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1、西安科技大学 硕士学位论文 土层自旋锚管的研究与工程应用 姓名：许刚 申请学位级别：硕士 专业：桥梁与隧道工程 指导教师：惠兴田 论文题目：土层自旋锚管的研究与工程应用 专业：桥梁与隧道工程 硕 士 生：许刚（签名） 指导教师：惠兴田（签名） 摘要 在广泛的土层支护工程领域，锚杆(土钉)被广泛采用，但同时也遇见了一些问题， 如基坑支护工程，常被用于支护的砂浆锚杆，由于砂浆凝固需要时间，不能及时支护， 往往导致岩土工程事故的发生；另外，还有很多作为临时支护的锚杆(土钉)不能回收， 导致污染地层，以及在松散的岩土体边坡中，锚杆(土钉)、锚索抗弯能力差，不能满足 抗滑的要求，致使边坡失稳等。这些问题
2、在一定程度上影响了锚杆的应用。然而，自旋 锚管在具有一般锚杆优点的情况下，又拥有较大抗弯能力，还能起到及时支护以及能够 回收，因此，对自旋锚管进行深入的研究有着重要的现实意义。 本文利用圆孔扩张理论建立修正的剑桥模型，并结合数值模拟的方法，对自旋锚管 作用机理进行了深入的理论分析，得出自旋锚管在安装的过程中，会对周围土体产生挤 压密实的作用，亦即杆体周围土体存在着以下几个力学状态区域：扰动区、弱扰动区以 及未扰动区，并且在自旋锚管全长范围内，其周围土体的塑性区分布基本相同，该区域 约为自旋锚管公称直径的 0.77 倍；其次，在靠近自旋锚管外端部位，扰动区大概是自旋 锚管公称直径的 1.4 倍，
3、这部分的长度约为自旋锚管全长的，随着距离自旋锚管外端31 越来越远，扰动区范围约为 1.15 倍公称直径，而这部分约为自旋锚管全长的，在157 靠近自旋锚管底端部位，扰动区范围约是公称直径的 1.25 倍，该部分大约是自旋锚管全 长的。51 鉴于自旋锚管沿杆体-土侧壁界面上发生土的圆柱形剪切破坏的破坏模式，本文推 导出了单根自旋锚管的锚固力计算公式，发现锚固力除了与其安装位置、自身参数以及 土体的基本物理力学参数有关外，还与反映土体塑性变形的塑性体应变()有着密切关 p v 系，这正证实了自旋锚管在安装之后能获得较大的初始锚固力。此外，本文通过实验研 究发现，当土层含水率在最优含水率和饱和含水
4、率之间变化时，自旋锚管的锚固力随土 层含水率的增加呈指数减小，但当土体接近饱和时，锚固力基本趋于零，这是非常有利 于指导自旋锚管施工的。 最后，本文结合西安地铁二号线张家堡站基坑支护工程，对自旋锚管的锚固力以及 桩顶位移进行了监测，发现自旋锚管拥有较大的初始锚固力，完全能够满足工程要求， 从而能起到了及时支护的作用；此外，它也很好的制约了桩体的位移，确保了基坑边坡 的稳定性。 这些与理论分析都是相符的， 因此达到了指导自旋锚管工程应用的预期目的 。 关 键 词：自旋式管状锚杆；圆孔扩张理论；修正的 Cambridge 模型；塑性体应变； 数值模拟 研究类型：应用研究 Subject:Study
5、 and Engineering Application of Self-screwedTubeBoltingin Soil Specialty:Bridge and Tunnel Engineering Name:Xu Gang(Signature) Instructor:Hui Xingtian(Signature) ABSTRACT Ina wide range of soil support engineering, anchor (soil nails) are widely used, but we also met some problems, such as mortar an
6、chor used in foundation pit support engineering, mortar solidification takes time so that the engineering is not supported timely, therefore, these often cause accidents in geotechnical engineering;Inaddition, there are a lot of temporary support of anchor (soil nails) being unrecycled, leading to p
7、ollution of formation, and in the loose rock and soil slope, bending ability of anchor (soil nails) and cablecannot meet the requirements of sliding, resulting in slope instability and so on.To some extent,these problems affected the application of the bolt. However, in the case of the self-screwed
8、tube bolting holding benefits of the general anchor, it has not only a greater dending capacity, but it alsocantimely support and be recycled, therefore, it has important practical significance to study in-depthonthe self-screwed tube bolting(SSTB). By using cavity expansion theory to create modifie
9、d Cambridge model, this article combined with numerical simulation methods, and providedanin-depth theoretical analysis of the mechanism of SSTB, so obtaining some conclusions, thatthe surrounding soil holds the effect of extrusion-dense during installation of SSTB.Inone word, there are several diff
10、erent mechanical states of the region in soil around the pole, that is, disturbed areas, weak disturbance areas and undisturbed areas. Then infullrange of SSTB length, the plastic zone distribution of the surrounding soil is basically the same, and the area is approximate 0.77 times larger than the
11、nominal diameter of self-screwed tube bolting;Secondly, close to the outer end of SSTB, the disturbed area is about 1.44 times larger than the nominal diameter, the length of this section is about one third of full-length, and when the distance from the outer end of SSTB is farther and farther, the
12、disturbed area becomes about 1.15 times larger than the nominal diameter, and the section is approximate seven fifteenths of full-length, then, near the bottom part of SSTB, the disturbed zone is about 1.25 times larger than the nominal diameter, and the length of the section is about one fifth of f
13、ull-length. According to the failure mode of SSTB, that is cylindrical shear failure along the interface of the rod and the side walls of the surrounding soil, this article educes the anchoring formula of single self-screwed tube bolting, then, finds that the anchoring force is not only closely rela
14、ted to its installed location, its own parameters and the basic physical and mechanical parameters of soil, but it also has close relation to plastic volumetric strains() p v reflecting the plastic deformation of soil, at the same time, it is proved that SSTBcanget a larger initial anchoring force a
15、fter installation.Inaddition, the experimental studyfinds that the anchoring force decreases exponentially withanincrease in soil moisture when soil moisture changes between optimal and saturated moisture content, however, when nearly saturated, the anchoring focre basically tends to zero, and it is
16、 conducive to guiding the construction of SSTB. Finally, combining with Zhangjiabao station Line 2 Xian Subway foundation pit support engineering, and according to the anchoring focre of SSTB and the displacement of pile top, this article finds that SSTB hold larger initial anchoring forces, and completelycanmeet the engineering requirements, so that itcanplay a role in a timely supporting;Moreover, it also constrains effectively the displacement of pile to ensure the stability of the pit
