多段扩体锚杆拉拔受力性能的数值分析
发布时间：2018-11-12 07:51
【摘要】：随着我国城市建设的迅速发展,高承载力锚杆在地下空间工程、边坡支护、基坑支护等领域的需求不断增加。与普通锚杆相比,扩体锚杆的抗拔承载力高、支护效果好、并且施工便利。本文提出的多段扩体锚杆是在端部扩体锚杆的基础上发展起来的一种新型锚杆。该类型锚杆在我国实际工程中应用较少,而且理论研究滞后,因此有必要进行深入研究。本文在西安理工大学结构大厅进行的多段扩体锚杆模型试验的基础上进行数值模拟,进一步研究了多段扩体锚杆的承载特性、破坏模式、群锚效应等,本文主要研究内容包括以下几方面:(1)在模型试验的基础上,应用ABAQUS软件对多段扩体的受拉性能进行数值模拟分析,研究了不同扩体个数和埋深对其破坏模式的影响。发现端部扩体锚杆周围土体的破坏模式为“倒立的灯泡形”,随着扩体的增加,其周围土体的破坏形态由“灯泡形”逐渐发展为呈串“火苗形”。而且浅埋扩体锚杆周围土体的破坏模式属于整体剪切破坏,破坏区一直与地表相连;深埋扩体锚杆周围土体的破坏模式属于局部剪切破坏。(2)通过数值模拟研究了埋深、锚杆尺寸对其抗拔承载力的影响。依据结果分析发现随着扩体直径、埋深的增加,其抗拔承载力也增大;当埋深足够大时随着扩体间距的增加其抗拔承载力也有所提高,只是效果不明显;另外,埋深一定时,锚杆的抗拔承载力并不随扩体长度、扩体个数的增加而增加,达到一定程度甚至会随它们的增加而减小。通过多组试验模拟数据得出其最优扩体长度为100mm-150mm,而扩体个数的最优解与扩体锚杆的埋深相关,埋深越大,最优扩体个数就越大。(3)对土体参数进行改变,研究了土体粘聚力、内摩擦角、及变形模量对多段扩体锚杆抗拔承载力的影响。通过数据分析发现随着粘聚力、内摩擦角、变形模量的增大,多段扩体锚杆的抗拔承载力会提高,但是变形模量贡献较小。(4)在实际工程中对群锚的应用颇多,本文又进一步研究了锚杆的水平间距、埋深、数量对群锚效应的影响。研究发现同一埋深,水平间距越大,群锚效应越小;埋深越大,为减小群锚效应所需的水平间距就越小,但不得小于4D。而且单根锚杆的扩体个数越多减少群锚效应需要的水平间距越大。锚杆数量越多,群锚效应越明显。
[Abstract]:With the rapid development of urban construction in China, the demand of high bearing capacity anchor rod in underground space engineering, slope support, foundation pit support and other fields is increasing. Compared with the common bolt, the expanded bolt has higher pull-out bearing capacity, better supporting effect and more convenient construction. This paper presents a new type of anchor which is developed on the basis of the end extension anchor. The application of this type of bolt in practical engineering in our country is less, and the theoretical research is lagging behind, so it is necessary to carry on the thorough research. In this paper, based on the model test of the multi-segment expanded anchor bar carried out in the structural hall of Xi'an University of Technology, the bearing characteristics, failure mode and group anchor effect of the multi-segment expanded bolt are further studied. The main contents of this paper are as follows: (1) on the basis of model test, the tensile performance of multi-segment expander is simulated with ABAQUS software, and the influence of different number of extenders and depth of burying on its failure mode is studied. It is found that the failure mode of the soil around the end extension bolt is "inverted bulb shape", and with the increase of the expanding body, the failure pattern of the surrounding soil gradually develops from "bulb shape" to "flaming shape". Moreover, the failure mode of soil around the shallow-buried anchor bolt belongs to the whole shear failure, and the failure zone has always been connected with the surface of the earth. The failure mode of the soil around the deeply buried anchor is local shear failure. (2) the influence of buried depth and bolt size on the uplift bearing capacity is studied by numerical simulation. According to the analysis of the results, it is found that the uplift bearing capacity increases with the increase of the diameter of the expanding body and the depth of burying, and the pull-out bearing capacity increases with the increase of the distance between the expanded bodies when the buried depth is large enough, but the effect is not obvious. In addition, the uplift bearing capacity of the anchor does not increase with the length of the expanded body, but the number of the expanded body increases, and even decreases with the increase of the depth of burying. The optimum length of the expanded body is 100mm-150mm, and the optimal solution of the number of the expanded body is related to the buried depth of the anchor rod. The larger the burying depth, the larger the number of the optimal extender. (3) the parameters of the soil are changed. The effects of cohesive force, angle of internal friction and modulus of deformation on the pull-out bearing capacity of multi-segment expansion anchor are studied. Through the data analysis, it is found that with the increase of cohesion, angle of internal friction and modulus of deformation, the pull-out bearing capacity of multi-segment expanded anchor will be increased, but the contribution of deformation modulus is relatively small. (4) the application of group anchors in practical engineering is quite extensive. The effects of horizontal spacing, depth and number of anchors on the group anchor effect are further studied in this paper. It is found that the larger the horizontal spacing is, the smaller the group anchor effect is, and the smaller the horizontal spacing is to reduce the group anchor effect, but not less than 4D. Moreover, the more the number of expansion bodies of a single anchor rod is, the greater the horizontal spacing is required to reduce the group anchor effect. The more the number of bolts is, the more obvious the group anchor effect is.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU476
[Abstract]:With the rapid development of urban construction in China, the demand of high bearing capacity anchor rod in underground space engineering, slope support, foundation pit support and other fields is increasing. Compared with the common bolt, the expanded bolt has higher pull-out bearing capacity, better supporting effect and more convenient construction. This paper presents a new type of anchor which is developed on the basis of the end extension anchor. The application of this type of bolt in practical engineering in our country is less, and the theoretical research is lagging behind, so it is necessary to carry on the thorough research. In this paper, based on the model test of the multi-segment expanded anchor bar carried out in the structural hall of Xi'an University of Technology, the bearing characteristics, failure mode and group anchor effect of the multi-segment expanded bolt are further studied. The main contents of this paper are as follows: (1) on the basis of model test, the tensile performance of multi-segment expander is simulated with ABAQUS software, and the influence of different number of extenders and depth of burying on its failure mode is studied. It is found that the failure mode of the soil around the end extension bolt is "inverted bulb shape", and with the increase of the expanding body, the failure pattern of the surrounding soil gradually develops from "bulb shape" to "flaming shape". Moreover, the failure mode of soil around the shallow-buried anchor bolt belongs to the whole shear failure, and the failure zone has always been connected with the surface of the earth. The failure mode of the soil around the deeply buried anchor is local shear failure. (2) the influence of buried depth and bolt size on the uplift bearing capacity is studied by numerical simulation. According to the analysis of the results, it is found that the uplift bearing capacity increases with the increase of the diameter of the expanding body and the depth of burying, and the pull-out bearing capacity increases with the increase of the distance between the expanded bodies when the buried depth is large enough, but the effect is not obvious. In addition, the uplift bearing capacity of the anchor does not increase with the length of the expanded body, but the number of the expanded body increases, and even decreases with the increase of the depth of burying. The optimum length of the expanded body is 100mm-150mm, and the optimal solution of the number of the expanded body is related to the buried depth of the anchor rod. The larger the burying depth, the larger the number of the optimal extender. (3) the parameters of the soil are changed. The effects of cohesive force, angle of internal friction and modulus of deformation on the pull-out bearing capacity of multi-segment expansion anchor are studied. Through the data analysis, it is found that with the increase of cohesion, angle of internal friction and modulus of deformation, the pull-out bearing capacity of multi-segment expanded anchor will be increased, but the contribution of deformation modulus is relatively small. (4) the application of group anchors in practical engineering is quite extensive. The effects of horizontal spacing, depth and number of anchors on the group anchor effect are further studied in this paper. It is found that the larger the horizontal spacing is, the smaller the group anchor effect is, and the smaller the horizontal spacing is to reduce the group anchor effect, but not less than 4D. Moreover, the more the number of expansion bodies of a single anchor rod is, the greater the horizontal spacing is required to reduce the group anchor effect. The more the number of bolts is, the more obvious the group anchor effect is.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU476
【参考文献】
相关期刊论文 前10条
1 肖卉;王振;;扩体锚杆拉拔破坏的数值分析[J];山西建筑;2015年33期
2 杨卓;吴剑波;高全臣;;端部包裹式扩体锚杆现场试验研究[J];科学技术与工程;2015年32期
3 林观茂;张丽娟;温忠义;;深基坑扩大头锚杆支护体系数值模拟[J];路基工程;2015年05期
4 赵彤;杨海松;王向军;;扩底抗拔桩在天津于家堡南北地下车库中的应用[J];岩土力学;2014年S2期
5 张继红;朱合华;;伞式扩底抗拔桩承载机理及其足尺试验研究[J];地下空间与工程学报;2014年02期
6 孙仁范;刘跃伟;徐青;蔡军;魏琏;;带地下室或裙房高层建筑抗浮锚杆整体计算方法[J];建筑结构;2014年06期
7 李粮纲;易威;潘攀;胡政;;扩大头锚杆最大抗拔力计算公式探讨与分析[J];煤炭工程;2014年01期
8 俞皓泷;吴R即，
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