摘要
由于形状参数较一般土体差异较大,已有桩基工程中的传统经验难以适用于火山渣地层。为分析东非裂谷区火山渣地层内灌注桩桩侧摩阻,利用四根钻孔灌注桩的现场静载试验测试火山渣地层的桩侧摩阻值,并对火山渣级配、颗粒形状(棱角度和表面粗糙度)、抗剪强度等物理力学性质进行试验。通过与一般角砾土进行对比,分析二者在颗粒棱角度和表面粗糙度上的区别及其对内摩擦角和桩侧摩阻的影响。结果表明:颗粒形状影响颗粒的内摩擦角和桩侧摩阻;火山渣虽属于角砾范畴,但因其棱角度和表面粗糙度远大于一般角砾,导致该土体在稍密状态下,不仅内摩擦角(42°)与一般角砾土的中密程度上限值(36°～42°)相当,桩侧摩阻极限值(124 kPa)也不低于规范中中密角砾土(90～150 kPa)。研究成果可为火山渣地层桩基工程设计施工提供一定的参考依据。
Due to the larger difference of the shape parameter from the normal soil mass, the existing conventional pile foundation engineering experiences are difficult to be applied to volcanic scoria stratum. In order to analyze the lateral friction characteristics of cast-in-place pile in the scoria stratum within the region of East African Great Rift Valley, the lateral friction value of the pile in the scoria stratum is tested through the static load test made with four bored cast-in-place piles, while the physical and mechanical properties, i.e. scoria gradation, particle shape(angularity and surface roughness) and shear strength are tested as well. Through comparing with the general breccia soil, the difference between them in grain angularity and surface roughness as well as their influences on the internal friction angle and pile lateral friction are analyzed. The result shows that both the internal friction angle and the lateral friction resistance of pile are affected by the particle shape. Though volcanic scoria belongs to the category of breccia, its angularity and surface roughness are far greater than those of general breccia, which leads to that the internal friction angle(42°) of the scoria soil mass is not only equivalent to the upper limit of the mid-density of the general breccia soil(36~42°), but the ultimate value of pile lateral friction(124 kPa) is also not lower than that of the mid-density breccia soil(90~150 kPa) specified in the relevant specification. The study result can provide a certaon reference for both the design and construction of the project of pile foundation in volcanic scoria stratum.
作者
孙彬彬
张兵
刘顺凯
SUN Binbin;ZHANG Bing;LIU Shunkai(CCCC Second Harbour Engineering Company Ltd., Wuhan430000, Hubei, China;China Road and Bridge Corporation,Beijing100013, China;School of Civil Engineering, Central South University, Changsha410075, Hunan, China)
出处
《水利水电技术》
北大核心
2019年第4期1-6,共6页
Water Resources and Hydropower Engineering
基金
中国交建重大基础研究发展项目(2017-ZJKJ-08)
北京市科技计划(18110000398005)
国家自然科学基金项目(51478481
51809292)
关键词
东非裂谷
火山渣地层
角砾
桩侧摩阻
内摩擦角
棱角度
表面粗糙度
岩土力学
East African Great Rift Valley
volcanic scoria stratum
breccia
lateral friction of pile
internal friction angle
angularity
surface roughness
geotechnical mechanics
