Applied Mechanics and Materials Vols. 580-583

Abstract: A three-dimensional DEM numerical model for analyzing rock failure process was developed by taking heterogeneities on microscopic scale into account with statistical mechanic. Failure processes of a series of rock samples with different heterogeneities were numerical simulated by uniaxial compressive tests. The influences of microscopic heterogeneity on macroscopic mechanical properties and failure behaviors were investigated. The results demonstrate that the numerical tests are able to illustrate the crack propagation occurring in different stages, and to predict the characteristic stresses and strains. With the increasing of heterogeneity index, except for Poisson’s ratios and crack damage strains that almost maintain constant, deformation parameters as well as characteristic stresses and strains increase following exponent functions. As heterogeneity increases, elasticity deformation of rock samples becomes longer, volume compression reduces, brittle failure characteristic presents more significant, failure mode changes from “X” pattern to coalescence surface pattern forming through the whole rock samples.

Abstract: Mohr-Coulomb strength theory is the most widely used in practical engineering, however, it is difficult to predict the cohesion and internal friction angle precisely. In fact, soft clay’s shear strength varies with the change of stress path and consolidation history, so it is vital to predict the shear strength in different construction phases, and the influence of soil structure is necessary to be taken into consideration to predict the shear strength under under arbitrary degree of consolidation. This study proposed a simple shear strength fomula under arbitrary degree of consolidation considering the enfluce of soil structure. The derived formula is much more convenient to plug the changing strength index into program.

Abstract: Through doing spot monitoring on stability of slope engineering management of Longmenhao Primary School, this paper does analysis on monitoring data for one month. Analysis results show that all of accumulation maximum displacement, change rate of horizontal displacement and accumulation maximum settlement of slope of Longmenhao Primary School do not surpass warning value thus knowing that slope of this section is basically stable which also provides references for stability detection analysis of engineering management.

Abstract: 3D-geomat protective slope is a new type of protective slope form which combines the 3D-geocell with the planting grass. Because the complex and dense spatial structure can tie the slope soil and has a reinforced effect on the slope surface, it has the advantage in soil and water conservation and ecological protection, and it gets more and more widely used in the present engineering construction. By using the finite element model, we compare the whole stability in the 3D-geomat slope and unprotective slope under the condition of different slope gradient. And then we get the relative results.

Abstract: This article mainly expounds the importance of in-situ monitoring on the construction process of deep foundation pit. Taking the deep foundation pit of some Shenyang metro station for example, the deformation features of the supporting structure and the internal and external of foundation pit is analyzed, according to the monitoring data of the fender pile displacement during the excavation of deep foundation pit. The conclusion is obtained that the timely and accurate in-situ monitoring information is necessary to guaranteeing construction safety. We should pay more attention to the excavation speed and exert the interior support timely during the excavation of foundation pit to avoid large deformation and danger. The analytical results of monitoring data shows that the whole stage of foundation pit excavation is stable and the fender pile with internal supports can guarantee the stability of foundation pit.

Abstract: In this paper, the formulae are deduced for the floatation response of pipeline buried in liquefied soil. The beam model based on the theory of beam on elastic foundation is used for the pipeline buried in non-liquefied and liquefied soil. The soil property is nonlinear, the floating force induced by the soil liquefaction is related to the position of pipeline, is nonlinear also. For the convenience and simplification of analysis, the nonlinear increment element method was used and lots of numerical analysis was conducted, including: the floatation response of pipeline buried in homogeneous soil, the floatation response of pipeline buried in non-homogeneous soil, and the floatation response of pipeline buried in discontinuous liquefied area. The influential factors on the floatation response of buried pipeline buried in liquefied soil including spring stiff of liquefied soil, the initial deformation, the length of liquefied area, the axial force acting on the pipeline, the material of pipeline, and the diameter of pipeline. The calculation results of discontinuous liquefied area draw a significant conclusion that for a long liquefied area, to make the soil non-liquefied in the middle of liquefied area may decrease the length of liquefied area and reduce the flotation displacement of pipeline greatly.

Abstract: Working well of nanjing city latitude three pass by river channel project is taken for example. Underground continuous wall was adopted in this project. Detailed monitoring scheme was formulated and lots of date was obtained by foundation pit. The monitoring data changed sharply analysis shows that the maximum horizontal displacement and the maximum strut axial forces is located near the excavation surface and along with the soil excavating. After structure construction, the change of deformation and internal force of enclosure structure gradually became stable. The theoretical analysis and test results are tend to be consistent. But this two have certain differences due to the influence of various factors.

Abstract: Study on bearing mechanism of jacked pipe pile in sand is useful of optimizing the pile foundation design, and the research of the regularity of side resistance and tip resistance of pile has a very important theoretical significance. In this paper, a new effective method is used to test the tip resistance of the jacked pipe pile during the press-in process, and then the side resistance can be deduced ^[1]. Based on the field tests, the inherent laws of interaction between pile and soil in sand is explored, which provides some theoretical basis for the pile foundation design and engineering application.

Abstract: A synthesized investigation is conducted of trench formation machine’s effect on trench wall in soft soil area. The failure pattern of the slurry-trench is analyzed by means of 3D FEM based on strength reduction method. The investigation shows that the global instibility occurs in the superficial layers and speads along the trench segment. The grab movement in slurry has an instant impact on the trench wall and may cause local instability. The overload and construction technique of trench formation equipment are both important concerns during trench construction to ensure safetry.

Abstract: The numerical-analytical solution of the axisymmetric problem of moisture-elasticity for hollow spherical soil massive is provided. We consider the steady-state water transfer. Inhomogeneity of the array due to the dependence of the deformation modulus on the soil moisture. Stress state of the array caused by forced deformations and uneven pressure rebuff of the soil. The method for solving non-axisymmetric problems with radial inhomogeneity in polar coordinates is described. Diagrams on the stress fields in homogeneous and inhomogeneous formulations of the problem are provided. It describes a method of calculating radial inhomogeneous axisymmetric problem of theory of elasticity for thick-walled spherical shell.