【作者】 梅源；

【导师】 刘增荣； 胡长明；

【作者基本信息】 西安建筑科技大学 ， 岩土工程， 2013， 博士

【摘要】 随着国民经济的迅速发展和西部大开发战略的全面实施，湿陷性黄土山区土地的大规模开发趋势得以清晰凸现，通过填方压实而形成的湿陷性黄土高填方地基将大量涌现。此类地基的变形及稳定性问题备受学术界及工程技术人员的关注。本文通过系统总结国内外关于湿陷性黄土高填方地基变形及稳定性的研究成果，围绕湿陷性地基的加固处理、黄土压实、压实黄土的变形及强度特性、高贴坡变形模式及稳定性、深堑填方地基变形规律等关键问题，依托吕梁机场试验段工程开展了以下内容的研究：（1）采用原状黄土与重塑黄土联合制作模型，开展大型土工离心模型试验，分析了湿陷性黄土高贴坡及深堑填方地基在天然含水量及饱和状态下的稳定性、变形的主导因素、工后变形量及变形速率的特征、工后沉降与变形稳定时间的关系、土体饱和时模型开裂破坏的模式及其原因等问题，在此基础上，采用数值方法分析了高贴坡合理的坡度及不同含水率状态下边坡的稳定性。（2）通过动力触探试验、桩间土室内土工试验及现场载荷试验对采用素土挤密桩和碎石桩处理后的试验场区湿陷性黄土地基进行检测，分析试验前后土体孔隙比、干密度、压缩模量、动力触探击数等物理力学参数的变化规律，得到处理后的土体变形模量、地基承载力特征值及其对应沉降量。从而明确了素土挤密桩和碎石桩处理试验场区深厚湿陷性黄土的效能，并给出了采用素土桩和碎石桩处理类似试验场区湿陷性黄土地基的合理施工参数。（3）针对试验场区高填方下深厚湿陷性黄土地基强夯加固参数及效果开展了系列试验研究，分析了强夯前后各试验区平均夯沉量和土体主要物理力学指标的变化规律，并给出2000kN·m、3000kN·m及6000kN·m能级条件下强夯加固的夯点中心距、最佳击数、停夯标准及有效加固深度等主要参数，在此基础上确定了类似试验场区湿陷性黄土地基强夯有效加固深度的估算方法。（4）针对试验场区马兰黄土的压实工艺开展了击实试验及系列现场试验研究，分析了含水量对压实效果的影响和单项工艺及新型组合工艺的压实工效，给出了压实马兰黄土主要物理力学性质、填筑地基承载力特征值及土体变形模量的参考值。（5）针对试验场区压实马兰黄土的变形及抗剪强度特性开展了压缩及直剪试验研究，分析了初始压实度及初始含水量与抗剪强度指标之间的关系及其对土体压缩变形的影响，并基于割线模量法提出了压实马兰黄土在初始压实度及初始含水量变化时的变形修正公式。该公式可以用于类似工程压实马兰黄土填筑地基变形分析与计算。更多还原

【Abstract】 With the full implementation of the western development strategy and the rapiddevelopment of the national economy，large scale development of the collapsibleloess mountain area is inexorable， and large numbers of collapsible loess highembankment formed by fill compaction will also appear. The deformation and stabilityproblems of such foundation receive an extensive concern from the engineeringtechnicians and the academia. On the basis of the related research achievements at homeand abroad, this paper mainly researches problems of reinforcement treatment ofcollapsible loess foundation, compaction of loess, deformation and strength property ofcompacted loess, deformation modes and stability of high sticking slope, anddeformation law of deep cutting fill foundation. Relying on the Lvliang airport testsection, the following research works are carried out.(1)Large scale geotechnical centrifuge model tests are carried out on models madeby intact loess and remolded loess. Under the condition of natural water content,problems about the collapsed loess high slope and deep-graben embankment, includingthe stability, the dominant factor of deformation, the post-construction settlement, thecharacteristics of deformation rate, the relation between post construction settlementand deformation stability time, and the failure modes of models and the reasons whensoil is saturated, are studied. On this basis, the reasonable gradient and the stabilityunder different moisture contents are analyzed by numerical methods.(2)With the use of dynamic sounding tests, loess collapsibility tests and fieldloading tests, this paper analyzes the change rule of physical and dynamical parametersof test area, including void ratio, dry density, modulus of compressibility and dynamicpenetration number, and then obtains deformation modulus of treated soil, characteristic number of ground bearing capacity and its corresponding settlement for the similarengineering.(3) A series of tests are conducted to study the dynamic compaction parameters andtheir effects on the deep collapsible loess foundation under super high fill in test area.Analyses are made on the average settlement of each test area before and after dynamiccompaction and on the regularity of the main physical and mechanical indexes of soil.The main parameters under the different energy levels of2000kN.m,3000kN.m or6000kN.m are gained, such as the centre distance of dynamic compaction points, thebest impact number, the standard of cutting out, and the effective reinforcement depth.Hence, the empirical formula of the effective reinforcement depth of dynamiccompaction is determined for the similar engineering.(4) Proctor compaction tests and a series of field tests are carried out to study thecompaction characteristics of Ma-lan loess in test area. The compaction effect of thesingle and the new combination technology is analyzed along with the influence ofwater content on it. The reference indexes of main physical and mechanical propertiesof compact Ma-Lan loess are gained. Meantime, this paper also gives out the referencevalue of ground bearing capacity feature value and elasticity modulus.(5) In order to study the deformation and the shearing strength characteristics ofcompacted Ma-lan loess in test area, compression tests and direct shear tests areconducted. Analyses are made on the relationship between the initial compaction degreeas well as the initial water content and the shear strength indexes, and also on theireffects on the compressive deformation of soil. By employing the secant modulusmethod, the modified formula of deformation is established when the initial compactiondegree and water content of compacted Ma-lan loess change. The modified formula ofdeformation can be used to analyze and calculate the deformation of foundation filledby compacted Malan loess.更多还原