation. Therefore, the fractal theory has a great significance in the effective use of the monitoring data, the reorganization of the evolving stage and the prediction of the deformation trend for the landslide.

Abstract: With the rapid economic development of loess area, engineering loess landslides have become a serious danger to loess area people. It is an important engineering geological problem. Through making classify narrate to the harmful of engineering loess landslides. The main effects of engineering loess landslides are divided into four types. First type is human water activity cause loess landslides. Second is load and unload activities cause the loess landslides. Third is mechanical vibration effect inducing loess landslide. Fourth, loess landslides are induced by underground mining activities. Presents the performance characteristics and take conceive of engineering loess landslides to further research advances.

Abstract: The effective reinforcement depth was the main design basis of dynamic consolidation. The concept and affecting factors of the effective reinforcement depth were analyzed in the paper. The evaluating standards and determining methods were also summarized. The effective reinforcement depth could be determined from the field test and the in-situ test index. Three kinds of methods could be used to determine the effective reinforcement depth: field testing method, numerical simulation method and formula method.

Abstract: We simulate the rock’s movement and defoemation process in the coal mining, and research the overlying strata movement and deformation under the conditions of shortwall and longwall mining. The conclusion of the experiment indicates: with the method of double deck mining, the rock’s damage level in caving layer is more serious, the final subsidence curve presents a tooth geometry. The subsidence curve of fissure and flexure zone is simily with the longwall mining condition.

Abstract: Geotechnical tests are performed to study the strain-stress behavior and mechanical parameters by using the automatic KTG triaxial shear apparatus. This study shows that the strain softening phenomenon emerges after the peak values of strain-stress relations appear for the sliding-body soils, and that the strain-stress relations are in the sate of strain hardening all the time for the sliding-zone soils although the water content keeps sameness. The variation laws of cohesion and internal friction angle with water content are respectively consistent with an exponential function and linear relation.

Abstract: Risk analysis of shrinking and swelling of expansive soils and improved expansive soils with lime (IESL) for airport runway projection is a complex uncertainty problem. To select the rational foundation treatment plan and ensure the safe operation of runway, herein combined with the features of expansive soils in the runway area of Xinqiao international airport of Hefei, a novel risk analysis method was proposed to classify shrinkage and swell of expansive soils and IESLs by means of coupling set pair analysis with stochastic simulation of triangular fuzzy numbers. A function of six elements connection number was introduced to depict hierarchy and fuzziness of membership between the evaluation sample and the classification standard. Moreover, triangular fuzzy numbers simulated by a stochastic simulation method were presented to specify the component coefficients of discrepancy degree. Then a risk analysis model was described to calculate reliable degree corresponding to a confidence interval. Finally, comparisons of shrinkage and swell for foundation treatment plans of different lime content were conducted. The results will provide basis for the risk design and risk management of runway project on the expansive soils.

Abstract: The loess area ecology environment is very fragile, happening various geological disasters, loess landslides is one of the most mainly the geological disasters in loess area. Lvliang region loess hilly develops common, with the human economic activities increasing, inducing a lot of loess landslides. Taking typical loess landslides as the main research object, the loess landslides of Lvliang region from two aspects of characteristics and mechanism are analyzed. It is considered that the main types of the loess landslides are located within the layer of loess. Landslide is controlled by topography and lithology, landslide mechanism is induced by human economic activities. Through research for the region loess landslides hazard prevention provide the scientific basis.

Abstract: Based on the panel data of 30 provinces, municipalities and autonomous regions from 1994 to 2008, this paper uses the method of non-parametric estimation to do empirical analysis for the relations of physical capital stock, labor input and government public expenditure with GDP. The research results show that: The elasticity of physical capital stock, labor input and government public expenditure are e different at different times respectively; And the marginal effect of government public expenditure changes with the change of physical capital stock, labor input and government public expenditure.

Abstract: This paper attempts to simulate the stress-strain relations of Pontida silty clay under triaxial tests in accordance with the latest theory of geotechnical nonlinear deformation analysis-breakage mechanics of geomaterials. The result proves that the binary medium model of over-consolidated clayey soil can effectively reflect the deformation mechanism of soil mass and the brittle break phenomenon, thus possessing good suitability and effectiveness. This also lays down the foundation and provides new ways for the further discussion of establishing the elastic-plastic constitutive model of clayey soil softening properties and intensity attenuation effects with the consideration of large shear displacement.