【作者】 彭小云；

【导师】 折学森；

【作者基本信息】 长安大学 ， 道路与铁道工程， 2009， 博士

【摘要】 黄土沟壑区湿软地基有着不同于沿海一般软土以及湿陷性黄土的特殊工程性质。对此，以往结合冲积平原地区的工程实践开展了一些研究，还没有形成系统的理论体系，所得的研究成果主要局限于某一具体工程，在推广应用上有一定难度。本文结合黄陵—延安高速公路(以下简称黄延公路)沿线湿软地基的处理，在国内外资料调研总结的基础上，结合关中冲积平原地区湿软黄土地基的研究成果，研究了黄土沟壑区湿软地基的处理技术。本文对黄土沟壑区湿软地基的物理力学性质进行了深入系统分析。在大量现场调研基础上，结合黄延公路地质资料和课题补充勘探试验成果，总结了黄土沟壑区湿软地基的分布、地质结构特征、成因以及颗粒组成等基本特征。提出了黄土沟壑区湿软地基的定义，工程特性以及常见物理力学性质参数的范围。根据黄土沟壑区湿软地基物理力学参数之间的统计关系，分析得出了土体液性指数、压缩系数与容许承载力，压缩模量与容许承载力的经验关系。对黄土沟壑区湿软地基一般处理技术进行了试验分析和理论评价。结合黄延公路湿软地基处理的实践，在大量现场试验，包括标准贯入试验、触探试验、载荷试验以及沉降观测基础上，通过数值模拟分析，提出黄土沟壑区湿软地基的一般处理方法，并提出了总体处理思路。根据上述试验成果，提出了车载反力装置的载荷试验方法，通过与室内试验以及其它现场测试手段结果的比较，该方法试验结果合理可靠，适用于黄土沟壑区湿软地基承载力的测试。并对试验过程中该方法的不足进行了分析，提出了改进措施。对黄土沟壑区湿软地基变形特性和沉降规律进行了探讨。鉴于黄土沟壑区湿软地基特殊的工程性质，其沉降受多种因素影响，提出了基于神经网络范例推理的沉降预测方法。该方法可以综合考虑多种影响因素，并充分利用其它地区的成功经验。在该方法中，采用了一种新的范例相似度计算方法，通过引进效益函数反映范例之间更多的相似信息，最后通过神经网络仿真，使预测结果更加精确。经过计算，预测结果与实测值误差小于±10%，具有较高精度。深入分析了黄土沟壑区湿软地基处理方案选择时应考虑的各种因素。在传统层次分析法中引入可拓学的基本思想，可以使构造的判断矩阵自动满足一致性要求，从而节省大量的试算工作。同时，还能考虑人们判断的模糊性以及多位决策者的经验。通过在黄延公路湿软地基处理方案选择中的实践应用，表明该方法计算准确，易于掌握。在上述分析基础上，结合黄延公路实践，总结了黄土沟壑区湿软地基一般处理方法的原理、特性、适用范围以及适用性特点评价，提出了各种方法的质量控制措施。提出了黄土沟壑区湿软地基处理的主要处理技术要求和综合处理技术。通过分析黄土沟壑区高速公路湿软地基的工后常见病害以及产生原因，提出了防治措施。更多还原

【Abstract】 The soft ground in the loess ravine regions has special engineering properties which are different from the soft clay in littoral and the slumping loess. In the past, some researches were carried out to find out its characteristics based on the engineering practice in the Guanzhong alluvial plain. Its system info has not been built so far yet, the results were only located in idiographic project, which is hard to put them into generalization. In this paper, on the basis of plentiful productive practice in Huangling-Yan’an expressway, and the research results from Guanzhong alluvial plain regions as well as those from domestic and foreign, the treatment technology of soft ground in the loess ravine regions were analyzed and generalized.The physical and mechanical property of soft ground in the loess ravine regions has been analyzed deeply and systematically. On the basis of many aspects such as distributing, geological structure, cause of formation, grain size and its composition, the definition of the soft ground in the loess ravine regions was set up, its engineering property was described, and variety range of its familiar parameter was also presented. According to the statistical relationship between its familiar parameter and the admitted canying capacity, the empirical formula between the admitted carrying capacity of this kind of soil and liquidity index、the coefficient of compressibility, or and the modulus of compressibility were established.The common treatment methods to the soft ground in the loess ravine regions have been analyzed based on a great dead of in-situ soil test, settlement measurement and numerical simulation. The overall principle of soft ground in the loess ravine regions was also summarized. Because of the long and narrow terrain and the characteristic of highway engineering, the camion was used as counterforce device in load test. The compared analysis between it and other test data showed that this method is suit for the loess ravine regions. Its flaw presented in the test was analyzed and improved.The settlement of soft ground in loess ravine regions has many effect factors. So the method which based on case-based reasoning integrated with neural network was use to predict its settlement, which take the randomness and uncertainty of effective factors into account, as well as the successful experience in similar project. A new similarity calculation method was defined, through a new kind of utility function to let this method to show the distance and difference between the target case and the base case better. Finally with the simulation of neural network the prediction will approach the actual more. The calculation results showed the errors between the calculated and the measured was no more than±10%.After analyzing deeply the factors considered when select soft ground treatment scheme, some extension sets theory was introduced in the old AHP method, which make the judgment matrix fit the consistency condition automatically, so as to avoid a great deal of calculation work effectively. The extent AHP method take fuzziness of people’s judgment and engineering experience of more than one experts into account. The application in the Huangling-Yan’an expressway shows that this method is clear in conception and easy to put into practice.The basic principle of soft ground treatment in loess ravine regions was presented. The suitability of common treatment method of soft loess was generalized, as well as their requirement of quality control. At the same time the basic considered factors and the compositive treatment technology of this kind of soil were presented. The diseases after construction and their causes of this kind of soil were studied widely, their prevention measures were put forward.更多还原