Model Tests Study of Bearing Mechanism of Rock-Socketed DX Pile
摘要
新型DX嵌岩桩通过在强风化岩层设置承力盘、将桩端置于中风化岩表层
充分挖掘了强风化岩层的端承潜力
桩端阻力亦能较早发挥。与直孔嵌岩桩相比
具有高承载力低沉降、造价节约、工期缩短等优势
在广东、广西等地得到广泛应用
经济效益显著。然而现场静载试验难以达到其承载极限
目前对于DX嵌岩桩承载机理认识尚未充分。为研究极限荷载下DX嵌岩桩承载特性
依托于防城港钢铁原料厂项目
通过3组18根桩的DX嵌岩桩与直孔嵌岩桩模型试验
对其荷载传递特性及承载机理进行了研究。结果表明:①DX嵌岩桩Q—s曲线呈缓变型;②同等条件下
DX嵌岩桩极限承载力较直孔嵌岩桩提高118%~131%;当直孔桩嵌岩深度增加时
DX嵌岩桩承载力仍较其提高56%~64%;③单个承力盘在加载初期承担桩顶荷载百分比达30%~33%
同时桩端承担荷载百分比达14%~16%;随荷载增加
承力盘底部岩体发生局部破坏
盘阻力增长速率逐渐减小
端阻力则加速增长;极限荷载下
盘阻力占总承载力百分比下降至20%~22%
端阻力占总承载力百分比增长至36%~38%
与现场试验结果较为一致。
Abstract
The new type of rock-socketed DX pile is formed by setting bearing plates in the highly weathered rock stratum and resting the pile tip on the surface of moderately weathered rock stratum
which fully mobilizes the bearing capacity of highly weathered stratum and the tip resistance is mobilized at the early stage. It has advantages of high bearing capacity
small displacement
cost-saving and short contract period compared with the conventional rock-socketed straight pile
and become widely used in foundation engineering in Guangdong and Guangxi due to the economic benefits. However
field static load tests were difficult to reach the limitation of rock-socketed DX piles
and the exploration to the bearing mechanism was inadequate. Based on the stock yard of steel project in Fangchenggang
model tests of three groups of eighteen piles were conducted in order to investigate the load transfer behavior and bearing mechanism. The results showed that :(1) The Q s curves of rock-socketed DX pile presented a gradual failure process.(2) The bearing capacity of rock-socketed DX pile was 118%—130% higher than the rock-socketed straight pile under the same condition
when socket depth of straight pile increased
the bearing capacity of DX pile was still 56%—64% more than the straight pile.(3)The load sharing ratios of the single bearing plate and pile tip reached 30%—33% and 14% —16 % of the applied load separately
and the value changed when regional failure occurred in the rock mass beneath the bearing plate. The load sharing ratio of the bearing plate decreased to20 %—22 % of the applied load while the loading sharing ratio of pile tip increased to 36 %—38 %of the applied load
which were in accordance with the filed static load tests.