【作者】 孙志亮；

【导师】 刘杰；

【作者基本信息】 天津大学 ， 结构工程， 2006， 硕士

【摘要】 本文在对单桩荷载传递试验的理论研究和发展现状调查的基础上,进行了一定数量的静压预应力管桩的足尺试桩的荷载传递试验。试验桩身内力测试元件采用电阻式应变计,埋设在管桩混凝土外壁,并附环氧树脂胶和钢片保护。试验得出各试桩的实测Q-s曲线、桩身实测应变、桩身轴力分布曲线,并分析得出各土层阻力与位移的关系曲线,为分析静压预应力管桩荷载传递特性提供足够的实测数据。分析预应力管桩的桩侧阻力的发挥性状,提出各土层极限侧阻力的取值范围,认为桩侧土体材料在发挥极限侧阻力后均出现明显的应变软化。各土层发挥桩侧阻力所需的桩土间相对位移不尽相同,一般不超过10mm,均己先于端阻力发挥出来。土层随深度增大而侧阻力相应增大,浅部土层受挤土影响,侧阻力趋于定值。分析预应力管桩桩端阻力的发挥性状,提出各土层极限端阻力的取值范围,认为充分发挥桩端阻力所需的桩端沉降比相对其他桩型是非常小的,发挥极限端阻力所需的桩端沉降约为桩端直径的5~10%。研究预应力管桩的荷载-沉降特性,分析影响沉降的主要因素,研究了该桩型主要荷载传递特性,并将荷载传递参数与其他桩型进行比较。同时对比分析了敞口管桩与闭口管桩的Q-s曲线形态,研究了其沉降特性,得出荷载沉降的解析算式,提出了相同受力情况下,闭口管桩较敞口管桩在控制沉降问题上有很大的优越性。本文对一定数量预应力管桩竖向静载试验结果进行了统计归纳,并对管桩实际承载力与设计计算承载力之间的差异进行了分析研究,提出了《建筑桩基技术规范》(JGJ94-94)中的经验公式的修正,并通过用实测结果与计算值对比,验证了修正公式的实际意义。更多还原

【Abstract】 Based on theoretical research and developing investigation on load transfer testing on single pile, this paper carries on a serial of full-scall load transfer test on static pressure pre-stressed steel pipe pile. The piles were instrumented with strain gages which were installed on the surface of pile’s concrete outer wall and were protected by the epoxy and the steel disk. According to the results of static loading test, we have the load-settlement cures, the data of strain in the pile shaft and the axial force distribution curves of the test piles. At the same time we can get the relation curve between the shaft resistance and the relativc displacement. The results are basic data for the analysis static pressure pre-stressed steel pipe piles.Analyzed the behavior of shaft resistance on pre-stressed steel pipe pile, the range of the ultimate value of shaft resistance in every soil layer is presented, the relative displacements to mobilize the ultimate resistance is different when soil is different, generally, it is not larger than 10 mm. The significant strains soften happened after the ultimate resistance were mobilized.Because of the squeeze efect the shaft resistance at the shallow depth is constant. The deeper the depth, the greater the shaft resistance is. Analyzed the behavior of end resistance of piles, the range of the ultimate value of end resistance is presented. Compared to the other types of piles, the settlement of the pile to mobilize end resistance is very litle. Generally, it is 5%~10% of the end diameter for the ultimate end resistance. The existing of residual stress near pile end increases end resistance and shaft resistance near pile end.This paper researched the load-settlement characteristic, anlysized the settlement influence factor and load transmission characteristic. Through the pre-stressed aperture pipe piles and the blind pipe piles’load - settlement test, contrasted their Q-S curve shape, analyzed their settling qualities, and obtained that under the same condition the blind pipe piles are more superior than aperture pipe piles in controlling settlement.At the same time, this paper contrasted the difference between the actual result and the predicted value and supposed a formula revision, and confirmed the correlation formula practical significance.更多还原