沥青混凝土路面裂缝产生原因及养护措施

介绍了沥青砼路面裂缝的四种常见形式,分析形成裂缝的5种因素,提出有效治理龟裂、块状裂缝、横向裂缝、纵向裂缝的措施。     

“七天酒店”混凝土裂缝的调查分析与处理

在建筑工程中裂缝往往是结构发生破坏的前兆,因此裂缝一旦出现就给人以不安全感;住宅建筑叉和人们的日常生活息息相关,一旦出现裂缝若不及时进行分析处理,往往会引发许多矛盾。但并非所有的裂缝都为危险裂缝,混凝土产生裂缝的原因是多种的,根据工程的具体情况对具体工程出现的裂缝进行原因分析和鉴定,才是对裂缝的危害性进行评定和修补加固的依据。     

关于钢筋砼结构裂缝分类与整治的探讨

裂缝分类是按照钢筋砼裂缝产生的时间和原因划分的;作者通过对裂缝划分方法及裂缝特征的分析论述,阐明了依据裂缝的特征而应采取的措施和处理方法。     

混凝土裂缝自动愈合机理研究

通过对混凝土裂缝渗水量影响因素的研究,确定了单位渗水量与裂缝宽度等的关系曲线,以及混凝土裂缝可能产生自愈合的时间及裂缝宽度;还对混凝土裂缝自愈合机理进行了研究。     

砖混结构墙体裂缝的分析与防治

砖混结构墙体常发生裂缝。主要分析了温差裂缝与不均匀沉降产生裂缝的原因,对温差裂缝提供了防治措施。     

浅谈混凝土裂缝与施工

混凝土内出现的裂缝按深度的不同,分为贯穿裂缝、深层裂缝及表面裂缝三种。为了保证出现最少的裂缝,就必须在混凝土施工时掌握它的基本性能,并根据实际应用情况采取有效措施,以确保施工质量。     

泵送砼裂缝的防治

本文论述了泵送砼结构裂缝产生的原因及裂缝的具体裂缝的防治措施。     

商品混凝土裂缝的成因和防治措施

主要阐述了商品混凝土早期收缩裂缝、干缩裂缝、温度裂缝产生的原因和预防措施。     

混凝土楼板裂缝的分析、控制和防治

本文时楼板裂缝产生的原因进行了分析,从裂缝原因、裂缝防治措施和处理等方面进行了论述,指出只要按规范进行设计与施工,即可使裂缝得到有效的控制.     

砖砌体裂缝原因及其防治

从两方面论述了砖砌体产生裂缝的原因及裂缝现象,并阐述了防治裂缝的措施。     

Microfracture in wood monitored by confocal laser scanning microscopy

The paper deals with the experimental characterisation of damage evolution within the radial (R)–tangential (T) growth plane of softwood loaded in tension perpendicular to the grain. The reported investigations comprise in-situ monitoring of crack propagation by means of Confocal Laser Scanning Microscopy (CLSM) and evaluations of crack patterns of broken specimens. Three types of notched specimens, representing different crack propagation systems, were tested; for all configurations, both, loading and crack propagation direction were located within the RT plane of wood. The CLSM pictures of broken specimens show distinct differences among the regarded configurations with respect to crack paths. Two different damage mechanisms were identified being rupture of earlywood cell walls in the case of crack propagation in tangential direction and debonding of wood fibers, i.e. rupture of the interface zone between adjacent tracheids, in case of crack progression in radial direction. In the case of an intermediate crack system with an angle of 45° between initial notch direction and radial direction the crack evolution was monitored in-situ during the tension test, whereby the combined action of both basic fracture mechanisms was observed.     

混凝土现浇楼板裂缝产生的原因及预防措施

本文对现浇混凝土楼板产生裂缝的各种原因进行了分析,并论述了产生裂缝所带来的各种危害;同时提出了一些相应的控制措施,以防止现浇板产生裂缝,保证工程质量。     

谈对混凝土裂缝的处理

工程结构出现裂缝是比较普遍的现象;而结构裂缝大部分是能够通过设计阶段、施工措施来避免的,本文对构件裂缝的成因、预防及处理进行了详细探讨。     

Fracture behaviour of laminated veneer lumber under Mode I and III loading

Mode I and Mode III loading experiments were performed on side grooved CT specimens of two types of Laminated Veneer Lumber (LVL). Steady state crack propagation was maintained in order to detect complete load displacement diagrams. Fracture behaviour and influence of fiber orientation were studied and all important fracture mechanical values (stiffness/compliance, microstructural damage, crack initiation energy, specific fracture energy etc) were determined. Much higher crack initiation energies and specific fracture energies resulted in mode III loading than in mode I loading for both material types. Under external mode III loading, crack initiation occurs in mode III and crack propagation however takes place under mode I owing to crack surface interference. The influence of fiber orientation on fracture mechanical properties of LVL was discussed. Received 15 September 1999     

桥梁大体积混凝土裂缝与温度关系的研究

本文结合浙江省某大桥的工程实例,针对大体积混凝土的特点,采取各种措施控制承台裂缝的产生,并对裂缝与温度的关系进行了研究。     

玻纤格栅抵抗不同宽度裂缝反射性能的研究

以加铺玻纤格栅提高沥青面层抗反射能力为研究背景,在室内进行静载有侧限、静载无侧限和动载三种情况,模拟不同宽度的裂缝进行抗反射裂缝试验,并为保证格栅与结构层的粘结性能进行最佳沥青用量试验,结果表明,格栅可以抵抗一定宽度内裂缝发展,但对裂缝的初裂性能上影响较小,对于裂缝在沥青加铺层中的扩展具有良好的改善作用,裂缝的发展形态与路面结构、材料和原始裂缝相关,格栅的有效能力为15%～40%,基层的侧限强度对裂缝扩展影响很大。     

杨树的冻裂与预防的初步探讨

杨树人工林冻裂率为60%以上。冻裂的相关因子为品种、密度、郁闭度、林龄、坡向、植被、抚育一次比抚育三次杨树冻裂少,生长量无大差异。试验证明:对杨树进行涂白、包草和抚育一遍、树干周围留草可以预防杨树冻裂。     

Examination of the onset of stable crack growth under fracture toughness testing of paper

Successive temperature distribution images around the notch tips during fracture toughness testing of paper were obtained by means of an infrared thermography system. Analysis of the images gave the critical times when the temperature significantly rose at the notch tip and when the distance between two maximum temperature spots started to decrease during the testing. Other successive microscopic images around the notch tips showed the relation between crack opening and displacement and the transitional point of the relation. The onset of stable or unstable crack growth as indicated in these critical times and the point agree with each other. For the specimen with a small width, an unstable crack starts to grow at the maximum load point without the stable crack growth period. On the other hand, a stable crack grows before the maximum load point unless the specimen width is small.The period of the stable crack growth increases with an increase in width. Differing from the methods based on thermal images to determine the onset of crack growth, the microscopic method is applicable at a wide range of strain rates and is thus suitable for quasistatic fracture toughness testing.This work was presented in part at the 8th annual meeting of the Society of Packaging Science and Technology, Japan, Tokyo, June 1999