Liquefaction of silts: the Adapazari criteria

Abstract

Ground failures in the form of liquefaction, loss of bearing capacity and soil softening have been observed during the 1999 Marmara (Turkey) earthquake. Research to understand the failure phenomena has been carried out since the earthquakes. This paper attempts to provide explanations to the liquefaction failure of silts in seismic conditions. Findings from a large amount of data collected in the city of Adapazari on the physical and mechanical properties of soils is presented. A geomorphological map of the city has shown that there are surprising horizontal and vertical variations of the facies due to the activity of rivers in the past. Cases of liquefaction appear to have concentrated in former backswamp areas where silts and sandy silts were deposited by crevasse splays. Properties of the soils in zones of liquefaction and non-liquefaction have been determined down to a reasonable depth by measuring the average size, clay content and liquidity index as well as cone penetration resistances with porewater pressures to discover that there is significant discrepancy among those profiles susceptible to liquefaction and non-liquefying deposits. A set of "Adapazari Criteria" is proposed which is intended to improve over the "Chinese Criteria" and is simple enough to be universally applicable. This classification is similar to the existing criteria but emphasizes more on the clay content in addition to measuring the liquid limit and the liquidity index as well as the average size.

GIS – based evaluation of the effect of local soil properties on the earthquake damage patterns

“…Damaged buildings have been recorded both in Arifiye and Geyve by official institutions [19] [21]. The damage distribution maps were prepared using data obtained from studies after the 1999 earthquake in Arifiye and Geyve and are presented in Fig.…”

“…4, high plasticity clays are the dominant soil type in Arifiye. In Geyve, predominantly clays, but gravels and sands do occur [18] [19].…”

“…Generally, in the town center of Adapazarı, the liquefaction was observed to have occurred in the low plasticity silts and fine sands at shallow depths [22]. To understand the process of liquefaction in these particular layers, the Adapazarı criterion has been developed [25]. According to this criterion, liquefied strata must have the following properties: soil group should be ML (NP), natural moisture content should be equal or higher than the liquid limit (in this conditon liquidity index is higher than unity: IL≥1), liquid limit should be less than 30 and clay fraction (D≤0.002 mm) should be less than 15%.…”

Endüstri Yapısı Temeline Yönelik Vaka Analizi

“…Bu tip zeminlerden öncelikle ML sınıfında olanların sıvılaşma analizleri ince daneli zeminler için geliştirilmiş olan Adapazarı kriterine göre yapılabilmektedir [2]. Adapazarı kriterine göre YASS altındaki doygun siltlerde Mw>7 olması durumunda sıvılaşmanın gerçekleşebilmesi için şu koşulların sağlanması gerekmektedir: a) Likit limit %33'ten az olmalı, b) Sıvılık indisi (IL) veya wn/wL 0.…”

Siltlerin Boşluk Boyutu Dağılımı Ve Radyal Konsolidasyon Özelliğinin Sıvılaşma Potansiyeline Etkisi

“…Zemin özelliklerinin hangi koşullarda belirlendiği ve geçerliliğini koruduğunu anlamadan ve bu konuda yeterli tecrübe birikimine sahip olmadan güvenli ve ekonomik mühendislik çözümleri elde etmek mümkün olmamaktadır [4].1999 Marmara depremindeki arazi gözlemleri ve sonraki ölçümler geoteknik açıdan laboratuvar kent hüviyetine sahip olduğu söylenebilecek olan Adapazarı'nda yer alan fluviyal siltler üzerinde Sakarya Üniversitesi'nde gerçekleştirilmiş araştırmalar siltlerin sıvılaşma yeteneğinin zeminin fiziksel özellikleri ile kolayca saptanabileceği bulgularını getirmiş ve bu amaca yönelik olarak Adapazarı Kriteri'nin revize edilmiş biçimi önerilmiştir [5,6]. Bu kriterde 25 <w L < 33 ve 10 < % C < 15 aralıklarında numunelerin dinamik deneylerle değerlendirilmesi önerilmiştir [5].…”