Pipe Jacking and TBM tunnelling in soft soil conditions
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Abstract:Main objectives for the thesis:- To gather information about the Pipe Jacking method, through a theoretical study and field work on the Pipe Jacking project Sorek feed line outside Tel Aviv.- Gather information about pipe jacking productivity (utilization, net-penetration).- Gather information about bentonite?s influence on cutterhead torque and TBM productivity in soft ground.- Gather information about the influences of cutting force, cutterhead torque and rotation of cutterhead on advance speed.- Gather soil samples and geotechnical data from the current projects, and perform laboratory tests on the sample in order to measure required torque, measureable abrasivity and influence of bentonite and possible chemical additives.Results:Pipe Jacking method:The Pipe Jacking method offers some clear advantages over the conventional method of open trench in urban areas. This thesis can provide the basic elements of the method.Bentonite?s influence on cutterhead torque and TBM productivity in soft ground:Bentonite?s influence on TBM productivity is already extensively documented in literature. As for bentonites influence on cutterhead torque, the lab results in this thesis indicates a reduction of the torque with increasing bentonite content up to a certain point. Because of uncertainties in the lab tests, further testing for establishing the influence of bentonite on cutterhead torque is needed.The influences of cutting force, cutterhead torque and rotation of cutterhead on advance speed:From the observations done in this thesis, the cutterhead torque proved to be the factor with most influence on the advance speed. But to establish a relationship between these TBM parameters and the advance speed, further research is required in varying geological conditions and with varying TBM types.