软土地层中阶梯型变截面桩变形特性与荷载传递机理研究

The step tapered pile is one of the structural types of pile foundation. It has been used in the engineering field. Through a large number of practices, this kind of pile is indicated to bear greater transverse internal forces as well as higher bearing capacity of in unit concrete vertically. Its development and application has great economic value and technical advantages. But the researches on the foundation deformation and bearing characteristics of this type of pile are still unsystematic and incomplete. The subject is established based on the model tests by the applicants previously.Two straight piles and two segmentally variable cross-section piles will be designed respectively. Field tests will be carried out in clay around Po-yang Lake regin. According to the indoor test results, the vertical load transfer mode, as well as the calculation method of bearing capacity of step tapered piles, is established. The pile deformation, calculation method of internal force and bearing capacity under horizontal load are also established. The pile-soil modulus ratio is brought in to make an in-depth study of the mechanical and economic applicability index of the step tapered piles. Numerical and theoretical analysis will be used to further explore the bearing and deformation characteristics of the step tapered piles under the action of vertical and horizontal static load. Several methods are synthesized to analyze the research results. The bearing characteristics, deformation characteristics and applicability of the step tapered piles piles around Po-yang Lake regin are analyzed deeply and systematically. Then, relevant program is developed. The conclusion of this study is expected to further improve the research achievement of deformation and bearing characteristics of step tapered piles,which will provide a theoretical basis and technical guidance for its broader application.

阶梯型变截面桩是基桩结构形式的一种，在工程领域得到了一定程度的应用，实践证明该类型桩横向受力更合理、竖向单位混凝土承载力更高，其发展应用具有良好的经济价值和技术优势，但对该类型桩基础的变形及承载特性的研究尚不系统、不完善。本项目拟设计阶梯型变截面桩和等直径桩各2根，选取环鄱阳湖地区典型的粘土地层开展现场试验研究，引入桩土模量比、桩形影响因子等参数，建立鄱阳湖地区粘土地层阶梯型变截面桩竖向荷载传递模式和承载力计算方法，横向静荷载作用下桩身变形、内力计算模式和承载力计算方法。借用数值和理论分析，探讨多阶阶梯型变截面桩竖向和横向静载荷作用下承载和变形特性。通过对比研究，系统分析阶梯型变截面桩承载特性、变形特性及桩土相互作用。预计研究成果将进一步完善阶梯型变截面桩变形及承载特性理论，为其更广阔的应用提供理论基础和技术支持。

阶梯型变截面桩是基桩结构形式的一种，在工程领域得到了一定程度的应用，实践证明该类型桩横向受力更合理、竖向单位混凝土承载力更高，其发展应用具有良好的经济价值和技术优势，但对该类型桩基础的变形及承载特性的研究尚不系统、不完善。本项目设计阶梯型变截面桩和等直径桩各2根，选取了环鄱阳湖地区典型的粘土地层开展现场试验研究，引入桩土模量比、桩形影响因子等参数，建立了阶梯型变截面桩竖向荷载传递模式和承载力计算方法，横向静荷载作用下桩身变形、内力计算模式和承载力计算方法。借用数值和理论分析，探讨了多阶阶梯型变截面桩竖向和横向静载荷作用下承载和变形特性。通过对比研究，系统分析了阶梯型变截面桩承载特性、变形特性及桩土相互作用。揭示了阶梯型变截面桩竖向承载情况下存在最优变截面比，推荐值为0.8，横向承载情况下弹性桩存在最优变截面位置，推荐值为0.48；基于弹性桩基本理论构建了单桩、群桩竖向及横向荷载作用下，内力及变形求解方法，并研发了相关计算程序，研究成果将进一步完善阶梯型变截面桩变形及承载特性理论，为其更广阔的应用提供理论基础和技术支持。