Osman SİVRİKAYA, Ergün TOĞROL

İnce daneli zeminlerde SPT sonuçlarının düzeltilmesi üzerine bir çalışma

Standart Penetrasyon Deneyi (SPT) zemin incelemelerinde en sık kullanılan ve en eski arazi deneylerinden biridir. Son yıllarda düzeltilmiş SPT-N değeri ile çeşitli zemin özellikleri arasındaki ilişkiler bir çok araştırmacı tarafından incelenmiştir. Bu bağlamda, arazide ölçülen değerler üzerinde yapılan düzeltmeler, çok önemli olmaktadır. Bu çalışmada, düzeltme faktörlerini belirlemek amacıyla Türkiye'de SPT'nin uygulaması ve deneyde kullanılan aletleri içeren geniş kapsamlı anket çalışması yapılmıştır. SPT-N ile serbest basınç mukavemeti $(q_u)$ arasında korelasyonlar araştırılmış, daha önceki çalışmalarla karşılaştırılması ve Türkiye'nin çeşitli bölgelerinde yapılan bir çok zemin araştırmasından elde edilen veriler üzerinde düzeltmelerin etkisinin kontrolü yapılmıştır. SPT kullanılarak, $q_u$ gibi ince daneli zeminlerin mühendislik özelliğinin büyük bir doğrulukla belirlenebileceği gösterilmiştir.

A study on corrections of SPT results in fine-grained soils

The Standard Penetration Test (SPT) is one of the oldest and the most frequently used penetration test in soil exploration. In recent years several researchers attempted correlations between corrected field measured values with several soil properties. In that context corrections applied to field values become crucial. These corrections /consist of the effects of rod length, bore hole diameter, liner, anvil, hummer cushion, hammer type and its release mechanism, overburden, blow count frequency and underground water level. In this study a questionnaire including the performance of the standard penetration test and equipment used in Turkey is circulated in order to determine the relevant correction factors. Thus the appropriate and correct corrections are used in obtaining corrected SPT-N values. In engineering applications information concerning soil types and soil conditions necessary for design can be limited due to the difficulties encountered in sampling, testing, and the costs involved. Therefore it is useful to determine the unconfined compressive strength $(q_u)$ in relation to easily obtainable and reliable data. In this study the relationship between SPT-N and $q_u$ is examined, and comparisons are made with previous studies. Also this study aims at checking the relevance of the corrections with regards of the data obtained from a large number of soil investigations performed in Turkey. Standard penetration test is found to be sufficient for reliable assessment of $q_u$.

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