为得到冷弯薄壁C型钢双肢闭合拼合柱的极限承载力的计算公式，采用有限条软件CUFSM以及直接强度法DSM计算得到单肢冷弯薄壁C型钢构件的极限承载力，并运用ABAQUS有限元分析软件计算出轴压作用下的冷弯薄壁C型钢双肢闭合拼合柱的极限承载力。通过对比不同截面几何参数下的单肢冷弯薄壁C型钢构件与冷弯薄壁C型钢双肢闭合拼合柱的极限承载力，分析得到各个参数对拼合柱组合效应系数的影响规律，确定出组合效应系数与两个重要参数的函数关系。采用1stopt拟合软件对大量已得到的组合效应数值进行回归分析，建立了冷弯薄壁C型钢双肢闭合拼合柱的组合效应系数简化公式以及极限承载力计算公式。

建筑垃圾资源化处理是建筑垃圾减量化的重要途径,我国建筑垃圾资源化利用项目在建设和运营过程中逐渐暴露出许多的问题及风险。为解决这些问题,本文以案例分析的方式,利用系统动力学方法,对2个建筑垃圾资源化利用失败项目进行研究,从管理和政府政策的角度对项目利益相关者及宏观层面的深层次原因进行了分析。发现我国建筑垃圾资源化处理主要面临的四大问题,即建筑垃圾资源化立法少、处理标准低、政策的强制性弱和销售渠道窄等。对应这四大问题,提出具体的建议措施,指出在总体经济增长和技术进步的同时,政府政策对行业发展发挥着重要的作用,以期为更多的建筑垃圾资源化项目提供借鉴和参考。

Shale gas produced from wells contains free water, solid particles, and other corrosive substances, so shale gas production lines are at high risk of failure. The bending pipe of gas production in Shunan Gas Mine failed during service. In order to find out the causes of the failure of the bends and to provide technical support for the safe transmission of shale gas, Tensile testing machine, Vickers hardness tester, Charpy notch impact testing machine and metallographic microscope were used to test the mechanical properties and metallographic structure of the pipe sample material. The corrosion by-products were analyzed by scanning electron microscope, energy dispersive spectrometer and X-ray diffractometer. Finally, the Computational Fluid Dynamics (CFD) is used to simulate the erosion behavior of the curved pipe under different working conditions. The results show that the chemical composition, tensile strength, yield strength, hardness, impact performance and grain size grading of the gas bending pipe meet the relevant requirements. The corrosion by-product was identified as FeCO3 by the microstructure characterization analysis, energy spectrum analysis and XRD. The corrosion by CO2 was the main cause for perforation and pitting pits. CFD simulation results show that sand gas has obvious erosion phenomenon on the pipe wall, and with the increase of flow rate, the erosion rate of sand and gravel on the pipe sample increases, and the larger the particle size, the higher the erosion rate of sand and gravel on pipe sample. Combined with the erosion and corrosion results, it is concluded that the erosion of sand-bearing gas makes the inner wall material of the elbow fall off, accelerates the corrosion of CO3 on the pipe wall, and finally leads to the failure of the gas production elbow.

钻具连接螺纹接头强度和密封性能会对钻具的正常工作产生直接影响。为了保证油气开采顺利进行,有必要对钻具螺纹接头进行强度和密封性能分析。为此,以双台肩超高抗扭钻具连接螺纹为研究对象,考虑螺纹不对称性、螺旋升角以及主副台肩接触和螺纹齿面接触等因素,建立了包含进刀槽和退刀槽的钻具螺纹接头三维有限元模型。采用有限元分析方法开展了不同公差配合尺寸、不同载荷形式和不同材料下螺纹接头强度和密封性能分析。研究结果表明:由于间隙的存在,极限配合公差尺寸下螺纹应力比名义尺寸下螺纹应力大25%左右,且其副台肩密封失效;弯矩使螺纹应力和接触压力分布均呈现一侧增大一侧减小的现象,轴向载荷使螺纹应力大幅增大,最大增大了75%,同时主台肩密封失效;不同材料螺纹应力分布规律相同,在弹性模量减小的条件下,螺纹应力以及接触压力均减小8%左右。因此,极限配合公差尺寸以及过大的轴向载荷会破坏螺纹接头的密封性能,材料对螺纹接头的性能影响不大。研究结果可为钻具螺纹接头设计和应用提供参考。

In fracture mechanics, the fatigue evaluation depends on the precise provisions of the stress intensity factor (SIF), which is a quantitative factor established to evaluate the effect of stresses along the crack front. Stress intensity factor performs a definitive role in reflecting material fracture and estimating fatigue life of tubular joints. Some researchers have proposed a series of parametric equations to predict SIF values; however, it gave arguably inaccurate results. There is still a need to improve the accuracy of the SIF prediction’s equation. Thus, to overcome this shortage, this study introduced back-propagation (BP) neural network with conjunction to genetic algorithm (GA) (GA-BP) in predicting the SIF of cracked tubular T/Y-joint. To train and verify the results of the hybrid algorithm GA-BP SIFs’ database covers a wide variety of cracked tubular T/Y joints were simulated by ABAQUS and verified against experimental results. Meanwhile, the SIFs’ result produced by the GA-BP optimization method were compared with those SIF calculated from the accessible parametric equations. The comparison indicated that the GA-BP neural network optimization method is reliable, precise and capable tool in calculating the SIFs of cracked T/Y joints and it also provides higher accuracy than common methods.
© 2020, Korean Society of Civil Engineers.

The first-stage absorber, which is often used to purify crude oil or highly acidic natural gas, is the core equipment of petrochemical enterprises. Uniaxial strength is checked considering axial stress, hoop stress, and radial stress which is the main design idea of high-pressure vessel. However, absorber integrity issues, due to corrosion, thermal stress, and residual stress caused by welds, can cause absorber deformation, strength degradation, and even explosion. In this paper, mathematical models for absorber strength degradation, due to corrosion and thermal stress, are established. Another finite element model by element activation is established to evaluate the residual stress caused by the welding process. According to the parametric study, the effects of various parameters on residual strength of damaged absorber are studied. Strength check is carried out based on Lame thick-walled solution, and von Mises yield a criterion for the absorber according to the stress distribution of the absorber considering corrosion, thermal stress, and residual stress under tri-axial stress. Finally, accuracy of the mathematical model and the element model, of the effect of corrosion, thermal stress, and residual stress on residual strength, is verified according to actual service environment of the absorber. The research results presented in this paper can offer a technological basis and theoretical foundation for residual strength evaluation and absorber design of the firststage principal absorber with weld considering corrosion and thermal stress in a sour environment.
© 2020 by ASME.

According to the tubing string failure statistics in the oilfield, fatigue crack of tubing joint thread in high temperature high pressure (HTHP) ultradeep gas wells remains a problem because it can cause tubing strength degradation, tubing fracture failure, well workover, and even well abandonment. In order to obtain a better understanding of tubing thread fatigue and quantify the fatigue life of tubing joint thread in HTHP ultradeep wells, experimental study, elastic-plastic mechanical simulation, and multi-axial fatigue calculation are carried out in this paper. Based on the similarity theory, the vibration mechanical testing device of the tubing string is designed, and the multi-axial load of the tubing joint thread in the actual working condition is obtained. Meanwhile, tubing joint BX1 thread model is established with ansys software, and the stress distribution of tubing joint thread is analyzed on the boundary condition acquired from experiments of vibration test of tubing string. Finally, according to the multi-axial fatigue theory, the fatigue life prediction value of the tubing thread made of Super 13Cr110 and Super 15Cr125 is compared and analyzed. The work presented in this paper can provide theoretical method and technological basis for the study on the frequent failure mechanism of tubing joint thread in HTHP ultradeep gas wells.

针对高产气井中油管柱振动问题建立特殊螺纹接头密封面在动载荷作用下接触应力的力学模型。分析密封面接触应力、密封球面半径、密封面表面摩擦系数对特殊螺纹密封性能的影响。针对油管柱的高频振动,提出特殊螺纹密封面之间将会产生微振磨损,并基于能量耗散模型,分析不同螺纹锥度情况下,振荡载荷对油管柱接头能量耗散的影响。结果表明:公接头密封球面半径越小,接触应力越集中,接触应力也就越大,密封接触宽度也越小;同时,螺纹密封面锥度越小,密封面能量耗散值也越小,而当密封面锥度小于11°时能量耗散几乎与锥度无关;建议在高压高产气井中,应适当减小特殊螺纹密封面锥度,且密封面结构优先采用锥面对锥面密封结构形式,其次采用球面对锥面结构。

建筑工程项目具有投资巨大、过程复杂、单个项目由多个企业参与建设等特点,项目管理的方法和水平直接影响到各个企业效益的高低。为提高建筑项目工程质量,保障项目开发进度,降低工程项目成本,本文以"互联网+"背景下建筑工程项目管理的思维,对项目全生命周期的信息进行集成化管理,实现各参建企业之间信息共用共享,做到过程留痕,结果可溯的信息化项目管理。并利用案例对基于"互联网+"云平台的项目信息集成化管理进行验证分析,证明了基于"互联网+"云平台的项目信息集成化管理的可行性、可操作性与优越性。