[1]康亚明,贾 延,罗玉财.立方体测混凝土抗压强度时的破裂形态与机制[J].西安建筑科技大学学报(自然科学版),2018,50(02):202-208.
 KANG Yaming,JIA Yan,LUO Yucai.Fracture morphology and mechanism of concrete cube test blocks subjected to compression failure[J].J. Xi’an Univ. of Arch. & Tech.(Natural Science Edition),2018,50(02):202-208.
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立方体测混凝土抗压强度时的破裂形态与机制()
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西安建筑科技大学学报(自然科学版)[ISSN:1006-7930/CN:61-1295/TU]

卷:
50
期数:
2018年02期
页码:
202-208
栏目:
出版日期:
2018-05-28

文章信息/Info

Title:
Fracture morphology and mechanism of concrete cube test blocks subjected to compression failure
作者:
康亚明1贾 延2罗玉财1
1:北方民族大学 化学与化学工程学院,宁夏 银川 750021;2: 北方民族大学 数学与信息科学学院,宁夏 银川 750021
Author(s):
KANG Yaming1 JIA Yan2 LUO Yucai1
1.School of Chemistry and Chemical Eng. , Beifang Univ. of Nationalities, Yinchuan 750021,China;2.School of Mathematics and Information Science, Beifang University of Nationalities,Yinchuan 750021,China
关键词:
破裂形态边界条件应力集中莫尔-库仑准则剪切破坏形状效应
Keywords:
fracture morphology boundary condition stress concentration Mohr-Coulomb criterion shear failure form effect
分类号:
TU451
文献标志码:
A
摘要:
混凝土抗压强度测试时压头与试块接触面之间存在摩阻力,该阻力约束了试块上下表面水平方向的位移,这种边界条件最终对真实强度产生了影响,针对这一现象,对强约束条件下立方体中的剪切带进行了分析,并基于单位化的莫尔-库仑准则,再结合试验数据反算了普通混凝土真实的破裂角范围与最危险破裂角,结果表明: (1)立方体中存在左右对称的崩解区和上下对称的刺入区,前者有脱离立方体向外侧脱落的趋势,刺入区实质上是端头约束影响区,竖直方向有刺入立方体的趋势;(2)单轴压缩时普通混凝土的真实破裂角在64~83°之间,最危险破裂角在73°附近,而立方体中45°以上的破裂面受到边界约束的影响,致使实际破裂面与真实破裂面不重合,导致测得的抗压强度比真实值偏大,引起了形状效应;(3)增加高宽比可以改变边界约束对破裂路径的影响,对于工程上的普通混凝土,三倍高宽比是消除形状效应的临界值.
Abstract:
There is friction between the machine head and the contact surface of the concrete test block in the test of the compressive strength, this force constrains the displacement of the upper and lower end face of the test block. Finally, the boundary conditions of the upper and lower surfaces have an influence on the real strength. In view of this phenomenon, the shear band in the concrete cube subjected to strong constraint was analyzed, moreover, the actual crack angles range and the most dangerous rupture angles of ordinary concrete were calculated based on the Mohr-Coulomb criterion of unitization and the test datum .The results show that: (1) There are two kinds of zone in the cube, one kinds of zone is disintegration zones which are left-right symmetric. These zones have a tendency that will detach from the cube. Another kinds of zone is thrust zones which are top-bottom symmetric. These zones are within the influence of the end restraint, which has a trend of penetration into the cube in the vertical direction ;(2) The true rupture angles of ordinary concrete are between 64 °~83° subjected to uniaxial compression, and the most dangerous rupture angles are at about 73°, but the fracture surface which dip angle is 45 ° and above are affected by the boundary constraint. These make the actual fracture surface does not coincide with the true rupture surface, so the measured compressive strength is larger than the true value. This phenomenon is the shape effect; (3) The boundary constraint has an effect on the rupture path, which can be changed by adding depth-width ratio. For eliminating the shape effects, the critical height to width ratio should be 3:1 for ordinary concrete used in engineering.

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备注/Memo

备注/Memo:
收稿日期:2017-03-02 修改稿日期:201804-02
基金资助: 国家自然基金资助项目(51369001;51569001)
作者简介:康亚明(1980-),男,博士,副教授,硕士生导师,研究方向为岩石力学与地下工程.E-mail: scu.kym@foxmail.com
更新日期/Last Update: 2018-05-28