摘要
对于下伏溶洞的基桩,工程中有时存在其嵌入溶洞顶板深度与顶板厚度之比(嵌岩比)较高的情况。为研究在高嵌岩比条件下溶洞顶板厚度对基桩竖向承载特性的影响,开展了嵌岩比为0.5时溶洞顶板厚度由1倍桩径逐步增加至5倍桩径情况下基桩模型载荷试验。基于试验结果提出了基桩极限承载力分析模型,根据极限平衡原理推导了基桩极限承载力计算公式。结果表明:(1)溶洞顶板破坏模式呈喇叭形冲切破坏,无量纲化后的破裂面拟合函数表达式能较合理地预测顶板破裂范围。(2)桩顶荷载–位移曲线呈陡变型,陡变点出现前荷载–位移关系呈近似线性特征。(3)随着顶板厚度逐步增加,基桩极限承载力逐渐呈非线性增大,桩端阻力承担上部荷载比例从35.4%增大至72.4%。(4)所提出的方法计算得到的基桩极限承载力与试验值的相对误差为−12.8%~12.1%,该计算方法具有较好的合理性。
For piles above underlying karst caves,the ratio of rock-socketed depth to cave roof thickness(rock-socketed ratio)can be high in certain projects.To study the influence of karst cave roof thickness on the vertical bearing characteristics of piles with high rock-socketed ratio,load tests were conducted on model piles with a rock-socketed ratio of 0.5,while the cave roof thickness was gradually increased from one to five times the pile diameter.Based on the test results,an analysis model for the ultimate bearing capacity of the pile was proposed,and a calculation formula was derived using the limit equilibrium principle.The results show that:(1)The failure mode of karst cave roof is trumpet-shaped punching failure,and the dimensionless fitting function for the fracture surface can reasonably predict the range of roof fracture.(2)The load-displacement curve at the pile top exhibits a steep change type,with an approximately linear relationship before the steep change point.(3)As the roof thickness increases,the ultimate bearing capacity of the pile increases nonlinearly,and the proportion of pile tip resistance supporting the upper load rises from 35.4%to 72.4%.(4)The relative error between the ultimate bearing capacity calculated by the proposed method and the test value ranges from−12.8%to 12.1%,indicating the method’s good rationality.
作者
杨柏
覃超
张银海
王威
肖世国
YANG Bai;QIN Chao;ZHANG Yin-hai;WANG Wei;XIAO Shi-guo(Faculty of Geosciences and Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China;School of Architecture and Transportation Engineering,Guilin University of Electronic Technology,Guilin,Guangxi 541004,China;School of Transportation Engineering,East China Jiaotong University,Nanchang,Jiangxi 330013,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu,Sichuan 610031,China)
出处
《岩土力学》
北大核心
2025年第6期1839-1850,共12页
Rock and Soil Mechanics
基金
广西自然科学基金(No.2024GXNSFBA010011)
广西高校中青年教师科研基础能力提升项目(No.2024KY0212)
国家自然科学基金(No.51578466)。
关键词
嵌岩桩
下伏溶洞
顶板厚度
竖向承载特性
模型试验
rock-socketed pile
underlying karst cave
cave roof thickness
vertical bearing characteristics
model test
