The Determination of Ground Properties by the Cone Penetration Test

Abstract

Determination of the physical, mechanical and hydraulic properties of soils is one of the most important tasks in geotechnical engineering. The conventional approach of drilling a borehole and attempting to procure undisturbed samples often present difficulties due to sample disturbance, in addition SPT procedures still have human and equipment based problems. So, some other alternative in-situ tests started to being widely used. The use of the cone penetration test for the determination of soil properties is a novel approach to soil investigation because of its speed and requiring minimum human intervention on the readouts. Today, the standard penetration test, a long time favourite is full of pitfalls in implementation and interpretation whereas the CPT with pore pressure measurements has been used increasingly in respect to improving technology to determine some other parameters (ie: chemical properties of water, electrical resistivity, pH, temperature) in addition to geotechnical properties of soils and detecting soil stratigraphy. This paper describes the advantages of the CPT through the results obtained in the city of and Adapazarı during the past fourteen years.

Keywords

• Soil investigation, cone penetration, disturbance, pore water pressure, shear wave velocity

Koni Penetrasyon Deneyi ile Zeminlerin Karakterizasyonu

Abstract

Zeminlerin fiziksel, mekanik ve hidrolik özelliklerinin belirlenmesi Geoteknik Mühendisliğinin en önemli konularının başında gelmektedir. Buna yönelik olarak uzun yıllardır sondajlı zemin incelemesinde sıkça uygulanan standart penetrasyon deneyinde (SPT); sonuçları etkileyen faktörlerin çokluğu, uygulama ve yorum yanlışlıkları, bunun yanında tüp içine alınan ve örselenmemiş tabir edilen numunelerin laboratuvar denemelerinde doğal durumundan büyük oranda farklı durumda olduğu gerçeği, diğer arazi deneylerinde gelişmelere neden oluşturur. Gelişen teknoloji sayesinde boşluk suyu basınçlarını da ölçebilen Arazi Koni Penetrasyon Deneyi (PCPT) ile zeminlerin çeşitli özelliklerini artık kesintisiz olarak belirlemek mümkün olmuştur. Koni penetrasyon deneyi, insan müdahalesi olmadan yapılan sürekli ölçüm sayesinde zemin profilinin ayrıntılı ve gerçeğe en yakın şekilde elde edilmesine olanak vermektedir. Deney; kısa zamanda istenilen sayıda tekrarlanabilmekte, zemin parametreleri numune alınmasına ve laboratuvar çalışmasına gerek duyulmadan elde edilebilmekte, ayrıca deneyin yapılmasının ve sonuçların yorumlanmasının diğer yöntemlere göre daha az zaman alması, işgücü ve maliyet açısından avantaj sağlamaktadır. Bu çalışmada deneyin özellikleri yanında Adapazarı zeminlerinde yapılan 350'nin üzerindeki boşluk suyu basıncı ölçümlü koni penetrasyon deneylerinden seçilmiş örnek ile uygulama ve değerlendirme aşamaları anlatılmaktadır.

Keywords

• Zemin incelemesi, koni penetrasyon, örselenme, boşluk suyu basıncı, kayma dalgası hızı

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