模型基樁負摩擦力試驗之設計

A Model Test Designed for Measuring Negative Friction Response of an End Bearing Pile

黃俊鴻(Jin-Hung Hwang) ； 謝依航(Yi-Hang Sie) ； 葉品毅(Pin-Yi Yeh)

《中國土木水利工程學刊》 22卷1期 (2010/03) Pp. 1-10

https://doi.org/10.6652/JoCICHE.201003_22(1).0001

摘要

本文設計一套模型點承基樁負摩擦力試驗之量測系統與試驗方法，發展一套1/2電橋連接虛擬基樁模型之設計，以消除長期溫度變化對試驗量測結果的影響，可成功量測基樁負摩擦力長期試驗之各項反應。試驗結果顯示基樁負摩擦力之發展與樁─土相對位移的發展一致，絕大部分負摩擦力發生在壓縮層主要壓密階段，隨著二次壓縮沈陷的發生，負摩擦力亦隨之緩慢增加；中立點位置隨著壓密沈陷的發展，往壓縮層底部移動，接近0.9倍壓縮層厚度之深度；壓縮層產生之負摩擦力由承載砂層樁段之正摩擦力與樁底承載力共同承載。

關鍵字

模型基樁 ； 負摩擦力 ； 中立點 ； 溫度效應 ； 主要壓密

並列摘要

This paper presents a design of model test for measuring the negative friction response of an end bearing pile. A half bridge connection of strain gauges is proposed to eliminate the influence of temperature fluctuation during the long term test. A dummy model pile embedded in the same environment as the test pile is used. Test results show that the negative friction response is closely related to the relative displacement on the pile-soil interface. Most of negative friction occurs during primary consolidation stage. The negative friction increases slowly with the secondary compression of soil. As the primary consolidation proceeds, neutral point gradually moves to the bottom of the compressible layer. The final position of neutral point is close to a depth of 0.9 times the thickness of compressible layer. The downdrag force caused by the compressible layer is fully balanced by the increased positive friction on the pile segment between neutral point and pile bottom as well as the end bearing capacity of the pile.

並列關鍵字

model pile ； negative friction ； neutral point ； temperature effect ； primary consolidation