Applied Mechanics and Materials Vols. 638-640

Abstract: Measuring the height of overlying strata fracture belt with the “Double-plugging device” after mining the 3 upper coal, obtained the height, inverted the mechanical parameters of overlying strata according to the height, then conducted the numerical simulation with UDEC, and getting the height of overlying strata fracture belt when mining 3 down coal, with the data of this study we could expect the height of overlaying strata crack belt under the similar conditions, We can improve the upper limit of coal mining with the data of this research, and ensure safety in coal mining under the water.

Abstract: This work presents the closed-form solutions of the long-term thermal stresses, displacements and temperature increment of the cross-anisotropic strata subjected to a point heat source at great depth. The medium is initially modeled with cross-anisotropic mechanical and thermal properties. Under this assumption, the properties of the materials are different between the planes on and normal to the isotropic plane. Using Hankel and Fourier transforms, this paper presents the analytic solutions to soils or rocks affected by the point heat source, such as the repositories of nuclear wastes. The general solutions are further simplified to cases of materials with isotropic mechanical properties, and they are finally extended to fully isotropic in each property of the strata. Based on numerical results, the thermal stresses, displacements and temperature change of the thermoelastic half space are significantly affected by the anisotropy of mechanical and thermal properties of the strata.

Abstract: In the paper, based on soil-water coupled finite deformation analysis, theoretical considerations and numerical calculations were carried out under undrained three-dimensional condition in order to reproduce a uniform deformation field. At first, a theoretical consideration was assumed to realize a uniform deformation for a saturated soil, according to which the initial velocity and acceleration in both vertical and circumferential directions should be applied to each node to remove the influence of inertia effect. This first theoretical analysis is useful and can guide the numerical calculation. Next, the paper realized a uniform deformation of a three-dimensional cylinder specimen under undrained boundary conditions using the soil-water coupled analysis in which the SYS Cam-clay model is employed as the constitutive model for soil skeleton. The numerical results show that without the inertia forces there is no localized deformation in the specimen.

Abstract: Analyzing wave behavior on acoustic emission laboratory tests from relationship between stress and AE rate , the rock AE signal wave in laboratory is decomposed into high and low frequency elements. Analysis and compare with the details elements include, the approximation elements and original AE wave, the results show that rock AE wave characteristics are not same in the course of transform fracture on stages, found AE wave characteristics storehouse, it is a matter of great significance for utilizing monitoring and prediction regularity and development trend in the course of fracture transform. The error between the original signal and the signal of wave coefficient of the approximation elements reconstructed is minor to, wavelet analysis makes accuracy and reliability of rock AE wave characteristics monitoring and prediction improved, States that wavelet analysis is a great efficiency method.

Abstract: Based on the introduction of the characteristics of the supporting project of a large building foundation pit, the paper analyzed the main reasons for side wall collapse and pile fracture, including leakage water in the backfill soil, complex geological environment and unreasonable soil pressure value, low safety factor and improper design parameters, and then respectively proposed three kinds of treatment schemes for side wall sliding and pile breaking, landslides and other dangers. Finally, tracking observation showed that the satisfactory effect can strongly verify the suitability and validity of the main control parameters for the deformation of deep foundation pit, which may provide reference for the design and construction of similar projects.

Abstract: For the abandoned quarry complex rock slope project, the slope stability calculation is always the key technical problem, but due to the complex geological conditions and other factors, it makes the calculation of 3D modeling and the stability of the slope geological body and structure of the division, rock unit has always been the difficult problems in the field. This paper proposes a new method based on the rock mass structure combined with the degree of rock mass element, and then FLAC 3D, Midas GTS three-dimensional numerical calculation software are used, structure and surface topography in the slope, the slope surface fault, soft interlayer, complex geological 3D modeling, overcomes the problem of modeling of complex geological body, and the factors of rainfall, earthquake effect of the slope are consider for stability calculation, the calculation result is consistent with the reality, it has certain directive significance to the abandoned quarry re-greening slope stability analysis.

Abstract: In this paper, the ultimate bearing capacities of piles of a super high-rise dual-tower building structure in Guiyang were investigated. A stepwise test procedure was developed and carried out to obtain the pile capacity because of the limitation of experimental equipment and the complicate geological conditions. In the proposed procedure, the deep plate test, side friction test, and an in-situ test of full-scale pile were all carried out in the same hole in sequence. The equipment and procedure of the stepwise test are described in details. The test results are meaningful to provide reference values for investigating mechanical behaviour of pile and statistical analysis of pile capacity in the typical karst geology of Guizhou province. Since such a large-scale field test in Guizhou is limited, some recommendation values are also given to engineers for the pile foundation design in this district.

Abstract: In order to analysis of the mechanical properties of geogrid-reinforced granular soil, a simulation model of unconfined compression tests is proposed based on the laboratory tests conducted before by the author. This numerical method, after modified by the laboratory test data, is adopted to carry out a simulation of unconfined compression tests using large specimens of geogrid-reinforced granular soil. Each large specimen, with the diameter of 175cm and the height of 300cm, varies in reinforcement spacing of 30 cm, 37.5cm, 50 cm or 75 cm. For comparison, the same simulation test is also demonstrated for the granular soil without geogrid. A series of simulated compression stress-strain relationship curves are presented, on which a detail analysis is carried out. The following conclusions are obtained: (1) The geogrid-reinforced granular soil is a strain-hardening mass if the reinforcement spacing is less than about 50 cm. (2) While the reinforcement spacing is smaller enough, there is no sliding at the geogrid-soil interface and, therefore, the geogrid-reinforced granular soil may be taken as a composite material.

Abstract: The post-peak stress strain relationship expression of intact rock cannot well reflect post peak properties of rock masses with joint, in order to obtain post peak stress-strain relationship suitable for rock masses with joint, based on the test data, based on the Kulun strength criterion, analysis evolution of post peak strength parameters of rock masses with joint. According to rock masses with joint under different confining pressure and fracture dip at different post peak behavior, the post peak stress-strain relationship is simplified as new kind type, regarding maximum principal strain as strain softening parameter, on the assumption cohesion and internal friction angle are the piecewise linear functions of maximum principal strain, the method of solving express of new post-peak stress-strain relationship of rock masses with joint is obtained.

Abstract: According to the three characteristics of deep surrounding rock: high stress, high temperature and high seepage, the three field coupling control equation of temperature-stress-seepage are established, the finite element method is used for solution. Considering stress transference of surrounding rock after creep and deformation, the finite element incremental equations is deduced. Combining the finite element method and strength reduction method, The defect of deep surrounding rock stability that never quantitatively assess before was overcome. The proposed calculation method is applied to project, the analysis results show that the proposed method is feasible.