水泥混凝土道面结构在多轮荷载作用下的响应分析

为研究多轮荷载作用下对道面结构的响应,以ABAQUS分析软件为基础,采用多层结构的线弹性材料,建立了9块水泥混凝土面层板的"软弱地基-道面结构-飞机轮载相互作用"三维有限元模拟模型,建模过程中考虑了纵向横向接缝的传荷能力,为大型飞机轮载作用下的道面结构体系及其力学响应研究提供了先进、可靠的分析平台。     

水泥混凝土道面抢修车在机场的运用

随着我国民航业的飞速发展，对机场跑道、滑行道和机坪道面的要求也越来越高。各机场对道面病害的处理，必须做到及时、高效，这就要求机场管理机构提高作业人员自身素质和寻求更加高效的设备工具。参照公路维护方面的做法，水泥混凝土道面抢修车也可推广到民用机场。水泥混凝土道面抢修车是将多种道面修补的必要工具集成在一辆车上，实现设备工具一体化，其能快速到达现场，第一时间开展作业，缩短道面病害处置时间，减少道面病害对机场运行的影响。     

水泥混凝土道面施工质量通病及预控方法

机场水泥混凝土具有强度高、稳定性好、使用寿命长、维护费用少等优点,已成为我国机场道面结构的主要形式,但在施工过程中也伴随着水泥混凝土质量通病。因此,研究和解决这一问题,对保证机场水泥混凝土道面质量、延长道面使用寿命具有重要意义。     

连续配筋混凝土路面动荷响应分析

将连续配筋混凝土路面视为粘弹性地基上正交各向异性板,运用三角级数和积分变换方法,对路面受局部冲击荷载作用时的动力响应做了分析,得到了路面的挠度、内力和应力的解析解,进行了数值计算分析,并和不考虑地基粘性时的静力、动力响应做了比较。最后,讨论了荷载冲击周期及地基粘性对动态响应的影响。     

不均匀飞机轮载作用下沥青道面结构力学响应

为了研究不均匀飞机轮载作用下沥青道面结构力学响应,基于机轮条纹状接触面积假设和轮胎花纹,确定了轮胎的竖向应力函数,再结合已有研究确定了轮胎的纵、横向接触应力,计算获得了A380-800,B747-400,B777-300ER三维非均布接触应力;基于三维有限元分析模型,得到飞机三维非均布轮载作用下的道面结构力学响应,并分析了三种机型的力学响应的差异。研究结果表明：在三维非均布荷载作用下沥青道面的力学响应大于在均布竖向荷载下的力学响应;荷载的不均匀性对于沥青道面力学响应的影响沿沥青道面面层向土基逐渐减小;在三维非均布荷载作用下,沥青道面的力学响应受飞机的最大滑行质量、起落架构型、胎压、机轮个数等因素影响;随着沥青混合料模量增大,各力学响应参数的变化率也逐渐减小。     

水泥混凝土道面早期抗裂性能试验研究

针对传统的普通道面混凝土施工后经常出现裂缝的现象,分析了裂缝产生的原因,提出在普通道面混凝土中掺加粉煤灰、聚丙烯纤维的新型道面混凝土,采用平板法进行了抗裂性能对比试验。结果表明：在普通道面混凝土中单掺粉煤灰或聚丙烯纤维,都能提高混凝土的抗裂性,而粉煤灰和聚丙烯纤维双掺的新型道面混凝土更能有效防止裂缝的发生,显著延长道面使用寿命。     

滑移爆炸冲击荷载作用下矩形复合板的动力响应分析

以工程振动理论为基础建立矩形板的冲击动力学响应的粘弹性地基板数值计算模型,运用薄板横向振动的基本微分方程和三角函数级数展开法对常速运动面荷载作用下粘弹性地基板进行了分析,求得了板的动力响应的解析解,该模型能用来模拟移动冲击荷载作用于薄板时的动力反应、分析评价基板屈服状态。     

大尺寸高性能水泥混凝土道面施工要点浅析

本文简述了大尺寸混凝土道面的意义及优点，分析了施工中需要逐一解决的问题，并就施工中的支模、混合料的拌和运输、摊铺、振捣、作面、养护、拆模、切缝、灌封等工序需要注意的要点进行了阐述。     

基于半解析有限元的水泥路面荷载响应分析

基于半解析有限元原理和MATLAB软件,开发了水泥路面荷载响应分析程序CP-SAFEM（cementpavement semi-analytical finite element method）。将CP-SAFEM应用到具体工况中,与现行规范和ABAQUS进行了荷载应力的对比验证。结果表明：对于单层板路面,CP-SAFEM与规范公式计算结果误差不超过1%;对于双层板路面,CP-SAFEM与规范公式计算结果误差约为6%; CP-SAFEM与ABAQUS各项力学响应计算结果最大误差不超过5%;当横断面采用相同的网格划分时,CP-SAFEM的计算时间为ABAQUS的1/6;以弯拉应力作为力学指标确定了水泥路面的临界荷位。各项研究表明CP-SAFEM具有良好的计算精度和运算效率。     

冲击荷载下橡胶混凝土道面应变响应研究

为阐明冲击荷载作用下橡胶混凝土道面的应变响应,基于光纤光栅应变计和重型落锤式弯沉仪(heavy weight deflectometer, HWD),设计了一种道面冲击应变响应的测试方法。通过该方法,对比分析了冲击荷载下橡胶混凝土道面与普通混凝土道面的应变响应差异,并通过监测不同尺寸的橡胶混凝土道面,研究道面板尺寸对应变响应的影响。试验结果表明：相较于普通混凝土道面,橡胶颗粒的加入改变了冲击荷载下道面的应变响应分布,使混凝土道面板中的水平应变均减小,而板边、板角的水平纵向应变增加;并且随着板长增加,橡胶混凝土道面板中、板边、板角处最不利应变响应方向的应变逐渐增加,其中板角处纵向应变增加最快,即道面板长增加将使橡胶混凝土道面冲击荷载下的最不利位置和方向从板边横向转移至板角纵向,因此在大尺寸橡胶混凝土道面设计与建造中,板角应变也应被考虑。     

横观各向同性黏弹性沥青路面动力响应解析解

提出了移动荷载作用下各向异性层状地基上柔性路面结构动力响应分析的半解析解法。基于土-结构相互作用理论,建立了柔性路面-层状地基的动力耦合模型。对近场道路结构建立波数域有限元模型,基于精细积分及谱元法原理建立远场地基的谱元模型,利用子结构法来确定近-远场耦合界面处的边界条件,进而实现近场和远场结构的耦合,利用快速Fourier变换获得柔性路面在时空域的动力响应解答。该文方法既可以考虑道路结构的几何特性,也可以计入地基层状分布及各向异性特性的影响。近场有限域模型尺寸不会受到地基层数及层厚的影响,数值求解稳定。通过与解析解的对比,验证了提出方法的有效性与合理性。数值算例对比分析了道路-地基耦合模型与以往整体层状道路模型所得动力响应的差异,并讨论了道路结构层弹性模量的影响规律。

     

Influence of texturing method on tyre/road noise of cement concrete pavement

The texture of pavements influences the tyre/road noise. This refers especially to cement concrete pavements. This article presents the results of studies on sound level on concrete pavements in Poland, which were textured using burlap drag, broom drag and exposed aggregate methods. It was established that on exposed aggregate cement concrete, the maximum aggregate size, which is a key factor in the surface’s macrotexture, has a significant influence on tyre/road noise. It should not exceed 8 mm in the upper layer. When using aggregate size 11 mm, the maximum sound level of a passing-by car increases by approximately 2 dB. Pavements textured using the broom drag and burlap drag methods turned out to be not a beneficial solution due to the sound levels emitted by heavy vehicles moving at a speed above 80 kph. Pavement texturing using the transverse broom drag emits sound levels from heavy vehicles which are approximately 3 dB higher in comparison to values noted on SMA11. The methods of pavement texturing using diamond grinding, used in some countries, point towards the possibility of obtaining beneficial acoustic properties.     

Numerical comparison of flexible pavement dynamic response under different axles

A three-dimensional finite element model was utilised to examine the flexible pavement dynamic response under single, tandem and tridem axles at different speeds. Using two different hot-mix asphalt (HMA) layer thicknesses, 15.2 and 25.4 cm, the dynamic effects of moving axles were investigated on critical responses. These responses include the tensile strain at the bottom of asphalt layer, compressive strain on the top of subgrade and tensile and compressive strain on the surface layer. In this study, the HMA layer and other layers were characterised as linear viscoelastic and elastic material, respectively. Since this research focuses specifically on the time and dynamic effects, considering the transient dynamic loading and inertia forces, implicit dynamic analysis was done. The important findings are as follows. (1) Strains induced by tridem axles could be greater than tandem axles or even equal at different speeds. (2) It cannot be stated that axles always induce greater critical response value to road systems at lower speed because at higher speed they can also induce greater critical response value in pavements than that at lower speed. (3) Changing trend and changing rate of strains with speed are strongly affected by pavement thickness. In general, the effects of different axle configurations are strongly affected by moving speed and surface layer thickness.     

Dynamic response of top-down cracked asphalt concrete pavement under a half-sinusoidal impact load

A 3D finite element analysis model of cracked asphalt pavement is established by the FEM software ABAQUS. Based on dynamics mechanics, fracture mechanics and finite element theory, this paper studies the influence of various vehicle speeds, crack location, crack depth, damping ratio etc. on the dynamic response. The results show that the surface deflection, the maximum tensile strain at the bottom of the asphalt layer, and the maximum shear stress of the asphalt layer decreased with the increase in vehicle velocity when there is no crack in the pavement. No matter where the transverse position of the crack is the stress intensity factors increase with the increase in crack depth and decrease exponentially with the increase in longitudinal distance between the vehicle center and the crack. In the case of the crack locating in the center of wheel clearance, the surface deflection increases with the crack depth increasing. But if the crack is at the edge of the wheel track, there will be a critical vehicle velocity where the surface deflection is smaller than the asphalt pavement without crack if the vehicle velocity is above it. The maximum tensile strain at the bottom of the asphalt layer and the maximum shear stress of the asphalt layer are also smaller than the asphalt pavement without crack. The maximum tensile strain and the maximum shear stress decrease with the damping ratio increasing. So the increase in damping ratio can help to alleviate the propagation of cracks.     

基于正交试验思想有限元分析的水泥砼路面板角脱空判定方法研究

利用正交试验设计的思想,针对使用贝克曼梁法检测旧水泥砼板板角脱空建立三维有限元分析模型。分析结果表明,检测弯沉和接缝传荷能力是判定板角脱空状况的充分必要约束条件。根据分析结果,建立定量判定板角脱空状况新方法。     

爆炸荷载下泡沫混凝土减振层动力响应分析

为研究爆炸荷载下泡沫混凝土减振层厚度对岩体拱结构的减振性能影响,基于ANSYS/LS-DYNA动力有限元分析软件,建立炸药-空气-结构流固耦合模型,在岩体与衬砌间设置0、0.2、0.4、0.6、0.8、1.0、1.2 m不同厚度泡沫混凝土减振层。应用流固耦合算法对比分析了衬砌外层拱顶、拱肩和拱脚单元最大有效应力、峰值压力及峰值位移。拱顶上方单元压力与TMB5-855-1公式吻合良好,验证了模型有效性。数值模拟结果表明:设置减振层后拱顶、拱肩和拱脚最大有效应力变小,拱脚减少超过80%;随减振层厚度增加,拱顶、拱肩和拱脚峰值压力减小,峰值位移增加,当厚度超过0.6 m,减振抗爆效果不明显,峰值位移趋于稳定;拱顶作为响应强烈部位,应采取加固措施;综合考虑经济因素,建议设置0.6 m厚减振层。     

Comparison of response for three different composite pavement sections to environmental loads

Composite pavement structures are constructed mainly either as Portland cement concrete (PCC)-over-PCC or hot mix asphalt (HMA)-over-PCC. Several successful in-service projects have been reported in Europe. The design and construction of these sections in the United States, however, still require effort. The current study includes the analysis of the response of three different composite pavement sections to the environmental loads. These sections were constructed in May of 2010 at the Minnesota Road Research Facility. The sections are constructed in three individual cells, Cell 70, a HMA-over-PCC with recycled concrete aggregate (RCA), Cell 71, exposed aggregate concrete (EAC)-over-RCA and Cell 72, EAC-over-economical concrete. All cells were heavily instrumented with thermocouples, moisture sensors, and static and dynamic strain gauges. This study characterises the structural response of HMA-over-PCC pavements and also PCC-over-PCC to the environmental loads.     

爆破冲击荷载下混凝土T梁桥实验

为了揭示爆破荷载作用下混凝土T梁桥的动态响应及破坏律,制作了两种不同纵向长度的混凝土T梁桥模型,测量T梁桥模型的应变值,以及爆炸前后模型的加速度值和声波速度,进行分析比较。研究表明,T梁桥模型的动态响应在横向1/4处比梁中心更敏感;纵向长度长的混凝土T梁桥在相同荷载作用下更容易发生破坏;混凝土T梁桥在存在损伤积累以后,梁肋板更容易先破坏;这为桥梁抢修和设计提供依据,提高其抗爆性。     

受荷混凝土中钢筋锈蚀速率计算方法

为研究荷载对钢筋锈蚀速率及结构耐久性的影响,在潮汐区与盐雾区开展不同荷载条件下氯离子扩散试验,荷载大小分别为无荷载、0.3倍和0.5倍混凝土抗折强度.在混凝土中掺入氯盐,开展不同浓度氯盐条件下的钢筋锈蚀试验.通过氯离子扩散试验得到荷载对氯离子扩散影响系数与荷载大小的关系,修正菲克第二定律中的氯离子扩散系数.钢筋锈蚀试验中测试不同时间下混凝土构件中钢筋的锈蚀电流密度,拟合出钢筋锈蚀电流密度与氯盐浓度和锈蚀时间之间的关系.结合混凝土中考虑荷载影响的氯离子扩散模型与钢筋锈蚀模型,给出荷载作用下混凝土中钢筋锈蚀速率的计算方法.该方法对于海洋环境中荷载作用下钢筋混凝土结构耐久性寿命计算具有重要意义.