【作者】 何振星；

【导师】 树学锋；

【作者基本信息】 太原理工大学 ， 固体力学， 2009， 博士

【摘要】 水泥混凝土路面具有强度高、耐久性好、使用寿命长、能适应多种车辆通过的优点,多年来得到了广泛应用。但是,在长期的使用过程中,水泥混凝土路面也出现了各种问题,如路面脱空问题、路面层间接触问题以及路面嵌缝处理问题等,这些问题若不能很好解决,将严重影响水泥混凝土路面的使用性能乃至其使用寿命。本论文首先即是针对水泥混凝土路面的几个问题进行深入研究,得到一系列重要结论,对工程实际有重要的指导意义。另一方面,船和桥墩相撞的事故不断发生,造成严重的人员生命、财产损失和环境污染,而桥墩由于遭受船舶撞击而发生坍塌的损失是非常巨大的。本论文最后对船和桥墩相撞的问题进行了深入研究,通过对实船与大桥主桥墩及其防护装置的碰撞过程进行仿真分析,为工程设计人员提供了有价值的数据。本文主要完成了以下几方面的工作:1.采用水泥、石灰,石膏、早强剂、高效减水剂以及膨胀剂等材料,得到了水泥混凝土路面脱空板灌浆浆体新材料。浆体材料具有和易性好,流动度高,凝结后具有早期强度高,后期弹性模量低,且有微膨胀等等优良性能,基本满足了路面脱空板灌浆材料的一系列要求,实验表明,采用这种低弹性模量材料作为脱空灌浆材料将可以有效地提高水泥混凝土路面的使用寿命。2.利用大型动力非线性有限元程序LS-DYNA3D对混凝土路面板脱空、灌浆后承受冲击载荷作用下的弯沉问题进行了计算分析,结果表明:混凝土路面板脱空后,灌浆材料的弹性模量对混凝土路面板有较大的影响;使用中应尽量使灌浆材料的弹性模量和原来的水泥稳定砂砾层的弹性模量所匹配,否则会造成板内应力分布不均匀或者偏高;当灌浆材料的弹性模量低于无脱空时的水泥稳定砂砾层的弹性模量时,同样造成混凝土路面板内的应力增大。同时建立了具有普遍意义的弹性地基上的混凝土路面板变形的基本方程,推导了路基不均匀沉降时路面板弯沉的解析解。3.采用有限元程序ANSYS对考虑了层间接触的普通水泥混凝土路面进行了数值模拟,得到以下结论:层间摩阻系数对面层和基层的力学响应值均有较大影响,层间粘结作用的加强有利于荷载传递和扩散;层间摩阻系数对水泥混凝土路面早期收缩时的力学响应有很大影响,若层间连续,板底在未开放交通前就有大量微裂纹,这将大大降低路面使用性能,导致混凝土路面在低应力水平下的断裂破坏;将有限元分析结果和线弹性断裂力学相结合分析水泥混凝土路面断裂力学性能,分析结果表明:基层对面层收缩的限制是水泥混凝土路面早期裂纹产生的主要原因。4.通过有限元计算方法,分析了HX型嵌段共聚物改性沥青砼接缝路面板在各种行车载荷作用下的动态力学响应、沥青路面接缝受力变形特性、路面接缝的挠度传递能力以及最大挠度变形等。得出如下结论:HX型嵌段共聚物改性沥青砼具有较大的弹性承载范围,能够满足路面接缝设计要求;计算发现,车辆紧急制动容易造成路面发生永久破坏;超载车辆容易使路面产生较大的竖向弯沉和永久车辙。因此,车辆在路面行驶时,应尽量避免紧急制动,同时应尽量避免超载车辆在路面上的行驶。进一步,提出了材料的“模量”和“位移能力”的概念,通过材料性能设计,保证接缝密封无论从粘接界面还是密封胶本体都不发生破坏,同时开发了新型路用密封嵌缝材料及配套施工机具,将路面使用寿命提高了三倍。5.利用大型非线性动态响应分析程序LSDYNA3D,通过对一艘50000DWT的散装货轮在4m/s的航速下以不同风流压偏角撞击桥墩进行数值模拟,并与桥墩无防护装置时的结果进行分析比较,发现设置防撞结构能有效地降低对桥墩的直接破坏。结果表明,在碰撞过程中,防撞结构能有效降低碰撞力峰值,同时通过合理设计防撞结构的结构形式及刚度,可以限制桥梁在碰撞中受到的最大碰撞力载荷和最大变形;防撞装置可以延长“低撞击力”作用下的历时,从而让船头有足够时间转变方向,使船的总动能中以尽可能少的部分参与撞击能量交换;系统变形所吸收的撞击能中,防撞装置的变形起了主要作用,从而尽可能降低了船的变形破坏。更多还原

【Abstract】 Taking the advantage of high strength, good durability, long service life and being suitable for various of vehicles to pass, cement concrete road surface was widely used. Meanwhile, problems emerged, such as surface breaking-away, contact of surface layers, management of surface gaps and so on. The service properties and the working-life would be seriously influenced if these problems were not well settled. The first part of this study is to investigate some of those problems deeply and a series of important conclusions are obtained which have the benefit for actual engineering.Furthermore, ship-bridge-impact accidents took place frequently, causing serious pollution and grievous loss of people and possessions. The damage would be much worse while the abutment collapses due to a ship impact. The other part of this study is to investigate the ship-bridge-impact problem and provide some useful data for the designers, through simulating the impact of a real ship to the main abutment and the protecting device.The main contents of this study includes the following,1. Obtain a new slurry material for surface breaking-away grouting, made of cement, calcareousness, plaster, early strength admixture, high efficiency water reducing agent and swelling agent etc.. It possesses many outstanding properties, such as good workability and fluidity, high early strength and low elastic modulus after coagulation, minimum inflation, etc., which almost satisfies all the requirement to be kind of surface breaking-away grouting material. It was revealed in the experiment that this new material could effectively prolong the service life of the road surface.2. Investigate the deflection of the breaking-away and grouted road surface under impact load with LS-DYNA3D, a powerful dynamics nonlinear FEA program. Results indicated that the elastic modulus of the grouting material had a great effect on the breaking-away road surface, and it should be similar to the modulus of the original stabilized gravel layer to avoid an irregularly distributed stress field or a higher stress point, and this would take place even if the grouting modulus is lower. A universal basic equation was established for the deformation of the cement concrete road surface on an elastic foundation. The analytic solution of the deflection of the road surface was obtained while the differential settlement occurred on the foundation.3. Simulated the cement concrete road surface with the ANSYS program, with the contact of the inner layers taken in account. The following results were available. The coefficient of friction resistance between layers greatly influenced the mechanical response of the surface layer and the foundation layer. The enhanced adhesive effect between layers would be good for the transfer and diffusion of the loads. The coefficient of friction resistance between layers also greatly influenced the mechanical response of the surface layer during the early shrinking period. If the layers of the road were continuous, a great amount of micro-cracks would appear at the bottom of the foundation layer before the road was put into traffic. That would greatly decrease the service performance of the road surface, like inducing fracture at low stress level. The fracture mechanics properties of the cement concrete road surface were studied, through combining the FEA results and the linear elastic fracture mechanics analysis. Results indicated that the main reason of the appearance of the early cracks on the road surface was due to the restriction of the foundation layer against the shrinking of the surface layer.4. Employ the FEA method to study the dynamic respons of HX type sandwich copolymer modified asphalt concrete road seam under various vehicle loads, the mechanical properties of the asphalt road surface seam, the deflection transfer capability and the maximum deformation of the seam, etc.. The following results were available. HX type sandwich copolymer modified asphalt concrete had a wide elastic load-supporting range, which means it could satisfy the requirement of the road seam design. Calculation also indicated that emergent braking of vehicles could easily cause permanent damage of the road surface, and overloaded vehicles often result in greater vertical deflection and permanent tracks. Thus, those conditions should be avoided or restricted. Furthermore, the conception of‘material modulus’and‘deflection capability’were brought forward. The seam could be well sealed through proper design of the material properties, and no damage would occur on the adhesive surfaces or in the sealant itself. And a new road surface seam-sealing material and the corresponding construction tools were invented, with which the service life of the road could be 3 times increased.5. Simulate impact of a 5000DWT bulk carrier against the abutment from different angles at 4m/s speed with LS-DYNA3D. The results of impact with and without abutment protection devices were compared, which showed that the protection devices effectively weakened the direct damage against the abutment and decreased the peak value of the impact force. The maximum impact force and deformation of the abutment could be restricted through proper design of protective structures and the stiffness. The protection structures could prolong the interactional time so that the ship had enough time to turn around and the impact part of the whole kinetic energy could be as low as possible. The deformation of the protection devices played the leading role in absorbing the impact energy. Thus the damage of the bulk carrier could be reduced to the lowest level.更多还原