【作者】 孙筠；

【导师】 项贻强；

【作者基本信息】 浙江大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 在浙江省的东部沿海地区,软土分布极为广泛。软土本身承载力弱、沉降明显的特点给该地区公路桥梁的正常运营带来不利的影响。如何正确处治、分析和评价已建软土地基上道路与桥梁构筑物之间的差异沉降和冲击响应问题,具有理论价值和工程指导意义。本文以典型的已建桥梁的软基桥梁桥头跳车问题处理为背景,研究提出了深层混凝土过渡板和EPS混凝土换填法两种新的处治方法,并进行了现场试验研究。对深层过渡板处治的路桥过渡段进行了有限元数值模拟计算、过渡板作用机理、影响因素及理论分析探索,结果表明,桥头深层混凝土过渡板具有均匀分布车辆荷载及避免车辆直接冲击作用,减小路桥过渡段沉降差,结构处理整体性较好的优点。EPS混凝土轻质换填材料在施工前进行室内配合比及材料特性试验研究,得到该材料的一般强度推荐值。通过长期现场试验研究观测及过渡段静力分析,得到EPS混凝土换填后路桥过渡段的受力及变形规律。结果表明,采用EPS混凝土换填路桥过渡段路基可以明显降低路基填料的自重、减小地基的沉降及提高路基的稳定性,同时土体的侧向压力对原桥台的推挤作用小,造价合理,兼顾废料回收利用更加环保。通过将深层混凝土过渡板简化为在Winkler地基上双向受力的弹性地基板模型,结合弹性地基梁理论,推导了均布荷载作用下具有特定边界条件的弹性地基板挠度曲线及板底地基反力的解析解。文中还通过将深层混凝土过渡板简化为Kelvin地基上上覆弹性土介质的无限大Kirchhoff薄板模型,对上覆弹性土体采用Navier波动方程模拟,并对土体的位移场进行Helmholtz矢量分解,结合Fourier正逆变换,导出了该板在移动简谐点荷载作用下的挠度响应半解析解表达式。通过将路桥过渡段表层路面板结构体系简化为粘弹性地基上半无限长薄板模型,采用半波正弦荷载来模拟车辆对路桥过渡段的冲击作用,结合Fourier-Laplace变换及逆变换变化,求解得到路桥过渡段表层路面板结构体系在车辆冲击荷载作用下的瞬态挠度；并进一步探讨了将路桥过渡段表层路面板结构体系简化为粘弹性地基上无限大的薄板,在其上作用移动恒定的均布矩形荷载,导出了移动四轮车辆荷载作用下路桥过渡段表层路面板结构体系的稳态响应,并进行了相应的参数分析。最后,通过建立采用两种不同处治方法后的路桥过渡段有限元动力模型,其上作用简化的车辆冲击荷载,分析研究了路桥过渡段路面、过渡板、路基及土基的动力响应。结果表明：深层混凝土过渡板处治和EPS混凝土回填处治的路桥过渡段减振隔振效果好,可为今后路桥过渡段设计、养护及维修的选择、提高车辆行驶的安全性、舒适性及路桥过渡段的交通服务水平等级提供依据。更多还原

【Abstract】 The soft soil is widely distributed in the east coastal area of Zhejiang province. The characteristic which the bearing of soft soil is weak and the settlement is obvious has the adverse influence of the normal operation on the traffic bridge structure for the area. It is theoretical value and engineering guiding significance how to process, analyze and appraise the different settlement and impact response between the road and the bridge structure built on the soft soil.The study puts forward the deep-seated concrete slab and EPS concrete replacement method on the background of the typical bridge approach with vehicle bumping problem built on soft foundation in country provincial highway. The field experimental research was carried out. The finite element numerical simulation analysis of the bridge approach with deep-seated concrete slab, the mechanism analysis of transitional slab, influencing factors and theoretical study show that there are the advantages of distributing the vehicle loads, decreasing the settlement difference and the processed structure wholeness are better for the bridge approach with deep-seated concrete slab.By virtue of test study on EPS concrete light filling materials for indoors mix proportions before the constructing, the recommended values of the normal strength is obtained. By the long-term observation of the field experiment and the finite element analysis on the soil elastic-plastic characteristics for the bridgehead settlement, gains the study on the law of the stress and deformation form of bridge approach filled with EPS concrete. Using the EPS concrete light filling materials can decrease the dead-weight obviously, reduce the soil foundation settlement and increase the stability of the roadbed; the soil lateral pressure has little broaching effect on original abutment, thus cost is reasonable, considering to recycle and use the waste for more environmental protection, this method is much economic and environmental protection.The deep-seated slab is simplified to the elastic foundation plate under bidirectional stress on the Winkler foundation. The analytical solution deflection and base reaction of the foundation plate with specific boundaries under uniform load are calculated by elastic foundation beam theory. The deep-seated slab is also simplified to the infinite Kirchhoff plate under the elastic medium of soil on the Kelvin foundation. The elastic medium of soil is simulated by Navier wave equation where the displacement field of soil is establish by Helmholtz vector decomposition.The corresponding expression of plate under moving harmonic point load is calculated by Fourier inverse transform.The structure system of superficial pavement slab at bridge approach is simplified to the model of semi-infinite thin plate on viscoelastic foundation. The sinusoidal half-wave impact load is described as the vehicle impact action on bridge approach. Combined with Fourier-Laplace transformation and inverse transformation, the superficial pavement slab’s deflection of transient response under the vehicle impact load can be derived. For the further discussion, the structure system of superficial pavement slab at bridge approach is also simplified to the model of infinite thin plate on viscoelastic foundation under moving invariable load. The steady-state response of the superficial pavement slab at bridge approach under moving load, each uniformly distributed over four rectangular areas, is derived and parameter analysis is carried out.From the finite element dynamical analysis of bridge approach models with two kinds of,treatment methods, in which vehicle load is simplified to impact load, the results show that the bridge approach treated by the deep-seated concrete slab and EPS concrete exhibit good effect on vibration reduction and isolation. The analysis results of dynamic responses of the superficial pavement slab, transitional slab, subgrade and soil foundation provide evidence for the design and the maintenance of bridge approach. Therefore, the safety and comfortableness during the vehicle driving and service level of the bridge approach can improve.更多还原