震后公路隧道抢通技术

通过对震后公路隧道抢通技术的研究,从洞口洞门段到洞身段,根据地震对隧道破坏程度以及破坏类型进行分类,针对简单的隧道洞口清理、坑道穿越法、隧道洞门震害处理、一般情况洞内抢通、坍塌及变形抢通、异常涌水等情况进行应急处理技术研究,提出施工方法。保证地震灾害发生后,震害隧道在抢通工作上做到快速有序、科学可靠、安全适用,保证震区灾后恢复重建的快速、科学、有效进行。     

塑料套管混凝土桩在宁波南外环路的应用

该文结合宁波市南外环路东段工程一般路段软土地基处理,介绍塑料套管混凝土桩(简称TC桩)的特点与设计、施工要点,及其与预应力管桩、水泥土搅拌桩等相比在处理效果、工程费用、施工控制等方面的优越性。     

国道109线十七沟至清水河段高填方路基的设计与施工

为了解决黄土地区高填方路基普遍出现的路基沉陷、路面开裂以及过大的工后沉降等病害,以国道109线十七沟-清水河段一级公路为例,提出了高填方路基的设计与施工方法,为黄土地区高填方路基的填筑提供一定的参考。     

高填土桥坡软土地基设计探讨

本文结合实际工程论述了堆载预压法和真空井点降水堆载联合预压法加固软土地基的设计、施工技术与经验。实践证明 ,在一定的地质条件下 ,即使工期不很充分 ,只要运用得当 ,堆载预压法和真空井点降水堆载联合预压法能够有效地减小工后沉降 ,消除桥头跳车     

高温后中空夹层钢管混凝土柱轴压性能研究

为了分析高温后中空夹层钢管混凝土（简称CFDST）构件轴心受压力学性能,在试验验证的基础上,采用数值模拟的方法对高温后的轴压工作机理进行剖析,探讨温度、空心率、名义含钢率、内外钢管屈服强度及混凝土抗压强度对CFDST力学性能的影响。研究结果表明：随着构件曾经历温度的升高,极限承载力呈下降趋势;外钢管屈服强度对CFDST构件极限承载力的提高有显著影响,混凝土强度对提高常温阶段构件的极限承载力影响较大,但随着温度的升高,影响逐渐降低,空心率、内钢管的屈服强度对高温后CFDST构件极限承载力影响很小。     

双相不锈钢在化学品船建造中的应用

文章介绍了化学品船建造中首次采用双相不锈钢中防止板材损伤和防止板材污染,以及焊接以后不锈钢表面处理的技术措施,保证了装焊的合格率达到98%以上,达到较高的质量标准,受到船东好评。     

夹芯强度对新型液舱防护效能的影响

舰船防护液舱在高速弹体作用下会发生大变形,防护难度较大。文章对新型防护液舱结构进行了分析,建立了含方格夹层板的液舱结构模型,通过与实验数据对比验证了数值计算方法的有效性,并对不同弹体速度、不同芯层强度下的夹层板防护效能进行了比较,并进行了机理分析。研究结果表明:(1)适当降低芯层强度能降低液舱前后板测点的压力载荷和比冲量,明显降低液舱前板的塑性变形;(2)芯层强度降低提高防护效能的主要机理是减小了液舱中的超空泡滞后流;(3)液舱新型防护夹层设计应考虑具体侵彻弹体载荷,适当降低芯层强度的同时应避免防护夹层前后壁发生贴合碰撞。研究结论为新一代航母防护液舱设计提供了参考。     

Transition choice probabilities and welfare analysis in random utility models with imperfect before–after correlation

Welfare in random utility models is used to be analysed on the basis of only the expectation of the compensating variation. De Palma and Kilani (De Palma, A., Kilani, K., 2011. Transition choice probabilities and welfare analysis in additive random utility models. Economic Theory 46(3), 427–454) have developed a framework for conditional welfare analysis which provides analytic expressions of transition choice probabilities and associated welfare measures. The contribution is of practical relevance in transportation because it allows to compute shares of shifters and non-shifters and attribute benefits to them in a rigorous way. In De Palma and Kilani (2011) the usual assumption of unchanged random terms before and after is made.The paper generalises the framework for conditional welfare analysis to cases of imperfect before–after association of the random terms. The joint before–after distribution of the random terms is introduced with postulated properties in terms of marginal distributions and covariance matrix. Analytic expressions, based on the probability density function and the cumulative distribution function of the joint before–after distribution, and simulation procedures for computation of the transition choice probabilities and the conditional expectations of the compensating variation are provided. Results are specialised for multinomial logit and probit. In the case without income effects, it is proved that the unconditional expectation of the compensating variation depends only on the marginal distributions.The theory is illustrated by a numerical example which refers to a multinomial logit applied to the choice of the transport mode with two specifications, one without and one with income effects. Results show that transition probabilities and conditional welfare measures are affected significantly by the assumption on the before–after correlation. The variability in the transition probabilities across transitions tends to decrease as the before–after correlation decreases. In the extreme case of independent random terms, the conditional expectations of the compensating variation tend to be close to the unconditional expectation.     

柴油机SCR后处理控制策略开发与研究

为选择性催化还原技术提出了还原剂喷射的控制策略。它根据原机NOx排放浓度脉谱、排气温度和空速脉谱等计算还原剂的喷射速率。分别通过试验研究了NH3/NOx比值、排气温度和空速对NOx转化率和氨泄漏浓度的影响以及SCR催化剂的氨吸附和脱附特性,并根据研究结果,分别确定稳态和瞬态工况下尿素溶液喷射的控制方案,因而实现了ESC稳态循环和ETC瞬态循环下的控制目标。此外,冷机起动试验表明,该阶段的排气温度低,NOx排放浓度较高,故应采取措施减少低温工况下NOx的排放。     

浅谈泡沫轻质土技术在滨海地区道路软土地基处理中的应用

泡沫轻质土具有轻质性、高流动性、低渗透性、固化后的自立性及整体性好,低弹减震性、强度可调节性、隔热性、耐久性等物理力学特性,能解决滨海地区软土地基处理工后沉降大等难题;同时可减少因超载预压放坡引起的土地征地、拆迁等问题,缩短施工工期。该文结合实际工程,对泡沫轻质土在滨海地区道路软土地基处理工程中的应用进行一些有益的探讨,可供同行参考。