“道路工程”课程线上教学研究

在信息化教学中,应该将问题导向、交叉融合、新技术应用和创新发展的特征体现出来,充分运用移动设备来获得多样化的媒体信息,使学习过程朝着泛在化和个性化的方向发展。信息化教学技能指的是教师利用网络资源,获得与教育教学有关的信息,并具备对学习资源及过程做出设计、应用、评价和管理的一种教学能力。教育信息化是一种以教学为中心的信息化,它所关注的重点是如何为学生提供各种方便的信息互动方式。课程设计的科学性和合理性,将直接关系到课程的质量和学生的素质。那么,在教学活动中运用信息化混合式手段,开展信息化混合式教学模式,提高课堂教学质量,就成了我校交通运输工程专业课程教学改革的出发点。

建构主义模式下“道路工程”课件设计

在建构主义理论模式下,学生作为认知主体.本文探讨了在"道路工程"课件设计中如何体现学生学习的主动性和积极性的设计思想,引导学生成为知识意义的主动建构者,通过自主学习加深对知识的进一步理解,最终达到符合要求的意义建构.

高校“道路工程”教学浅析与改进

针对现有普通高校工科教学,尤其是土木工程类教学中理论知识烦琐、枯燥、专业基础课向专业课过渡期间学生实际体验性不强等问题进行了简要分析并提出三点改进措施:课前课后观看工程类电视纪录片;结合“项目学习”教学方法,在课堂内以企业优秀工程汇报片为线进行串讲;积极推进校企合作,鼓励学生在专业课学习之前进行专业见习并重视实习的考核与评价。

课程思政在“道路桥梁工程施工”课程中的实践探索

为推进课程思政在“道路桥梁工程施工”课程中的融入,教师以优秀工程案例和杰出工程人物为出发点,以课堂授课、课堂研讨、优化考核的方式,深度挖掘专业课程中的思政元素,并在此基础上进一步促进课程思政与专业知识的深度融合。同时,提出“由点到线、由线到面”的穿插式思政融入模式和“由远及近、由表及里”的引导式思政学习模式,潜移默化地提升学生思政素养,坚持传授与引领并重,培养学生高尚人格,使其树立远大职业发展目标和社会责任感。

“道路工程检测”课程融入思政教育的实践研究

伴随着教育体制的改革,思政教育与专业课程的融合已成必然趋势,其主张让学生掌握专业知识的同时,能够养成良好学习习惯,逐渐形成完善人格。而“道路工程检测”课程作为典型的技术类课程,具有一定的掌握难度,而学生对其的积极性也参差不齐,所以为强化学习效率,提升课堂参与度和思政考核及格率,二者的融合需要继续深入探究。基于此,本文通过分析“道路工程检测”课程融入思政教育的现状和专业难点,明确对应的实践及优化路径,以期获取客观思路,提升融合度。

突出应用能力培养的“道路工程施工技术”课程教学改革

道路工程施工技术是我校道路桥梁与渡河工程专业一门专业性较强的课程,通过本课程的学习,能提升学生的专业水平,达到实践应用能力的培养目标。在进行课程教学改革过程中,学校改进了教学内容,调整了教学制度,突出了课堂的实操性,能够让学生有更真实的操作感受,提升实践应用能力。本文对“道路工程施工技术”课程教学改革进行了讨论。

Numerical simulation of dynamic pore pressure in asphalt pavement

For studying the driving role of dynamic pressure in water-induced damage of asphalt pavement, based on the fast Lagrangian finite difference method and Biot dynamic consolidation theory, fluid-solid coupling analysis of the pavement is conducted considering asphalt mixtures as porous media. Results reveal that the development and dissipation of the dynamic pore pressure are coinstantaneous and this makes both the positive and negative dynamic pore pressure and seepage force alternate with time. Repetitive hydrodynamic pumping and sucking during moisture damage is proved. The dynamic pore pressure increases with vehicle velocity. Effective stress and deflection of pavement decrease due to the dynamic pore water pressure. However, the emulsification and replacement of the asphalt membrane by water are accelerated. The maximum dynamic pore pressure occurs at the bottom of the surface course. So it is suggested that a drain course should be set up to change the draining condition from single-sided drain to a two-sided drain, and thus moisture damage can be effectively limited.

Mechanics analysis of vehicle bumping at approach slabs with superelevation

In order to analyze the pavement stress caused by vehicle bumping at an approach slab, a simplified four-wheeled bi- axle vehicle-moving model is proposed. The effect of damping and vibration reduction in the process of vehicle-moving is not considered. Based on the position change of vehicle wheels at the approach slab, the vehicle dynamic vibration equations are summarized. Meanwhile, the undetermined coefficients of the vibration equations are obtained using the boundary and initial conditions of the vehicle. The analytical motion solutions of rear and front wheels at different stages are concluded. Consequently, a four-wheeled vehicle model is developed and vibration equations are provided, which can be used to analyze the impact of complicated stress on pavement. The results show that the excessive stress and stress concentration will occur at the approach slab, and it needs to be strengthened.

Analysis on fatigue cracking for asphalt surface layers based on field cores

Field cores from typical cracking locations were tested by the semi-circular bending test and the digital image correlation method to evaluate the anti-fatigue performance of different asphalt pavements. Test results were analyzed by different fatigue models. Causes of fatigue cracking for different pavement sections were determined by extraction and sieving test results. It is found that the ranking （from high to low） in terms of the anti-fatigue performance for field cores is the crumb rubber modified asphalt mixture, densegraded modified asphalt mixture, continuous graded asphalt treated base, gap-graded stone asphalt concrete, and half open-graded asphalt macadam. Compared with the half opengraded asphalt macadam, the fatigue life of the crumb rubber modified asphalt mixture improves by 2. 0 to 3. 8 times. Fatigue lives of different mixtures and distress ratios of actual pavements can be accurately predicted by the dissipated energy density ratio. Causes of fatigue cracking vary with mixture types.

突出应用能力培养的“道路工程施工技术”课程教学改革研究

“道路工程施工技术”课程是道路桥梁与渡河工程专业的一门专业课,具有很强的实践性,学生需要通过课程学习来了解道路发展情况,并掌握道路建设设计的有关理念与方法,熟悉其施工工艺、路面材料具体要求、施工要点等内容。分析现阶段教学模式,可以发现教学内容与学生的实践作业难以有效结合,教学效果无法有效彰显,因此,创新和改革目前的课程教学方式十分必要。基于此,该文主要研究了突出应用能力培养的“道路工程施工技术”课程教学改革。

Mixing ratio design of emulsified asphalt cold recycled mixture based on gyratory compaction molding

In order to study the application of gyratory compaction molding method in emulsified asphalt cold recycled mixture and optimize the relevant technical parameters, the study was carried out according to splitting strength, stability and water stability test;the design of the experiment involved changing gyration number, emulsified asphalt and water content, molded specimen temperature and other factors to analyze the volume parameters, mechanical properties and water stability. The results show that both the maximum dry density and dry and wet splitting strength ratio(DWSSR) of emulsified asphalt cold reclaimed mixture are improved by the rotary compacting method, while the porosity and the optimal dosage of water are reduced. Furthermore, with the increase of compaction times, the porosity and splitting strength index both change exponentially. DWSSR and porosity are consistent with quadratic functions. The use of gyratory compaction for 70 times at 25 °C and the optimum dosage of emulsified asphalt can be determined based on the splitting strength ratio. The high-temperature stability and water damage resistance of the pavement can be improved by the use of rotary compacting method effectively, and the early strength and road performance are higher than the regulatory requirements.

Evaluation of rutting and low-temperature cracking resistancesof warm-mix recycled asphalt bindersunder the secondary aging condition

The rutting and low-temperature resistances of warm-mix recycled asphalt binders under the secondary aging condition were measured by the dynamic shear rheometer test and bending beam rheometer test.Effects of different types of warm-mix asphalt(WMA)technologies and additives were evaluated.Aging and improvement mechanisms were investigated by the Fourier transform infrared spectroscopy test.It is found that recycled binders after the secondary aging are more resistant to rutting and less resistant to low-temperature cracking.The two warm-mix asphalt technologies have opposite effects.Using the Sasobit WMA significantly improves the rutting resistance and reduces the low temperature resistance for the recycled binders due to its morphological change at different temperatures.The rutting factor values of recycled asphalt binders with the Sasobit additive increase by 4.6 to 5.6 times.However,using the Evotherm WMA causes the deterioration of the rutting resistance due to the structural lubrication effect.The rutting factor values of recycled asphalt binders with the Evotherm additive show the reduction of 52%to 62%.It is recommended to add the styrene butadiene rubber latex or crumb rubber powder into the warm-mix recycled asphalt binders to simultaneously improve the rutting and low-temperature cracking resistances.

Dynamic response of a beam on a Pasternak foundation and under a moving load

The dynamic response of an infinite beam placed on a Pasternak foundation when the system was subjected to a moving load was investigated.We used the double Fourier transform and its inversion to solve the formulations of the problem.A closed form analytic solution of the beam was obtained by the theorem of residues.We selected a numerical example to illustrate the dynamic response of the beam on Pasternak and Winkler foundations,respectively.We discuss the effect of the moving load velocity on the dynamic displacement response of the beam.The maximum deflection of the beam increases slightly with increased load velocity but increases significantly with reduced shear modulus of subgrade at a given velocity.The maximum deflection of a beam resting on a Pasternak foundation is much smaller than that of a beam on a Winkler foundation.

Measuring crack propagation in reinforced asphalt concretes

Two different reinforcing methodologies are applied：modification of the overlay characteristics by adding chopped glass fibers to the hot mixture asphalt （HMA） and reinforcing asphalt overlay with glass grids.Theory of fracture mechanics （FM） is employed to determine crack growth rates for the suggested anti-cracking overlay systems.Asphalt mixture designing tests,three point bending tests and fatigue crack propagation tests were carried out.The critical stress intensity factors KIC are determined for plain and reinforced asphalt concrete.Depending on the fatigue crack propagation,the crack growth rate is determined for each type of anti-cracking system and the cracking process is also analyzed.One of the significant points in this study is the attempt to give better understanding of the crack propagation for multilayer asphaltic overlay or what are suggested herein to be called composite structure anti-cracking overlay system.The results indicate that the reinforcing materials improve anti-cracking characteristics of the asphalt concrete.Composite structure anti-cracking overlay gives a good solution for the reflective cracking phenomenon over old cracked pavements.

Inproved grade length limitation of freeways

A method of ascertaining grade length limitation of freeways in mountain terrain is presented. The relationship models between 15 th percentile speeds and grades were built through the surveys and analyses of operation speeds on 7 typical sections of 3 freeways in mountain terrain. Using 15 thpercentile and 85 th percentile as speed limitations, the methods of determining admitted velocities were put forward according to the grades. Deceleration distances of longitudinal slopeways were analyzed utilizing the theories of vehicle. According to the results of analysis, grade length limitation was loosed. Finally the values of grade length limitation for freeways were put forward. The results could be used as references for freeway design.

Effects of freeze-thaw cycle on engineering properties of loess used as road fills in seasonally frozen ground regions,North China

Compacted loess is widely used as fills of road embankments in loess regions of northern China.Generally, densely-compacted loess can satisfy the requirements of embankment strength and postconstruction deformation. However, uneven subsidence, pavement cracks and other related damages can affect the integrity of loess subgrade after several years of operation,and even cause some hazards, especially in North China, where the strong freeze-thaw erosion occurs. In this study, cyclic freeze-thaw tests for both densely and loosely compacted loess samples were performed to determine the variation in engineering properties such as volume, void ratio, collapsible settlement,microstructure, and the related mechanisms were addressed. The experimental results showed that an obvious water migration and redistribution occurred within the samples during freeze-thaw cycles. Ice lenses and fissures could be identified in the upper frozen layers of the samples. After freeze-thaw cycles,the dry densities of the upper layers of samples changed significantly due to strong freeze-thaw erosion. The dry densities decreased for the dense sample and increased for the loose sample. It can be found that dense samples become loose, while loose samples became dense with the increasing number of freeze-thaw cycles. Their related void ratios changed reversely. Both void ratios tended to fall into a certain range, which verified the concept of a residual void ratio proposed by Viklander. The loosening process of densely compacted samples involves the formation of large pores, volume increase and density reduction as well as the related changes in mechanical properties because freeze-thaw cycles may be important contribution to problems of loess road embankments.Adverse effects of freeze-thaw cycles, therefore,should be taken into account in selecting loess parameters for the stability evaluation of road embankment in seasonally frozen ground regions.

Key Techniques for the Construction of High-Speed Railway Large-Section Loess Tunnels

The successful completion of the Zhengzhou-Xi＇an high-speed railway project has greatly improved the construction level of China＇s large-section loess tunnels, and has resulted in significant progress being made in both design theory and construction technology. This paper systematically summarizes the tech- nical characteristics and main problems of the large-section loess tunnels on China＇s high-speed railway, including classification of the surrounding rock, design of the supporting structure, surface settlement and cracking control, and safe and rapid construction methods. On this basis, the key construction tech- niques of loess tunnels with large sections for high-speed railway are expounded from the aspects of design and construction. The research results show that the classification of loess strata surrounding large tunnels should be based on the geological age of the loess, and be determined by combining the plastic index and the water content. In addition, the influence of the buried depth should be considered. During tunnel excavation disturbance, if the tensile stress exceeds the soil tensile or shear strength, the surface part of the sliding trend plane can be damaged, and visible cracks can form. The pressure of the surrounding rock of a large-section loess tunnel should be calculated according to the buried depth, using the corresponding formula. A three-bench seven-step excavation method of construction was used as the core technology system to ensure the safe and rapid construction of a large-section loess tunnel, following a field test to optimize the construction parameters and determine the engineering measures to stabilize the tunnel face. The conclusions and methods presented here are of great significance in revealing the strata and supporting mechanics of large-section loess tunnels, and in optimizing the supporting structure design and the technical parameters for construction.

Cultural Aspect of Belt and Road Initiative and Project Mausam: Strategy for Engagement

The paper seeks to examine the cultural aspects of the two initiatives to justify the fact that enhancing cultural connections is a two way process and would certainly enable both civilizations to learn from each other. B&R's people-to-people bond strategy and Mausam's initiative to revive cultural linkages are not contradictory in nature but supplement each other. In the backdrop of Doklam Stand-off, the shaken mutual trust between the two neighbors can be healed by further increasing cultural and people-to-people contacts.

University culture, project culture and enterprise culture jointly build the training road of the excellent engineers

The ＂Education and training plan of excellence engineers＂ is the base to comprehensively improve the training quality of the engineering talents, and is the power and guarantee of our country to march towards the great power of the engineering education fi＇om the engineering educational power. In the training process, not only it is required to complete the training and improvement of the theoretical knowledge, the practical abilities and the engineering qualities in the colleges, but it also needs the active participation and the close cooperation of the enterprises. Therefore, the students will have the influence of the effects and edification from the university culture, the project culture and the enterprise culture, and will feel the power and benefits a variety of cultures bring about by interleaving. This paper expounds the important position and the function of the university culture, the project culture, and the enterprise culture in the personal training, and elucidates that the complete fusion of the three is the social ideal and support to complete the task of cultivating the outstanding engineers.