﻿ 由沉降控制荷载的超长单桩设计理论推导 Theoretical Deduction of the Design Load Controlled by Deposition for the Super-Long Single Pile

Hans Journal of Civil Engineering
Vol.04 No.04(2015), Article ID:15741,6 pages
10.12677/HJCE.2015.44022

Theoretical Deduction of the Design Load Controlled by Deposition for the Super-Long Single Pile

Yanfen Wang, Yuangang Ma, Yanfeng Liu

Bridge Science Research Institute Ltd., China Railway Major Bridge Engineering Group, Wuhan Hubei

Email: yinying20015@163.com

Received: Jun. 29th, 2015; accepted: Jul. 17th, 2015; published: Jul. 24th, 2015

ABSTRACT

There are differences for mechanisms of bearing forces and distortions between super long piles and common short piles. Practical engineering needs to control loads by deposition, which results in its design in the contradiction theory with practice. By the experience of practical engineering, this paper sums up the load transfer formula of the super-long single pile. Then considering the soil influence factors and combining with the existing load transfer formula of pile end, the load theoretical formula of pile head controlled by deposition of pile head is educed. Subsequently the computing procedures are compiled. The instance result answers to the actual. The results of the paper have reference value for the design and further study of super-long single pile.

Keywords:Super-Long Single Pile, Deposition, Load Transfer Mechanism of Pile Side, Load Transfer Mechanism of Pile End

Email: yinying20015@163.com

1. 引言

2. 大直径超长基桩荷载传递机理

2.1. 大直径超长基桩桩侧阻力传递机理

(1)

(2)

(3)

(4)

(5)

(6)

(7)

2.2. 实例

3. 由桩顶沉降控制超长单桩竖向承载力

(8)

Table 1. C value scope

Table 2. K value scope

(a) (b) (c),(d)

Figure 1. The relationship contrast figure of pile side friction and the relative displacement between of piles and soil by test and calculation; (a) pile 1; (b) pile 2; (c) pile 3; (d) pile 4

(1) 按不同土层划分桩身单元，共n层，计n + 1个截面；

(2) 当桩身处于承载极限状态时，各土层侧阻及端阻均得到充分发挥，侧阻实际变形均应不小于变形临界值，桩端土的变形应不小于。桩身各截面的轴力和变形计算如式(8)。根据Bowles [4] 的研究，发挥最大侧阻所需土层滑动量的数量级大约为5~10 mm，计算时根据岩土的实际情况取值；

(3) 式(8)还可用于计算当桩身处于非极限状态时桩身的荷载分布和沉降。此时，各土层侧阻及端阻尚未充分发挥，侧阻实际变形及桩端土的变形可取较小值0~5 mm。

，取较大值；

，取较大值。

4. 计算实例

Figure 2. Program calculation diagram

Table 3. The measured soil data

Figure 3. The axial force distribution along the pile shaft when the pile load is 10,000 kN

Figure 4. The load-displacement (Q-S) curve

5. 小结

Theoretical Deduction of the Design Load Controlled by Deposition for the Super-Long Single Pile. 土木工程,04,173-179. doi: 10.12677/HJCE.2015.44022

1. 1. 阳吉宝 (1996) 确定超长桩有效长度方法. 建筑科学, 1, 37-38.

2. 2. 南京水里科学研究院 (2004) 苏通长江公路大桥主桥索塔群桩基础与土体共同作用离心模型试验研究报告. 2004, 4.

3. 3. 阳吉宝 (1998) 超长桩的荷载传递机理. 岩土工程学报, 20, 108-112.

4. 4. Bowles, J.E. (1987) 基础工程分析与设计. 唐念慈译, 中国建筑工业出版社, 北京.