77. Acta Geotechnica Slovenica, 2019/2 M. Örnek et al.: Soil based design of highway guardrail post depths using pendulum impact tests SOIL BASED DESIGN OF HIGHWAY GUARDRAIL POST DEPTHS USING PENDULUM IMPACT TESTS Murat Örnek (corresponding author) Iskenderun Technical University, Faculty of Engineering and Natural Sciences, Civil Engineering Department 31200, Iskenderun, Hatay, Turkey E-mail: murat.ornek@iste.edu.tr Ali Osman Atahan Istanbul Technical University, Civil Engineering Faculty, Civil Engineering Department 34469, Istanbul, Turkey E-mail: atahana@itu.edu.tr Yakup Türedi Iskenderun Technical University, Faculty of Engineering and Natural Sciences, Civil Engineering Department 31200, Iskenderun, Hatay, Turkey E-mail: yakup.turedi@iste.edu.tr Izvleček Varovalne ograje so pasivni cestni zadrževalni sistemi (RRS), ki se uporabljajo ob robovih in na sredini cest za izboljšanje varnosti v cestnem prometu. V primeru nezadostne globine vpetja stebrov, vtisnjenih v zemljino, se lahko zgodi, da ne delujejo kot je predvideno, zato konstrukcija ne more zago- toviti zadostne varnosti ali varnosti za vozila, ki udarijo v njo. Na splošno je višina jeklene varnostne ograje med 1600 in 2400 mm. Vendar pa se lastnosti tal, v katerih so vgrajene varnostne ograje, praviloma ne upoštevajo. Z drugimi besedami, ne glede na vrsto tal, se izvaja konstantna globina vpetja stebrov zaščitne ograje. Globine vpetja stebrov (PED) v sistemih jeklenih zaščitnih ograj so trenutno določene na podlagi visokih trdnosti tal. Zmogljivost teh modelov za trk ni primerna za lokacije, kjer so trdnostne karakteristike tal nižje od predpostavljenih v osnovnem izračunu. V tej študiji so bili opravljeni terenski udarni preizkusi na stebre vpete v tla, da bi določili optimalno globino vpetja ZASNOVA GLOBINE STEBRA AVTOCESTNE OGRAJE GLEDE NA LASTNOSTI TAL Z UPORABO UDARNIH PREIZ- KUSOV Z NIHALOM Ključne besede ograja; steber; globina vpetja; lastnosti tal; interakcija steber-tla; preizkus z nihalom Keywords guardrail; post; post embedment depth; soil properties; post-soil interaction; pendulum test DOI https://doi.org/10.18690/actageotechslov.16.2.77-89.2019 Abstract Guardrails are passive road restraint systems (RRS) used at roadsides and medians to improve road safety. In the case of inadequate post embedment depth of soil driven posts may not function as intended and design cannot provide adequate safety nor security for the impacting vehicles. In general, the height of the steel guardrails varies between 1600 and 2400mm. However, the characteristics of the soil where the guardrails are driven are not taken into consideration. In other words, a constant depth of guardrail is used regardless of the type of soil. Post embedment depths (PED) in steel guardrail systems are currently determined based on strong soil properties. Te crash performance of these designs may not be appropriate for locations where soil conditions are weaker than tested conditions. In this study, a series of feld impact tests were performed on soil embedded posts to determine optimum PED for M. Musab Erdem Iskenderun Technical University, Faculty of Engineering and Natural Sciences, Civil Engineering Department 31200, Iskenderun, Hatay, Turkey E-mail: musab.erdem@iste.edu.tr Murat Büyük Sabancı University, Integrated Manufacturing Technologies R&A Center 34956, Istanbul, Turkey E-mail: muratbuyuk@sabanciuniv.edu