【作者】 翁升；

【导师】 马时冬；

【作者基本信息】 华侨大学 ， 结构工程， 2001， 硕士

【摘要】 随着我国基本建设的发展，在软土地区兴建高速公路、机场跑道等高级道路工程日益增加，这类道路对工后沉降有明确的要求。然而，现有设计规范中的基于单向固结理论的沉降计算方法，不能考虑软土路基由于塑流引起的侧向位移所产生的附加沉降，致使设计计算的最终沉降量小于实际沉降量，造成工后沉降偏大，影响工程质量。因此，改进现有的沉降计算方法有重要的工程意义和理论价值。 本文依托漳诏高速公路软基试验路段，通过对实测沉降、分层沉降、孔压、侧向位移等资料的分析，掌握了软土路基变形的实际性状。特别证实了在深厚软土路基中，侧向位移的长期性。 由于软基塑流的复杂性，要准确计算塑流引起的附加沉降有相当大的难度，为此，工程技术人员往往根据现场实测沉降过程线来推算最终沉降量。常用的有指数曲线法、对数曲线法等。本文采用灰色理论进行最终沉降量预测，用三次B-Spline函数将原始沉降数据进行等时距处理，并用缓冲弱化算子的概念，以消除灰色预测模型的无限增长性，提高长期预测精度。通过比较说明：灰色预测精度最高，指数曲线法次之，对数曲线法最低。 但是上述方法都要求较长的放置预压期（不少于半年），然而，一般的工程因受工期限制不能取得足够长时间的实测沉降资料，这就会影响了预测的准确程度。为此，在灰色预测最终沉降量的基础上，采用有限元方法，通过二步优化反演分析了Duncan-Chang模型中的K、K_ur参数。再用反演得到的参数进行有限元正分析，证明通过上述方法得到的参数具有一定的可靠性。我们有理由相信：只要我们积累了一定数量的数据，在将来类似的工程实践中，完全有可能采用这些参数应用有限元方法对软基最终沉降量作出更为准确的预测。 本文的研究是依托漳（州）诏（安）高速公路8公里软基试验路段进行的。更多还原

【Abstract】 Along with the development of country capital construction, more and more projects such as highway, airdrome run way, etd. were built in the area of soft clay, these projects require the settlement after construction completed definitely. However, in the existing design criterion, the calculation methods which base on one-dimensional consolidation theory can take into account the additional settlement caused by the lateral displacement that generated by the plastical flow of the soft foundation. It leads the calculation final settlement to be less than the actual settlement which leads the settlement after construction completed to be on the big side, and affect the project quality. So, it is possessed of great engineering meaning and theoretical value to improve the existing methods which are used for calculating the sefflement of the soft foundation.This paper which relies on the research of the test section of the soft foundation of the Thang-Zhao highway. Through analyzing the in-situ datum such as total settlement, layered settlement, lateral displacement and pore water pressure, we mastered the actual deformation behavior of soft foundation, and specially approved the chronicity of the lateral displacement in the soft foundation.Because of the complexity of the soft foundation plactic flow, it is much difficult to calculate the additional settlement caused by the plactic flow well and truly. So, the engineers often forecast the final settlement basing on the measured settlement curve. The general methods to forecast the soft foundation final settlement which base on the measured settlement curve are exponential curve method, logarithmic curve method, etc. The gray theory is used for forecasting the soft foundation final settlement in this paper, and the cubic B-spline function is used to make the original datum to be same spatio-temporal, and the buffered softening arithmetic is used to eliminate the infinite increase of the gray forecasting model to increase the forecasting precision. Through the compare we can draw a conclusion that the gray forecasting precision is the best, the exponential curve method is the second best, and the logarithmic curve method is the worst.The methods above all need the foundation having a long preloading period. But, to the general projects, because of the time limit, sometimes it can get the long period of measured settlement data, which will affect the veracity of the forecast result. In this paper, based on the gray forecasting final settlement, two parameters K and ~ of the Dun can-Chang model were back analyzed through two-step optimization back analyses using the FEM method. The FEM analysis was carried using back analytic parameters, it is proved that the parameters got through the methods shown above are of reliability We can believe with reason that as long as we accumulate a number of data, we will have the possibility to use these datum to make more exactly forecasting result of the final settlement of the soft foundation in the similar projects in the future through the FEM method.This paper is based on the research of the test section of the 8-kilometers-long soft foundation of the Zhang-Zhao highway.更多还原