Proposed chart for the selection of ımpact hammer

• A new laboratory tool to determine minimum breaking energy of rocks is developed.
• Rock Structure Index is developed to determine rock breakability with impact hammers.
• Rock Mass Breakability Chart is developed.
• The chart performance is satisfactory.

Twenty-five different slope excavation and 19 different tunnel excavation observations, measurements and field studies were performed in order to create a Rock Mass Breakability Chart (RMBC) to select an excavation machine. These fields comprise different rock mass conditions. This developed chart consists of Rock Structure Index (RSI), which was developed in this research and rock mass definition formed in this study. RSI includes test results of Impact Hammer System (IHS), which was designed in this study to determine the breakage energy of rocks with impact, and also rock strength, the structure of rock mass and discontinuity properties. In regards to the rock mass classification, the definition that was already suggested by ISRM was used. Impact hammers used in different excavation fields were compared by using RMBC. It was concluded that the performance of the proposed chart is satisfactory.