砖混结构墙体裂缝的分析与防治

房屋墙体裂缝的产生给人们造成了很大经济损失及心理压力,由于地基不均匀下沉、温度变化和施工质量、使用材料的影响,使砖砌墙体表面产生一些形状不规则、宽度不等的裂缝,特别是在地震及其他荷载作用下,容易引起提前破坏.本文作者就这三方面的原因阐述了墙体裂缝产生的原因及防范措施,旨在减少和防止裂缝的发生     

加气混凝土砌块墙体裂缝产生的机理及防治

加气混凝土砌块在应用中,由于本身的干缩变形等特点会导致墙体裂缝现象。本文从分析加气混凝土砌块的主要特点入手,探讨了加气混凝土砌块墙体裂缝形成的机理及产生的原因,并提出了相应的防治措施。     

浅谈采用新型砌块墙体裂缝产生的原因及其防治措施

用新型砌块砌筑的墙体产生裂缝,是我国墙体材料革新后产生的一种新的质量通病,已引起人们的重视,本文就墙体产生裂缝的原因及防治措施进行分析和探讨.     

多层建筑承重墙体裂缝处理

承重墙体出现裂缝的原因是多方面的，本文针对墙体冻胀及地基不均匀沉降使墙体产生裂缝，结合三项工程实例。说明裂缝处理的施工过程及采取的补墙方法，并收到了良好的效果。     

某工程主厂房封闭砖墙墙体裂缝原因分析

本文对某厂房墙体裂缝的原因，从设计规范，设计到施工质量进行了剖析。通过理论计算与分析，对不同荷载布置形式进行了对比，指出了产生墙体裂缝的主要原因，阐明了按国家规范进行建筑结构设计的严肃性和重要性。     

某砖混结构住宅楼顶层墙体裂缝原因分析及预防

介绍了住宅楼墙体裂缝形成的主要原因 ,阐述了解决问题的技术措施。     

蒸压加气混凝土砌块墙体裂缝的防治

介绍了蒸压加气混凝土砌块的特性，施工准备及施工工艺，分析了蒸压加气混凝土砌块墙体裂缝产生的原因，提出了有效防治墙体裂缝的措施，需从设计和施工两个方面入手，才能确保砌块墙体的施工质量。     

浅谈砌体结构墙体裂缝成因及控制

分析了砌体结构墙体裂缝产生的原因,并指出了一些常见的砌体结构墙体裂缝产生的防治措施。     

试谈民用建筑顶层温度裂缝的防治措施

本文简要地论述了混合结构住宅楼顶层墙体裂缝原因，施工防治措施及处理方法。     

地基不均匀沉降和温度变化引起墙体裂缝的防治

本文分析了混合结构房屋由于地基不均匀沉降和温度变化引起墙体裂缝的原因,提出了在混合结构房屋设计和施工中为了防止墙体裂缝应采取的措施.     

宝钢厚板边裂成因分析和改善

边裂是影响宝钢厚板质量的一个重要因素.对厚板边部的非连续弧形裂纹缺陷取样,进行金相分析,并对连铸板坯进行对比轧制试验,证实钢板边裂是由连铸板坯角部横向裂纹引起.分析了影响板坯角部横裂的结晶器保护渣、二冷水、结晶器、浇注速度等工艺因素.在此基础上,提出了改善板坯角部横裂的有效措施,即改进保护渣性能、优化二冷水水量分配、弱化结晶器冷却、稳定结晶器锥度和采用合适的浇注速度等等.实施以上措施后,钢板边部裂纹大幅度减少.     

宝钢1BF炉身炉壳开裂成因分析及预防措施

详细分析宝钢1BF炉身炉壳开裂的成因,得出了高温及温差引起的热应力造成炉身炉壳开裂的结论.提出了炉身炉壳开裂的预防措施,确保1BF的正常生产,为1BF的长寿奠定了基础.     

Numerical Study of Scale Effects on the Stiffness Modulus of Rock Masses

The purpose of this paper is to contribute to the study of scale effects on the stiffness modulus of discontinuous rock masses from a mechanical point of view. The study has been conducted on the basis of the observation that the length and density of the natural discontinuities (cracks) in rock masses increase with the volume of the mass. Compressive tests on specimens containing open and closed flat cracks have been simulated through a numerical procedure that is based on the displacement discontinuity method and the fictitious stress method. Cracks have been generated, through a random process, with dips in the 0°–180° range. Both open and closed cracks have been considered. The numerical results obtained for specimens containing open cracks are found to approach the values obtained through an analytical solution. Then, the numerical method has been applied to the study of scale effects on the stiffness modulus of specimens with closed cracks. The numerical results show a decrease in the stiffness modulus with an increase in the size of the rock volume.     

Quality Control for Continuously Cast Slab of High Strength Weathering Steel Q450NQR1

In order to reduce the transverse corner cracks of high strength weathering steel Q450NQR1,the factors influencing transverse corner cracks on continuously cast slab,such as level fluctuation of molten steel in mold,mold taper,primary cooling,mold powder,secondary cooling,nitrogen content in steel,spray nozzle structure,processing parameters and equipment of CC,etc.,were analyzed.Based on this,a series of comprehensive countermeasures have been proposed.The operation shows by the use of key technologies,including stabilizing steel level,optimizing the mold taper,weakening the primary cooling and the secondary cooling,reforming the mold powder,and adjusting spray nozzle structure,the transverse corner cracks on continuously cast slab have been significantly reduced,and the edge cracks on hot rolled sheet have been eliminated due to the transverse corner cracks.The qualified slabs are delivered to produce weathering cold forming sectional steel,whose yield strength is greater than 450MPa.     

Forensic Study of Warranty Project on US82

This forensic study is unique in that it involves a pavement warranty specification. Extensive field and laboratory testing was conducted to determine the cause(s) of longitudinal cracks observed on the surface. Four trenches were cut and removed to allow more testing on top of each pavement layer. The tests found that the stiffness of the foamed asphalt base is higher than that of a typical flexible base. However, the subgrade modulus is low compared with the average subgrade modulus in Texas. Water seeped into two trenches (dug into the road where there were surface cracks) within 20 min of digging. No water was observed in the other two trenches, where there were no surface cracks. The two trenches with surface cracks have lower base density and higher base moisture content than the two with no surface cracks. Based on observations of the trenching and coring operations, the same surface cracks have been detected in the base layer. Cracks up to 150 mm into the base layer have been observed. Although cracks have been observed in the base (and they can be related to lower stiffness and higher falling weight deflectometer deflections), it is difficult to determine if the cause of surface cracks is due to the base layer alone. It is difficult to prove if the layer is responsible for the failure, except by properties listed in the specification. One faulty pavement layer can easily cause the failure of other layers. For warranty purposes, layer-specific failure criteria should be clearly outlined. The base did not meet the gradation specification. The field material was substantially finer than specified. While some specifications may have been violated, there is little evidence to show that the cause of the longitudinal cracking is primarily related to the foamed-asphalt-stabilized base.     

Small and large fatigue cracks in aluminum alloys

Crack opening loads and the displacements near the crack tip have been measured by stereoimaging for large (through) cracks and small (surface) cracks. These results have been published. The present paper combines these observations and considers them in a new way, showing the relationship between small and large cracks, and provides a method for computing an effective driving force (ΔK_eff) for small and large fatigue cracks.     

3250宽板坯投产初期主要缺陷分析

对宽中厚板坯投产初期主要缺陷表面纵裂进行分析，提出工艺控制措施，使板坯表面纵裂纹缺陷得到改善。     

连铸板坯内裂纹对策初探

从生产实际需要出发，与实践相结合，分析连铸板坯中心裂纹和三角区裂纹产生的原因与预防措施，从而减少连铸板坯内裂的发生。     

同步器齿毂裂缝剖析及对策

在普通液压式粉末成形机上压制成形同步器齿毂压坯的过程中 ,对压坯常见的裂缝进行了剖析 ,并提出了避免裂缝的措施 ,以提高其批产合格率     

高强度中厚钢板表面裂纹的原因探讨

系统研究了济钢开发的高强度中厚钢板的表面裂纹,分析了表面裂纹的形成原因,采取了相应的技术措施,使高强度中厚钢板的表面裂纹大幅度减少。