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Westergaards equations are widely used in the design of rigid concrete highway and aircraft pavements. The equations assume that the pavements are either infinite or semi-infinite in extent. Recently, a numerical design procedure using finite elements has been introduced for finite sized precast concrete pavement units [raft units]. The present paper compares the computed stress results from the two methods for the interior loading on a two metre square raft unit. The results show that there is no simple “slab-size correction factor” to correlate the stress output from the two design methods as suggested by other authors. Westergaards analysis should not be used to design finite sized raft units; the numerical design procedure is recommended. 相似文献
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John W. Bull 《国际地质力学数值与分析法杂志》1986,10(2):115-123
Precast concrete pavement units are used in areas with low subgrade CBR values and high static and dynamic loadings. Unlike flexible pavements and rigid pavements, there are no design charts from which pavement engineers can design precast concrete pavements. The author has investigated analytically the relative importance of the factors affecting the ultimate stress and subgrade bearing pressures in precast concrete pavements. Presenting the results in graphical form, the design charts are used toillustrate the new design method. 相似文献
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针对多年冻土区路基路面病害多发的现状,从路面材料入手,对水泥混凝土和沥青两种路面下路基温度场的变化规律进行研究。研究结果表明,在计算高度范围内,对于8.5 m路面宽幅的路基来说,沥青路面下的最大融深大于混凝土路面下的最大融深,尤其在路基高度较低时两种路面下的融深差异更大。最大融化深度和最大融化深度发展速率均与路基高度和路面宽幅有紧密关系,通过研究可以提出有效的措施来保持路基热稳定性,从而减少路基路面病害的发生和公路的运营成本,为今后类似工程提供参考 相似文献
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影响混凝土路面抗折强度的原因分析 总被引：4，自引：0，他引：4
笔者在农村公路检测中发现,多数混凝土路面抗折强度达不到4．0MPa设计标准。本文从原材料、掺合料、外加剂及配合比设计等方面,综合分析探讨了道路混凝土抗折强度的影响因素,并在原材料的选用和配合比设计上,为配制道路混凝土提供了参考。 相似文献
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车辆动荷载是引起路面损坏的最主要原因。目前国内外相关研究多集中于单一车辆对路面结构所产生的动荷载,实际上路面结构所承受的是车流荷载,而且车流在行驶过程中各车辆的车速和车辆之间的距离会产生变化,但关于这方面的研究甚少。针对这一工程实际问题,采用微观交通流模型中的跟车模型来模拟车流行驶过程中各车辆的速度以及它们之间车距的变化,车辆振动模型采用1/4车身结构的两自由度模型,并根据国家标准GB7031-86[1]规定生成路面轮廓的时域信号。最后分析了某水泥混凝土路面在生成的车流荷载作用下的动力响应,为研究车流荷载作用下路面结构动力响应提供了基础性成果。 相似文献
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214国道不同路面形式下碎石护坡工程效果实测分析 总被引：1，自引：1，他引：0
沥青路面和水泥路面是214国道江河源段采用的两种基本路面形式,由于该路段地处高温不连续多年冻土区,碎石护坡等多种工程措施被尝试用来稳定冻土路基.对两种路面形式下碎石护坡路段的地温监测资料进行综合分析发现,碎石护坡能显著降低路基边坡坡面的年平均温度,减小路基边坡坡面温度的年较差,并对坡脚、路肩和路基中心具有从大到小的冷却... 相似文献
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This article presents the development of a J2 small strain plasticity model based on bounding surface concept, along with numerical examples to demonstrate model behaviors and identification of model parameter using laboratory test data. The model is motivated by the need for simulating permanent deformation accumulation of asphalt concrete mixtures, which leads to rutting in flexible pavements under repeated traffic loading. The proposed model accounts for the observation that rutting is mostly caused by shearing and takes advantage of the fact that bounding surface concept allows for the progressive accumulation of plastic deformation under constant amplitude loading condition. Analytical solutions are given for typical laboratory testing conditions. The model can be calibrated using repeated simple shear test data that are typically available for asphalt concrete mixtures. It is shown that the model is easy to use and provides a promising alternative for modeling permanent deformation accumulation in materials subjected to repetitive (cyclic) loading. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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本文通过建立一个不同地面覆盖层土体温湿度监测试验场,对沥青、水泥、多孔砖、草地和裸土5种覆盖层条件下的土体进行了为期2a的观测。观测结果表明:不同覆盖层介质对于下覆土体温湿度场的影响是不同的。在混凝土、沥青、多孔砖、草地和裸土5种地面覆盖层中,混凝土、沥青和多孔砖等硬质地面所对应的土体温度场明显高于裸土和草地,而在3种硬质地面覆盖层中,沥青地面的土体温度场最高,多孔砖最低。在湿度场观测中,多孔砖覆盖层下的土体湿度最大,其次是混凝土和沥青,草地和裸土的湿度最小。因此,多孔砖硬化地面具有很好的保湿性和降低地温场的效果,在城市建设中,应大力推广铺设这类多孔介质硬化地面,以提高城市的生态功能,减少城市热岛效应。 相似文献
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Mettas Christodoulos Agapiou Athos Themistocleous Kyriacos Neocleous Kyriacos Hadjimitsis Diofantos Michaelides Silas 《Natural Hazards》2016,83(1):83-96
Natural and physical hazards accelerate the deterioration of asphalted surfaces. Climatic factors are unavoidable and can affect the properties of asphalt mixtures, making them weaker and less durable. Thus, continuous monitoring of bituminous surfaces is something that can reduce the risks of public health. Remote sensing techniques have become an effective, noninvasive method for early detection of damaged asphalt pavements. This paper outlines a range of different remote sensing methodologies that can be used to monitor asphalt road pavements. This is complemented by the use of field spectroscopy for the examination of asphalt pavements of varying age and conditions. The results of the study found spectral differences regarding asphalt defects, such as physical cracking, patched cracking and polishing. These spectral changes were examined through “in-band” simulation analysis of the Landsat 7 ETM+ sensor, using appropriate relative spectral response filters, concluding that the ratio band 5/band 1 can be used to distinguish asphalt pavements of different date of construction and condition. 相似文献
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INTRODUCTIONThe design methods of asphalt pavement areusually based on the static and elastic analysis sys-tem,though the actual loads such as wheel loads andtemperatureloads are kinetic.The mechanic responseof the pavement is sensitive to the ti me-dependentvariables.Thereis an obvious difference betweentheresults obtainedfromthe kinetic systemandthe stat-ic system.Thus,the dynamic analysisis necessarytodescribe explicitly the working condition of the as-phalt pavement.The dynamic charac… 相似文献
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An algorithm based on the finite element method is developed to analyze the dynamic response of multiple, jointed concrete pavements to moving aircraft loads. In the finite element idealization, the pavement-subgrade system is idealized by thin plate finite elements resting on Winkler-type viscoelastic foundation represented by a series of distributed springs and dashpots. The dowel bars at the transverse joints are represented by beam elements. It i assumed that the dowel bar is fully embedded into the pavement thus neglecting dowel-pavement interaction effects. The longitudinal keyed or aggregate interlock joints are modeled by vertical spring elements. The dynamic aircraft-pavement interaction effects are considered in the analysis by modeling the aircraft by masses supported by spring-dashpot systems representing the landing gear of the aircraft. It is assumed that the aircraft travels along a straight line with a specific initial velocity and acceleration. The aircraft-pavement interaction takes the form of two sets of coupled equations which result ina non-symmetric stiffness matrix. An approximate mixed iteration-direct elimination scheme is used to solve for the dynamic equations. The accuracy of the computer code is verified by the available experimental and analytical solutions. A parametric study is conducted to investigate the effects of various parameters on the dynamic response of pavements. 相似文献
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旧路拓宽全过程三维有限元分析 总被引：17，自引：1，他引：16
旧路拓宽是西部山区高等级公路建设中的重要课题。运用岩土工程专业软件包P laxis 3D Tunnel,对旧路拓宽进行了全过程的三维弹塑性有限元数值模拟,包括新路基的填筑,路面各结构层的铺筑及轮载最不利位置的施加等,重点分析了新旧路基不均匀沉降变形及应力分布的规律,比较了拓宽方式、新老路基土模量差异对路面变形和使用寿命的影响,并就实际施工提出了一些建议。 相似文献
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寒区路面 总被引：1，自引：0，他引：1
The article mainly discusses several essential problems of cold region pavement, including thermal cracking of asphalt concrete, cracking deterioration and heaving, frost heave, seasonal and long term roughness induced by different frost heave, frost heave cracking, bearing capacity loss during spring thaw. The reason for these problems is that cold region pavements are subjected to intense solicitation by climatic and environmental factors. The author offers several models corresponding to the solicitation. Furthermore in conclusion of the article the author indicates future research for cold region. 相似文献
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《Geomechanics and Geoengineering》2013,8(1):31-39
In the present paper, dynamic response of rigid pavements subjected to moving vehicular loads is presented using an analytical procedure based on the finite element method. The vehicle–pavement interaction effects are taken into account while developing the solution algorithm. The concrete pavement is discretized by finite and infinite beam elements. Infinite elements are helpful in appropriate modeling of end conditions. The main purpose of the development of infinite elements is to model the unbounded domain. The underlying soil medium is modeled by Pasternak model which assumes the existence of shear interaction between the spring elements. The moving vehicle is represented by a mass supported by a spring-dashpot system. The vehicle -pavement interaction force is modeled with Dirac-delta function. Dynamic equilibrium equation is solved with Newmark-Beta integration scheme. It has been observed that the dynamic interaction between the moving load and the pavement has significant effect on pavement response. Parametric study is carried out to investigate the effect of vehicle–pavement interaction (VPI) and soil parameters on the response of pavement. 相似文献
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Transportation is vital for the economic and social development and prosperity of every country. Weather phenomena can significantly affect transportation, having huge impacts on the economy and transport user safety. Research indicates that the road transportation system is the most vulnerable system to weather effects. Results from a nine-year period in Cyprus showed that extreme weather conditions resulted in a 5.8 % increase in fatalities on the roads. On the other hand, there is pressure to develop more environmentally sustainable materials to be used in roads, considering the availability of natural aggregate resources and the amount of waste concrete material arising from construction and demolition. This paper describes the use of recycled aggregate concrete (RAC) as a paving material in roads and its properties related to weather effects. Eight different concrete mixtures containing recycled concrete aggregates (RCA) were tested for the weather-related parameters of sorptivity, porosity and permeability. Results showed that the use of RCA and eventually RAC will affect the behaviour of road pavements, due to their higher sorptivity, porosity and permeability. However, it is believed that this will not be detrimental to the quality of road surfaces. 相似文献
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Durability is a notion that is integrated with the performance of stabilized pavement materials. Also, because it can be quantified and measured, it carries significant influence on the design of pavements. This study focuses on using support vector machine, a machine learning algorithm, in assessing the performance of stabilized aggregate bases subject to wet–dry cycles. Support Vector Regression (SVR) is a statistical learning algorithm that is applied to regression problems and is gaining popularity in pavement and geotechnical engineering. In our study, SVR was shown to be superior to the least‐squares (LS) method. Results of this study show that SVR significantly reduces the mean‐squared error (MSE) and improves the coefficient of determination (R2) compared to the widely used LS method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献