无黏性土中筒型基础静压下沉模型试验研究

发布时间：2019-03-11 09:57

【摘要】：筒型基础是海洋结构物特别是海上风力机的重要基础型式之一,其下沉阻力的研究是该种基础型式成功应用的关键。以往下沉阻力计算多以静力触探的锥尖阻力为基础,考虑渗流对土体有效应力的影响,通过试验确定筒侧壁与端部阻力系数得到最终的下沉阻力,但对于下沉过程中筒-土间的挤压特性及摩擦系数研究较少。本文开展了3种不同厚径比的筒型基础静压下沉模型试验,测量了下沉过程中筒内外侧壁及端部土压力与总的下沉阻力;基于孔穴扩张理论及土塞效应建立了筒内外土压力的计算方法;以地基承载力公式为基础推导了筒端土体阻力的计算方法。研究表明筒型基础下沉过程中筒土间摩擦系数约为0.4,DNV规范推荐的k_f=0.001~0.003仅适用于计算筒外壁摩阻力,实测的筒内壁摩阻力远大于计算值,端阻力系数k_p与土体的有效内摩擦角相关,k_p=1.8时计算值与实测值吻合较好。
[Abstract]:Cylindrical foundation is one of the most important foundation types for marine structures, especially for offshore wind turbines. The study of sinking resistance is the key to the successful application of this type of foundation. In the past, the calculation of settlement resistance was based on the cone-tip resistance of static penetration, considering the influence of seepage on the effective stress of soil, and the ultimate subsidence resistance was obtained by testing the drag coefficient of the side wall and end of the cylinder. However, there is little research on the extrusion characteristics and friction coefficient between the cylinder and soil in the process of sinking. In this paper, three kinds of static pressure subsidence model tests of tube foundation with different thickness-diameter ratio are carried out, and the soil pressure and total subsidence resistance of the inner and outer side walls and ends of the cylinder are measured during the sinking process. Based on the theory of hole expansion and soil plug effect, the calculation method of soil pressure inside and outside the cylinder is established, and the calculation method of soil resistance at the end of the tube is derived based on the formula of bearing capacity of foundation. The results show that the friction coefficient between the cylinder and soil is about 0.4 during the sinking process of the cylindrical foundation. The k_f=0.001~0.003 recommended by the DNV Code is only suitable for calculating the frictional resistance of the outer wall of the cylinder, and the friction resistance of the inner wall of the cylinder measured is much larger than the calculated value. The end resistance coefficient k _ p is correlated with the effective internal friction angle of the soil, and the calculated value is in good agreement with the measured value in k_p=1.8.
【作者单位】：天津大学水利工程仿真与安全国家重点试验室;天津市市政工程设计研究院;
【基金】：国家自然科学基金面上项目(51279127);国家自然科学基金优秀青年基金项目(51322904) 国家重点基础研究发展计划(2014CB046802) 天津市应用基础与科技前沿项目(13JCQNJC07800)
【分类号】：TU473.1

【相似文献】