连拱隧道洞口线形设计方法探讨

结合连拱隧道自身的结构形式及其特点,对不同线形条件下连拱隧道洞口接线设计方法作一介绍,可为分析、总结连拱隧道洞口接线设计在山区高速公路中的应用情况提供一定的理论依据。     

工程量清单招标方法及其特点

工程量清单招标是国际上普遍通行的招标方法,而在我国积极试行的工程量清单招标方法,大胆探索合理低价中标,符合当前建筑市场的发展所需,值得推广使用。     

传递系数法在边坡稳定分析中的应用

提出了利用传递系数法计算边坡稳定性的方法,供设计人员参考。     

城市轨道交通既有线路开行快慢车方法研究

城市轨道交通既有线路有效提升运营服务品质的途径相对较少,既有线路开行快慢车作为一种大胆尝试和创新突破,在高质量发展的背景下,具有非常广泛的应用需求。针对既有线路开行快慢车的方法进行系统梳理,根据不同线路特点和运营需求,提出既有线路开行快慢车的 4 种方法,分别是利用大的行车间隔开行快车、利用交替式跨站停车开行快车、利用故障停车线开行快慢车、利用小交路折返开行快慢车。结合国内外应用实例,对各种方法的开行原理、优缺点以及运营要求等进行详细分析,并介绍既有线路开行快慢车需要改造的内容     

Identification of ice loads on shell structure of ice-going vessel with Green kernel and regularization method

Ice loads are important environmental loads that can influence the structural safety of ships during navigation in ice-covered waters. The identification of ice loads on ship hulls is the core of ice load monitoring. In this study, a new ice load identification model based on Green kernel and regularization methods is established. First, the forward model for ice load identification is developed through the discretised convolution integral of ice loads. Next, three commonly used regularization methods, including Tikhonov, truncated singular value decomposition, and least square QR-factorization (LSQR) are adopted to reduce solution errors. The LSQR method is thereafter selected as the optimal regularization operator, and its regular property is proved by numerical cases with ice-induced strains that contain noise. Finally, two load identification cases are conducted on an experimental rig to evaluate the feasibility of the model in ice load identification. The identified loads can determine the signal features of applied loads in the time domain with good accuracy. This identification model provides new insights for full-scale ice load monitoring.     

Numerical calculation of coupled damage effects on ship subjected to internal blast loading of warhead北大核心CSCD

［Objective］This paper studies the coupled damage effects of a ship's structure due to the internal blast loading of a warhead. ［Methods］Blast tests with cased charge data are conducted to verify the effectiveness of the coupled SPH-FEM approach, and numerical calculations are then performed on real ship compartment scale model tests to analyze the coupled fragmentation and shockwave damage effects of an explosion in a confined cabin.［Results］The results show that the fragments caused by the detonation of the warhead will first cause local damage to the cabin structure. The shockwave will exacerbate the local damage, and blasted openings will further increase the space for the propagation and diffusion of the shockwave inside the chamber, which will in turn cause damage to the adjacent structures. The simple equivalence of the warhead to a bare charge does not give a true picture of the effect of the warhead on the ship's structure, and fragmentation plays a significant role in the detonation of the warhead.［Conclusions］The results of this study show that employing the coupled SPH-FEM numerical method to calculate the coupling damage effects on a ship's structure can accurately reproduce the warhead damage pattern in tests, thereby providing support for the improved assessment of the damage of naval structures under warhead detonation. © 2022 Chinese Journal of Ship Research. All rights reserved.     

Sequential sampling method using Gaussian process regression for estimating extreme structural response

A methodology for estimating extreme response statistics for marine structures, that takes both the long-term variability of the metocean environment and the short-term variability of response into account is presented. The proposed methodology uses Gaussian process regression to estimate parameters of the short-term response distribution, based on output from computationally expensive hydrodynamic simulations. We present an adaptive design strategy for sequential updating of the model, focusing on the metocean conditions that contribute the most to the long-term extreme. With this approach, only a limited number of hydrodynamic simulations are needed.The suggested approach is demonstrated on the problem of estimating the 25-year extreme vertical bending moment on a ship. We show that a relatively small number of iterations (full hydrodynamic simulations) are needed to converge toward the “exact” results obtained by running a large number of simulations covering the entire range of sea states.The results suggest that the proposed method can be used as an alternative to contour-based methods or other methods that consider a few sea states using accurate numerical simulations, with little or no added complexity or computational effort.     

冲压件品质控制

在整车开发过程中,整车外观品质至关重要,因其决定顾客对整车的第一感官印象,而冲压件品质直接决定整车外观品质,因此对冲压件品质有较高的要求。冲压件品质主要受产品设计和过程工艺设计2个阶段影响,文章主要从产品设计和过程工艺设计2个方面阐述了影响冲压件品质的一些注意事项及控制方法,指出冲压件品质直接影响整车白车身品质,冲压件从设计到量产任何一道工序都不能疏忽。     

降雨入渗对土石坝边坡稳定性影响的分析研究

降雨入渗是土质边坡失稳的主要诱发因素,很多土石坝坝坡滑坡都与降雨有着密切的关系。在饱和-非饱和渗流理论及土石坝填土土—水特征曲线的基础上,对土石坝在降雨入渗情况下非饱和区基质吸力的变化及暂态饱和区的形成进行分析,结合工程实例,采用极限平衡法在考虑不同降雨强度及持续时间下对非饱和渗流土石坝下游坝坡稳定性的影响进行分析。计算结果表明,降雨入渗导致土石坝浸润线的升高,从而使得原浸润线以上区域出现暂态饱和区,孔隙水压力增加,最终导致坝坡稳定性的降低,降雨强度越大或降雨历时越长,坝坡安全系数降低越多,坝坡安全系数在降雨持续2～4 h时降低的最快。     

近年国内常用非开挖施工技术施工方法综合概述

与传统开槽施工技术相比,非开挖技术可以使管道施工造成的的环境问题、社会问题和交通问题的影响程度降到最低。因此,非开挖技术广泛应用于铺设新管线、修复置换旧管线、探测原有管网等方面。其施工方法主要有水平导(定)向钻进铺管法、顶管铺管法、盾构铺管法、气动矛铺管法、无缝衬装置换法、管道翻衬置换法和爆(碎)管衬装置换法等。该文对近年我国常用的非开挖施工技术、施工方法,以及部分应用实例作了阐述。