英文篇名
INTEGRITY TESTING OF BORED PILES
作者
張清秀、王文禮、黃文
摘要
近年來由於國內經濟蓬勃之發展,大型土木建築工程如高層建築物、橋樑或其他荷重量大之結構物漸漸地增多;相對地為使這些荷重量甚大之各種建築物能座落於良好之承載層上,基樁遂大量地被採用;尤其是在地層軟弱之處,長大基樁之使用更是普遍。此外,由於環境保護意識之興起,為維護都市內原有生活品質不受到基樁施工時噪音與震動的干擾,鑽掘式基樁施工方法遂漸成為大眾所援受的基樁工法。
然而,鑽掘式基樁工程之成敗,受基樁施工的技術與品質影響甚大,不良的施工技術極易造成樁體本身之缺陷,此種缺陷可能為蜂窩、裂縫、縮頸、鋼筋保護層不足、混凝土包含雜質異物、混凝土水泥及細骨材流失等等,這些缺陷影響基樁之正常功能甚大。根據目前已發表的文獻記載,許多基樁工程常由於施工方法或地質條件等因素,導致基樁完整性不佳或承載力不足的現象,因而影響上部結構物之安全。Lambert(1973)在其調查中發現有危險而必須加以修補之基樁佔全部基樁數量的比例約為7%。Davis and Dunn(1974)發現有問題的基樁約佔總數的9%。Preiss and Caiserman(1975)發現有問題者約佔19%,其中需修補者約佔8%,另案發現有問題者約佔16%,其中需修補者約佔6%。Fleming(1985)發現有問題者約佔2%。根據上述文獻之記載,鑽掘式基樁發現問題的基樁比例不可謂少,對這些有問題的基樁事先若能加以檢驗出來,且加以修補,對整個基礎工程之安全將非常有助益。因此基樁完整性檢驗乃應運而生,對已完成之基樁直接進行樁體完整性檢驗,以提昇鑽掘式基樁施工之工程品質。
英文摘要
To assure the quality of bored cast-in-place piles, it is usual to carry out a limited number of pile loading tests. Those tests are, in general, very costly and time-consuming. More expedient and cheaper tests have been used for many years in Europe and America to verify the integrity of the bored pile as a structural unit.
In the Republic of China, the use of bored piles has steadily increased in the last decade due to the need of a foundation to carry heavier load from larger and taller buildings or upper-structures. To obtain good bored pile foundation and to avoid unnecessary delay and increase in cost, the application of the pile integrity tests during the construction becomes necessary and is proven worthwhile.
In this paper, the function and the importance of pile integrity testing are explained. Various integrity test methods, both direct and indirect, are described. The aim of this paper is to familarize the readers with those different test techniques, their advantages and disadvantages. And it is with the hope that the pile integrity testing will be accepted in our country as an effective means to improve the quality of the bored piles.