Research on bearing capacity of inclined pile under vertical load
Inclination of piles may occur due to different reasons. How to determine the bearing capacity of inclined piles is a tough problem in practice. Field load tests on inclined piles, the required characteristics of soil for FEM analysis were obtained to conduct numerical analysis. The bearing capacities of piles with different degrees of inclination under different soil conditions were studied. It was shown that the settlement of piles was obviously influenced by the soil conditions, and that under the same vertical load the settlement of piles with the degree of inclination no more than 5 percent was even smaller, but the settlement of piles with the degree of inclination more than 5 percent increase obviously. With the inclination increases its bearing capacity is decreased obviously, thus the degree of inclination is the main factor of which control the vertical bearing capacity of inclined piles.
Effect of Pile Leaning on Pile's Carrying Capacity
Using static press on prestressed pipe pile foundation in fluid and plastic sludge floor,the eccentricity is easy to exceed the criterion of the acceptance specification because of the improper control of pressing the pile,earth excavate etc.This has been a kind of “common fault of the quality”. Through engineering example,the paper gives a way on how to use the eccentric pile after analyzing the theory according to related technical specification.
Analysis of the stress wave effect during coal breakage by a high-pressure abrasive air jet
In view of the defects of borehole collapse, inhibition of gas desorption and migration of gas existing in hydraulic fracturing and other hydraulic permeability–increasing measures for soft coal seams with low-permeability technology is proposed for coal breakage by a high-pressure abrasive gas jet for relieving pressure and increasing permeability. The comparative analysis of gas jet flow field structure between convergent nozzle and Laval nozzle has been given by numerical simulation. For Laval nozzle, the expansion wave and compression wave alternate and move forward steadily in gas jet and vanish when potential core length reaches maximum. So, the Laval nozzle can form more stable flow filed structure of gas jet and avoid shock wave in gas jet. Furthermore, a high-speed camera is adopted to analyze the jet structure and verify the conclusion of numerical simulation. Based on thermodynamic theory, this article calculates and analyzes the critical local sound velocity and pressure generated from the stress wave during the process of coal breakage by the gas jet. Furthermore, experimental coal breakage by a high-pressure abrasive gas jet is carried out. The high-pressure abrasive gas jet impacts the coal body as a quasi-static load and a dynamic load and forms corrosion pits on the surface of the coal body. Penetrating cracks are formed within the coal in the pattern of the loaded stress wave which leads to coal breakage. The effects of porosity and permeability on the propagation of the stress wave in coal are analyzed by establishing the dispersion equation for the spread of the stress wave in coal. The results show that porosity has a significant effect on wave velocity and that the attenuation of the stress wave is intensified with an increase in porosity. Moreover, the stress wave attenuation is more obvious at high frequency. The effect of permeability on the wave velocity is not significant at low frequencies. In contrast, at high frequency and relatively low permeability, the wave velocity increases with the permeability, and the attenuation of the wave velocity initially increases and then decreases. When the permeability is greater than 10−11 m2, the wave velocity is not affected by the permeability. However, the stress wave is not attenuated.