查询词典 crack

To give the definition of the mass concrete and to concrete\'s cracks together with practical meanings of control ,and give a brief review on the research in the field at home and abroad, at last, methods to control temperature crack of the mass concrete from several aspects such as design measures,concrets material, construction schedules.etc are summed up; To explain the physical mechanics of the concrete and computing methods-Difference Method and Finite Element Method, and illustrate the application of their specific methods repectively;Several temperature factors that can influence the temperature stress of mass concrete baseplate are analyzed. The influence degree of temperature factor can be got through the ANSYS simulation computation the control of temperature can control the temperature stress, consequently control the temperature crack of mass concert baseplate; through the influence of the crack resistance ability of mass concrete baseplate which takes the reinforcement as a part is analyzed. By ANSYS simulation, the best suited volume ratio of reinforcement is found out, at same time the layout of reinforcement with the same volume ratio can also affect the resistance ability of mass concrete baseplate. Sum up of above analysis, anti-crack function of steel bar in early mass concrete baseplate is obvious, so it\'s necessary to consider beneficial effect of construction steel bar in research of temperature control on mass concrete baseplate.

本文先容了大体积混凝土及混凝土裂缝的基本概念，对国内外在这个领域里的研究现状作了扼要叙述，并从结构设计、混凝土材质、施工措施等方面总结了大体积混凝土温度裂缝控制的方法及防止措施；阐述了混凝土的基本物理力学性能，总结了大体积混凝土温度计算的方法——差分法和有限元法，并分别举例说明其具体应用的方法；分析了影响大体积混凝土底板温度应力的几种温度因素，利用ANSYS模拟计算，得出了每种因素的影响程度，通过分析提出了在这几种温度影响因素下如何通过控制温度以达到控制温度应力从而来控制裂缝的具体建议；针对大体积混凝土基础底板中配筋的不同对混凝土底板抗裂能力的影响不同，利用ANSYS进行模拟分析，得出底板中最合适的体积配筋率，同时分析了在相同体积配筋率下钢筋的具体布置对大体积混凝土基础底板抗裂能力的影响，分析表明，配置钢筋对混凝土结构的开裂阻止作用明显，在研究大体积混凝土温度裂缝题目时，要考虑钢筋在其中的有利作用。

The mechanism of lock corridor crack is rather complicated due to the unique structure of corridor. As a result construction technique improvement cannot totally eliminate corridor crack occurrence. According to the construction process and results of Jinghang Cannel Huaiyin 3rd Lock,certain technical measures and improvements in construction techniques,can efficiently control the corridor crack and avoid the occurrence of crack as much as possible.

船闸廊道裂缝的产生机理较为复杂，由于廊道独特的结构形式，仅仅从改善施工工艺方面来完全消除廊道裂缝的出现是很难的，从本次京杭运河淮阴三线船闸工程实施过程及结果来看，通过一定的技术措施和改善施工工艺，可使廊道裂缝得到有效的控制，同时避免了有害裂缝的产生。

The application of reflected optical difference system in surface crack of aluminum detection is also discussed. By analyzing the experimental data, we found that the reflected pulsed wave techniques could be used to measure the position of crack precisely and depth imprecisely. Transmitted wave contain much size information of the crack, despite without position information. The spectrum of transmitted is sensitive to the depth of crack. The deeper the crack is, the narrower the spectrum bandwidth is.

使用自建的光偏转差分检测系统，对铝样品中多种表面缺陷进行了检测，对表面波直达波，反射波，透射波波形及频谱进行了分析，讨论超声表面波与各种缺陷相互作用后的变化，通过对实验结果的分析，发现缺陷脉冲发射法可以精确测定缺陷位置，粗略估计缺陷深度；而透射法测的波形无法定出缺陷位置，但包含了缺陷大小信息，透射波频谱对缺陷深度非常敏感，随缺陷深度的加深，频谱不断的左移。

According to the stress-strain complete process curve, the total volumetric strains and crack induced 1 volumetric strains is adopted as damage parameters for analyzing the five phases during the crack growth (crack closure , linear elastic, stable crack growth, unstable crack growth and post failure).

通过压缩试验获得的脆性岩石的全应力应变曲线，利用体积变量和裂纹体积变量等损伤变量分析得出裂纹发展的五个阶段即：压密、弹性、微裂纹稳定扩展、裂纹非稳定扩展和峰后失稳等。

Based on fuzzy feature that the concrete crack width affects concrete structure durability, the membership function that the crack width belongs to the durability failure is established, the calculation method of fuzzy probability about structure durability failure is submitted, and classifing standard of the sturucture durability state is proposed, In accordance with the stochastic nature that cracks on concrete bridges occur and grow, and by assuming that crack occurrence obeys nonstable Poission process, predicting and evaluating methods about future crack condition and durability state of concrete bridge structures are suggested.

依混凝土裂缝宽度对混凝土结构耐久性影响的模糊特性，建立了裂缝宽度隶属耐久性失效的隶属函数，提出了结构耐久性失效的模糊概率计算方法，并建议了结构耐久性状态的划分标准；针对混凝土桥梁裂缝发生、发展的随机性，以裂缝的发生服从非稳态的泊松过程的假设为前提，提出了混凝土桥梁结构裂缝未来状况及耐久性未来状态的预测评估方法。

Interface crack propagation problems under the influence of the central zone of the crack subjected to homogenous loads, the edges of the crack subjected to homogenous loads, the edges of the crack subjected to moving concentrated variable loads Px/ t and the origin of the coordinates subjected to point loads are studied separately, and analytical solutions of dislocation distribution functioncan also be attained.

对裂纹中心区受均布载荷、裂纹表面受均布载荷、裂纹表面受到运动集中变载荷、坐标原点受集中载荷作用下界面裂纹的扩展问题分别进行了研究，也获得了位错分布函数的解析解。

The micro mechanism considers that the inclusion in material, called micro defect crack, is the nucleus of internal crack initiation, interaction, between the stress field of the micro defect crack tip as loading and strain field of crystal lattice caused by crystal point passim (as vacancies or interstitial atom, H, O, N et al), will trap the point passim, and cause the enrichment of point passim around the micro defect crack.

其中疲劳裂纹内部萌生的核心是材料中的第二相粒子、夹杂物或微空洞，称为微裂纹；而微裂纹的长大是材料中间歇原子或空位等点缺陷在微裂纹尖端富集沉淀的过程，微裂纹的长大速率受到点缺陷富集扩散速率和疲劳载荷的双重影响。

Employed the Hamiltonian system theories of elastic mechanics, a series of crack singular analytical elements satisfying different boundary conditions along crack surfaces in the vicinity of crack tip are constructed. These hyper-elements can describe the crack tip fields accurately for different simplified fracture models.

应用弹性力学哈密顿体系理论，在裂纹尖端构造出满足不同裂纹表面边界条件的一类裂纹奇异解析元，该类超级单元能够准确描述不同简化模型下的裂纹尖端场。

According to the concept of strain energy of cracked materials, the orientation tensor of crack was defined. Considering the crack-closing and friction between crack surface under compression, The damage tensor, damage strain and effective elastic modulus were formulated. A method for discrete description of damage mechanism was given, and the evolution equation of discrete orientation density of crack was obtained. The relationship of micromechanism and the macro-representation of concrete failure were studied.

从含裂纹材料的变形能出发，引出了裂纹的方位张量；在考虑裂纹受压闭合与滑动摩擦的基础上，给出了损伤张量、损伤应变和有效弹性系数的表达式，在损伤机构离散化方法的基础上，给出了方位密度的演化方程；将上述损伤理论应用于混凝土的损伤分析，研究了混凝土破坏的微观机制与宏观表现的关系及Griffith准则和Mohr-Coulomb准则的相似性问题，对修正的Griffith准则进行了改进。

Secondly, the paper carries on the destruction processes and the stress distribution situation numerical simulation of the concrete three point bending specimen with bias crack under static load function,, and analyze specimen crack expansion and the destruction mechanism, obtain the reason that the crack expanding flectional way is because the material nonuniformity, in the same time, from the specimen destruction process chart we can see that the crack bias degree has some influence on the crack expansion way.

其次论文对含偏置裂纹的混凝土三点弯曲试件在静态载荷作用下的破坏过程和应力分布情况进行了数值模拟，并对试件的裂纹扩展和破坏机理进行了分析，得出裂纹扩展的曲折性是由于材料不均匀性所引起的，同时从试件的破坏过程图中可以看出，裂纹的偏置程度对裂纹的扩展路径有一定的影响。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了