模拟PRC管桩加固缺陷桩抗剪试验研究与数值分析

发布时间：2018-06-17 03:23

本文选题：水平荷载 + 缺陷桩　；参考：《广西大学》2017年硕士论文

【摘要】：随着现代工程建设领域不断发展,高层建筑、大跨建筑、港口码头、边坡岸堤等高要求的工程项目需要地基基础具有较大的抗弯剪能力。桩基础作为一种具有众多优点的深基础型式,受到了广泛应用。在实际工程中,由于地质、施工条件等因素影响,桩基础容易出现缺陷问题。规范中,对桩身完整性进行了判定和分类,对桩缺陷严重者不予使用。缺陷桩处理一般费工费时,找到合理的缺陷桩加间方法具有重要意义。本文结合水平荷载下桩承载理论和实际工程中缺陷加固案例,对缺陷桩产生原因、检测方法、加固方法进行归纳总结,基于钢管混凝十叠合柱承载理论,采用钢管-注浆加固缺陷桩,模拟PRC管桩植桩加固法,对模型桩桩身受力变形进行试验研究。本文设计了一套缺陷加固模型桩试验方案,在室内完成了完整模型桩、缺陷模型桩、缺陷加固模型桩、完整内配钢管模型桩制作(共计4类13组试验方案)并进行对照试验,试验主要包括模型桩材料基本性质试验、模型桩桩身抗弯剪强度试验。得出如下结论:缺陷位置和加载点位置相互关系对桩身承载力影响较大:三种缺陷位置下,缺陷模型桩桩身极限承载力分别为完整桩的24.92%,44.66%,73.77%。缺陷位置越靠近加载点,桩身承载力降低越多,缺陷位置越靠近约束端,桩身承载力降低越少,越接近于完整桩。缺陷桩加固后,桩身承载力基本得到恢复:三种缺陷位置下,采用小直径钢管注浆加固后,模型桩桩身极限承载力分别达到完整桩的86.12%,102.19%,114.54%;采用大直径钢管注浆加固后,模型桩桩身极限承载力分别达到完整桩93.85%,117.87%,125.09%。对应的桩身位移与缺陷桩相比有所增大,桩身结构延性得到增强;缺陷桩加固后,改变了缺陷桩破坏形态,荷载传递得到部分恢复;增大钢管管径,可以提高桩身承载力和增强桩身延性。本文基于某项目工程资料,对桩的水平静载试验进行了数值模拟。采用PRC管桩植桩加固方法,得出了完整桩、缺陷桩、缺陷加固桩的相关承载性状规律。得出如下结论:缺陷位置对桩身水平抗剪承载力影响较大:三种缺陷位置下,缺陷桩桩身水平承载力特征值分别达到完整桩的54.90%,91.37%,83.63%。缺陷出现在桩上部时,桩身水平位移较大,桩身水平荷载-位移曲线出现陡降段,桩基水平承载力降低较多:缺陷出现在桩身中部和下部时,桩基承载力降低较少。桩身出现缺陷时,桩身存在负向弯矩。最大弯矩值点随缺陷位置下移而下移,数值增大;最大负弯矩值点随缺陷位置下移而下移,数值减小;桩身弯矩与剪力曲线在缺陷位置上下呈反向增大和正向增大两种趋势;桩身剪力值在桩顶面附近达到最大值。缺陷桩加固后,桩身承载力得到较大的恢复。随管桩置换面积增大,桩身承载力有所提高,桩身弯矩最大值随置换面积比例增大而增大,当置换面积比例达到35%后,桩身弯矩提升较小。桩身最大剪力值随置换面积比例增大而有减小趋势。
[Abstract]:With the continuous development of modern engineering construction, high building, large span architecture, port wharf, slope bank embankment and other high demand engineering projects need foundation foundation with large bending shear ability. Pile foundation has been widely used as a kind of deep foundation with many advantages. In practical engineering, due to geology, construction conditions, and so on In the norm, the pile integrity is judged and classified, and it is not used for those with serious pile defects. The defect pile treatment is usually time-consuming and time-consuming. It is of great significance to find a reasonable defect pile method. This paper combines the pile bearing theory with the horizontal load and the defect reinforcement case in the actual project. In this paper, the causes of the defect pile, the detection method and the reinforcement method are summarized. Based on the bearing theory of the ten steel pipe mixing column, the steel pipe grouting reinforcement defect pile is used to simulate the pile reinforcement method of the PRC pipe pile, and the experimental research on the deformation of the model pile is carried out. Complete model pile, defect model pile, defect reinforcement model pile, complete internal steel pipe model pile making (total 4 types of 13 groups of test schemes) and controlled test are carried out. The test mainly includes the basic properties test of the model pile material and the bending shear strength test of the model pile body. The following conclusions are drawn: the relationship between the position of the defect and the position of the loading point is the relationship between the position and the position of the loading point. The bearing capacity of the pile is greatly influenced: the ultimate bearing capacity of the pile body of the defect model pile is 24.92%, 44.66%, and the 73.77%. defect position is closer to the loading point, the more the bearing capacity of the pile body is reduced, the more the position of the defect is near the constraint end, the less the bearing capacity of the pile body is reduced, the more the pile body bearing capacity is reduced, the more the pile body bearing capacity is loaded, the bearing capacity of the pile body is bearing the bearing capacity of the three defects. The force is basically recovered: under the three defects, the ultimate bearing capacity of the model pile is 86.12%, 102.19%, 114.54% respectively after the grouting of small diameter steel pipe, and the ultimate bearing capacity of the model pile is reached to the pile body displacement and defect corresponding to the whole pile 93.85%, 117.87% and 125.09%. respectively. The pile body structure ductility is enhanced. After the defect pile is strengthened, the failure form of the defective pile is changed and the load transfer is partially restored. Increasing the pipe diameter can improve the bearing capacity of the pile and enhance the ductility of the pile. In this paper, a numerical simulation of the horizontal static load test of the pile is carried out based on a project engineering data. The PRC tube is used. The strengthening method of pile planting pile has obtained the related bearing behavior law of complete pile, defective pile and defect reinforcement pile. The following conclusion is drawn: the position of defect has great influence on the horizontal shear bearing capacity of pile body: under the three defects, the characteristic value of the horizontal bearing capacity of the defective pile is 54.90%, 91.37%, and 83.63%. defect appears in the upper part of the pile, respectively. When the horizontal displacement of the pile is larger, the horizontal load displacement curve of the pile is steep, and the horizontal bearing capacity of the pile foundation decreases more. When the defect appears in the middle and lower part of the pile, the bearing capacity of the pile foundation is reduced less. When the pile body is defective, the pile body has negative bending moment. The maximum bending moment point moves down with the position of the defect, the value increases and the maximum negative bending is increased. The moment point moves down with the defect position and decreases, and the pile body bending moment and shear curve are two trends in the position of the defect, and the pile body shear value reaches the maximum value near the top of the pile. The bearing capacity of the pile body is greatly restored after the defect pile is strengthened. The bearing capacity of the pile body is increased with the increase of the displacement area of the pipe pile. The maximum bending moment of the pile increases with the increase of the displacement area ratio. When the displacement area ratio reaches 35%, the pile body bending moment increases less. The maximum shear value of the pile body decreases with the increase of the displacement area ratio.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU473.1

【参考文献】