随着自重湿陷性黄土场地中建设项目的增多，伴随出现的桩基负摩阻力问题日益复杂，桩基负摩阻力在不同工况及土层条件下差异很大。为深入研究桩土相互作用，分析区域性自重湿陷性黄土中桩基负摩阻力的特性，避免直接应用相关技术规范造成的偏差，结合荷载传递法与试验研究法，对自重湿陷性黄土中桩基负摩阻力的相关问题进行研究，主要结论如下： （1）参考大量资料，结合室内试验，研究西安某区域自重湿陷性黄土变形特性及影响因素，确定各因素影响权重，选取天然含水量、天然孔隙比、塑性指数建立该区域黄土自重湿陷系数的预测模型。 （2）应用模糊数学法评价该区域黄土的湿陷性，建立天然含水量及天然孔隙比与黄土自重湿陷系数间模糊关系矩阵，利用模糊近似推论，通过信息集中，进行误差分析，验证模型的可靠性，评价研究区域黄土的湿陷性。确定其湿陷类型为自重湿陷性，湿陷等级为Ⅱ级，为类似工程提供参考。 （3）基于荷载传递法，选取双折线传递函数，建立了考虑自重湿陷性黄土浸水引起负摩阻力效应的单桩受力模型，假设土层浸水沉降曲线符合直线或指数分布，推导出在荷载、浸水、荷载及浸水共同作用三种条件下摩擦型单桩的负摩阻力、中性点位置以及桩身轴力的解析表达式。结合实例，分析土层性质及桩身参数对桩身受力的影响。 （4）选择西安某区域进行了试坑及桩基浸水试验，得出该地区地表累计沉降曲线随土层深度变化呈指数分布。试坑各截面均呈高斯分布，试坑地表沉降量从试坑中心向试坑外方向逐渐减小，据此可确定试坑浸水影响范围；对比天然状态及浸水条件下桩身轴力及桩侧阻力的试验与理论计算结果，分析浸水对自重湿陷性黄土中单桩受力影响。

The project in collapsible loess field is more and more, accompanied by the NSF problem is complex, pile negative resistance varies greatly in different conditions and soil conditions. In order to study the interaction of soil-pile, analysis of regional collapsible loess NSF’s feature, to avoid wasting by direct application of the relevant technical specifications caused, Based on this, studied the related issues of pile’s negative friction in collapsible loess by theoretical analysis and experimental method, the main conclusions as follows: (1) Reference large amounts of data, combined with laboratory test, Xi’an area’s collapsible loess characteristics were studied, analyzed the factors of affecting the region collapsible coefficient, established the regression model by the natural water content, void ratio, plasticity index, analysis the influence of heavy weight of each factor, determined the coefficient prediction model collapsible. (2) Application of Fuzzy Mathematics Assessment in the region of loess collapsibility, establishing the fuzzy relationship matrix approximation of natural moisture and natural void ratio between the weight loess collapsibility coefficient, using fuzzy inference, by centralizing information, using the error analysis to verify the reliability of the model, evaluated the collapsible areas. Determining the area of collapsible type is self-weight collapsible loess, collapsible classification is grade Ⅱ, so providing a reference for similar projects. (3) Based on load transfer method, using bilinear hardening transfer function model to establish a mechanical model of single pile, considering the effect of negative skin friction caused by collapsible loess flooding. Supposed soil subsidence flooding curve in line with a straight line or an exponential distribution, derived the pile of negative friction resistance, neutral point and analytical expression of axial force in load, water, load and water three cases. With examples to analyze the effect of soil properties and pile on the pile parameters of sustained force. (4) The pit and pile foundation water immersion were test in region of Xi’an area, got the surface settlement curve, the test area’s curve of deep settlement is with soil depth exponentially distributed, each cross-section showed a Gaussian distribution, the settlement of field test pit table is amount from the test center to test pit outward direction gradually decreases, and the amount of soil collapsible amount related to flooding, according to this can determine the scope of the test pit flooding; compared the experimental and theoretical natural state of flooding conditions axial force and pile side resistance calculations, analysis of pile foundation for collapsible loess soaking influence.