水泥路面早期损坏原因及检测修复

使用中的水泥路面,由于多种原因而产生断裂、裂缝、磨损等多种形式的损坏,严重影响道路运输效果和社会经济效益。针对水泥路面损坏的原因,介绍了水泥路面状态现代检测技术和修复机械。     

水泥路面早期损坏原因及检测修复新工艺

水泥路面是高等级公路主要路面结构型式之一。使用中的水泥路面,由于多种原因会产生断裂、裂缝、磨损等多种形式的损坏,严重影响道路运输效果、经济效益和社会效益。因此,需要及时的保养维护或修复。针对水泥路面损坏的机理、原因、介绍了水泥路面状态现代检测技术和修复机械。     

水泥混凝土路面的绿色改造施工技术研究

针对传统水泥混凝土路面修复难题,研发了一种千斤顶+吊机组合抬升路面板,再注浆转换并抬高路基结构层的路面改造绿色施工技术。该施工技术对破碎板的处理采用先破板后浇筑混凝土的方式,其节点连接牢固可靠,传力路径明确,对路面的深裂缝具有较强的改善作用。经实际工程验证,有效地预防了路基渗水对路面的病害,路面改造效果良好,大大减少了今后的维修费用。     

混凝土旧路面改造技术探讨

目前对混凝土旧路面实施"白加黑"改造有多种方式,既要能解决旧混凝土路面的问题,又要能大幅度提高路面的舒适性和安全性。但以往的混凝土旧路面"白加黑"改造技术在应用过程中容易受到各种因素的影响,导致旧路面改造效果不佳。这里将结合实际案例,着重分析和探讨如何优化实施混凝土旧路面"白加黑"改造技术。     

哥伦比亚麦德林市混凝土路面砖路面

<正>用普通块型的混凝土路面砖,通过专业设计、采用两种或多种颜色的混凝土路面砖,不规则的图案铺设的人行道,同样可使城市产生了活力。     

城市快速路沥青路面养护维修新技术及应用

采用现场检测方法调查了原路面技术状况,结合调查结果对路面病害原因进行了分析,制定了现状道路的路面养护对策,并提出了采用抗车辙沥青混合料组合结构处治路面车辙病害及采用薄层铺装改善道路路面的使用性能的方法,处治效果良好。     

高速公路路基压密注浆加固效果研究

对唐津高速公路基加密注浆加固的效果进行了试验,采用土工试验法、原位测试法、物探法、扫描电子显微镜法、路面弯沉试验法等多种方法,综合试验检测研究结论表明：通过压密注浆,道路路基填土孔隙比降低,强度提高,道路承载能力明显提高。压密注浆处理唐津高速公路路基填土达到了预期效果。     

水泥混凝土路面快速修补方法的探索

根据某路面的损坏情况,确定采用钢纤维混凝土修补加固方案,重点介绍了用钢纤维混凝土快速修补水泥混凝土路面所采用的材料及施工工艺,分析了SFRC的使用效果,得出使用效果良好的结论。     

公路养护中温拌超薄磨耗层施工分析

由于传统技术养护效果较差,公路路面裸露基底面积较大,为此提出公路养护中温拌超薄磨耗层施工分析.对施工技术中的材料配比、温拌以及路面铺筑进行了分析.经试验证明:设计技术公路路面裸露基底面积小于传统技术.     

校园水泥混凝土路面快速罩面修复技术

本文采用新型BC型水泥混凝土路面快速罩面修复材料进行路面修复,经校园内多处破损路面试点考验,表现出良好的界面粘合,较好的抗压强度、耐磨性和抗冲击性能,是一种比较经济实用的修复方法。     

中间加劲复杂卷边槽钢纯弯构件弹性畸变屈曲应力计算方法研究

为了研究中间加劲复杂卷边槽钢纯弯构件弹性畸变屈曲应力简化计算方法,采用有限条分析软件CUFSM对不同参数的复杂卷边槽钢、∑形复杂卷边槽钢以及腹板V形加劲复杂卷边槽钢各70个构件的畸变屈曲应力进行数值分析.在此基础上,借鉴现有板件局部屈曲应力的表达方式,引入畸变屈曲系数,经拟合分析提出上述构件畸变屈曲应力的简化计算公式,并将复杂卷边槽钢和腹板V形加劲复杂卷边槽钢的公式进行合并,对公式的有效性进行验证.     

设置角缝现浇钢筋混凝土框架节点楼板抗震性能研究

利用有限元软件ADINA对现浇钢筋混凝土框架节点做了拟静力分析。对普通梁柱节点及周围楼板设角缝节点的计算结果做了对比。结果表明,随着加载位移的增加,梁肋附近楼板钢筋应力有明显增加,说明楼板对梁的抗弯能力有增强的作用。在不影响节点承载力的条件下,楼板设角缝能局部削弱梁的抗弯能力,梁受力主筋屈服时间明显提前,梁筋屈服时柱身混凝土裂缝也有所减少,梁端与柱端塑性铰出现时间间隔加大,使节点在受到地震作用破坏时更接近梁铰机制的特点。     

一稿多投及其治理对策

分析了一稿多投产生的原因：作者广种薄收的心理,作者急功近利的心理,编辑部门对稿件处理不及时,征稿简则规定不明确或无征稿简则等;提出了治理一稿多投的系列措施和对策,如在报刊上定期刊登约稿启事,编辑部门及时处理稿件,编辑部门之间加强联系等。     

Simulation of buoyancy-driven natural ventilation of buildings—Impact of computational domain

Two computational domains have been used for simulation of buoyancy-driven natural ventilation in vertical cavities for different total heat fluxes and wall heat distributions. Results were compared between cavities with horizontal and vertical inlets. The predicted ventilation rate and heat transfer coefficient have been found to depend on the domain size and inlet position as well as the cavity size and heat distribution ratio. The difference in the predicted ventilation rate or heat transfer coefficient using two domains is generally larger for wider cavities with asymmetrical heating and is also larger for ventilation cavities with a horizontal inlet than those with a vertical inlet. The difference in the heat transfer coefficient is generally less than that in the ventilation rate. In addition, a ventilation cavity with symmetrical heating has a higher ventilation rate but generally lower heat transfer coefficient than does an asymmetrically heated cavity. A computational domain larger than the physical size should be used for accurate prediction of the flow rate and heat transfer in ventilation cavities or naturally ventilated buildings with large openings, particularly with multiple inlets and outlets. This is demonstrated with two examples for natural ventilation of buildings.     

城市规划毕业设计教学改革与实践

本文根据社会的发展和人才需求的变化,探索城市规划专业教学新模式,提出以高教改革为前提,以客观制约条件为基础,对毕业设计教学进行大胆改革和取舍,以期通过实践环节锻炼,培养关注社会的意识和发现问题、解决问题的能力,开展学生综合素质的锻炼,提高毕业生全面执业能力。     

The UWO contribution to the NIST aerodynamic database for wind loads on low buildings: Part 3. Internal pressures

Wind tunnel tests of generic low buildings have been conducted at the University of Western Ontario for contribution to the National Institute on Standards and Technology (NIST) aerodynamic database. Part 1 provided the archiving format and basic aerodynamic data. In Part 2, the data of external pressures were compared with existing wind load provisions for low buildings. This paper, Part 3, deals with an investigation of wind-induced internal pressures of low-rise buildings with realistic dominant opening and leakage scenarios. Data from one building model with four different opening sizes were compared with numerical simulations. The existing theory, using the unsteady orifice discharge equation, works well for the building models used in this study, given the external pressures near the openings, irrespective of shifts of wind direction and upstream terrain. Numerical simulations can capture the temporal variations of the internal pressure fluctuations, as well as mean values.The internal pressure fluctuations for the building with leakage (nominally sealed building) are attenuated as they pass through the openings, while mean values are consistent with spatially averaged external pressures. Internal pressure resonance occurs for the dominant opening (3.3% open ratio) with building leakage. Effects of oblique wind angles on internal pressure dynamics are not significant, at least for the openings in the centre of wall, as is the case herein. Peak internal pressures occur for a wind direction normal to the wall with a dominant opening. Measured internal pressure coefficients are compared with current wind load provisions. Some peak values were found to exceed the recommended design values for the dominant windward wall opening cases.     

不同应变速率下非贯通裂隙介质的力学特性研究

针对地震、爆破等动力荷载作用下节理裂隙岩体的稳定性问题,采用含2条、3条闭合非贯通裂隙的类砂岩模型试样,对应变速率为1.7×10-5s-1、1.7×10-3s-1、1.7×10-1s-1条件下的含裂隙试样进行了单轴加载试验。结果表明:裂隙试样的变形与内部裂隙的贯通过程紧密相关,且呈现显著的局部化渐进破坏特征;随着应变速率的增加,裂隙试样应力-应变曲线斜率显著增加,裂隙试样与无裂隙试样弹模差别减小;不同应变速率下裂隙试样强度明显受控于裂隙的空间位置,且共面非贯通裂隙试样在倾角为35°左右时峰值强度呈现最低值,这与贯通裂隙试样在60°左右时强度出现最小值不同;不同应变速率下含3条预制裂隙试样破坏时的强度与预制裂隙间的贯通模式有关,且与发生相同贯通模式时的含2条预制裂隙试样峰值强度基本相同;裂隙试样峰值强度随应变速率的增加而增加,且含3条裂隙试样强度增幅较含2条裂隙试样、无裂隙试样明显,即随着应变速率的提高,含裂隙试样的弱化作用降低。     

对于泰斯模型的几点新认识

通过对泰斯模型的讨论 ,分别给出了变流量的地下水头计算公式 ,地下水恢复水头计算公式 ,特别是变流量抽水时的恢复水位的计算公式。同时给出了导水系数变化时的水位计算公式和定降深时的流量计算公式。拓展了泰斯公式的应用范围     

How heterogeneous are adolescents’ preferences for natural and semi-natural riverscapes as recreational settings?

Recent research has indicated that the younger generations may be disconnected from nature and even show some dislike for natural conditions. This study addressed adolescents’ preferences for riverscapes with varying fluvial dynamics as recreational settings. A stated choice survey with digitally calibrated river scenarios asked Austrian pupils (N = 281) about their preferences for several physical and social characteristics of a floodplain landscape. Pupils perceived riverscapes with a high water dynamic as best for recreation, while water bodies with low water levels and algae, dry river sites, floods and littered trails were disliked. Heterogeneity among the pupils was found with one smaller segment preferring settings with high water dynamic and low human impact, while the larger one preferred settings with more human impact and low water dynamic. This segment that shows some dislike for natural conditions had less experience with rivers and scored lower on natural river-related attitudes and perceptions. Implications for recreational river planning and aesthetic assessments are derived.     

Numerical study of the circular opening effect on mechanical behaviour of rock under confinement

Opening holes in rock including their size and distribution can affect the performance of rock-related structures. A good understanding on this will contribute to, for example, rock cavern design, and construction, tunnelling, and mining engineering. To improve the understanding, a comprehensive investigation of the opening hole effect on the rock mechanical behaviour under biaxial loading condition is carried out by virtue of a hybrid continuum-discrete element method. Laboratory specimens with both single hole and multi-hole of various radii are investigated and compared with the cases subjected to uniaxial compression. It is demonstrated that the confining pressure can increase both the stiffness and strength due to delaying the crack initiation and propagation. The increase due to the confining pressure is more evident for the compressive strength. For single hole specimens with 0.75 mm radius hole, the increase ratio of the compressive strength is a linear increasing function with width and the increase ratio ranges from 2.15 for the specimen with 3.5 mm width to 2.45 for 10 mm width. For the single hole specimen with 10 mm width, the increase ratio starts at 2.13 for the specimen with 0.75 mm radius hole, ascending to the peak of 2.37 for the specimen with 1 mm radius hole, followed by a decline to 2.2 for the specimen with 1.25 mm radius hole. However, for the multi-hole specimens, the increase ratio varies from 1.66 to 3.13. In addition, to verify the influence of confining pressure magnitude on the performance of the rock specimens, totalling 10 confining pressure levels are applied and modelled. The simulation results show that even though there are opening holes in the specimens, the simulated compressive strength generally follows the generalised Hoek-Brown model.