海洋石油平台吊艇架结构安全评估

海洋石油平台吊艇架结构安全直接关系到整个平台的救逃生。为全面评估吊艇架结构承载安全性,采用ABAQUS有限元软件进行吊艇架结构动静态力学分析,并在现场进行无损探伤及功能试验。研究结果表明:吊艇架结构在2.2倍工作负荷下最大等效应力为70.81 MPa,满足强度要求;最大位移3.38 mm,变形较小;模态分析显示吊艇架结构自振频率较大;吊艇架结构关键焊缝及应力集中部位无缺陷,救生艇升降时吊艇架无明显变形及异常。通过对吊艇架结构的有限元分析及现场检验,为吊艇架的安全评估提供了一种新的思路。     

An analytic study of the effect of saltation on wind profiles

An analytic study of wind profiles above the saltation layer, in which the motion of uniform saltating grains of sand or snow occurs, is conducted. In this study, analytic solutions of the Ekman layer equation that governs the motion of air in a barotropic, neutral atmosphere are obtained in order to investigate the effects of the saltation on the airflow at large distance from a smooth surface. Solutions are derived subject to expressions of the eddy viscosity K(z) defined above the saltation layer up to the Ekman layer. The wind profiles and boundary layer interactions with the saltation process are discussed. With the assumptions that the eddy viscosity varies smoothly from the surface layer to the Ekman layer and K=0.4u _* z(1–z/h), the solutions are found to be consistent with bottom boundary conditions, specified by the velocity profile law outside the saltation layer. These solutions can be either used as an alternative to predict the saltation or used to test the sensitivities of the parameterization scheme designed to simulate dust emissions in a climate or general circulation model (GCM).     

Human walks carefully when the ground dynamic coefficient of friction drops below 0.41

This study investigated the available and utilized friction during non-slip gait in level walking, and determined the limit which human starts to walk carefully to adapt to slippery surface. Sixteen floor–footwear-contaminant conditions with different slipperiness (dynamic coefficient of friction, DCOF, from 0.11 to 1.06) were employed. Fifteen harnessed Chinese male performed ten self-paced walking trials in each condition without slips. The utilized friction (COF_u) was obtained from the maximum value of shear to normal ground reaction force ratio during the first 25% stance. ANOVA and Tukey tests showed three subsets with similar COF_u, and confirmed the hypothesis that the utilized friction drops gradually when the available friction drops below a certain critical limit. Non-linear regression models were applied to the data to determine the COF_u to be 0.20 and the limit of available ground friction which human starts to walk carefully to adapt to slippery surface (DCOF_limit) to be 0.41.     

高喷插芯组合桩极限承载力的灰色预测

高喷插芯组合桩(JPP)是一种新的桩型,具有承载力高、造价低等优点。许多工程单桩的静载荷试验只能加到两倍设计荷载,无法达到试桩的极限或破坏荷载,因此利用有限的实测数据比较准确地预测高喷插芯组合桩的极限承载力具有一定的现实意义。根据灰色理论,介绍了预测单桩竖向极限承载力的自调整非等步长GM(1,1)模型,讨论了三种不同的灰色模型在有限的实测数据条件下预测单桩极限承载力以及荷载—沉降关系的方法。通过对达到破坏和未达到破坏的工程实例的分析计算,证明三种模型的预测精度是令人满意的,其中等维新息模型预测精度最高。     

高耐磨化学复合镀层的研究

为了改善化学镀Ni-P合金镀层的耐磨性能,提高化学镀Ni-P合金镀层的使用寿命,实验中分别在化学镀液中加入了硬质相SiC粒子、Al2O3粒子以及具有自润滑性能的PTFE粒子,使它们与Ni-P合金一起共沉积,从而制备出具有特殊功效的高耐磨复合镀层.实验结果表明:化学镀Ni-P-SiC以及Ni-P-Al2O3复合镀层由于硬质粒子的加入使镀层的耐磨性比Ni-P镀层提高了6倍左右;Ni-P-PTFE复合镀层的摩擦系数可达0.063,远小于Ni-P镀层0.2的摩擦系数,同时耐磨性能也比Ni-P合金镀层有了较为明显的提高.     

煤矿开采地表沉陷盆地边界的再认识

为了研究厚松散层条件下煤矿开采沉陷盆地边界的界定及其影响因素，基于现场实测资料和误差传播定律，建立了厚含水松散层条件下地表沉陷监测点点位中误差函数模型；以辛置煤矿五采区为工程背景，采用UDEC离散元数值分析方法，揭示了采动程度与边界角之间的协同作用关系。研究结果表明:不同国家对沉陷盆地边界的界定并不统一，厚含水松散层条件下，沉陷盆地边缘15 mm的水平移动点可作为沉陷盆地的边界，对于特级保护对象，建议以2 mm下沉点作为沉陷盆地的边界。随着采动程度的增加，沉陷盆地上、下山边界角呈现先缓慢减小再逐渐增加的趋势，二者服从Lorentz函数模型，相关度分别为0.88和0.99，该函数模型能够表达研究区域采动程度与边界角之间的内在联系。     

基于智慧生态城市建设的西部主要城市绿色发展研究

十八届五中全会提出绿色发展理念,成为指导中国未来经济与社会发展的重要指导方针.西部地区在加快城市化进程的同时面临资源环境与经济发展之间的矛盾.大数据与信息时代的来临,使智慧生态城市建设成为城市发展的主流,绿色发展也成为智慧生态城市的核心举措.通过分析智慧生态城市的建设背景,测度西部主要城市的生态足迹与环境承载力,明确城市绿色可持续发展的目标,提出基于智慧生态城市推进西部城市绿色发展的路径与对策.     

Slip safety risk analysis of surface properties using the coefficients of friction of rocks

This study was conducted to determine the most appropriate surface processing techniques (SPT), environmental conditions (EC) and surface roughness (SR) to minimize the risk of slipping when pedestrians walk on a floor covering of rocks barefoot and with shoes. Coefficients of friction (COFs) and values of SR were found using five different types of rocks, four SPT and two (ramp and pendulum) tests. Results indicate that the parameters which affect the COF values of rocks include SR, EC and SPT. Simple linear regression was performed to examine the relationship between the values of the COF and the SR. The value of the COF was identified as R²?≥?0.864. Statistical results, which are based on experimental measurements, show that rocks are classified according to their safe use areas depending on their COF and SR values.     

Coefficient of friction,walking speed and cadence on slippery and dry surfaces: shoes with different groove depths

Objective. The present study aimed to determine the coefficient of friction (COF), walking speed (WS) and cadence while walking on slippery and dry surfaces using shoes with different sole groove depths to predict likelihood of fall. Background. Design of shoe sole groove is crucial to prevent slipping during walking. Methods. 22 healthy young men (mean age 24.5, body mass index 22.5) volunteered for this semi-experimental study. Six different conditions of the test (combination of three shoes and two surfaces) were defined and the condition was repeated three times. In total, 396 trials (22 subjects?×?3 groove depths?×?2 surfaces?×?3 times) were obtained for data analysis. COF was recorded by force platform at 1000?Hz and walking parameters recorded using 3D motion analysis with six infrared cameras at 200?Hz. Results. The highest COF was obtained from the deepest groove depth (5.0?mm) on both dry and slippery surfaces. The COF on slippery surfaces was significantly lower in comparison with dry surfaces. WS and cadence were not significantly different on dry and slippery surfaces. Conclusion. The deeper groove is better to prevent slipping because the COF increases by increasing the shoe sole groove depth. WS did not change on dry and slippery surfaces.     

基于地震易损性的连续梁桥减隔震方案研究

减隔震措施的合理配置是高速铁路地震经济性目标控制的关键。为了对采用不同减隔震装置的高速铁路连续梁桥抗震性能进行量化研究,基于桥梁系统地震易损性分析,选用4种减隔震方案进行对比分析。4种方案分别为:全桥抗震设计方案（方案1）、全桥双曲面球型隔震支座+粘滞阻尼器方案（方案2）、中墩摩擦摆+边墩普通支座与阻尼器配合方案（方案3）和全桥摩擦摆+边墩阻尼器方案（方案4）。结果表明:高烈度高速铁路桥梁须通过减隔震设计才能满足抗震设防目标,综合经济性和抗震性能2方面因素,方案4有效降低了结构内力响应和位移响应,为所列方案中的最优方案。