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In February 2015 Cofra Dynamic Compaction (CDC), a heavy Rapid Impact Compaction (RIC) technique to compact granular subsoil, was performed on the Berth 9 Quay Extension project in Felixstowe, UK. The extension consists of a 15.000m2 reclamation between sheet pile walls. The compaction of the reclamation was required to reduce future settlements and improve the properties of the sand behind the quay wall. An extensive compaction trial was performed before the start of the project to assess the compaction procedures and work method in relation to the specifications but also to assess the impact of the compaction on the Quay wall. Compaction effort was monitored during compaction with the use of the crane monitoring system which registers the (induced) settlement with increasing blows. The effect of the compaction has been measured with the use of pre- and post-compaction CPT's. The main quay wall displacements were continuously monitored by a manual station and a robotic total station. During the trial an inclinometer was used to gather more data. The paper focusses on the gathered data, findings and observations during the project and the compaction trials.

Pojav likvifakcija predstavlja izgubo strižne trdnosti oziroma strižne nosilnosti zasičene zemljine zaradi hipnega porasta pornega tlaka kot posledice monotonih, impulzivnih ali ponavljajočih se obremenitev. Potres je eden izmed najbolj pogostih dejavnikov za nastop likvifakcije. V okviru diplomske naloge opišemo osnovni mehanizem izgube strižne trdnosti zemljine, zaradi katerega pride do utekočinjene zemljine, opišemo dve vrsti likvifakcije (likvifakcija s tečenjem in ciklična mobilnost), pri katerih pogojih nastopijo ter značilnosti obeh. Analiziramo, kateri geološki pogoji in pogoji, povezani z materialom, vplivajo na pojav likvifakcije, kriterije določenih avtorjev za nastop likvifakcije ter kako potres kot sprožitelj s svojimi karakteristikami vpliva na pojav likvifakcije. S pomočjo zgodovinskih primerov in teoretičnega znanja opišemo posledice in običajne ukrepe, ki se izvajajo proti nastopu likvifakcije tal. V praktičnem delu naloge smo ovrednotili potencial likvifakcije na podlagi rezultatov CPT preiskave, ki je ena izmed pogostih geotehničnih terenskih preiskav. Dovzetnost do pojava likvifakcije preverjamo na podlagi znanih metod (Robertson in Wride, 1998 ter Boulanger in Idriss, 2014) in rezultate obeh medsebojno primerjamo. Za primerjalne analize smo uporabili podatke iz luke Ploče na Hrvaškem. V okviru naloge smo v kratkem opisali značilnosti lokacije, geološke in seizmološke značilnosti ter zaradi občutljivosti zgornjih slojev na utekočinjenje predlagali sanacijsko rešitev. Liquefaction represents loss of the shear strength and shear resistance of the saturated soil due to the sudden increase in pore pressure caused by monotonous, impulsive or repeated loads. The earthquake is one of the most common factors for the onset of liquefaction. The thesis describes the basic mechanism of the loss of shear strength of the soil that may result in the ground liquefaction. Two types of liquefaction (soil liquefaction and cyclic mobility) are described together with the conditions for their occurence and the characteristics of both phenomena. The geological conditions and material properties required for liquefaction are presented and the criteria for liquefaction innitiation proposed by some authors are given. The influence of earthquake parameters as a triggering event for liquefaction are also discussed. Historical examples and theoretical knowledge are used to describe the consequences of and the usual measures to be taken against liquefaction. In the practical part of the thesis we evaluate the liquefaction potential using the results of CPT investigation, which is widely used geotechnical in-situ test method. Susceptibility of the ground for the liquefaction occurance was assessed on the basis of known methods (Robertson and Wride, 1998 and Boulanger and Idriss, 2014) and the results of both were compared. The data from port of Ploče in Croatia were used. A short description of the site with its geological and seismological properties is included. Finaly, the remedial measures for the upper sandy layer that was found to be prone to liquefaction, were proposed.

Tijekom nekoliko proteklih godina brzo udarno zbijanje postalo je popularna metoda za poboljšanje tla. Da bi se procijenila korisnost te metode na području Perzijskog zaljeva, brzo udarno zbijanje primjenjeno je za poboljšanje tla površine 29.000 m2 na gradilištu u blizini Dubaija, gdje je zabilježena visoka razina podzemne vode. Statički penetracijski pokus i proračuni slijeganja provedeni su prije i nakon poboljšanja tla. Ispitivanja su pokazala poboljšanje nosivosti tla i smanjenje očekivanih slijeganja., In recent years, the Rapid Impact Compaction has gained popularity as a ground improvement technique. To evaluate the usefulness of this technique in the Arabian Gulf Region, the RIC is used to improve an area of 29,000 m2 on a project site near Dubai, UAE, where the groundwater level is shallow. Cone Penetration Tests and settlement calculations were carried out before and after soil improvement. Test results show improvement in the soil bearing capacity and reduction in expected settlements.