基于标贯击数估计海上钢圆筒最大可沉入直径  

Estimating the maximum installable diameter of offshore cylindrical caisson foundations using standard penetration test blow counts

作　　者：张晖 沈晓鹏 申辰 莫伟彬 呼延彬 王睿[2] ZHANG Hui;SHEN Xiaopeng;SHEN Chen;MO Weibin;HUYAN Bin;WANG Rui(CNOOC Research Institute,Ltd.,Beijing 100028,China;State Key Laboratory of Hydroscience and Engineering,Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China)

机构地区：[1]中海油研究总院有限责任公司,北京100028 [2]清华大学水利水电工程系,水沙科学与水利水电工程国家重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2024年第12期2144-2154,共11页Journal of Tsinghua University(Science and Technology)

基　　金：国家重点研发计划(2022YFC3102303)。

摘　　要：插入式钢圆筒通常采用振动式沉桩方法安装,安装前需对钢圆筒振沉能力进行评估,现有的评估方法需要开展大量土工试验以确定土层的强度参数,经济成本和时间成本较高。该文提出了一种基于场地标贯击数快速评估钢圆筒振沉能力的方法,通过经验公式将土层的标贯击数和强度参数关联,计算不同直径钢圆筒振入过程中的阻力。经检验,该方法计算得到的阻力与规范方法的结果基本一致,与现场施工记录到的最大激振力相符。该文分析了土层性质及土层的分层情况对振沉能力的影响,当标贯击数较小时,相同标贯击数的黏土比砂土对钢圆筒振入的阻碍作用更大,标贯击数较大时则反之;当土层含有夹层时,存在一个临界标贯击数,当夹层土的标贯击数大于该临界值时,振沉能力随夹层土标贯击数的增大迅速减小。该文提出的方法与分析得到的结论可为插入式钢圆筒快速、合理地设计和施工提供参考。[Objective] Vibration-sinking caissons are increasingly popular in coastal engineering because of their low cost,ease of installation,and high stability.However,verifying excitation force and vibration amplitude before installation is essential.Current specifications require extensive geological surveys and geotechnical tests,which are costly and time-consuming.A rapid and reliable assessment of vibration-sinking feasibility with simple on-site tests is essential,especially for large-diameter caissons.[Methods] This study proposes a method for quickly evaluating the vibration-sinking feasibility of steel cylindrical caissons based on standard penetration test(SPT) blow counts.The proposed method correlates soil shear strength with SPT blow counts through empirical relationships to calculate installation resistance during the vibrating penetration process of steel cylindrical caissons.The accuracy of the method is verified by comparing results with current specifications and on-site records.In addition,a quantitative analysis assesses the influence of soil properties and interlayers,represented by SPT blow counts,on the maximum installable diameter of the caisson.[Results] The calculated installation resistance at different depths using the proposed method generally aligns with current specifications.For a steel caisson with a 24-m diameter,the maximum installation resistance calculated during the vibration sinking matches the maximum vibratory force recorded on-site with an 8% error,demonstrating the reliability of the method.When the SPT blow counts are small,installation resistance in clay is greater than that in sand for the same SPT blow counts,whereas higher blow counts yield greater resistance in sand than in clay.For shallow installation depths,vibration amplitude requirements dominate the feasibility analysis,whereas excitation force requirements become primary for deeper sinking depths.The consideration of interlayers is important for feasibility analysis,with a critical number of SPT blow counts identif

关 键 词：钢圆筒 振沉施工 土层条件 标贯试验 最大直径 

分 类 号：TU473.1[建筑科学—结构工程]