基于现场试验的超长桩端阻力承载性状研究  

STUDY ON BEARING BEHAVIORS OF PILE TIP RESISTANCE OF SUPER-LENGTH PILES

作　　者：蒋建平[1] 章杨松[2] 高广运[3] 

机构地区：[1]上海海事大学海洋环境与工程学院,上海201306 [2]南京理工大学土木工程系,南京210094 [3]同济大学土木工程学院地下系,上海200092

出　　处：《工程力学》2010年第2期149-160,共12页Engineering Mechanics

基　　金：国家自然科学基金项目(50678128);上海市教委科研创新项目(09YZ250);上海海事大学科研基金项目(2009160);港口;海岸及近海工程校重点学科项目(2009445878)

摘　　要：为弄清大直径超长桩端阻力承载特性,基于15个场地中共32根桩的现场试验资料,采用作图法、归一化处理法、数学模型拟合法研究了大直径超长桩端阻力随桩端沉降的发挥性状。发现,桩端阻力随桩端沉降的变化主要有3种类型,即类型一(近似直线增加型)、类型二(转折点后增幅大为变缓的双折线增加型)、类型三(转折点后增幅几乎为0的双折线增加型),3种类型代表着大直径超长桩的破坏型式大致分为类型三代表的桩端刺入破坏和类型一、类型二代表的桩端整体剪切或局部剪切破坏;玻耳兹曼数学模型拟合桩端阻力-桩端沉降归一化曲线的效果好,相关系数R2达0.95以上;桩端阻力达到极限状态时的桩端沉降值至少在0.444d―123.433d之间,显示超长桩端阻力极限状态时的桩端沉降基本上无定值,但大部分在1.00mm―40.00mm之间;注浆后的端阻力为注浆前的2.5倍以上。结果表明,超长桩的端阻力不能被忽略,应加强研究,应充分利用它。In order to investigate the bearing behaviors of pile tip resistance, based on the field testing data of 32 piles in 15 sites, with illustration, unitary disposal method, mathematic model regression method, the mobilization behaviors of pile tip resistance with pile tip settlement for large diameter and super-length piles are studied. It is found that there exists 3 types for pile tip resistance versus pile tip settlement, that is type 1 （approximate linear increasing type）, type 2 （double linear increasing type）, type 3 （double linear increasing type that pile resistance having arrive at ultimate state）, that three kinds of type denote that there are two types for the failure of large diameter and super-length piles, the failure of penetrating into and the failure of shearing of pile tip. The regression effect of unitary curves of pile tip resistance versus pile tip settlement with Boltzmann mathematics model is good, and the correlativity coefficients R2 are more than 0.95; the pile tip settlement is from 0.444d to 123.433d, but is from 1.00mm-40.00mm mostly when the pile tip resistance arrives at ultimate state; the pile tip resistance after pile tip grouting is more 2.5 times than the pile tip resistance before pile tip grouting. The following conclusion can be drawn that pile tip resistance cannot be ignored, and it should be utilized.

关 键 词：桩端阻力 桩端沉降 现场试验 大直径超长桩 发挥性状 

分 类 号：TU473.1[建筑科学—结构工程] TU317.2[建筑科学—土工工程]