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桩的屈曲破坏属于突变理论的范畴,可采用突变理论进行桩的稳定性分析。首先对Y型桩的计算宽度进行了分析,并将尖点突变理论应用于确定基桩失稳破坏临界荷载的研究中,建立了顶部自由、底部嵌固情况下,顶部绞结、底部绞结情况下桩失稳的尖点突变模型,分别适用于部分入土、桩端嵌入较好持力层和全入土、桩端嵌入相对持力层的情况。从而提出了一种新的确定基桩临界荷载的方法。并将计算结果与室内模型试验和现场试验的测试结果进行了比较,验证了该方法的可行性。并对同截面面积的Y型桩、方形桩、圆形桩在部分入土和全入土情况下的临界荷载进行了比较。同截面面积,即相同混凝土用量的情况下,全入土和部分入土情况下,Y型桩压屈临界荷载均远高于方形桩、圆形桩,在假定的计算条件下,与大直径Y型桩相比方形桩、圆形桩的压屈临界荷载均只达到其0.65、0.62。Y型桩通过异形化提高了侧摩阻力的同时,也有效的增大了压屈临界荷载。
The buckling failure of pile belongs to the category of catastrophe theory, and catastrophe theory can be used to analyze the stability of pile. Firstly, the calculation width of Y-shaped pile is analyzed and the cusp catastrophe theory is applied in the study of determining the critical load of the pile under instability failure. Under the condition of top free and bottom embedded, top twist, bottom twist In the case of cusp catastrophic cusp catastrophe model, it is suitable for partial embedment, pile end embedment is better holding layer and full of soil, pile end embedded in the relative bearing layer situation. Thus a new method of determining the critical load of pile foundation is proposed. The calculation results are compared with the test results of the indoor model test and field test to verify the feasibility of the method. The critical loads of Y-shaped piles, square piles and circular piles with the same cross-sectional area under partial and full penetration are compared. With the same cross-sectional area, that is, the same amount of concrete case, the full access to soil and part of the soil into the case, Y-pile bending load is much higher than the square buckling, square pile, circular pile, under the assumed calculation conditions, and large diameter Y Pile compared to the square piles, circular piles buckling critical load reached only 0.65,0.62. Y-shaped piles by lateral deformation to improve the side friction, but also effectively increase the critical load buckling.