岩体裂隙开挖卸荷扩展机理研究

岩体开挖卸荷作用导致岩体应力重分布,使得处于压剪状态的岩体内部原生裂隙失稳扩展,发生卸荷损伤。文章以岩体断裂力学为基础,考虑岩体开挖卸荷作用三种基本模式:(1)围压卸荷作用;(2)大主应力与围岩同时卸荷作用;(3)主应力方向旋转卸荷作用。采用岩体压—剪断裂理论研究这三种卸荷模式下岩体裂隙扩展的条件,阐述了岩体裂隙开挖卸荷扩展机理。最后,通过具体算例验证了本文方法的合理性,进一步得到三种典型开挖卸荷模式下岩体裂隙的启裂条件。     

Application of Charpy Impact Absorbed Energy to the Safety Assessment Based on SINTAP

The European Structural Integrity Assessment Procedure(SINTAP) was applied to the assessment of welded joints of the API 5L X65 pipeline steel with an assumed embedded flaw and surface flaw at the weld toe. At default level (level 0), the assessment point was established by estimating fracture toughness value KIC conservatively from Charpy energy test data. At the same time, the analysis level 1 (basic level)was applied based on the fracture toughness CTOD. Then the two assessment levels were compared. The assessment results show that all assessment points are located within the failure lines of analysis levels 0 and 1. So the welded joint of the pipeline is safe. It can be concluded that the assessment based on Charpy absorbed energy is practicable when other fracture toughness data are not available, or cannot be easily obtained. The results are conservative.     

论护理英语教学中的小组合作学习

文章根据中高职学校的教育培养目标和学生的英语实际水平,针对护理英语教材特点,论述了小组合作学习在英语教学中的可行性和有效性。小组合作学习是一种以学生为中心,以小组合作形式进行语言交流的学习活动。在英语教学实践中,小组合作学习减轻了学生的心理负担,克服了学生以往“哑巴”式学英语的弊端,提高了学生的语言交际能力和知识发展水平,增强了学生的合作意识,激发了学生参与学习的积极性和创造性。     

Improving the Fatigue Performance of the Welded Joints of Ultra-Fine Grain Steel by Ultrasonic Peening

Contrast tests were carried out to study the fatigue performance of the butt joints treated by ultrasonic peening, aiming at the improvement of ultrasonic peening treatment(UPT) on welded joints of a new material. The material is a new generation of fine grain and high purity SS400 steel that has the same ingredients as the traditional low carbon steel. The specimens are in two different states:welded and ultrasonic peening conditions. The corresponding fatigue testing data were analyzed according to the regulation of the statistical method for fatigue life of the welded joints established by International Institute of Welding(IIW). Welding residual stress was considered in two different ways: the constant stress ratio R = 0.5 and the Ohta method. The nominalstress-number (σ-N) curves were corrected because of the different plate thickness compared to the standard and because there was no mismatch or angular deformation. The results indicated that: 1 ) Compared with the welded specimens, when the stress range was 200 MPa, the fatigue life of the SS400 steel specimens treated by ultrasonic peening is prolonged by over 58 times, and the fatigue strength FAT corresponding to 106 cycles is increased by about 66％; 2) As for the SS400 butt joint ( single side welding double sides molding) , after being treated by UPT, the nominal S-N curve (m = 10) of FAT 100 MPa(R =0.5) should be used for fatigue design. The standard S-N curves of FAT 100 MPa (R = 0.5, m = 10) could be used for fatigue design of the SS400 steel butt joints treated by ultrasonic peening.     

辨几组同音近义易混词

1.“词”与“辞”这两个字(词)在一般情况下可通用。如:辞(词)典,辞(词)章,辞(词)令等。所不同的是:①都可做文体名。但概念不同。辞:汉代常把辞与赋统称为辞赋。辞产生于战国时期的楚国之地而叫楚辞。又以屈原《离骚》为代表,故又称骚辞。词:一种韵文形式,由三言诗或七言诗和民间歌谣发展而成。起于唐代,盛于宋     

Combined Cycle Fatigue Testing with Ultrasonic Frequency Component of S350 Steel Welded Joint

A combined cycle fatigue （CCF） testing system with ultrasonic frequency component was developed toevaluate the CCF properties of S350 steel welded joints in this study. The fatigue testing results indicated that the S-Ncurves of CCF did not have fatigue limit, which agreed with those of pure high frequency fatigue of welded joints. TheS-N curves showed that the CCF strength of welded joints dropped greatly with the increasing interaction between highand low frequency fatigue loading. An approximation design method of CCF was presented using amplitude envelopeas the stress range.     

提高电气化铁路牵引供电功率因数的探讨

通过张集电气化铁路功率因数对公司经济效益的关系,从设备、技术、管理方面分析了功率因数比较低的原因,阐述了功率因数低对设备、线路的影响,并对如何提高功率因数方法进行了探讨说明。     

谈多媒体在英语教学中的使用

多媒体技术使英语课堂变得丰富多彩,英语学习不再是单调乏味的。教师能够借助多媒体全方位地展示英语知识,让学生全面地进行英语的听说读写练习,因而更能体现英语的交际功能。多媒体让英语课堂变得生动有趣,学生课堂学习效率显著提高。     

建筑工程变更索赔的风险问题

工程变更索赔是指工程在施工过程中,发生了量的变更,致使业主或承包商在施工中发生了额外的费用,对方根据有关规定合理地要求赔偿施工中所受的损失.在建设施工项目中,工程变更和索赔是不可能避免的.业主和承包商在招标阶段就应该考虑可能存在的工程变风险,并应采取积极的措施来避免.一旦发生变更,应及时合理处理由此导致的索赔,保证工程有序开展.     

建筑工程变更索赔的风险问题

工程变更索赔是指工程在施工过程中，发生了量的变更，致使业主或承包商在施工中发生了额外的费用，对方根据有关规定合理地要求赔偿施工中所受的损失。在建设施工项目中，工程变更和索赔是不可能避免的。业主和承包商在招标阶段就应该考虑可能存在的工程变风险，并应采取积极的措施来避免。一旦发生变更，应及时合理处理由此导致的索赔，保证工程有序开展。