湿陷性黄土高填方地基处理技术及稳定性试验研究

发布时间：2018-07-03 01:20

本文选题：黄土高填方 + 地基处理　；参考：《西安建筑科技大学》2013年博士论文

【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。
[Abstract]:With the rapid development of the national economy and the comprehensive implementation of the strategy of developing the western region, the large-scale development trend of the collapsible loess mountain land becomes clear and obvious, and the collapsible loess high fill foundation formed by the filling compaction will emerge in large numbers. The deformation and stability of this kind of foundation have attracted much attention from academic circles and engineers. This paper systematically summarizes the research results of deformation and stability of collapsible loess high fill foundation at home and abroad, and revolves around the strengthening treatment of collapsible foundation, the compaction of loess, the deformation and strength characteristics of compacted loess. Based on the key problems such as the deformation mode and stability of high slope, the deformation law of deep cutting fill foundation and so on, the following research is carried out based on the Lv Liang Airport Test Section: (1) the model is made by using the undisturbed loess and the remolded loess. The large scale geotechnical centrifuge model test was carried out to analyze the stability, the leading factors of deformation, the quantity of deformation and the deformation rate of collapsible loess high slope and deep cut fill foundation under the condition of natural water content and saturation state, as well as the characteristics of post-construction deformation amount and deformation rate. On the basis of the relationship between post-construction settlement and deformation stabilization time, the mode of cracking and failure of the model when soil is saturated and its causes, etc., The numerical method is used to analyze the slope stability of high slope with reasonable slope and different moisture content. (2) through dynamic penetration test, Indoor geotechnical test and field load test of soil between piles were used to detect collapsible loess foundation in the test site treated by plain soil compaction pile and gravel pile. The porosity ratio, dry density, compression modulus of soil were analyzed before and after the test, and the soil void ratio, dry density and compression modulus were analyzed before and after the test. The variation law of physical and mechanical parameters, such as the number of dynamic penetration, the deformation modulus of the treated soil, the characteristic value of the bearing capacity of the foundation and the corresponding settlement are obtained. Thus, the effectiveness of the treatment of deep collapsible loess in the test site with compacted piles and gravel piles in plain soil is clarified. The reasonable construction parameters of collapsible loess foundation treated by plain soil pile and gravel pile in similar test site are given. (3) the parameters and effect of dynamic compaction for deep collapsible loess foundation under high fill in test site area are given. A series of experimental studies have been carried out, The variation rules of average tamping volume and main physical and mechanical indexes of soil in each test area before and after dynamic compaction are analyzed, and the main parameters such as the center distance of tamping point, the optimum hit number, the standard of stopping consolidation and the effective reinforcement depth are given under the energy levels of 2000kN mNM and 6000kNm. On the basis of this, the method of estimating the effective reinforcement depth of collapsible loess foundation in similar test ground is determined. (4) compaction test and a series of field tests are carried out on the compaction technology of Ma Lan loess in test site. The influence of water content on compaction effect and compaction efficiency of single process and new combined process are analyzed. The main physical and mechanical properties of compacted Ma Lan loess are given. The characteristic value of bearing capacity and the reference value of soil deformation modulus. (5) Compression and direct shear tests are carried out on the deformation and shear strength characteristics of compacted Ma Lan loess in the test site. The relationship between initial compaction degree, initial moisture content and shear strength index is analyzed, and the influence of initial compaction degree and initial moisture content on soil compression deformation is analyzed. Based on the Secant Modulus method, the deformation correction formula of compacted Ma Lan loess under the change of initial compaction degree and initial moisture content is presented. The formula can be used to analyze and calculate the deformation of compacted Ma Lan loess foundation in similar projects.
【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU444

【参考文献】