Experimental Comparison of Horseshoe Prefabricated and Spray Anchor Initial Support Structures
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摘要:
为研究新型马蹄形预制初期支护结构的力学变形特征,与喷锚初期支护结构进行比较,开展2类结构的原型加载试验,系统性地从结构设计、衬砌预制、试验加载及结果分析等方面进行详细介绍,并对试验结果进行深入分析. 研究结果表明:预制初期和喷锚初期,支护结构的极限承载力分别为2.80倍和1.32倍设计荷载,前者的极限承载能力约为后者的2.12倍;预制初期,支护结构在拱顶、拱腰位置受正弯矩和负轴力作用,在拱肩和拱底位置受负弯矩和正轴力作用,喷锚初期,支护结构与之相近,临近破坏阶段,前者的最大弯矩约为后者的1.39倍,最大轴力约为后者的1.45倍;预制初期支护结构和喷锚初期支护结构凹凸变形趋势基本一致,结构破坏时呈现右拱肩外凸,右拱腰内凹,且型钢与混凝土产生剥落,前者极限变形能力约为后者的1.20倍.
Abstract:In order to study the mechanical deformation characteristics of the new horseshoe prefabricated initial support structure and compare its difference with the spray anchor initial support structure, the prototype loading tests of two types of structures were carried out. The structural design, lining prefabrication, test loading, and result analysis were introduced systematically, and the test results were deeply analyzed. The results show that the ultimate bearing capacity of the prefabricated initial support structure is 2.80 times the design load, and that of the spray anchor initial support structure is 1.32 times the design load. The ultimate bearing capacity of the former is about 2.10 times that of the latter. The prefabricated initial support structure is affected by the positive bending moment and negative axial force at the vault and the arch waist, as well as the negative bending moment and positive axial force at the arch shoulder and the arch bottom. The spray anchor initial support structure is similar. The maximum moment and the maximum axial force of the prefabricated initial support structure are about 1.39 and 1.45 times that of the spray anchor initial support structure near the destruction phase, respectively. The concave and convex deformation trend of the prefabricated initial support structure is basically the same as that of the spray anchor initial support structure. The right arch shoulder is convex, and the right arch waist is concave, with steel and concrete spalling when the structure is damaged, and the ultimate deformation capacity of the prefabricated initial support structure is about 1.20 times that of the spray anchor initial support structure.
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表 1 材料参数
Table 1. Material parameter
类别 参数名称 取值 围岩级别Ⅴ级 弹性抗力系数/(MPa·m−1) 150 变形模量/GPa 1.5 围岩密度/(kN·m−3) 19 内摩擦角/(°) 25 计算摩擦角/(°) 45 泊松比 0.38 衬砌材料 C30 混凝土 弹性模量/GPa 3.0 抗压强度/MPa 22.5 抗拉强度/MPa 2.2 钢筋种类 HRB400 强度标准值/MPa 400 强度设计值/MPa 360 弹性模量/GPa 200 表 2 截面每延米抗压能力
Table 2. Compressive capacity per meter of section
kN 部位 拱顶 拱肩 边墙 仰拱 抗压承载力 4789.35 4561.20 6300 6300 -
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