A boring assembly extending along a main axis (A-A') and comprising: - a boring head including: + at least one first nozzle; + at least one second nozzle, the or each second nozzle being different from the or each first nozzle; - a first delivery device configured to deliver a jet of abrasive-free water at a pressure of between 2000 bar and 4000 bar to the at least one first nozzle; - a second delivery device configured to deliver a jet containing at least one abrasive material at a pressure of between 2000 bar and 6000 bar to the at least one second nozzle, wherein the boring head is cylindrical, and has a central head axis (B-B') extending along the main axis (A-A'), the boring assembly comprising: - a frame, - a first rotational drive of the boring head relative to the frame around the central head axis (B-B'), - a body, - a first cylindrical support having a first support central axis (C-C') different from the central head axis (B-B'), - a second rotational drive of the first support relative to the body around the first support central axis (C-C'), the at least one second nozzle being arranged on the first support, and the first support being connected to the body in rotation around the first support central axis (C-C'); wherein: * the at least one first nozzle is arranged on the first support; or * the boring assembly comprises a second cylindrical support having a second support central axis (D-D') different from the first support central axis (C-C'), the second support being inserted into the first support, the at least one first nozzle being arranged on the second support. - a boring head including: + at least one first nozzle; + at least one second nozzle, the or each second nozzle being different from the or each first nozzle; + at least one first nozzle; + at least one second nozzle, the or each second nozzle being different from the or each first nozzle; - a first delivery device configured to deliver a jet of abrasive-free water at a pressure of between 2000 bar and 4000 bar to the at least one first nozzle; - a second delivery device configured to deliver a jet containing at least one abrasive material at a pressure of between 2000 bar and 6000 bar to the at least one second nozzle, wherein the boring head is cylindrical, and has a central head axis (B-B') extending along the main axis (A-A'), the boring assembly comprising: - a frame, - a first rotational drive of the boring head relative to the frame around the central head axis (B-B'), - a body, - a first cylindrical support having a first support central axis (C-C') different from the central head axis (B-B'), - a second rotational drive of the first support relative to the body around the first support central axis (C-C'), the at least one second nozzle being arranged on the first support, and the first support being connected to the body in rotation around the first support central axis (C-C'); wherein: * the at least one first nozzle is arranged on the first support; or * the boring assembly comprises a second cylindrical support having a second support central axis (D-D') different from the first support central axis (C-C'), the second support being inserted into the first support, the at least one first nozzle being arranged on the second support. the at least one second nozzle being arranged on the first support, and the first support being connected to the body in rotation around the first support central axis (C-C'); wherein: * the at least one first nozzle is arranged on the first support; or * the boring assembly comprises a second cylindrical support having a second support central axis (D-D') different from the first support central axis (C-C'), the second support being inserted into the first support, the at least one first nozzle being arranged on the second support. * the at least one first nozzle is arranged on the first support; or * the boring assembly comprises a second cylindrical support having a second support central axis (D-D') different from the first support central axis (C-C'), the second support being inserted into the first support, the at least one first nozzle being arranged on the second support.