Applied Mechanics and Materials Vols. 204-208

Abstract: Based on Biot’s theory and integral transform method, the velocity of moving loads impact on the vibration isolation effect of pile rows embedded in a poroelastic half space is investigated in this study. The free field solution for a moving load applied on the surface of a poroelastic half space and the fundamental solution for a harmonic circular patch load applied in the poroelastic half space are derived first. Using Muki’s method and the fundamental solution for the circular patch load as well as the obtained free field solution for the moving load, the second kind of Fredholm integral equation in the frequency domain describing the dynamic interaction between pile rows and the poroelastic half space is developed. Numerical solution of the frequency domain integral equation and numerical inversion of the Fourier transform yield the time domain response of the pile-soil system. Numerical results of this study show that the same pile rows can achieve a better vibration isolation effect for the lower load speed than for the higher speed. Also, the optimal length of piles for higher speed moving loads is shorter than that for lower speed moving loads.

Abstract: Abstract: Based on the design and construction of the south shaft of Yellow River Crossing Project, this paper calculated the grouting reinforcement range by theory method, which includes block strength theory, clay soil slippage theory and soil disturbance limit equilibrium theory. Owing to the thickness value was calculated by those theory methods which are conservative[1], so this paper will reduce the thickness value on the basis of theoretical value, then made the analysis on the stability through shield-driven numerical simulation , emphatically analyzed the displacement field. We can find that reducing the range of reinforced soil is feasible. In addition, the dimension of reinforced soil should satisfy the requirement from waterproof and collapse-proof. The research result is hopeful to provide theoretical basis and help for the design and construction of shield-driven.

Abstract: Compaction piles is one of the conventional methods for foundation treatment in collapsible loess, there are very few research results about soil compaction effect between piles when forming the piles. Firstly, the stress field and displacement field of soil around compaction piles are elastic-plastic analyzed on the basis of the cavity expansion theory; then a series of FLAC 3D numerical simulations were performed to evaluate the treatment effect of the compaction pile composite foundation. The result shows that all bearing capacity has improved, and quicklime compaction pile composite foundation has been increased remarkably. It embodies the correctness of the computation theory. And the feasibility of the compaction piles composite foundation on collapsible loess area is further proved.

Abstract: Duchuanbian collapse is located inside Micangshan avenue in Nanjiang county, Sichuan province, consisting of 6 dangerous rock bands. It is in a basically stable state overall now, with partial area in a semi-stable or unstable state. Qualitative analysis is carried out in stereographic projection method taking 1st dangerous rock band of Duchuanbian collapse for example, so as to understand the structure feature of slope rock mass, and judge it may occur collapse in falling type.And then static force analysis method is used for quantitative calculations, thus determining that 1st dangerous rock band is in semi-stable state under natural condition, and it may occur collapse under action of torrential rain, earthquake and other unfavorable factors. Therefor, it requires to take reasonable measures for comprehensive treatment.

Abstract: Anti-slide pile deformation of pile retaining wall in expansive soil region was analyzed in this article. Main factor which affected deformation of the anti-slide pile was discussed. The result showed that expansive power and pile embedded solid depth was the main factor which affected the deformation of the pile in expansive soil region. Engineering measure related to the anti-slide pile deformation was alalyzed to show that the anchor cable could effectively controlled the deformation. As well as the order of the anchor cable and slaking effect of expansive soil had a great impact on the pile deformation. It can be used as reference for the design and construction of the pile retaining wall in the expansive soil region in future.

Abstract: Compare to common river bed, the erosion and deposition of debris flow gully have a distinctive phenomenon except big changes of scour depth and deposition thickness. Due to its particularity, the process of gully erosion and deposition, variation of gully longitudinal slope is hardly obtained from field survey and observation. The paper analyzed the research of variation of gully erosion and deposition firstly, then prior to probe the changes of gully surface elevation under debris flow erosion, the variation laws of longitudinal slope of gully with debris flow density, initial angle of gull slope and bed materials through flume experiments.

Abstract: The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

Abstract: Three different numerical tests, i.e. no rolling test, free rolling test and rolling resistance test, in the framework of discrete element method (DEM) are carried out to simulate the micro-structure development in shear bands. The rotational angles and effective strain in the specimen under different conditions are given out. By contrast, it can be concluded that the development of shear bands in granular material can be simulated well when the rolling resistance is taken into account in DEM.

Abstract: The water filling preloading method is the common ground treatment method adopted to reinforce soft tank foundation. The influence laws of load speed, soil parameters on the reinforced effect of soft tank foundation were analyzed by the three-dimension finite element numerical analysis procedure. The research shows that the fovea deformation of single tank bottom under preload is similar to the pan bottom shape; the influence of soil constrained modulus on settlement is remarkable and it also affects the settlement time curve shape; when the constrained modulus is constant, with the permeability coefficient decreasing, the surface doming phenomenon around the tank foundation increases, and the range of upheaval is related to constrained modulus; the influence of loading function on the final settlement is very small, but the influence on pore water pressure is remarkable.

Abstract: To study the influence of active earth pressure caused by the ditch after retaining wall, we will treat the ditch as unloading, and use the resolve of uniformly distributed load on half-infinite plane boundary to get the calculation method to get the influence of active earth pressure caused by the ditch after retaining wall. At last, from an example, we will get the picture of active earth pressure caused by the ditch after retaining wall, and analysis the regular pattern and characteristics.