基于南宁典型地层组合模型长螺旋钻孔压灌桩与螺纹桩的适用性研究

发布时间：2018-04-18 10:05

  本文选题：长螺旋钻孔压灌桩 + 螺纹桩　； 参考：《广西大学》2017年硕士论文

【摘要】：基于南宁盆地地层组合模型,本文对长螺旋钻孔压灌桩和螺纹桩的适用性进行了研究。为此,试验小组历时一年多选择在两个相同地层组合中组织了两类似设计参数的试验桩进行了相应的工程试验。并从两类桩的承载机理、施工控制、技术特点、工程试验结果等多方面进行了详细分析、计算和研究。得出如下结论:(1)长螺旋钻孔压灌桩和螺纹桩在工程实践中均以中小直径桩出现,两类桩在施工工艺、压灌混凝土、钢筋笼植入、现场施工文明度等方面具有相同或相似的特点。但在承载机理、成桩机械、成桩质量控制要点、造价方面相差较大。(2)两类桩成桩设备均存在入岩困难,但长螺旋钻孔压灌桩桩机入岩困难不仅不会降低其单桩承载力,反而有助于提高其单桩承载力;而螺纹桩桩机一旦出现入岩(或钻进)困难,则对其单桩承载力影响较大。(3)通过两个类似地层组合场地及类似设计参数的基桩试验,长螺旋钻孔压灌桩通过选择好的桩端持力层,适当加大混凝土的压灌力,可以显著提高单桩承载力。而螺纹桩在螺纹段成孔或成桩过程中,如果不能采用同步技术,则作为单桩承载力主要来源的螺纹段承载力下降较大,该部位的承载力仅有正常成桩时的46%左右。(4)当螺纹桩螺纹段螺牙间土受到扰动后,螺纹桩螺纹段的桩侧阻力相当于桩径为螺纹桩内径的干作业钻孔桩的桩侧阻力,并通过对试验结果参数的分析,对螺纹桩技术规范的公式参数进行了修正,提出了螺纹桩单桩承载力下限值计算公式。(5)如果减小螺纹桩的入岩深度,保证螺纹段正常形成,则螺纹桩应用于地基处理具有相对优势。(6)在现阶段,两类桩桩机均存在入岩困难的前提下,在南宁盆地典型组合地层(Ⅰ、Ⅱ级阶地)上,长螺旋钻孔压灌桩具有比螺纹桩更好的适用性。两类桩在南宁盆地的高阶地(泥岩型)地层组合作为工程桩则适用性均较差。
[Abstract]:Based on the stratigraphic combination model of Nanning Basin, this paper studies the applicability of long spiral bored pile and threaded pile.For this reason, the test group took more than one year to select two test piles with similar design parameters in two same strata assemblages to carry out corresponding engineering tests.The bearing mechanism, construction control, technical characteristics and engineering test results of the two kinds of piles are analyzed, calculated and studied in detail.The conclusions are as follows: (1) the long spiral bored pile and the threaded pile all appear as medium and small diameter piles in engineering practice. The two kinds of piles have the same or similar characteristics in construction technology, pressure pouring concrete, steel cage implantation, field construction civilization and so on.However, there are two kinds of piling equipment, such as bearing mechanism, piling machinery, pile quality control points, and cost difference. There are two kinds of pile-forming equipment, which are difficult to enter rock. However, the difficulty of drilling pile machine with long helical drilling hole does not reduce the bearing capacity of single pile.On the contrary, it helps to improve the bearing capacity of single pile, but once the screw pile machine is difficult to enter rock (or drill), the bearing capacity of single pile will be greatly affected by two similar ground combined sites and similar design parameters.The bearing capacity of single pile can be significantly increased by selecting a good bearing layer at the end of the pile and properly increasing the compressive force of concrete.However, if the synchronous technology is not adopted, the bearing capacity of the thread section, which is the main source of the bearing capacity of single pile, will decrease greatly in the process of forming holes or piles in the thread section.The bearing capacity of this part is only about 46% of that of the normal pile formation.) when the soil between the screw teeth of the threaded pile is disturbed, the pile side resistance of the threaded thread section is equal to the pile side resistance of the drilled drilled pile whose diameter is the inner diameter of the threaded pile.Based on the analysis of the parameters of the test results, the formula parameters of the technical specification for threaded pile are revised, and the formula of the lower limit value of bearing capacity of single pile with threaded pile is put forward. (5) if the penetration depth of the threaded pile is reduced, the normal formation of the threaded section can be ensured.Therefore, the application of threaded pile in foundation treatment has a relative advantage. At the present stage, both kinds of pile machines are difficult to enter rock, and on the typical assemblage strata (鈪，

本文编号：1767895