摘要
岩溶区钻孔灌注桩工程一般需先对溶洞进行填充处理,采用流态土填充溶洞后会形成桩-流态土这种新的接触关系,对于竖向受荷桩而言,掌握桩-流态土界面的剪切特性至关重要。首先通过大型直剪试验研究了流态土与混凝土的界面剪切特性,然后通过室内桩基模型试验研究了不同填充范围流态土中的桩基竖向承载特性,对比分析了桩侧摩阻力的差异,确定了满足桩侧摩阻力发挥的最小流态土填充范围,并分析了流态土强度对流态土-混凝土界面抗剪强度和桩侧摩阻力的影响。结果表明:流态土-混凝土界面的剪应力-位移曲线存在峰值,剪切过程中界面发生脆性破坏。流态土强度越高,流态土-混凝土界面抗剪强度越大,抗剪强度完全发挥所需的剪切位移越小;界面抗剪强度与法向应力之间符合摩尔-库仑强度准则。当流态土填充范围为5倍桩径时,桩侧摩阻力即可充分发挥,且流态土强度越高,桩侧摩阻力越大。零法向应力条件下直剪试验测得的界面抗剪强度值能够较准确地反映流态土中最大桩侧摩阻力的大小。
The drilling and construction of cast-in-place piles in karst areas generally requires filling the karst cave first.The utilization of fluidized soil to fill these caves establishes a novel material contact relationship between the pile and the surrounding soil.For vertically loaded cast-in-place piles,it is crucial to understand the shear characteristics of the pile-soil interface.To this end,the interfacial shear characteristics of fluidized soil and concrete were studied by large-scale direct shear test firstly,and then the vertical bearing characteristics of pile foundation in fluidized soil with different filling ranges were studied by indoor pile foundation model tests,the difference of pile side friction resistance was compared and analyzed,the minimum fluidized soil filling range to meet the pile side friction resistance was determined,and the influence of fluidized soil strength on the shear strength of fluidized soil-concrete interface and pile side friction resistance was analyzed.The results indicate the shear stress-displacement curves of the fluidized soil-concrete interface exhibit a distinct peak,followed by brittle failure during shearing.The shear strength of this interface increases with the strength of the fluidized soil,and the shear displacement required for the shear strength to be fully exerted is smaller.The relationship between the interfacial shear strength and normal stress adheres to the Mohr-Coulomb strength law.When the filling range of fluidized soil extends to five times the pile diameter,the pile skin friction reaches its full potential.Moreover,the higher the strength of the fluidized soil,the greater the pile skin friction becomes.The interfacial shear strength value obtained from direct shear tests conducted under zero normal stress conditions accurately reflects the maximum pile skin friction achievable in fluidized soil.
作者
黎冰
郑克西
张睿达
龚维明
陆成克
李海山
莫芸非
LI Bing;ZHENG Ke-xi;ZHANG Rui-da;GONG Wei-ming;LU Cheng-ke;LI Hai-shan;MO Yun-fei(School of Civil Engineering,Southeast University,Nanjing 210096,Jiangsu,China;Guangxi New Development Transportation Group Co.,Ltd.,Nanning 530029,Guangxi,China;Guangxi Communications Design Group Co.,Ltd.,Nanning 530029,Guangxi,China)
出处
《中国公路学报》
北大核心
2026年第2期41-49,共9页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51578145)
广西重点研发项目(2021AB22140)。
关键词
路基工程
剪切特性
试验研究
钻孔灌注桩
流态土
岩溶
侧摩阻力
subgrade engineering
shear characteristic
experimental research
cast-in-place pile
fluidized soil
karst cave
skin friction
