Applied Mechanics and Materials Vols. 90-93

Abstract: Submarine mining is unprecedented in China. XinLi Mining area, affiliated to Sanshandao Gold mine, is the first metal mining carrying out submarine mining exploitation in domestic. No occurrence of uniform settlement, cracking and collapse is the key point during the mining exploitation. According to the mining choosing principle and combining the production practice and relevant experience of Sanshandao Gold mine, the representative schemes are put forward. Two representative test stopes of 63# and 71# are chosen. After the comprehensive comparison and analysis, high-drift back-filling method is adopted to research the safety of submarine mining. Industrial test results show that the high-drift back-filling method has the significant advantages of safety mining, low ore dilution and so on. The mining production ability is improved greatly, obtaining remarkable effect and realizing the key points of higher efficiency and lower loss rate of ores.

Abstract: φThe circular tunnel is a common structure in civil engineering. Mohr-Coulomb strength theory has been used to analyses pressure tunnel in the field of rock engineering for many years. Because it could only solve the problems with one kind of material, the application of the theory was greatly restricted. In this paper, the formulas calculating yield range and stresses are deduced based on the proper choice of the first principal stress used in the unified strength theory according to loads and in-situ stresses. The applicability formulas is gained based on the critical pressures, which can be obtained in other situations or strength thoeries simplified by assuming the parameter value in the formula. An example is analyzed, and the yield range versus the inner pressure and stress distribution are presented. Results are compared to those based on the traditional method and significant disparity is observed. The results indicate that the coefficient b, cohesion c, friction angle φ all have significant influences on the yield range and stresses.

Abstract: The anti-explosion effects and anchored mechanism of tunnels reinforced by bolts were studied by numerical analysis. Comparing with compression-stress curve of the experiments and numerical simulation on the same location of the vault, it indicates that the simulation results are reliable. By contrast the vault displacement of anchored tunnel and unlined tunnel, it can be found that the vault displacement of the tunnel is significantly reduced through the reinforcement with anchor bolts. By comparing the crack distribution of the anchor tunnel and unlined tunnel, it shows that cracks of unlined tunnel are significantly thicker and wider than that of the anchored tunnel, which indicates that the anti-explosion effects of anchor rods are better. It can be known that the anchored bolts supporting can take effect of reinforcement and anti-explosion according to the time-histories curve of the anchor-head.

Abstract: Based on the existing research results, this paper proposes a temporal-spatial relational expression of displacements of tunnel perimeter during tunnel excavation. Taking Guanjiao tunnel as example, using the expression, temporal-spatial effect for Guanjiao tunnel in the fault-rupture zone are analyzed and studied. Comparison of theoretical solutions with measurements has proved that temporal-spatial effect for soft rock tunnel can be reflected by the expression and these results provide reasonable proposal for the optimum time to construct the secondary lining.( the constructing time of secondary lining) and reserved deformation.

Abstract: A hybrid simulation method is used to generate two group artificial ground motions that are compatible with the same acceleration response spectrum, same peak displacement and different peak ground velocity (PGV). The influences of PGV on the internal forces of subway station are studied. For the time histories with the same response spectrum and same peak displacement, the larger PGV of input motions may lead to the great plastic deformation of the soil, and then cause the larger internal forces for the most elements of subway station. The influence of PGV should be considered reasonably in determination of design ground motion parameters for underground structures.

Abstract: According to analyze the settlement characteristics of storage tank foundation at water-filling preloading stage and stable loading stage based on numerical simulation, and researching the settlement characteristics of storage tank foundation. The research results show that the deformation of storage tank foundation is “tray” in shape, and the maximum settlement appears at the place 0.65D away from the center of storage tank bottom, D is the radius of storage tank. Uplift appears at the place 1.3D away from the center of oil tank bottom, and the final uplift value is 10mm.The main factor which influences the consolidation speed of storage tank foundation is permeability coefficient.

Abstract: Three cases for 1-D wave propagation in ideal elastic rock, through single rock joint and multiple parallel rock joints are used to verify 1-D wave propagation in rocks. For the case for 1-D wave propagation through single rock joint, the magnitude of transmission coefficient obtained from UDEC results is compared with that obtained from the analytical solution. For 1-D wave propagation through multiple parallel joints, the magnitude of transmission coefficient obtained from UDEC results is compared with that obtained from the method of characteristics. For all these cases, UDEC results agree well with results from the analytical solutions and the method of characteristics. From these verification studies, it can be concluded that UDEC is capable of modeling 1-D dynamic problems in rocks.

Abstract: By using three kinds of subgrade soil and controlling dry density and moisture content，the correlation between strength parameters of pavement subgrade soil, California Bearing Ratio(CBR) and Resilience modulus E, and their shear wave velocity are studied through CBR Penetration test, lever pressure meter test and shear wave velocity test. Then the analytical models of CBR and Resilience modulus E by shear wave velocity are proposed. These models are valuable to acquire airport pavement subgrade soil parameters by nondestructive technique.

Abstract: Abstract. Based on the three-dimensional wave theory,the coupled torsion vibration of the end bearing pile embedded in viscoelastic soil is researched by using the separation of variables technique. Calculation formulas of the torsional complex stiffness and admittance of pipe pile embedded in viscoelastic soil are obtained and the influence of shear modulus ratio, viscous damping coefficient ratio and the ratio of inner and outer radius on the torsional complex stiffness and admittance of pipe pile are discussed.Finally, the following conclusions are drawn.(1) Shear modulus ratio of soil inside and outside the pile, viscous damping coefficient ratio and the ratio of inner and outer radius have no effect on dynamic damping of pipe pile. The impact of shear modulus ratio of soil inside and outside the pile and the ratio of inner and outer radius on pipe pile in low frequency range is little. With the increase of frequency, the influence is increasing. Viscous damping coefficient ratio does not cause real stiffness of pipe pile. (2) Shear modulus ratio and the ratio of inner and outer radius have a significant influence on the admittance of pipe pile top.The greater shear modulus ratio and the ratio of inner and outer radius, the amplitude of the speed admittance curve of pipe pile top is larger .

Abstract: Highway maintenance is the main new task after highway construction. In order to predict pavement performance reasonably, and choose the most reasonable maintenance plan, based on investigating and inspecting the pavement condition , use computer language of VB from inputting the data module, establishing evaluation module, maintenance module, prediction module, economic evaluation module and statements processing module of pavement maintenance management system. Put the original data into this system. The system can predict pavement performance and choose maintenance scheme automatically, and use multi-objective optimization model, the effect of the definition and dynamic programming method to optimize the scientific and reasonable maintenance plan, which is from technical and economic aspects to realize by using the limited maintenance funds to achieve the best maintenance effect and to obtain the biggest social and economic benefits.