Study On Working Performance And Settlement Of Rigid Pile Composite Foundation

Rigid pile composite foundation is widely used in the projects because of the strength and high stiffness of piles, it can substantially improve the foundation bearing capacity and effectively reduce the settlement, and suitable for the treatment of clay, silt, sand, artificial fill soil and other soil foundation. It has notable feature of strong adaptability and capacity increases, and the small amount of the settlement. Due to its advantages as mentioned above, this type of composite foundation is widely used in china, and achieved remarkable economic and social benefits. However, the rigid pile composite foundation bearing capacity and settlement theory is lagging far behind in engineering practice. This thesis puts forward the bearing capacity formula of crushed stone grouting pile, and deduces the calculation formulas between pile-soil stress ratio and the negative friction area on piles and the evaluation method of consolidated area considering the interaction of pile-soil-cushion. Compared with the actual project and obtained better result.(1) The existing common formula of bearing capacity of rigid pile composite foundation is summarized and the consolidation mechanism of crushed stone grouting pile is analyzed. The revised formula of bearing capacity is introduced considering the traits of crushed stone grouting pile compound foundation. Comparing with the measurement results of practical project, the formula is applicable for the calculation of the crushed stone grouting pile bearing capacity.(2) The existing common formula of pile-soil stress ratio of rigid pile composite foundation is summarized. This formula is based on the load-bearing characteristic and the deformation model of rigid pile composite foundation. The relationship between the calculation formulas of pile-soil stress ratio and the negative friction area on piles considering the interaction of pile-soil-cushion was deduced. This calculation formula is evaluated and confirmed through tested example.(3) Based on the load-bearing characteristic and the deformation model of rigid pile composite foundation and used Berrum formulas, the calculation method of consolidated area considering the interaction of pile-soil-cushion was deduced. Comparisons between results from presented method show that the agreement is satisfactory.