英文篇名
INTRODUCTION TO THE APPLICATION AND DEVELOPMENT OF PENETRATION TESTS
作者
李延恭
摘要
根據歐美地區之工程經驗,一般建築之所以超出預算約有80%是由於基礎施工遇到與原先預估不同之土層情況,其他15%是由於施工規劃之變更,5%則由於施工之錯誤。由此可見良好的地質調查之重要性。
地質調查目的在瞭解地面下之土壤及岩石各種不同層次之分佈、深度、與性能,其所得資料可提供土木結構基礎設計之依據,一般土木結構基礎土壤之調查方法大致有下列三種即:
(1)現地足尺(Full Scale)模型載重試驗
(2)不擾動土樣試驗室試驗
(3)現地土壤測探
上述第一種方法如樁載重試驗、平鈑載重試驗等工期較長,費用又高不適合一般之工程調查。第二種方法係於土壤鑽探之同時取得不擾動土樣進行各種試驗,以求取土壤之工程特性,應用此法取樣時須極其小心,以避免使樣品擾動失去代表性。此法雖廣為國內採用惟仍有其缺點,例如對不均勻土層不易研判及分析,人為因素影響大,砂質土壤不易取樣研制,即使取樣亦受極大的擾動等。
第三種方法現地土壤測探(Sounding)是直接而有效的地質調查法之一種,其原理非常簡單是將一根鐵桿用靜壓力或動壓力打入地層中而記錄其貫入阻力,由貫入阻力之記錄可以判斷地層各層次的變化。如果貫入阻力與土壤性能有足夠相關資料的話,常可從貫入阻力之記錄用半經驗方式來估算土壤強度或壓密度。
各國由於其地理環境之差異而發展出各種不同的貫入設備及試驗方法。本文乃就目前較廣為世界各國採用之幾種貫入試驗加以研討!
英文摘要
Among the all different types of penetration, the Standard Penetration Test(SPT)is by far the most popular one used in the soil investigation in Taiwan.
Owing to the simplicity of testing procedures and the extensive applications, it is very likely to be misconceived by some engineers that SPT can be applied to any kinds of soil investigation. As a matter of fact, the SPT has its advantages, however, there are lots of disadvantages as well. Many efforts have been made by engineers to try the alternative kind of penetration test instead of SPT for the site investigation in foreign country.
This paper provides a brief introduction on the types and characteristics of penetration tests which arerecently used popularly in the world. This information can be adopted as reference for the engineers who intend to conduct site investigation by means of any other types of penetration test besides SPT.