盘截面形式对混凝土扩盘桩抗压破坏状态的影响研究
发布时间：2018-07-24 21:43
【摘要】：混凝土扩盘桩是一种新型桩,是在直孔桩的基础上,在桩身的合适位置设置扩大盘来提高承载力,降低混凝土用量并能够有效的缩短桩长,降低工程成本。混凝土扩盘桩有较强的抗压、抗拔、抗倾覆能力,因此具有较高的实用价值,得到了广泛的应用。目前对于该桩的研究已经取得了一定的成果,在理论研究上,主要从抗压和抗拔两种情况研究其计算模式及破坏状态等。在试验方面,有室内原状土小比例半面桩试验法和现场大比例半截面混凝土扩盘桩灌注桩实桩抗压试验。在以上的所有研究中涉及的参数主要包括扩大盘间距、扩大盘高度、盘坡角等,但是在目前的施工机具中有很大一部分机具形成的扩大盘上表面是曲线型的且上下是不对称的一种扩大盘,同时形成的是圆弧型盘端扩大盘并不是理论研究的尖角型盘端扩大盘,关于这种盘截面形式对于混凝土扩盘桩抗压破坏状态的影响需要进一步的研究探讨。本文研究的是曲线型上表面扩大盘和直线型上表面扩大盘以及扩大盘的上下对称性和盘端的形状对于混凝土扩盘桩抗压破坏状态的影响,验证混凝土扩盘桩抗压承载力公式的是否也适用于以上盘型的混凝土扩盘桩。为了更好地设计盘型并考虑到与实际施工机具接轨,本文选取实际施工中广泛应用的一种桩径及盘截面形式作为设计依据,保证了理论和实际的一致性。利用有限元软件ANSYS建立1:1的混凝土扩盘桩半面桩模拟,分析应力、位移、破坏状态的影响,并将ANSYS软件中的模拟桩尺寸按照1:40的比例缩小,制作成半面模型桩,进行室内原状土小比例半面桩试验,分析应力、位移、土体破坏状态的影响。通过分析ANSYS模拟结果和室内原状土小比例半面桩试验结果发现,尖角盘端混凝土扩盘桩和圆弧盘端的混凝土扩盘桩的抗压破坏状态基本一样,通过对比发现上表面是直线型的扩大盘和上表面是曲线型的扩大盘对于混凝土扩盘桩的抗压破坏状态没有影响,扩大盘上下是否对称对于混凝土扩盘桩的抗压破坏状态也没有影响,也同样说明了现有混凝土扩盘桩抗压承载力计算公式可以用于计算上表面是曲线的扩大盘和盘端圆弧形的混凝土扩盘桩的抗压承载力,为了验证结论和模型试验的准确性,将模拟和模型桩试验进行了对比分析,发现二者结论基本一致,说明了本文结论的准确性。通过本文的研究丰富了混凝土扩盘桩的理论,为该桩的实际应用起到了必要的补充,对混凝土扩盘桩的推广起到了一定的作用,同时本文也对室内原状土小比例半面桩试验方法进行了相关的改进,为以后的研究提供了有力的借鉴。
[Abstract]:The concrete expanded disc pile is a new type of pile, which is based on the straight hole pile, and the expansion plate is set up in the proper position of the pile body to increase the bearing capacity, reduce the concrete content and effectively shorten the pile length and reduce the project cost. The concrete pile with expanded plate has strong ability of resisting compression, drawing and overturning, so it has high practical value and has been widely used. At present, some achievements have been made in the research of the pile. In the theoretical research, the calculation mode and the failure state of the pile are mainly studied from the two situations of anti-pressure and anti-drawing. In the aspect of test, there are laboratory test method of small proportion half-face pile with undisturbed soil and field test of large proportion semi-section concrete pile filled with concrete expanding disk pile. The parameters involved in all of the above studies mainly include enlarging disc spacing, enlarging disk height, slope angle, etc. However, in the present construction machinery, a large part of the enlarged disk formed by a large number of machines and tools is curved and asymmetrical up and down. At the same time, the circular arc end enlarged disk is not a sharp angle end enlarged disk studied in theory. The influence of this type of disc section on the compressive failure state of concrete pile needs further study and discussion. In this paper, the effects of the upper and lower symmetry and the shape of the end of the expanded disk on the compressive failure state of the concrete pile are studied. It is verified that the formula of the compressive capacity of concrete pile is also applicable to the concrete pile with the plate type above. In order to better design the plate shape and take into account the connection with the actual construction equipment, this paper selects a widely used form of pile diameter and disc section in actual construction as the design basis, which ensures the consistency between theory and practice. The finite element software ANSYS is used to establish the half plane pile simulation of 1:1 concrete expanded disc pile. The influence of stress, displacement and failure state is analyzed. The size of the simulation pile in ANSYS software is reduced according to 1:40, and the half plane model pile is made. The influence of stress, displacement and failure state of soil is analyzed by laboratory test of small proportion half plane pile of undisturbed soil. Through the analysis of the ANSYS simulation results and the test results of the small scale half-plane pile of the undisturbed soil, it is found that the compressive failure state of the concrete expanded disc pile at the tip of the pointed corner is basically the same as that of the concrete expansion pile at the end of the circular disc. By comparison, it is found that the expansion plate with linear surface and the expanded plate with curved surface have no effect on the compressive failure state of concrete pile. Whether the top and bottom of the enlarged plate is symmetrical has no effect on the compressive failure state of the concrete pile. It is also shown that the existing formulas for calculating the compressive capacity of concrete pile can be used to calculate the compressive capacity of the expanded plate with curve on the upper surface and the concrete pile with circular arc at the end of the disk, in order to verify the accuracy of the conclusion and the model test. The simulation and the model pile test are compared and analyzed, and it is found that the two conclusions are basically the same, which shows the accuracy of the conclusion in this paper. The research in this paper enriches the theory of concrete expanded pile, plays a necessary role in the practical application of the pile, and plays a certain role in the promotion of concrete expanded plate pile. At the same time, this paper also improves the test method of the small proportion half plane pile in the indoor undisturbed soil, which provides a powerful reference for the future research.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1
本文编号：2142747
[Abstract]:The concrete expanded disc pile is a new type of pile, which is based on the straight hole pile, and the expansion plate is set up in the proper position of the pile body to increase the bearing capacity, reduce the concrete content and effectively shorten the pile length and reduce the project cost. The concrete pile with expanded plate has strong ability of resisting compression, drawing and overturning, so it has high practical value and has been widely used. At present, some achievements have been made in the research of the pile. In the theoretical research, the calculation mode and the failure state of the pile are mainly studied from the two situations of anti-pressure and anti-drawing. In the aspect of test, there are laboratory test method of small proportion half-face pile with undisturbed soil and field test of large proportion semi-section concrete pile filled with concrete expanding disk pile. The parameters involved in all of the above studies mainly include enlarging disc spacing, enlarging disk height, slope angle, etc. However, in the present construction machinery, a large part of the enlarged disk formed by a large number of machines and tools is curved and asymmetrical up and down. At the same time, the circular arc end enlarged disk is not a sharp angle end enlarged disk studied in theory. The influence of this type of disc section on the compressive failure state of concrete pile needs further study and discussion. In this paper, the effects of the upper and lower symmetry and the shape of the end of the expanded disk on the compressive failure state of the concrete pile are studied. It is verified that the formula of the compressive capacity of concrete pile is also applicable to the concrete pile with the plate type above. In order to better design the plate shape and take into account the connection with the actual construction equipment, this paper selects a widely used form of pile diameter and disc section in actual construction as the design basis, which ensures the consistency between theory and practice. The finite element software ANSYS is used to establish the half plane pile simulation of 1:1 concrete expanded disc pile. The influence of stress, displacement and failure state is analyzed. The size of the simulation pile in ANSYS software is reduced according to 1:40, and the half plane model pile is made. The influence of stress, displacement and failure state of soil is analyzed by laboratory test of small proportion half plane pile of undisturbed soil. Through the analysis of the ANSYS simulation results and the test results of the small scale half-plane pile of the undisturbed soil, it is found that the compressive failure state of the concrete expanded disc pile at the tip of the pointed corner is basically the same as that of the concrete expansion pile at the end of the circular disc. By comparison, it is found that the expansion plate with linear surface and the expanded plate with curved surface have no effect on the compressive failure state of concrete pile. Whether the top and bottom of the enlarged plate is symmetrical has no effect on the compressive failure state of the concrete pile. It is also shown that the existing formulas for calculating the compressive capacity of concrete pile can be used to calculate the compressive capacity of the expanded plate with curve on the upper surface and the concrete pile with circular arc at the end of the disk, in order to verify the accuracy of the conclusion and the model test. The simulation and the model pile test are compared and analyzed, and it is found that the two conclusions are basically the same, which shows the accuracy of the conclusion in this paper. The research in this paper enriches the theory of concrete expanded pile, plays a necessary role in the practical application of the pile, and plays a certain role in the promotion of concrete expanded plate pile. At the same time, this paper also improves the test method of the small proportion half plane pile in the indoor undisturbed soil, which provides a powerful reference for the future research.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1
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