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Search Results: 1 - 10 of 3784 matches for " 裂纹宽度 "
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粗细骨料比例和水泥石强度对混凝土断裂参数的影响
张君,王林,孙明,刘骞
工程力学 , 2004,
Abstract: 骨料对于混凝土断裂性能的影响是近年来各国学者普遍关心的课题.采用基于粘性裂纹模型(FCM)的数值分析方法,通过三点弯曲试验,评价了粗细骨料比例(砂率:0.30-0.67)及水泥石强度(混凝土抗压强度:40-80MPa)对混凝土断裂参数的影响.这些参数包括抗拉强度、抗弯强度、应力-裂纹宽度关系和断裂能.研究结果表明,骨料总量一定而粗骨料含量不同时,抗压强度几乎不受影响,而随粗骨料含量增加,抗拉强度、抗弯强度和断裂能均逐渐增大.同时,水泥石强度增高,开裂强度、抗拉强度、抗弯强度和断裂能均增大.
公路隧道衬砌裂纹扩展机理
Numerical investigation on the fracture propagation mechanism of highway tunnel lining

丁浩,李科,周小平,毕靖,练焱坚,徐潇
- , 2018, DOI: 10.11835/j.issn.1674-4764.2018.05.011
Abstract: 公路隧道衬砌裂缝作为公路隧道的主要病害,其问题日益突出,尤其是带裂纹工作衬砌的等级评价略显不足。为研究公路隧道带裂缝二次衬砌在受荷载作用下裂纹扩展规律,用离散元PFC软件对衬砌裂纹扩展规律进行数值模拟研究,揭示隧道衬砌中裂纹开裂的灾演机理,根据衬砌开裂状态进行病理灾害分析,并建立了相应的预测模型。衬砌的整体安全性受预置裂纹的影响,预置裂纹处往往是衬砌中较危险的位置;预置裂纹的深度对裂纹贯通时间有较大影响,随着预置裂纹深度的增加,预置裂纹贯通衬砌的时间逐渐减小;预置裂纹的深度对裂纹张开度的变化有较大影响,随着预置裂纹深度的增加,预置裂纹张开度逐渐增大,并在贯通衬砌时有明显的突变,这样便于确定衬砌治理时机。
As the major flaw of highway tunnels, lining cracks of highway tunnels is increasingly seriously. In order to study the mechanism of crack propagation in highway tunnels under loading, this article conducts numerical simulation on the crack propagation with discrete element software PFC, demonstrating the disaster mechanism of crack propagation in highway tunnels,and establishing the corresponding prediction models. The results showed that:integral safety of lining is subject to pre-existing flaws, and the positions of pre-existing flaws are generally relatively more dangerous in lining; the depth of pre-existing flaws plays an important role in the timing of crack coalescence,i.e.,the deeper the pre-exsiting flaws are, the less time is needed to achieve crack coalescence in the lining; the depth of pre-exsiting flaws has a great influence on the variation of crack opening, i.e. the deeper pre-exsiting flaws are, the increasing opening those fracture apertures will be, and there is an obvious abrupt change when the flaws coalesce.
MEASUREMENT OF CRACK WIDTH IN ROCK INTERIOR BASED ON X-RAY CT
基于X射线CT的岩石内部裂纹宽度测量

Ding Weihua,Wu Yanqing,Pu Yibin,Cao Guangzhu,Cui Zhongxing,
丁卫华
,仵彦卿,蒲毅彬,曹广祝,崔中兴

岩石力学与工程学报 , 2003,
Abstract: The deformation,propagation and expansion of crack in rock interior are the main mechanical process when the rock sample comes to its crack evolution stage. It is the subject of this paper how to detect the crack width through X-ray method. The relation between rock density damage and its volumetric strain is analyzed based on the meso-mechanism of rock deformation and rupture. For brittle rock,its volumetric strain has a unique quantitative relation with its density damage. Based on the increment formula of density damage,the volumetric strain formula is derived for rock. The universal calculation formula of crack width in rock interior is derived based on the volumetric strain formula. The formula is tested and compared with relative formula. The same results are obtained from the two different formulas. Two crack widths in rock interior under different stresses are calculated. As a result the problem how to measure a real-time crack width in rock interior is solved theoretically. The crack width of sandstone is no more than the order of magnitude of 10-1mm. It is verified that the actual crack width is not the same as the crack width in its CT image. Before the maximum strength,the crack width of sandstone has a stable expansion process. When the longitudinal and lateral deformation of rock sample are considered,this result can be verified indirectly.
齿轮疲劳裂纹计算方法的探讨
冯英
武汉理工大学学报 , 1996,
Abstract: ?分析齿轮疲劳裂纹振动信号的特点,建立了一套以信号平均、滤波、移频等相结合的计算诊断方法,比较方便、有效.
带悬挑钢筋混凝土圆板裂缝宽度探讨
郑作樵
福州大学学报(自然科学版) , 1989,
Abstract: 通过试验,观测了圆板裂缝开展的全过程,对使用荷载阶段裂缝宽度作了分析并建立了最大裂缝宽度计算公式,计算值与实测值吻合良好。
裂纹轴局部柔度计算
李昌鹤
力学与实践 , 1989,
Abstract: 本文介绍的分析——实验方法,定量地给出了横向裂纹对转轴局部刚度的影响,为高速转轴振动时,轴上裂纹复杂的开闭运动提供了一种较为精确的、具有普遍意义的力学模型,也为进一步研究裂纹轴横向振动特性打下基础.
疲劳试验新方法—显微疲劳试验
潘家祯
华东理工大学学报 , 1995,
Abstract: 介绍了显微疲劳试验-一个新的疲劳试验方法,由此研制的疲劳试验装置,能够在金相级的水平上进行十分精细的疲劳试验,全部实验过程可以进行实时观察和记录,用该细观手段实验观察,可望对金属疲劳进行更深层次的分析研究,能更好地理解工程零部件中实际疲劳裂纹的产生与扩展的过程。
单轴压缩下含倾斜单裂纹砂岩试件裂纹扩展量测研究
谢其泰,郭俊志,王建力,陈于高
岩土力学 , 2011,
Abstract: 选用砂岩作为试验材料,进行不同倾斜角度单预制裂纹的单轴压缩试验研究,透过裂纹扩展量测技术以及配合相关断裂准则,得到:(1)理论与实验的裂纹起裂角随裂纹倾斜角增加而增大;(2)透过相关断裂准则,砂岩试件在裂纹尖端产生反翼裂纹是因为剪力破坏;(3)在单轴压缩作用下砂岩试件裂纹扩展受单裂纹的倾斜角影响,当裂纹倾斜角较小时,裂纹不易起裂;当裂纹倾斜角较大时,裂纹起裂比较容易;(4)在单轴压缩作用下砂岩试件则受单预制裂纹的倾斜角影响,当裂纹倾斜角较小时,裂纹扩展属于非稳定扩展;当裂纹倾斜角较大时,裂纹扩展属于稳定扩展;(5)在单轴压缩作用下砂岩试件裂纹尖端a侧与裂纹尖端b侧的裂纹扩展平均速度随裂纹倾斜角增加而降低。
表面裂纹ⅰ型应力强度因子间的互相作用及影响规律
王庆丰,崔维成
江苏科技大学学报(自然科学版) , 2009,
Abstract: ?基于有限元软件france-3d对含有多个裂纹的平板进行应力强度因子计算.通过定义基础裂纹、干扰裂纹以及干扰参数r,α,β和2b等,给出了随干扰参数r,α,β改变,干扰裂纹对基础裂纹应力强度因子影响的λ-r,λ-α曲线,并分析其规律,其结果可为工程应用参考.
穿透短裂纹的预制和长度测定与处理
李建康
实验力学 , 1994,
Abstract: 本文介绍了一次开裂多序加工的预制穿透短裂纹方法,并建议采用直接观测和复型校核的短裂纹测量方法,并用面积等效处理短裂纹长度。
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