工程图简化画法若干问题的研究

图样简化是提高绘图速度,减少绘图工作量的重要途径.本文从工程图简化的原则出发,对机械制图国家标准中的有关规定进行了分析,研究了国内外工程图的简化及发展,结合我国实际情况,从图线、剖面符号、尺寸注法等方面,提出了进一步简化工程图画法的具体建议.     

火灾爆炸作用下921A钢力学性能及本构关系

采用万能试验机和霍普金森压杆(SHPB)系统,对火灾爆炸下921A钢高温力学性能及动态力学性能进行研究。基于试验数据,分别拟合Johnson-Cook本构模型、Cowper-Symonds本构模型,修正Cowper-Symonds模型应变硬化项,并通过试验验证了有效性。参考Johnson-Cook本构模型温度项耦合方法,建立综合考虑温度软化效应和应变率强化效应的921A钢本构模型。     

澳门建筑工程机电安装总承包商务管理

建筑机电设备安装工程商务管理的特点是专业复杂、技术性强、设备更新快。针对澳门氹仔新客运码头工程机电安装中商务管理所遇到的问题,分析商务管理中"背靠背"的原则、设计变更和资金管理的要点、商务争议的处理和如何更换专业分包商等诸多方面,得出"工程施工技术和商务不可分割、技术要服从商务"等观点,并着重阐述如何在工程实施中做好机电安装总承包的商务管理,进一步确认以商务为引领、以技术为支撑的结论,只有将这两大管理要素有机结合,才能保证项目的成功实施。     

特殊行车路线桥梁的受力性能研究

结合潼关至宝鸡高速公路上的某改扩建简支T梁桥,分别采用平面杆系和空间梁格法对其进行分析,结果表明对于该类特殊行车路线桥梁,常规的平面杆系分析方法误差较大,空间梁格法的计算结果更能反映结构的实际受力状况。     

结构参数变化对长寿命沥青路面力学性能的影响分析

选取合理的路面结构与参数取值范围,采用有针对性的网格划分方法,建立了科学的长寿命沥青路面结构力学响应三维有限元分析模型;并以典型长寿命沥青路面结构为对象,分析总结出结构参数变化时长寿命沥青路面力学响应的变化趋势.     

预应力索对连续曲线箱梁桥受力的影响分析

分别在箱梁顶、底板不同位置布置平弯索,并在箱梁腹板中不同高度布置竖弯(含平弯)索,计算分析不同布索方式对连续曲线箱梁的受力影响.结果表明,在箱梁顶、底板不同位置布置平弯索,会对梁体的位移和水平力矩产生较大的影响,而腹板内竖弯索主要影响梁体的竖向位移,同时顶板平弯索和在腹板内靠上布置竖弯索有利于减小扭矩,并使内外侧支座反力趋于均衡.     

The mechanism for the coupler and draft gear and its influence on safety during a train collision

A mechanical model of the coupler and draft gear was established to study the mechanism during an intercity train collision. The model includes four rigid bodies, one spherical joint, two nonlinear torsion spring units and two nonlinear hysteresis units. Simulation and test results show that the axial characteristics of the model are reasonable and the model can reasonably simulate the pitching movement of the coupler. The influence of the coupler and draft gear on the collision behaviour of the train is analysed considering a four-section intercity train. The results show that during the collision process, the amount of compression of the middle coupler is an important factor influencing the pitching deflection angle. The pitching motion posture of the coupler changes with the initial pitching deflection angle, but the initial pitching deflection angle has little effect on its yawing deflection angle. When the pitching angle of the middle coupler is elevated, as the elevation angle increases, the derailment risk of the ‘A’ end bogie of the previous vehicle increases, whereas the risk of derailment of the ‘B’ end bogie of the subsequent vehicle decreases. When the pitching angle of the middle coupler is depressed, the derailment trends for the front and rear bogies exhibit the opposite trend from that of the elevation angle. As the train collision speed increases, the pitching motion of the middle coupler is limited to forcing a yawing motion, causing the yawing deflection angle to increase sharply, which causes the wheel–rail lateral force to increase rapidly. From this, the derailment risk of the bogie increases, which further causes large displacement lateral buckling of the train. An anti-lateral buckling device can limit the yawing deflection angle of the middle coupler, preventing lateral buckling from large displacement and decreasing the risk of derailment.     

An improved dynamic model of friction draft gear with a transitional characteristic accounting for housing deformation

A white-box friction draft gear model has been developed. All components of the draft gear are considered. The distinctive feature of the model, as compared to its predecessor, is the transitional characteristic, which accounts for the effect of elastic deformations of the draft gear housing on the position of the friction wedge system components under loading. The adjustment of the model parameters for improved agreement with experimental data is discussed. The new model can be used in the simulation of shunting impacts for single cars and car groups represented by detailed finite-element models. An example of the simulation is presented and compared with experimental data obtained using a shunting hump test stand.     

保持交通运营扩宽Montedomini隧道:Nazzano工法的演化

在2000年初的Nazzano隧道(A1高速,毗邻罗马)扩宽工程中,首次尝试在不影响既有交通的情况下进行高速公路隧道的扩宽,而非更改线路或采用施工中降低隧道交通服务水平的方法。该工程证明了Nazzano工法的可行性和有效性,采用该工法最大限度地减少了土地占用量,在扩展干线公路、高速公路或铁路基础设施能力时,在建筑施工期间能够不降低其服务水平。由于其他方案(如开挖第3条隧道或在加宽车道处封闭交通)将增加更多的经济和社会成本,因而这种能够不干扰交通的隧道扩宽方案已成为投资方一种可靠有利的选择。     

构造形迹理论在断层判别中的应用研究

从地质力学的构造形迹理论入手,按力学性质将断层分为压性断层、张性断层、扭性断层和压扭性断层、张扭性断层5类,并分别阐述了上述断层在单期和多期复合活动中的宏观力学鉴定特征。在工程实践中通过对掌子面围岩构造形迹的准确观察,并配合TSP等地质超前预报技术能够准确判明前方断层性质,在隧道施工安全和经济方面取得了满意的效果。