Through unconfined compressive strength test, flexural tensile strength test, freeze-thaw test, dry shrinkage test and SEM, the improvement effect and mechanism of redispersible latex powder on the mechanical properties of recycled cement stabilized macadam were studied. The results show that the flexural and tensile strength of recycled cement stabilized macadam mixture increased and the compressive strength decreased slightly after adding latex powder. With the addition of latex powder, the BDR value of cement stabilized macadam increased, and the frost resistance of the mixture improved. Adding latex powder can reduce the shrinkage strain and shrinkage coefficient of cement stabilized macadam, and significantly improve its crack resistance. SEM images show that the latex powder polymer forms a network-like connection structure in the mixture, which can absorb the shrinkage deformation of mineral particles and hydration products in the material, and significantly reduce the shrinkage strain of the specimen.

The complexity of vortex-induced vibration (VIV) instability analysis originates from the variability of the wind environment, the randomness of the analytical model, the ambiguity of the failure criterion, and the high-dimensional nonlinearity and non-explicitness nature of the instability function. This paper addresses the low sampling efficiency and challenges in approximating failure probability in prior research on reliability. By integrating an adaptive sampling strategy with particle swarm optimization (PSO), an initial VIV reliability metamodel is established, which is subsequently resampled to create a more refined metamodel. A combination of multiple reliability algorithms is then employed to calculate the maximum amplitude of VIV and the failure probability of the VIV interval. The validity and accuracy of the proposed method are demonstrated through two representative numerical examples. The results indicate that the proposed radial basis function (RBF)-PSO-importance sampling (IS) analysis method and its adaptive random sampling strategy can significantly reduce the computational cost associated with extensive finite element model operations and the complexity arising from the high-dimensional nonlinearity and non-significance of the limit state function (LSF). This method enables researchers to achieve more accurate and time-saving solutions for VIV in steel–concrete composite bridges.

课程思政是落实立德树人根本任务的重要渠道,而专业课程教学是开展课程思政的重要载体,桥梁工程是土木工程专业道路与桥梁方向最主要的必修课程.该文以桥梁工程课程为例,对标《高等学校课程思政建设指导纲要》,优化和创新课程内容和教学方式,充分挖掘课程中蕴含的思政元素,针对性设计课程思政教学方案,并提供代表性实施案例,实现思政内容与专业内容深度融合,可为土木工程专业实施课程思政提供参考.

为研究可再分散乳胶粉对水泥稳定碎石材料性能的影响,开展水泥胶砂试验及无侧限抗压强度、抗折强度、干缩、温缩路用性能试验,并通过X射线断层扫描(X-ray computed tomography,XCT)、扫描电子显微镜(scanning electron microscope,SEM)微观试验分析胶粉的作用机理.试验结果表明:胶粉应用于低剂量水泥基材料时,对强度和抗裂性具有显著的提升效果.考虑水泥稳定碎石的抗压强度、抗折强度及韧性,5％胶粉用量最优.5％胶粉水泥稳定碎石7 d无侧限抗压强度提高9.8％、抗折强度提高9.6％、弯曲韧性提升21.0％.掺入胶粉后,水泥稳定碎石的7、28 d干缩系数分别降低41.5％、34.0％,温缩系数降低17.1％,收缩性能得到显著改善.XCT图像分析显示,加入胶粉改变了水泥胶砂的孔隙特征,减少了大孔的数量,孔隙率和平均孔径是影响胶砂强度的主要因素.SEM结果显示胶粉可以增强水泥稳定碎石的界面粘结,优化其孔隙结构,并且与水泥水化产物联结形成弹性空间网络结构,是水泥稳定碎石韧性和收缩性能提升的主要原因.

The idea of curriculum-based ideological and political education points out the direction of talent cultivation for universities in the new era. It offers an effective approach to facilitate the reform and improve the quality of education. As the basic carrier of curriculum-based ideological and political education, professional courses should not only impart knowledge and train abilities, but also play an important role in leading the value in an imperceptible way. Taking the course of Conceptual and Aesthetic Design of Bridges as an example, this study explores the method of ideological and political education construction in professional courses of civil engineering. Specific ideological and political targets are designed for each chapter according to the detailed contents.The mapping approaches between the ideological and political elements and professional contents are optimized in order to achieve the imperceptible education effect. It provides a valuable reference for curriculum-based ideological and political education in science and engineering courses of universities.

In order to analyze the simplification possibility of the 2S2P1D model in constructing the master curve of asphalt mixture, the fixed combinations of parameters in {E0, E infinity, delta, k, h, beta, tau ref} are proposed, evaluated and applied. By establishing a method of parameter sensitivity, the sensitivity classification of parameters for asphalt mixture using the 2S2P1D model is implemented. Then, the fixed value of each parameter in {delta, k, h, beta, tau ref} for asphalt mixture is obtained by a method of fixed parameter analysis. During these analyses, different shift factors and fitting functions using different types of test data are used to analyze the differences in constructing the master curve of asphalt mixture. The results show that each parameter in {k, h, beta} that has weak sensitivity for the 2S2P1D model can be determined for different types of asphalt mixtures. Comprehensive consideration changes of the goodness of fit and the shape of master curves of various moduli, the fixed combination of material pa-rameters Fix_beta-k-h-delta or Fix_beta-k-h-delta-tau ref is recommended to be used in combination with the shift factor WLF. Based on fixing some parameters of the 2S2P1D model, analyzing the fitting values of unfixed parameters for different types of asphalt mixtures can better compare the differences and statistical randomness, and these material features can be used in the future structural response analysis.

通过开展一系列劈裂强度测试、无侧限抗压强度测试和弯拉强度测试,研究了玄武岩短切纤维对水泥稳定多孔玄武岩碎石力学性能的增强作用.龄期为7d的混合料劈裂试验表明,玄武岩短切纤维对水泥稳定多孔玄武岩碎石的劈裂强度具有显著的增强效果,其中长度为18 mm的纤维对混合料劈裂强度的增强效果优于12 mm、24 mm的纤维.掺加长度18 mm玄武岩纤维的水泥稳定多孔玄武岩碎石,其劈裂强度、无侧限抗压强度、弯拉强度等随着纤维掺量增加先增大后减小;当掺量为碎石质量的0.10％时,纤维对混合料各项力学性能的增强效果最好;随着养护龄期的延长,混合料力学性能不断提升.研究表明掺加玄武岩短切纤维可提高水泥稳定多孔玄武岩碎石的路用性能.

The objective of this paper is to study the influence of aggregate morphology on dynamic modulus of asphalt mixture and establish a method to predict dynamic modulus of asphalt mixture at different temperatures and loading frequencies based on aggregate morphology and asphalt mortar material parameters. The Digital image processing (DIP) method is used to obtain statistical laws of the fractal dimension D and aspect ratio l(w) of aggregate section profiles, and the midpoint displacement method is used to generate virtual random aggregate sections. Based on the 2P2S1D constitutive model using the WLF time temperature equivalence, master curves of dynamic modulus of asphalt mortar at different reference temperatures are obtained and converted into the Prony series. Interface Transition Zones (ITZs) between asphalt mortars and aggregates are modeled by the Coulomb friction model, and dynamic moduli of asphalt mixture calculated by this model are in the range of calculation results by the tie model and the frictionless model. A total of 100 virtual specimens including random aggregates, asphalt mortars, ITZs and air voids are generated. Under different temperature and frequency combinations, extensive virtual tests of dynamic modulus of asphalt mixture are carried out on the virtual specimens. Based on the virtual test data of dynamic modulus, prediction master curves of dynamic modulus of asphalt mixture are obtained. The results show that aggregate morphology has a significant effect on dynamic moduli of asphalt mixture, and this effect has a clear correlation with the distribution laws of aggregate morphology indexes. By comparing with the test data of different literature, the probabilistic prediction method of dynamic modulus of asphalt mixture established in this paper is feasible. (C) 2021 Elsevier Ltd. All rights reserved.

可再分散性乳胶粉可以改善水泥砂浆的各项性能,改善砂浆的施工和易性.本文通过在一定配合比的水泥胶砂中掺入不同掺量的可再分散性乳胶粉,测定掺之后的水泥胶砂流动度,探究了可再分散性乳胶粉对水泥胶砂流动度的影响.试验表明,掺入可再分散性乳胶粉会使水泥胶砂的流动度明显提高,且胶粉掺量越大,水灰比越小.

在水泥混凝土中掺入硅灰等外掺剂可以改善其性能并延长使用寿命,提高工程质量,在水泥胶砂试件中掺入硅灰也可改进其性能.本文研究了不同硅灰以及不同掺入方式对水泥胶砂试件抗折抗压性能的影响规律.结果表明:硅灰在内掺情况下对水泥胶砂试件抗折强度的提升不明显,对早期的强度形成甚至有抑制作用,而外掺情况下对抗折强度的提升较为显著;掺加硅灰能够明显提升水泥胶砂试件的抗压强度.抗压掺量为8％ 时,效果最好的硅灰内掺、外掺的28 d水泥砂浆抗折强度分别提高了5.2％,18.2％,抗压强度分别提高了19.8％,36.2％.随后分析了硅灰提升强度以及2#硅灰效果最好的原因.最后展望了未来的研究方向,应继续加强对硅灰性能的理论研究和试验探究,应用到生产工程中使其资源化.

燃煤发电产生的炉渣是工业固废物的主要来源之一.如果大量炉渣没有充分利用,就会占用土地资源,污染环境.本文首先概述了燃煤电厂炉渣的基本性能和综合利用的发展现状,然后总结了燃煤电厂炉渣目前主要的利用方式,最后分析了综合利用过程中存在的问题并提出建议,以期更好地进行炉渣综合利用.

在沥青路面工程中,纤维较多应用于提高沥青混合料的高温抗车辙性能,如城市道路交叉口或公路的长大纵坡路段.纤维沥青胶浆的抗剪切性能直接影响沥青混合料的高温抗车辙性能.采用沥青胶浆的直剪试验,探究不同纤维沥青胶浆的抗剪切力学性能,并对比不同纤维及纤维的掺加方式对沥青胶浆高温性能的改进效果.试验结果表明:沥青胶浆中加入纤维,其抗剪强度显著提高.玄武岩纤维+聚酯纤维胶浆的抗剪强度最高.纤维沥青胶浆抗剪强度的提升原因是黏聚力C和内摩阻角φ的增大,但主要是黏聚力C增大,其对抗剪强度的贡献率约为78％;掺入纤维的沥青混合料动稳定度明显提高,聚酯纤维+玄武岩纤维混掺地效果最好,这与沥青胶浆剪切试验结果一致.

玄武岩纤维为天然矿物纤维,整体强度较高,抗腐蚀及高温性能较好,且具有电绝缘性能.玄武岩纤维掺入沥青混凝土用以提高其高温稳定性、低温抗裂性以及抗疲劳性能等.本文采用低温小梁试验对玄武岩纤维沥青混合料、普通沥青混合料进行对比试验,发现掺入玄武岩纤维能有效增强沥青混合料的低温抗裂性.

在硅粉可取代矿粉用于沥青混合料中,具有低成本、易添加、高环保等特点.本文采用直剪试验方法,在25℃条件下对沥青胶浆分别进行直剪试验,用抗剪强度τf、黏聚力c及内摩擦角ψ,评价沥青胶浆的抗剪切性能,即沥青胶浆的高温性能.试验结果表明,采用硅灰替代矿粉可以有效提高沥青胶浆的抗剪切强度,提高其高温稳定性.

受铺筑厚度的制约,水泥稳定碎石基层实际中多采用分层施工,形成层间非连续状态,降低了基层作为一个整体结构层的承载能力,这对基层受力是不利的.层间连接状态影响水泥稳定碎石基层的强度及回弹模量指标.三种不同层间状态的无侧限抗压强度由高到低:完全连续状态>半连续状态层间有连接>光滑状态.对于水泥含量5％ 的试件,完全连续状态试件的抗折强度比半连续状态高51.2％,比光滑状态高73.5％.90d龄期时,层间连续试件的回弹模量比层间半连续状态高11.3％,比层间光滑状态试件高13.5％.

将冰雪抑制剂通过体积置换法添加到沥青混合料中,形成自融雪沥青混合料.通过浸水马歇尔试验、冻融劈裂试验、长期冻融劈裂试验重点研究自融雪沥青混合料的水稳定性.试验结果显示:可采用等量置换法进行自融雪沥青混合料配合比设计;掺加冰雪抑制剂后,残留稳定度在50%、70%掺量时,没有影响;掺加冰雪抑制剂后,冻融劈裂强度略有下降,但均满足规范要求;综合考虑自融雪沥青混合料的水稳定性及低温耐久性,推荐最佳自融雪沥青混合料替代量为70%.

In order to analyze tire footprints in different conditions and calculate dynamic responses of asphalt pavement with vehicle braking, a tire-pavement coupling simulation system, which can use a viscoelastic constitutive model of asphalt concrete considering temperature dependence, is established. The user subroutine of the material model was programmed by the FORTRAN language, and viscoelastic parameters of the material model were recognized based on dynamic strain data of dynamic impact tests, whose validity was verified by using test data in the literature. The tire-pavement coupling simulation system was established to analyze tire footprints in static and dynamic conditions at different temperatures of asphalt concrete layer, whose calculation accuracy of the numerical simulation was verified. Based on measured temperature data at different depths of an actual pavement structure and the corresponding simulation model, thermal parameters of each layer in the pavement structure were recognized. Field distributions of the viscoelastic parameters in the asphalt concrete layer of the coupling simulation system were obtained by using the heat transfer analysis and the user subroutine. Average braking decelerations of trucks at a chosen intersection were calculated according to the investigation data. Based on the tire-pavement coupling simulation system, peak values of dynamic shear strain in the asphalt concrete layer at the intersection were calculated, which considered the coupling effect between axle loads and temperature fields.

文章根据路况调查及养护实践,分析安徽省高速公路路面病害特征,建立与实际路况吻合的,且可用于大修养护决策的路面性能评价指标及预测模型.从而达到在有限养护资源的前提下,选择适宜的大修养护时间、适宜的大修路段及合适的养护措施,最大化的提高养护资金的利用效率,降低一条高速公路或整个高速公路网的全寿命周期养护成本,提高高速公路服务水平和资源利用效率.

我国冬季都会有较多的降雪天气,路面因积雪结冰而湿滑,撒布融雪剂是最主要的融冰除雪方式.本文在试验基础上,分别选择氯盐类和非氯盐类融雪剂,探究融雪剂的融雪性能及其对水泥混凝土结构的影响.所选用醇类融雪剂、氯盐融雪剂都具有良好的融雪效果.冻融循环试验、干湿循环试验结果显示,醇类融雪剂对混凝土动弹模损失的影响远低于氯盐.水泥混凝土强度越低,融雪剂溶液对其强度的影响越显著.掺加硅灰,提高水泥混凝土的强度,能减小融雪剂对混凝土的腐蚀及强度损失的影响.研究成果为融雪剂的科学合理使用提供依据.

针对旧路处理、混合料拌和、运输、摊铺和碾压五个阶段,从数据收集、计算等分析了沥青面层改建工程的能源消耗及排放,建立改建工程沥青面层能源消耗与排放的量化分析模型,计算了单位质量不同沥青面层混合料在改建工程施工过程的总能耗和环境排放总量.结果表明,SMA-13混合料拌和能耗比AC-20C、AC-25C混合料高11.2%、21.2%;沥青混合料拌和时加热环节的能耗占整个拌和过程的94.5%,通过选择热值高、排放低的能源是节能减排的有效措施;SMA-13混合料整体能耗比AC-20C、AC-25C混合料高9.8%、17.7%, AC混合料随着集料公称粒径的增大,能耗降低;沥青混合料拌和环节的能耗和排放占整个施工过程的79.6%~82.0%和84.1%~85.8%,因此沥青混合料拌和是降低能耗与排放的关键环节.