Development of fully controlled rock crushing method and its vibration impact during rockfall risk reduction at Assos ancient port: Experimental and field studies

Historical sites are vulnerable to significant damage caused by natural disasters such as earthquakes, rockfalls, floods, landslides, and fires. Protecting these invaluable regions necessitates preemptive measures against such disasters. This study delves into the rockfall risk assessment and remediation techniques for Assos, an ancient port with a history spanning over 2000 years. Initially, field surveys were conducted to identify active rockfall potential and precarious blocks within the area. Subsequently, intervention methods were devised, involving the removal of numerous hazardous blocks. A novel approach to rock crushing/breaking was developed specifically for the historical locale, comprising three distinct techniques: Fully Controlled, Splash Controlled, and Free Rock Crushing/Blasting. Additionally, two types of materials, namely Chemical Rock Breaking Powder and Cartridges Containing Pyrotechnic Class Explosives, were employed in refining the method. The subsequent phase of the research aims to evaluate the impact of recorded vibrations on historical artifacts and structures within the ancient site, with a particular focus on potential structural damage. To this end, seven rock crushing/breaking experiments were conducted, employing five different accelerometers strategically placed near the experimental site to measure vibrations in the historical structures. The findings have been analyzed in accordance with international standards, including DIN 4150/3, USBM RI-8507, and the Environmental Noise Assessment and Management Regulation. The assessment specifically scrutinized the condition of historical structures. In summary, during rock crushing operations employing chemical rock crusher powder (W=17 kg), the highest maximum particle velocity recorded at the closest distance to the operation point was 0.031 mm/s. These measurements fell comfortably below the specified damage criterion outlined in the norms. As a result, utilizing this method, over 7500 m³ of hazardous rock blocks were successfully broken and removed from the slope, while concurrently erecting rockfall protection structures. Ultimately, this comprehensive approach led to a reduction in regional rockfall risk, facilitating the safe reopening of Assos to visitors. • In this paper, a novel method of fully controlled rock crushing is developed for hazardous rock elimination in historical areas. • Comprehensive studies at Assos ancient port aim to develop a fully controlled rock-crushing process to remove hazardous blocks. • The impact of ground vibrations induced by rock crushing using chemical rock breaking powder and pyrotechnic-type explosives is investigated. • The risk of rockfall disasters has been eliminated indicating no substantial risk of structural damage from these operations.