En jämförelse mellan raiseborrning och vajersågning för drivning av vertikala schakt i berg
Sammanfattning: In this thesis the two non-blasting methods, raise boring and wire sawing, have been studied for the making of vertical shafts in rock. The methods have been compared to each other to see which similarities and differences there are. The comparison is directed towards shafts made in an urban environment when drilling and blasting can’t be used because of impact restrictions on the surrounding buildings. The purpose of the study is to clarify under which specific conditions a particular method is most suitable for use. A third method, thermal spallation, has also been studied to see if the method, which today is used in quarrying operations only, can be used for making vertical shafts in an urban environment. The report includes detailed descriptions of the three methods based on a literature review and has been completed with relevant information from an interview study, adding personal experiences of people who have worked with the methods. Case studies of shafts which have been executed by wire sawing or raise boring have also been done. Information about the time and cost have been collected from the respondents and analyzed. The focus of the work has been to create a understanding of how the two techniques differ on the following points; time, cost, length and inclination of the shaft, dimensions of the cross section, working area and establishment, impacts on the surrounding, rock quality/geology and support and sealing. A survey of the companies who work with the methods in Sweden has also been made. The result shows that the methods are similar in many ways, but the areas were they differ the most are time, cost, shaft length, inclination, and dimension of the cross section. Raise boring is more suitable for longer shafts and is a reliable method, especially if the shaft is inclined. Wire sawing is a flexible method were the shape of the cross section can have many different forms and only the rock that is cut loose sets the limitations. The case studies and the time analysis shows that raise boring is a faster method than wire sawing for the making of shafts, mainly because the rock that was cut loose with the wire got stuck in the shafts in many of the cases. The general cost analysis that was done shows that wire sawing is the cheapest alternative when the length of the shaft is shorter than 40 – 50 m. The reason for this is mainly that the cost of the establishment is 10 times higher for raise boring than for wire sawing. Based on the results and conclusions from this study a table has been made with guidelines for choosing which method to use in future projects. Thermal spallation as it is today is a technique which can‘t be used in an urban environment. With modifications to the required equipment, the method could compete with wire sawing and raise boring in the future.
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