Study On Calculation Of Bearing Capacity And Settlement Of Vibroflotation Composite Foundation

In recent years, therewith economical, reliable, fast and simple construction, the reinforcement effect of such characteristics, vibroflotation composite foundation has been widely used and promoted in foundation projects in china. The complexity characteristics of soils such as discontinuity, heterogeneity, anisotropy, uncertainty and the external loads' transfer mechanism and partaking lead to some difficult of calculation and distribution of stress fields and displacement fields for the stone columns composite foundation. Calculation of bearing capacity and settlement of stone columns composite foundation is one of the hotspots in geotechnical engineering at present. At present, it is inadequate to research on the capacity and settlement of compound foundation and other characteristics of composite foundation and understanding of the mechanism to work are still very vague. Design of vibroflotation composite foundation mainly relies on experience and engineering analogy. Reinforce studies to work mechanism and calculate theoretical of vibroflotation is of great significance to raising the scientific nature of the project.In this article we will focus on analysis and study the calculation method of the bearing capacity and settlement of vibroflotation composite foundation. At first analyze the stone columns technologies in the development, application, study actuality, and point out the existing problems and shortcomings of application. Then focus on the working mechanism of composite foundation stone, capacity and character of the settlement.Compare to vibroflotation composite foundation settlement calculation theory. There have accumulated more works and theoretical research results. Although composite foundation theory more mature, but there are still a lot of issues worthy of further study. How to determine bearing capacity of the soil and single pile and how reasonable estimate bearing capacity that piles and the soil around the columns contribute to the composite foundation bearing capacity is the key to calculation, but still unclear. The key to calculation of ultimate bearing capacity of a single pile is calculation of lateral ultimate stress.Brauns theory is theoretical bearing capacity, but omitted a number of factors, such as: pile weight, soil weight, pile-soil interface shear stress, so actual results have misfired. Through another way—use semi-infinite cylindrical cavity expansion space (thick cylinders) theory to calculate single lateral limit stress: Based on Moore--Coulomb stress conditions that on the assumption that there is cohesion and internal friction angle of the two semi-infinite nature of the earth. The derivation of cylindrical hole (2D) expansion of the general solution, which is that the soil in the hole expansion force, columns into the soil gradually by the elastic deformation of the plastic deformation, as the load increases. Soil plasticity region continues to develop. Limit State shall pile pressure on the lateral expansion hole ultimate stress. Then analyze the formula, spreadsheet, made its reasonable improvements. Come bearing capacity, to further standardize the recommended formula for the composite load-analysis spreadsheet, increase correction factor, after several works by checking data. Verified the composite foundation bearing capacity formula is more reasonable.Although study that composite foundation settlement calculation has made significant progress, the complexity of soil structure, there composite foundation mechanism, changes in the structure of the reinforced soil is not yet clear. Composite soil and sub-layer stress distribution is difficult to determine, since a longer period of time, composite foundation settlement theory is still immature, and lags far behind the level of composite foundation settlement terms with the needs of engineering practice, often through the theoretical estimate of the settlement amount is much greater than the actual settlement of composite foundation settlement. This paper mainly deals with a study priebe method settlement formula. To facilitate deduction priebe is made in the classical ideal and the assumptions derived from the established model. The results are of a little bit conservative. Based on the assumption that some inconsistent with the actual situation in a reasonable improvement, and the corresponding mathematical expressions. And to facilitate the rapid design or checking calculated by the formula and the parameters calculated to draw the sketch, finally, examples of their work for the certification. Proven to improve the project through the final count, improved composite foundation of this settlement formula verified, the data shows: This paper presents a formula commonly used with the current formula, its results closer to reality, and ahigher level of accuracy, and it could provide the reference and guidance for future design and construction.This paper is divided into five chapters, the first chapter introduces the development of vibroflotation composite foundation , introduced a variety of commonly used method for calculating composite foundation bearing capacity and settlement, point out the problems that exist in their development and ways to resolve the problem line. Chapter 2 analyzes the mechanism that stone columns reinforce the loose soil and destroy under the load, chosen as a model for studying mechanisms used inflated destruction. Chapter III focus on the study of bearing capacity of vibrofltation composite foundation, including the single columns and composite foundation bearing capacity. For the bearing capacity, based on the thick-walled cylinder compression expansion theory derived from detailed formula, based on the original formula analysis, pointing out its deficiencies, and other issues, for instance, is given a simple volumetric strain, The trial is estimated that the coefficient in the formula given area. Then analyzed composite foundation formula and based on the difference of pile-soil stress sharing, modified the parameters of formula. Finally some examples of projects certificated and come to a conclusion. Chapter 4 is mainly discussed the composite foundation settlement calculation, concentrate on the Priebe common law, pointing out the inadequacy of their modeling assumptions, and then invoked, analyzed, carried out improvements to be made to improve the formula for a more accurate and useful. In order to simplify calculations, drawing a diagram calculation, the calculated process is much shorter. Finally, practical examples and consolidation software dedicated to the improvement of the vibro-replacement formulas are tested, the results are satisfactory. Made a conclusion and prospect for of the full text in Chapter VI.