【作者】 刘全；

【导师】 何良德；

【作者基本信息】 河海大学 ， 港口海岸及近海工程， 2004， 硕士

【摘要】 为了有效控制软土地基的整体稳定和工后沉降量，需要在路基施工过程中进行沉降变形动态控制，以验证和优化设计，达到缩短工期、降低造价和提高工程质量的目的。因此，如何及时根据施工现场实测沉降资料反分析地基土参数来预测后期沉降，已成为沉降变形动态控制的关键技术之一。在现场实测数据的分析过程中发现，许多断面在卸载后并不发生回弹变形，而是继续产生沉降，沉降速率存在明显的变化。针对这一问题，本文对目前研究较少的卸载后有效应力的变化规律做了思考，提出相对于一般加载方式的双向荷载作用(加载—卸荷)的概念。从对单向荷载作用时地基的有效应力变化过程分析入手，引伸到对双向荷载作用时地基的有效应力变化过程分析，提出与实际情况更为符合的孔隙水压力消散过程。同时建立了双曲线模型、半对数模型、指数模型及泊松曲线模型四种本构模型，并结合有效应力过程分析给出了实用的沉降过程线的反演迭代公式。采用优化反演方法编制计算程序，对预测方法进行实例计算，验证了本文预测方法的正确性和可靠性。总结以往荷载稳定后的沉降预测方法，并将其划分为半数学方法与纯数学方法，寻找各种预测方法相互之间的联系与差别，提出复合指数曲线预测方法，并运用新方法对苏嘉杭高速公路重点段落的部分断面进行沉降预测，验证了新方法的预测功能和实用价值。最后，利用比奥固结理论的有限元解法，进一步验证本文提出的预测方法的优越性。更多还原

【Abstract】 For effectually controlling unitary stabilization and settlement of soft-soil ground, dynamic control for settlement distortion should be done in process of construction to reach the purpose of validating and optimizing design, shortening time, reducing cost and improving quality for project. So it becomes one of the key techniques on dynamic control for settlement distortion that how to back-analyze parameters of ground in time base on field test data. The problem, a large number of test sections did not display resilience but keep up subsiding after uninstalling loads, was found in analyzing field test data. Which arouses think in the change of effective stress during uninstalling loads. As the problem is concerned, two-direction load, which differences from the usual load process, is presented. From analyzing the change of effective stress in the process of one-direction to two-direction load, it is founded that the evanescing process of pore water pressure proposed in the paper shows a better agreement to fact. And four constitutive models are established, which are hyperbolic model, half-logarithm model, exponential model and Poisson model. Combined with the analysis of the change of effective stress, the iteration formulations of settlement calculation are provided. Through comparing field data with the calculated results by the program designed by optimization algorithm, the result shows that the method is correct and reliable. Various previous methods are summarized and classified into two categories: semi-math methods and pure-math methods. Based on discussion of the common and difference among these methods, multiple-exponential model is presented. Using the new method to predict settlement of some sections in SU-JIA-HANG expressway, the result indicates that the new method can accurately predict settlement and has practical value. In the end, through comparing the solution of FEM to Biot concretion theory with the result of predict method in this paper, the superiority of the method presented in the paper is further testified.更多还原