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混凝土环形约束开裂方法研究进展
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作者 刘圆圆 《河南建材》 2024年第4期55-57,共3页
在水泥基材料中,塑性收缩开裂一般在早期出现。文章针对塑性收缩开裂相关的试验方法圆环约束法进行了详细综述,包括实验室规模的评估方法、裂缝测量技术,并对现有技术进行了对比分析。
关键词 塑性收缩 开裂方法 圆环法
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CLBO晶体的开裂机理及防开裂方法研究 被引量:6
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作者 贺为国 沈光球 +1 位作者 王晓青 沈德忠 《人工晶体学报》 EI CAS CSCD 北大核心 2001年第3期267-272,共6页
CLBO晶体的开裂影响了这种性能优良的紫外倍频晶体的实际应用。如何防止晶体开裂 ,已成为研制CLBO晶体变频器件的关键问题之一。本文从分析CLBO晶体开裂的原因入手 ,探讨了晶体开裂的微观机理。在此基础上提出了防止晶体开裂的方法。使... CLBO晶体的开裂影响了这种性能优良的紫外倍频晶体的实际应用。如何防止晶体开裂 ,已成为研制CLBO晶体变频器件的关键问题之一。本文从分析CLBO晶体开裂的原因入手 ,探讨了晶体开裂的微观机理。在此基础上提出了防止晶体开裂的方法。使用溶胶凝胶法制备防潮薄膜 ,对晶体进行了防开裂实验 ,得到了初步的结果。 展开更多
关键词 CLBO晶体 开裂 溶胶凝胶薄膜 开裂方法 紫外倍频晶体 硼酸铯锂晶体
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岩石类材料拉裂过程模拟的三维可开裂拉格朗日元方法
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作者 王学滨 田锋 +1 位作者 马冰 钱帅帅 《应用力学学报》 CAS CSCD 北大核心 2023年第5期1171-1179,共9页
本研究提出了适于模拟岩石类材料变形-拉裂过程的三维可开裂拉格朗日元方法,其实质是三维拉格朗日元方法与断裂力学中虚拟裂缝模型的耦合方法,主要适用于立方体单元。以三维拉格朗日元方法为基础,引入虚拟裂缝模型的具体过程主要包括3... 本研究提出了适于模拟岩石类材料变形-拉裂过程的三维可开裂拉格朗日元方法,其实质是三维拉格朗日元方法与断裂力学中虚拟裂缝模型的耦合方法,主要适用于立方体单元。以三维拉格朗日元方法为基础,引入虚拟裂缝模型的具体过程主要包括3个关键步骤:首先,通过节点周围单元的应力获取节点的应力,进而利用节点的最大主应力和岩石单轴抗拉强度进行节点分离判断;然后,选择与节点最大主应力垂直平面最接近的单元边界作为裂缝扩展方向;最后,引入虚拟裂缝模型模拟裂缝的萌生和扩展过程。利用该方法模拟了单轴拉伸岩样和三点弯曲岩梁的变形-拉裂过程,并初步分析了Ⅰ型断裂能、岩样高度和单元尺寸的影响。同时,通过将本研究结果与单轴拉伸岩样峰值应力、临界位移的理论解和前人位移控制加载条件下三点弯曲岩梁的载荷-位移曲线的数值解进行对比,验证了本研究方法的正确性,这为将来的工作奠定了良好的基础。 展开更多
关键词 三维可开裂拉格朗日元方法 虚拟裂缝模型 单轴拉伸 三点弯曲 网格依赖性 尺寸效应
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基于开裂区平均化方法的混凝土开裂特性 被引量:2
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作者 李强 任青文 《河海大学学报(自然科学版)》 CAS CSCD 北大核心 2016年第3期226-232,共7页
为研究混凝土试件的开裂特性,基于细观力学理论对传统平均化方法进行了改进,提出了开裂区平均化方法。利用不同的平均化方法对级配与粒径分布相同的不同尺寸试件进行计算分析,研究混凝土试件的开裂特性和开裂尺寸依赖性的产生机理。结... 为研究混凝土试件的开裂特性,基于细观力学理论对传统平均化方法进行了改进,提出了开裂区平均化方法。利用不同的平均化方法对级配与粒径分布相同的不同尺寸试件进行计算分析,研究混凝土试件的开裂特性和开裂尺寸依赖性的产生机理。结果表明,开裂区平均化方法能够得到具有尺寸一致性的、表征试件开裂破坏全过程的开裂特性曲线,可确定重要开裂计算参数;开裂尺寸依赖性的出现是由于在试件尺寸变化时,试件中占较小空间的局部开裂区大小及其力学特性基本不受尺寸变化影响,而占较大空间的线弹性区大小及其力学性能却受尺寸变化影响较大,导致整体宏观响应受尺寸变化较大,并由此产生尺寸依赖性。 展开更多
关键词 混凝土 开裂特性 尺寸依赖性 标准平均化方法 开裂区平均化方法
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Analysis of factors and countermeasures of mining subsidence in Kaiyang Phosphorus Mine 被引量:11
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作者 邓建 边利 +2 位作者 李夕兵 赵国彦 王新民 《Journal of Central South University of Technology》 EI 2006年第6期733-737,共5页
Ground crack and subsidence were investigated in Kaiyang Phosphorus Mine as an example. Contribution factors to cause ground crack and mining subsidence were studied, including mining method, mining depth and ore thic... Ground crack and subsidence were investigated in Kaiyang Phosphorus Mine as an example. Contribution factors to cause ground crack and mining subsidence were studied, including mining method, mining depth and ore thickness and stope size, dip angle of orebody, geological structure, nature of overburden and water contents, and roof supports, etc. Countermeasures against cracks and subsidence were put forward. The uniaxial compressive strength of compounded phosphorus gypsum after 28 d of curing period was tested to be more than 1 MPa. Phosphorus gypsum can be used as materials for the backfill of stope. By comparison and numerical simulation, cut and fill mining method with middle-deep drilling holes and ore transportation by blasting force was selected as the optimum mining method in Kaiyang Phosphorus Mine. 展开更多
关键词 mining subsidence ground crack cut and fill mining method Kaiyang Phosphorus Mine
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高压引水隧洞衬砌配筋设计 被引量:1
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作者 李小磊 《黑龙江水利科技》 2017年第11期97-99,共3页
在引水式电站的建设过程中,高压引水隧洞的钢筋混凝土衬砌部分的投资占整个水电站投资的一大部分,因此科学合理的对混凝土衬砌进行设计可以有效节约工程投资和缩短工程工期。文章以某水电站的建设为例,采用开裂设计方法,通过考虑渗流作... 在引水式电站的建设过程中,高压引水隧洞的钢筋混凝土衬砌部分的投资占整个水电站投资的一大部分,因此科学合理的对混凝土衬砌进行设计可以有效节约工程投资和缩短工程工期。文章以某水电站的建设为例,采用开裂设计方法,通过考虑渗流作用,设计出一套新的衬砌配筋方法,这种方法不仅可以高效地完成水电站衬砌工程,还可以大大节约配筋量,极大地节约了工程投资和工期。 展开更多
关键词 高压引水隧洞 混凝土衬砌配筋 开裂设计方法 水电站
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PHYSICAL SIMULATION AND ANALYSIS OF METHANE TRANSPORT IN COAL SEAM 被引量:1
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作者 罗新荣 俞启香 《Journal of China University of Mining and Technology》 1994年第1期24-31,共8页
This paper studies the effect of ground stress, pore gas pressure and adsorbed methane on methane transport in coal seam. and researches into the applleability of Darey’s inw to methane transport. The additional expa... This paper studies the effect of ground stress, pore gas pressure and adsorbed methane on methane transport in coal seam. and researches into the applleability of Darey’s inw to methane transport. The additional expansion stress of coal induced by adsorbed methane is measured. The paper establishes the constitutive equation of methane transport, taking ground stress, pore gas pressure and Klinkenburg’s effects into consideration. The features of methane transport under the condition of given stress or strain have been analyzed. 展开更多
关键词 methane transport constitutive equation effective stress expansion stress
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Analysis of Three-dimensional Crack Propagation by Using Displacement Discontinuity Method 被引量:3
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作者 王飞 黄醒春 《Journal of Donghua University(English Edition)》 EI CAS 2010年第6期835-840,共6页
A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was described.When the crack is closed,the Mohr-coulomb rule on the ... A technique for modelling of three-dimensional(3D)quasi-statically propagating cracks in elastic bodies by the displacement discontinuity method(DDM)was described.When the crack is closed,the Mohr-coulomb rule on the two contacted surfaces of the crack must be satisfied.A simple iterative method was adopted in order to consider three different states of cracks.Under the assumption that the advance of the point on the crack front would occur only in the normal plane which is through this edge point,the maximum energy release rate criterion is modified to be used as the criterion for the crack growth.With discretization,the process of crack propagation can be seen as the advance of the vertices of the crack front.The program MCP3D was developed based on these theories to simulate the 3D quasi-static crack propagation.A numerical example of a penny-shaped crack subject to tension and compression in an infinite elastic media was analyzed with MCP3D,and the results in comparison with others' show that the present method for 3D crack propagation is effective. 展开更多
关键词 three-dimensional(3D)crack propagation displacement discontinuity method stress intensity factor(SIF) numerical simulation
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Introduction of a Japan Concrete Institute Guideline: Practical Guideline for Investigation, Repair and Strengthening of Cracked Concrete Structures 被引量:1
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作者 Nobuaki Otsuki Akiyuki Shimizu Toshiro Kamada 《Journal of Civil Engineering and Architecture》 2015年第2期213-224,共12页
There are many cracked concrete structures worldwide. Although there have been numerous efforts to eliminate cracks, some cracks are very harmful and should be repaired as soon as possible. On the other hand, some cra... There are many cracked concrete structures worldwide. Although there have been numerous efforts to eliminate cracks, some cracks are very harmful and should be repaired as soon as possible. On the other hand, some cracks are almost harmless. So, a good guideline regarding how to deal with cracks in concrete structures is needed. In this guideline, the practical investigation, repair and strengthening method of cracked concrete structures is discussed. And the detecting subjects are cracks generated immediately after casting and during the service time. This guideline targets on the owners (including managers) of concrete structure and the engineers working for the maintenance of concrete structure. JCI (Japan Concrete Institute) published first version of "Practical Guideline for Investigation and Repair of Cracked Concrete Structures" in 1980, and then the fourth version titled "Practical Guideline for Investigation, Repair and Strengthening of Cracked Concrete Structures--2009" was published. This guideline is very practical when cracks are observed in existing concrete structures, in any other countries as well as in Japan. These three authors led the establishment of this guideline. 展开更多
关键词 CRACK concrete structure INVESTIGATION REPAIR strengthening.
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