INSTRUMENTED FIELD DATA-BASED ASSESSMENT ON LOAD TRANSFER BEHAVIOR IN RAMMED AGGREGATE PIER® (RAP) ELEMENTS

Year 2025, Volume: 33 Issue: 3, 2066 - 2077, 19.12.2025

Ece Kurt Bal , Mustafa Kubilay Keleşoğlu , Kemal Önder Çetin

https://doi.org/10.31796/ogummf.1719084

Abstract

Among the methods of stone column installation, the use of Rammed Aggregate Pier® (RAP) elements offers an alternative to traditional methods like deep foundations or excavation/backfill for sites with challenging soil conditions that cannot meet the performance criteria of superstructures. The goal of using RAP elements is to reduce settlements to acceptable levels, increase load-bearing capacity, and minimize liquefaction potential. In this study, full-scale field load test was performed to identify the variation of shear resistance along RAP element installed by the Impact® System (displacement), making this research the first and only study conducted on RAP elements produced using the displacement system. More specifically, load cells were used to assess the mobilization of vertical load distribution along the column. By utilizing these load cells positioned at various levels along the column, the axial load distribution was monitored concurrently during the loading test. Full-scale load test results demonstrated that, under a 57.5 ton load, the displacement measured at the tell-tale element (reading bars mounted on load cells) varied relative to the displacement measured at the top level of the column, by approximately 15% at the 1 m level, and in the other levels (2 m, 4 m, and 6 m) by about 2-5%. When these results were evaluated in terms of the literature-defined settlement ratio (Rb >> 1), the measured displacements indicated that the response was governed by lateral expansion of the column. Furthermore, the load cells indicated that the applied load mobilized rapidly up to the 1 m level (~2D; D: pier diameter), with only about 10% of the load being transmitted; in other words, the load was accommodated predominantly by circumferential friction rather than transmission to the column tip. These findings support a deformation mechanism for RAP elements with L/D >> 3.5 (L: pier length) that is driven by circumferential friction rather than tip capacity.

Keywords

Rammed Aggregate Pier , Loading Test , Instrumentation , Load Transfer

Ethical Statement

The authors have no conflicts of interest to declare regarding the content of this article.

Thanks

This research has been sponsored by Sentez Insaat, Istanbul, Türkiye, whose contribution and support for the publication of the project data is greatly appreciated by the authors.

DARBELİ KIRMATAŞ KOLON® (DKK) ELEMANLARINDA YÜK TRANSFER DAVRANIŞININ ENSTRÜMANTASYONLU SAHA VERİ TABANLI DEĞERLENDİRİLMESİ

Abstract

Taş Kolon imalat yöntemleri arasında yer alan ve üst yapı performans kriterlerini karşılayamayacak özelliklere sahip olan zeminlerde derin temel ya da kazı/dolgu gibi mevcut yöntemlere alternatif olan Darbeli Kırmataş Kolon® (DKK) elemanları ile oturmaların uygun seviyelere indirilmesi, taşıma kapasitesinin arttırılması ve sıvılaşma potansiyelinin azaltılması hedeflenmektedir. Bu çalışmada, enstrümantasyonlu DKK elemanı üzerinde gerçekleştirilen tam ölçekli yükleme testi sonuçları değerlendirmeye alınmış olup, bu araştırma Impact® Sistemi (displacement) ile imal edilen Darbeli Kırmataş Kolon® elemanlarındaki yük mobilizasyonunun anlaşılmasına yönelik yürütülen ilk ve tek çalışma niteliğindedir. Bu kapsamda özel olarak tasarlanan ve kolonun farklı kademelerine yerleştirilen yük hücreleri ile yükleme testi sırasında ölçümler yapılarak kolon boyunca mobilize olan eksenel yük dağılımı eşzamanlı olarak ölçülmüştür. Tam ölçekli yükleme testi sonuçları, 57.5 ton yükleme altında tell-tale (yük hücrelerine monte edilmiş okuma çubukları) elemanlarında ölçülen deplasmanın, kolon üst kotunda ölçülen deplasmana göre 1 m seviyesinde yaklaşık %15’i, diğer seviyelerde (2 m, 4 m ve 6 m) ise %2-5’i aralığında değiştiğini göstermiştir. Elde edilen bu sonuçlar literatürde tariflenen oturma oranı (Rb >> 1) cinsinden de değerlendirildiğinde ölçülen deplasmanların kolonun yanal genişlemesinden kaynaklı olduğunu göstermiştir. Ayrıca yük hücreleri, uygulanan yükün 1 m seviyelerinde (~2D; D: kolon çapı) hızla mobilize olduğunu ve bu seviyelere yükün ancak %10’unun iletildiğini; başka bir ifade ile yükün kolon ucuna aktarılmadan çevre sürtünmesi ile karşılandığını göstermiştir. Bu sonuçlar, L/D >> 3.5 (L: kolon boyu) olan DKK elemanlarının, uç kapasitesinden ziyade çevre sürtünmesine dayalı olan çalışma prensibini de destekler mahiyette bulunmuştur.

Keywords

Darbeli Kırmataş Kolon , Yükleme Testi , Enstrümantasyon , Yük Transferi

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