Study On The Application Of Frustra-Like Crushed Stone Grouting Pile In Foundation Reinforcement

Coupled with the continuous and rapid economical development of China, construction and development of large-scale are still growing. China has a vast territory, terrain complex geological conditions, inevitably, soft soil and other highly compressible soft soils, which used to be considered technically unsuitable for construction, are encountered. Gravel pile is a common simple foundation treatment method of the soft ground in the China’s highway engineering, but the strength of gravel pile is low and the depth of the foundation this method of processing is limited; on the other hand, the grouting is provided with simple equipment and convenient construction, but has poor reliability.. The Frustra-like crushed stone grouting pile is a new type of foundation treatment technology which is combined with pile of gravel piles and post-grouting technology.In this paper, the following work is mainly done for this new type of grouting pile:(1) The gravel grouting pile composite foundation is summarized, frustra-like crushed stone grouting pile composite foundation and construction technology is put out, and the scope of application of the grouting pile is broaden.(2) By using element software ABAQUS to analyze the mechanism of reinforcement of the frustra-like crushed stone grouting pile composite foundation, the load transfer characteristics, and the influence of the replacement ratio of the serous influence zone land the load stiffness to this pile are mainly studied.(3) With a building foundation reinforcement, the working properties of frustra-like crushed stone grouting pile under rigid load is studied; with a highway foundation reinforcement, this pile under flexible load is studied.Based on the researches mentioned above, the following conclusions can be drawn:(1) The frustra-like crushed stone grouting pile composite ground can be classified into two categories:preliminary reinforcement and post reinforcement. In these two conditions, the mechanization and the structure of pile is not identical. (2) The emphasis focal point of frustra-like crushed stone grouting pile composite ground is also the interaction between column and soil. And the key techniques are as follows. The first is pile cap, it is used for adjusting the stress of column and soil and reducing the penetration deformation at the top and bottom of the pile The second is grouting, it can increase the integrality and pile tip resistance, side friction.(3) The P-S curve of frustra-like crushed stone grouting pile also follows the hyperbolic model, and has no marked inflexion. The bearing capacity of crushed-stone grouting column should be determined based on the settlement value.(4) When reinforcing the existing foundation with frustra-like crushed stone grouting pile, a combination of shallow grouting and deep grouting can have a good reinforcement.(5) The frustra-like crushed stone grouting pile composite ground is applicable for the soft soil foundation. Specially, the effect is better when the foundation has a low elastic modulus.