【摘要】 科学、合理地预测桥梁桩基工后沉降量是高速铁路建设的关键环节。鉴于京沪高速铁路桥梁桩基沉降曲线在多级荷载作用下呈明显阶梯形基本特征,而常规沉降预测模型不能反映全过程的沉降与时间的关系,引入荷载系数的概念,建立了变形过程指数模型,介绍了模型的求解过程及参数的确定方法。并结合沉降实测资料,运用指数曲线模型和Logistic模型进行对比分析。结果表明,变形过程指数模型能将架梁前期的观测数据纳入分析时间段内,其预测精度高,误差小,预测结果与实测数据基本吻合。进一步对模型参数的计算值进行粗差分析及归类,给出了不同地基土层、不同荷载作用下参数β的建议值。更多还原

【Abstract】 In this paper,we have obtained and worked out abundant accurate and reliable settlement data through long-term onsite monitoring investigation on the basis of exploring the pile foundation construction and finally made the following conclusion that,the settlement-time curve of bridge pile foundation in Beijing-Shanghai High-speed railway is ladder-shaped under the multiple loads. Therefore,it can be said that,if the conventional settlement prediction model fails to reflect the entire process of the relationship between the settlement and the time for its construction,it is critical to trace if the bridge pile foundation estimation is well done. It is for this essential need that we have proposed a very seriously done settlement prediction model in this paper,namely,the Modified Exponential model,in which we have defined the concept of the loading factors and the guiding principles in actual implementation. What is essential is that we have also carefully analyzed the post-construction settlements,and the application scope of the available construction means and ways. To promote the successful implementation of the building program,we have also laid out and illustrated the detailed process of the model formulation and parameters’ determination. Furthermore,we have made comparisons between the predicted and measured settlement values given by the exponential model,the Logistic model and the Modified Exponential model. The results of the successful implementation of the above said research show that:the modified exponential model has fully reflected the predicted data and information in the model than those in other models because it has taken into full account the measured data before erecting the beams and piles and has proved a highly satisfactory agreement between what is predicted and what has been realized in the actual construction process with minor malice. And,finally,when the effects of parameter beta at different levels and loading combinations were analyzed,the recommended parameter beta have been given by further gross error analysis and classification.And,thus,the predicted results show that the suggested prediction model proves to be ideal,scientific and applicable with quite a few testified examples.更多还原