水泥胶结钙质砂地层中单桩竖向承载特性试验研究  

Experimental study on vertical bearing characteristics of a single pile in cemented calcareous sand layers

作　　者：柴源 牛勇 吕海波 CHAI Yuan;NIU Yong;LÜHai-bo(College of Civil Engineering and Architecture,Guangxi University,Nanning,Guangxi 530000,China;Key Laboratory of Karst Ecosystem and Treatment of Rocky Desertification,Institute of Karst Geology,Chinese Academy of Geological Sciences,Guilin,Guangxi 541000,China;College of Architecture and Electrical Engineering,Hezhou University,Hezhou,Guangxi 542800,China)

机构地区：[1]广西大学土木建筑工程学院,广西南宁530000 [2]中国地质科学院岩溶地质研究所岩溶生态系统与石漠化治理重点实验室,广西桂林541000 [3]贺州学院建筑与电气工程学院,广西贺州542800

出　　处：《岩土力学》2022年第8期2203-2212,共10页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.51169005);广西自然科学基金重点项目(No.2018GXNSFDA281038)。

摘　　要：钙质砂属于岩土工程中一种特殊的岩土材料,除具有颗粒形状不规则、易破碎等特征,还具有胶结性。针对钙质砂具有胶结性的地质现状,通过室内模型试验研究了胶结钙质砂地层中钢管桩的承载能力、沉降情况及其影响因素,同时与未胶结钙质砂中的桩基承载特性进行了对比。研究结果表明:与未胶结钙质砂中的钢管桩相比,胶结钙质砂的相对密实度对桩基承载力影响程度明显减弱,桩的承载形式依然表现为端承桩,随着钙质砂胶结程度的提升,桩端阻力承载占比越来越高;胶结程度较高的钙质砂地层中桩身侧摩阻力发挥存在异步过程,这是因为桩基沉降时桩身下部破坏砂层形成了更为紧密的新接触面,该接触面对桩身的径向膨胀更为敏感;胶结钙质砂中桩基q_(s)-S_(u)曲线没有出现明显的硬化阶段,与未胶结钙质砂地层中桩基的q_(s)-S_(u)多段折线变化规律不同,胶结钙质砂地层中桩基的q_(s)-S_(u)曲线更为接近双曲线线型。According to the cemented geological status of calcareous sand layers,a series of indoor model tests was performed to study the behaviors of the steel pipe pile in the cemented calcareous sand layers such as bearing capacity,the settlement,and compared with uncemented calcareous sand.The results show that the influence of relative density on bearing capacity of the pipe pile in cemented calcareous sand layers is obviously weakened compared with that in the uncemented layers.The bearing form of the pile still presents as an end-bearing pile,and the bearing ratio of pile tip resistance becomes higher and higher with the increase of cementation degree of calcareous sand.In highly cemented calcareous sand layers,there is an asynchronous process in the development of side friction of the pile.This is because when the pile foundation settles,the lower part of the pile shaft destroys the sand layer to form a tighter new contact surface,which is more sensitive to the radial expansion of the pile body.The side friction of the pile in cemented calcareous sand layers has no obvious hardening stage in the q_(s)-S_(u) curve of pile in cemented calcareous sand,and different from the multi-segment broken line of the q_(s)-S_(u) curve of the pile in uncemented calcareous sand,the q_(s)-S_(u) curve of the pile in cemented calcareous sand is closer to a hyperbolic curve.

关 键 词：胶结钙质砂 模型试验 侧摩阻力 荷载-沉降关系 桩基础 

分 类 号：TU473[建筑科学—结构工程]