Advanced Materials Research Vols. 261-263

Abstract: Large-scale triaxial test has been conducted on various rockfill materials in an attempt to study the degrees of grain breakage. The result has shown that, the grain breakage occurred during sample preparation can not be neglected, and to maintain the initial gradation design prior to consolidation, the gradation design shall be adjusted downwards to a certain extent accordingly before sample preparation. The breakage of large-sized grains mainly occurs on the surface, and the grain breakage and confining pressure has shown linear relations after triaxial test.

Abstract: Based on existing models of main roof structure, combined with results of field observations, this paper put forward model of supporting rock structure during overlying strata movement in shallow depth. Through force and sliding instability analysis of the structure, it is obtained the relationship between block sliding and block’s lumpiness i and rotation angle θ, and determined a proper formula for calculating support resistance, and obtained the relationship between support resistance and block’s lumpiness i and rotation angle θ, which provides a theoretical basis for roof control and supports selection during shallow seam mining.

Abstract: This article adopts the general finite element analysis software——ANSYS to do the numerical analysis and research on some Composite Soil Nailing. The Drucker-Prager model modified with depth was adopted as the constitutive model. The article presents a lot of numerical calculations and analysis, researching the effects of excavation order, nailing length and nailing obliquity to the horizontal displacement of foundation wall, surface sedimentation and rise of the foundation bottom, giving some useful conclusion which can be used as the references to the design and construction of foundation supported with Composite Soil Nailing.

Abstract: The mechanism of soil arching effect is important for anti-slide pile design. With the 2D particle flow method (PFC2D), the forming and failure process of the soil arching between anti-slide piles are simulated. The results show that the forming mechanism of soil arching mainly depended on stress transit process of micro soil granule. In the anti-slide pile numerical models (PFC2D), the contact stress transit trace lines present the tree crown shape, which centered about the anti-slide pile. The load from far field is transited to the front and side part of piles through the compress soil. When the soil between anti-slide piles collapses, the failure surface presented the arching shape. The cross-section and spacing of anti-slide piles affect the soil arching shape strongly. With the same pile spacing and soil parameters, the ultimate bearing capacity of rectangular cross-section pile is larger than the circle cross-section pile.

Abstract: Shaking table test on soil-structure interaction system in harder site condition is presented briefly in this paper. Three-dimensional finite element analysis on shaking table test is carried out using ANSYS program. The surface-to-surface contact element is taken into consideration for the nonlinearity of the state of the interface of the soil-pile and an equivalent linear model is used for soil behavior. By comparing the results of the finite element analysis with the data from shaking table tests, the computational model is validated. Based on the calculation results, the paper gives the seismic responses under the consideration of soil-structure interaction in harder site condition, including acceleration response, contact analysis on soil pile interface and so on.

Abstract: With the development of oil industry, thousands of miles of pipelines for oil and gas transformation have been laid down in Bohai and Southeast Sea in China. By now, some pipelines have been reaching the end of the designed working duration and some have been damaged by fishing or anchoring activities. In order to maintain and repair the old or damaged pipelines, the details of the pipelines, such as the construction date, functions and owners, et al., should be found. It is difficult to collect such information in the conventional manner from the piling up of thousands of documents. Therefore, to develop a computerized database for pipeline investigating and monitoring is an urgent task. The principle and methodology of constructing the management system have been put forward and the configurations and functions of the established system expounded.

Abstract: In the paper, a mechanical model for the slab track was established. The mechanical characteristics and the deforming rule of slab track were analyzed using some parameters such as temperature load, the length and radius of circular curve, alignment irregularities, defects of fastening, etc. The results indicate that the lateral displacement of rails is periodically changed under the thermal force. The length and radius of circular curve has influence on the lateral displacement of rail. The lateral displacement of rails mainly influenced by resin’s elastic modulus, and has little relation with the length of circular curve. The mainly influence of resin’s elastic modulus is to the whole lateral displacement of track structure. alignment irregularities had a significant effect on the lateral displacement and track.

Abstract: The failure damage of granite under axial load are caused by the propagation and coalescent of cracks at mesoscale, so it is of important theoretical value and practical significance to to understand the mechnical properties of rock by experimental research on meso damage of granite. The microfracturing process of the pre-crack marble sample on surrounding rock in immerged Long-big tunnel in Jinping Cascade II Hydropower Station under uniaxial compression is recorded by using the testing scheme. According to stereology theory, the propagation and coalescent of cracks at meso-scale are quantitatively investigated with digital technology. Therefore, the basic geometric information of rock microcracks such as area, angle, length, width, perimeter, is obtained from binary images after segmentation. The results show that the new meso-mechanical testing scheme on rock meso-damage could be used to quantitatively analyzed from the geometric information of rock microcracks.

Abstract: The damage and failure of rock under loading are caused by the propagation and coalescent of cracks at mesoscale, so it is helpful to understand the mechanical behaviours of rock by quantitatively investigating on mesostructure of rocks. Based on the theory of damage mechanics, a digital experimental system on rock meso-structure is proposed. In this paper, the digital studies are conducted on the meso-structure of the marble from Jinping, Sichuan with the damage theory. Lots of meso-structure images are obtained through SEM observation. Based on digital image processing theory, some meso-level characteristics of micro-cracks are obtained such as length, azimuth, width, area and circumference. With the statistics theory and the Monte Carlo theory, the meso-level information of micro-cracks and their morphology are simulated in the representative volume element (RVE) of the Jinping specimen.

Abstract: The research is for the firs floods and the post-drought in Yunnan area in 2010. The strong rainfall and the hole pressure change are the red rock landslide most essential factor, so an apex post-modulus which indicates the effect of pore-water pressure on stress—strain curves transition is defined at the first. By combining with the stiffness criterion of landslide is analyzed. Consequently rainfall and other conditions changes have important effects induced landslides. It union research thinks of the elephant mountain landslide area, that red rock landslide slope body displacement and the rainfall amount relations and the slope body full water area compares and the stability of slope coefficient relations, establishes one under the strong rainfall function the red rock landslide cusp sudden change model, the quota and qualitative reveals the strong rainfall to the red rock landslide trigger action. This developed model may carry out some use full knowledge to understand the disaster mechanism and the evolutional or accumulative process of hazard factors in mountain red layer of the slope stability problem, which may mean the further to advance the technique of forecasting, it can provide important reference to the disaster prevention.