砂土中静压群桩承载力特性和桩与桩相互作用研究

发布时间：2018-05-24 17:19

本文选题：静压桩 + 模型试验　；参考：《河南工业大学》2017年硕士论文

【摘要】：近年来我国不断提高环境污染治理力度,同时大力提倡预制构件应用于工程建设领域以减少建设施工对环境的污染。静压桩以其环境污染小,无噪音振动污染,预制型桩体质量易于控制以及施工速度较快等优点,在基础工程中越来越受到设计人员的关注。本文简要地阐述了静压桩的发展历程及其常用的研究方式,通过模型试验对非饱和砂土中的静压单桩与静压群桩(双桩)承载力特性和双桩压入过程中桩与桩之间相互作用进行研究。本文主要研究内容如下:(1)采用多功能模型桩进行标定试验运用自主研制的落雨布砂装置成功在标定罐内制备了相对密度均匀的砂层用于开展标定试验。利用标定罐采用气标和砂标结合的方式有效避免了膜式土压力盒在标定时出现的卸载响应显著滞后现象,得到了在满足试验精度要求的前提下,尽可能采用大量程的土压力盒是减少“土拱效应”最有效的方式之一,同时取到了较为线性的标定结果,为进一步在压桩过程中对桩体受力特性研究做好了准备。(2)采用多功能模型桩开展单桩压入试验使用现有的静力压桩系统装置,对相同的两根模型试验桩开展单桩压入试验。研究压入过程中模型桩体受力情况,压入深度与承载力、压桩力、桩端阻力和桩侧摩阻力之间的关系。由试验结果可知,在压桩深度为12D范围内,随着桩体压入深度的增加,压桩力、桩端阻力、桩侧摩阻力以及桩体承载力均呈现出非线性增加;并且随着压入深度的增加,桩端阻力所占压桩力的比重逐渐减小;与之相反,随着压入深度的增加,桩侧摩阻力所占压桩力的比重逐渐增大。(3)研究静压群桩(双桩)承载力特性采用不同的桩间距开展双桩压入试验,研究桩间距和压桩深度与承载力、压桩力、桩端阻力以及桩侧摩阻力之间的关系。由试验结果可知,随桩间距的增加,双桩系统承载力逐渐增大,并逐渐趋近于两倍单桩承载力;后桩压入过程中的压桩力、桩端阻力和桩侧摩阻力逐渐减小,同时逐渐趋近于单桩压入状态;先压入桩体受到的土压力逐渐减小,并随后压桩压入深度的增加而增大。随着后压桩压入深度的增加,其压桩力、桩端阻力和桩侧摩阻力均呈非线性增加。(4)研究静压双桩系统中的桩与桩之间相互作用通过对后压入桩体引起的先压入桩体的位移量进行分析可知,随着桩间距的增加,先压入桩体的位移量逐渐减小;随着压入深度的增加先压入桩体的位移量逐渐增大。说明桩间距越小或压桩深度越深,其产生“土拱效应”对桩体稳定性的影响越明显。从而说明了,桩体压入过程中产生新的土体应力场影响范围随压入深度的增加而变大。
[Abstract]:In recent years, our country has continuously improved the environmental pollution control, and strongly advocated the application of prefabricated components in the field of engineering construction in order to reduce the environmental pollution caused by construction. Static pressure pile has been paid more and more attention in foundation engineering because of its advantages such as less environmental pollution, no noise vibration pollution, easy quality control of prefabricated pile body and faster construction speed. In this paper, the development of static pressure pile and its common research methods are briefly described. The bearing capacity characteristics of static pressure single pile and static pressure group pile (double pile) and the interaction between pile and pile in the process of compression of two piles in unsaturated sandy soil were studied by model test. The main contents of this paper are as follows: (1) the calibration test is carried out by using multi-function model pile. In the calibration tank, the sand layer with uniform relative density has been successfully prepared by using the self-developed rain cloth sand device to carry out the calibration test. By using the combination of gas and sand in the calibration tank, the obvious lag phenomenon of the unloading response of the membrane earth pressure box during calibration is effectively avoided, and the premise of satisfying the requirement of test precision is obtained. One of the most effective ways to reduce the "soil arch effect" is to use a large number of earth pressure boxes as much as possible, and at the same time, the calibration results are obtained. In order to further study the bearing characteristics of pile body in the process of pile-pressing, the multi-function model pile is adopted to carry out the single pile indentation test. The existing static pile-pressing system is used to carry out the single pile-indentation test for the same two model test piles. In this paper, the relationship between the bearing capacity, pile pressure, pile tip resistance and pile side friction is studied. According to the test results, in the range of 12D, with the increase of the depth of the pile, the pressure of the pile, the resistance at the end of the pile, the friction of the side of the pile and the bearing capacity of the pile show a nonlinear increase, and with the increase of the depth of the pile, The proportion of resistance at the end of the pile to the force of the pile decreases gradually; on the contrary, with the increase of the depth of the pile, Study on bearing capacity characteristics of static pressure Group pile (double pile) by using different pile spacing to carry out double-pile indentation test, study pile spacing, pile depth and bearing capacity, pressure pile force, The relationship between pile end resistance and pile side friction. According to the test results, with the increase of pile spacing, the bearing capacity of double pile system increases gradually and approaches to double bearing capacity of single pile, and the pile pressure force, pile tip resistance and pile side friction decrease gradually in the process of post-pile pressing. At the same time, the soil pressure of the first pile decreases gradually, and then increases with the increase of the pressing depth of the pile. With the increase of the indentation depth of the post-pressure pile, the pile-pressing force, The study on the interaction between pile and pile in static pressure double pile system by analyzing the displacement of the pre-pressured pile caused by post-pressing pile, we can know that with the increase of pile spacing, The displacement of the first pressure pile body decreases gradually, and the displacement of the first pressure pile body increases with the increase of the indentation depth. It shows that the smaller the pile spacing or the deeper the pile-pressing depth, the more obvious the influence of "soil arch effect" on pile stability. The result shows that the influence range of the new soil stress field in the process of pile pressing becomes larger with the increase of indentation depth.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

【参考文献】