Applied Mechanics and Materials Vols. 204-208

Abstract: The deep foundation pit engineering of Wanda Plaza in Yinchuan city is taken as a case study and the corresponding numerical model has been built. The deformation and stability of the foundation pit during sequential excavation has been analyzed by using of the FLAC3D software. The weak positions which may lose the stability are predicted by the results from the numerical simulation. A soil-nailing reinforcing scheme has been proposed to maintain the stability of the foundation pit. To analyze the support effects of the soil-nailing, the Cable structure elements have been adopted to simulate the interaction between soil and soil-nailing. The calculation results show that the maximum horizontal displacement occurs in the middle part of the pit wall and the minimum occurs in corner part of the pit wall. The soil nailing support significantly decreases the deformation of foundation pit by dispersing internal stress of soil. The reliability of the simulation results has been verified by the comparative analysis between the numerical simulation results and the deformation monitoring data of foundation pit. The proposed reinforcement scheme is not only helpful to ensure the safety of Wanda Plaza foundation pit，but also provides valuable experiences for the reinforcement of similar foundation pit engineering.

Abstract: High stress in the surrounding rock mass causes serious stability problems. The applied support system used in this conduction should be able to carry high loads and also accommodate large deformations without experiencing serious damage. In this paper, a brief overview of the history of yielding/energy-absorbing rock bolts is provided. And then, a new yielding bolt invented by the author is introduced in detail, including its layout and principle. Theoretical analysis shows that the bolt has large load-bearing and deformation capacities, thereby absorbing a large amount of energy to maintain the stability of surrounding rock.

Abstract: The damage mechanism of loessial soils was studied by the statistical theory.Based on the characteristics strength of loessial soils micro-unit with Weibull distribution, and parameters that described by distribution variable of Drucker-Prager creterion are used, loessial soils damage constitutive model considering damage threshold is established to reflect the full process of loessial soils failure. Conventional triaxial consolidation undrained shear test results of loessial soils are taken as example to verify the model. By comparing theoretical calculation results with test results, it is showed that the statistical damage constitutive model considering damage threshold is reasonable.

Abstract: Reinforcement using alkali substance produces plentiful calcium hydroxide, and calcium hydroxide has engendered long-term demolishment in laterite embankment. Particle contents were analysed and significant ions were tested at demolished laterite in embankment, and chemical reactions of acidic laterite with calcium hydroxide were canvassed. Accelerated life tests were performed, changes of basilic engineering indexes and content changes of significant ions were tested in laterite fore-and-aft demolished. Mechanism of laterite embankment scathed by calcium hydroxide was explored. Acid-alkali reaction is rootstock of benefit descending and life shortening, and is important inducement of permeability exacerbating in laterite embankment.

Abstract: Abstract: This paper takes the project of the navigation lock in Jialing River as an example to study the lock head structure design layout, and build up a three-dimensional finite element model and carry on the nonlinear numerical calculations by using large finite software ABAQUS, and calculating the structural internal force of the lock head by the 3D nonlinear finite element method. This paper utilizes the numerical analysis method to analyze soil strength parameters. Combining with the FEM calculation data, the data-fit between the influencing factors and the side piers’ stress and displacement was found. This provides new thoughts to analyze the influence of multivariate interaction on the lock head structure.

Abstract: Water of reservoirs shows acidity in laterite regions, and laterite engineering is chronically demolished by chloride ions in water. Ground on mechanism analysis, accelerated life tests were implemented. After permeability test, changes of grain-size-gradation were analysed at laterite remainder, microstructures of soil sample were observed, and concentration changes of iron ion as well as aluminum ion were affirmed in transudatory liquid. The harvests indicated that: sesquioxides (viscous substances in laterite) are consumed by chloride ions in water, and microstructures of laterite are demolished. Products from chemical reaction are dissolved by water and are schlepped off by seepage, so wispy leakage channels are created in engineering. The eroding of chloride ions has clearly debased security of laterite engineering.

Abstract: There will be a variety of problems in the process of dam using. The common problem is that the saturation line is high. When the saturation line is too high, it will not only lead to the increase of downstream leakage, but it may also cause dam break and finally causing the loss of life and property. So we need to pay much attention to the saturation line of the dam. When the saturation line is too high, it should be noted and if necessary we should adopt the measures of strengthening. This paper through the comparison and selection of several schemes and finally to determine the reasonable reinforcement method.

Abstract: Hole cleaning was very difficult in horizontal wells and extended reach wells (ERW), which was the technical bottleneck in raising the progress and success rate of petroleum exploration and production at present. A new type of treating agent for drilling fluid (CNRJ), designed for horizontal wells and extended-reach wells, was synthesized. CNRJ was added to drilling fluids, and the rheological properties, temperature-resisting property and suspension performance of drilling fluid system were analysed. The results indicate that CNRJ has good compatibility with drilling fluid system, and the dynamic plastic ratio of drilling fluid system can be adjusted from 0.20 to 1.12. In addition, the drilling fluid system has good static suspension ability for cuttings, good heat resistance and pollution resistance.

Abstract: In the effect of the external environment,the characteristics of the microscopic deformation in the soil may be induced by the microstructures such as the interaction of soil particles and interaction between soil particle and void. The microstructures have great influence on the engineering properties of soil. This paper studies the microstructures characteristics of the precipitated dredger fill in port-centered industry in Tianjin by the electronic microscope test. Finally, the characteristics and the distribution of the microstructure would be analyzed.

Abstract: As a special kind of engineering material, the mechanical properties and failure characteristics of rock directly determine the safety of the engineering works. In this paper, to estimate the indicator of rock failure under seismic loading, the axial plastic strain development of basalt under different lithology and different frequency is studied based on triaxial cyclic loading test. A magnitude of 10-3 is obtained for the critical plastic strain of basalt at failure. The mean value of critical plastic strain is 0.003. A seismic analysis of underground powerhouse complex of the Baihetan HPP is then conducted as a study case. The development of rock mass's plastic strain with seismic loading is studied, and failure zones which have the worst effects on the complex are revealed.