Some contributions on the estimation of performance and operational parameters of raise borers – A case study in Kure Copper Mine, Turkey

• Performance of a Raise Boring Machine (RBM) was investigated in a copper mine.
• Two different models based on rock cutting mechanics are validated.
• Specific energy obtained of the RBM is proved to be in same order as in TBMs.

Excavation of shafts and other vertical structures in mining and civil engineering fields for material and human transportation and ventilation purposes is a difficult job taking quite long time to realize. Raise boring provides a safe means of excavating shafts between two levels of underground structures without using explosives. A Raise Boring Machine (RBM) operates by the principle of first drilling a small diameter pilot hole and then, reaming the hole in one or more stages to the desired size. Raise boring system is the most up-to-date, secure and fast way for boring large diameter shafts. This paper concerns about the estimation of the performance and operational parameters of a RBM used to excavate ventilation shafts in a copper mine located at the city of Kastamonu, Kure Province, on Northern Turkey. Length and diameter of the ventilation shaft are 22 m and 2.6 m, respectively. Borehole samples were collected during pilot hole drilling operation for performing physical and mechanical tests in the laboratory. Excavation performance parameters of RBM such as, penetration rate, cutterhead torque, and total thrust force were theoretically estimated based on the experimental results. Then, the realized and predicted values were compared to serve a useful guide for future applications. The main points emerging from this study is that Tunnel Boring Machines (TBM) and RBM cuts the rock applying the same basic principles of rock cutting mechanics. Specific energy values for both machines are in the same order for similar depth of cut and similar rock formation enabling to predict penetration rates of RBM from huge data of TBMs already published in the literature. It is also proved that the thrust forces for RBM may be predicted in massive rock as it is done for TBM based on projectile area of the cutter and rock compressive strength.