Tunnel boring machine for excavating semicircular-arched tunnels

Abstract

A Tunnel Boring Machine (TBM) with a circular cutting profile includes secondary cutterhead components that produce a semicircular-arched tunnel profile for use in underground mining and/or civil construction operations, e.g., for boring in material containing rocks with Unconfined Compressive Strength (UCS) of up to 200 MPA or stronger. The machine is particularly suited to excavate long access tunnels, mine development drifts, road tunnels, and other types of tunnels that require flat bottom, semicircular-arched profiles. The substantially flat tunnel floor allows immediate and effective use of standard vehicles for material and crew transport as well as other construction and mining activities.

1 . A tunnel boring machine for boring a semicircular-arched tunnel having a tunnel wall, the tunnel boring machine comprising:
 a main support beam;   a main cutterhead assembly rotatably coupled to a front end of a cutterhead support slidable with respect to the main support beam, wherein the main cutterhead assembly is configured to rotate with respect to cutterhead support about a primary axis that is aligned with a centerline of a semicircular portion of the tunnel;   a plurality of gripper assemblies located rearward of the main cutterhead assembly, the gripper assemblies being configured to move between:
 a retracted position in which the gripper assemblies do not engage the tunnel wall; and 
 an extended position wherein the gripper assemblies engage the tunnel wall to impart axial movement to the main cutterhead assembly and to react to boring forces of the tunnel boring machine; 
   a pair of secondary cutterhead assemblies slidably mounted to and disposed on opposite sides of the main support beam, wherein each of the pair of secondary cutter wheel assemblies have a carrier operably coupled to a drive system configured to rotate the secondary cutterhead assemblies about a secondary axis perpendicular to the primary axis; and   at least one thrust cylinder configured to urge the pair of secondary cutterhead assemblies forwardly with respect to the main support beam independently of the main cutterhead assembly.   
     
     
         2 . The tunnel boring machine of  claim 1 , wherein the main support beam has an upper portion aligned with the primary axis and a lower portion having an elongate slot, wherein the pair of secondary cutterhead assemblies engage the elongate slots to permit the secondary cutterhead assemblies to move longitudinally with respect to the main support beam. 
     
     
         3 . The tunnel boring machine of  claim 2 , wherein the elongate slots are parallel to the primary axis, and wherein the secondary axis is horizontal. 
     
     
         4 . The tunnel boring machine of  claim 1 , wherein the secondary cutterhead assemblies are disposed on the main support beam rearward of the plurality of gripper assemblies. 
     
     
         5 . The tunnel boring machine of  claim 1 , wherein the drive system comprises a drive axle assembly extending between the carriers of the pair of secondary cutterhead assemblies. 
     
     
         6 . The tunnel boring machine of  claim 5 , wherein the drive axle assembly is a solid axle such that each of the pair of secondary cutterhead assemblies has a linked drive with respect to the other of the pair of secondary cutterhead assemblies. 
     
     
         7 . The tunnel boring machine of  claim 5 , wherein the drive axle assembly is a split axle such that each of the pair of secondary cutterhead assemblies has independent drive with respect to the other of the pair of secondary cutterhead assemblies. 
     
     
         8 . The tunnel boring machine of  claim 1 , further comprising:
 a forward shield adjacent to the main cutterhead assembly;   a telescopic shield located rearward of the forward shield, wherein the telescopic shield is configured to extend and retract in combination with translation of the main cutterhead assembly along the primary axis; and   a gripper shield located rearward of the telescopic shield and adjacent to the plurality of gripper assemblies.   
     
     
         9 . The tunnel boring machine of  claim 1 , further comprising a backup conveyor configured to collect primary muck created by the main cutterhead assembly during use and transport the primary muck rearwardly for removal from the tunnel. 
     
     
         10 . The tunnel boring machine of  claim 9 , further comprising a pair of peripheral conveyors each mounted adjacent to one of the pair of secondary cutterhead assemblies, wherein the peripheral conveyors are configured to collect secondary muck created by the secondary cutterhead assemblies during use and deliver the secondary muck to a common dump station above the backup conveyor such that the secondary muck combines with the primary muck for removal from the tunnel. 
     
     
         11 . The tunnel boring machine of  claim 10 , wherein the pair of secondary cutterhead assemblies each include a muck bucket operably coupled to each carrier and rotatable by the drive system, wherein the muck buckets are configured to collect the secondary muck and deliver the secondary muck to the peripheral conveyors. 
     
     
         12 . (canceled) 
     
     
         13 . A method of boring a tunnel having a semicircular-arched profile with a tunnel boring machine according to  claim 1 , the method comprising:
 positioning the gripper assemblies in the extended position wherein the gripper assemblies engage the tunnel wall to impart axial movement to the main cutterhead assembly and to react to boring forces of the tunnel boring machine;   excavating a circular main cutterhead boring area of the tunnel by rotating and simultaneously thrusting the main cutterhead assembly into a tunneling substrate;   collecting primary muck created by the main cutterhead assembly during excavation and transporting the primary muck rearward with a backup conveyor extending along the main support beam; and   excavating lower side portions of the tunnel by rotating and simultaneously thrusting the secondary cutterhead assemblies into the tunneling substrate.   
     
     
         14 . The method of  claim 13 , further comprising collecting secondary muck created by the secondary cutterhead assemblies during excavation and transporting the secondary muck rearward with peripheral conveyors positioned adjacent to the secondary cutterhead assemblies. 
     
     
         15 . The method of  claim 14 , further comprising depositing the secondary muck on the peripheral conveyors to a common dump station above the backup conveyor such that the secondary muck combines with the primary muck for removal from the tunnel. 
     
     
         16 . The method of  claim 13 , wherein the secondary cutterhead assemblies create secondary cutterhead boring areas that have substantially vertical sidewalls and flat bottom portions. 
     
     
         17 . (canceled) 
     
     
         18 . The method of  claim 13 , wherein the excavation of the lower side portions of the tunnel is performed simultaneous to or independent from the excavation of the circular main cutterhead boring area. 
     
     
         19 . A method of boring a tunnel having a semicircular-arched profile, the method comprising:
 providing a tunnel boring machine, having:
 a main support beam; 
 a main cutterhead assembly rotatably coupled to a front end of a cutterhead support slidable with respect to the main support beam, wherein the main cutterhead assembly is configured to rotate with respect to the cutterhead support about a primary axis that is aligned with a centerline of a semicircular portion of the tunnel; 
 a plurality of gripper assemblies located rearward of the main cutterhead assembly, the gripper assemblies being configured to selectively impart axial movement to the main cutterhead assembly; 
 a pair of secondary cutterhead assemblies slidably mounted to and disposed on opposite sides of the main support beam, wherein each of the pair of secondary cutter wheel assemblies are operably coupled to a drive system configured to rotate the secondary cutterhead assemblies about a secondary axis perpendicular to the primary axis; and 
 at least one thrust cylinder configured to urge the pair of secondary cutterhead assemblies forwardly with respect to the main support beam independently of the main cutterhead assembly; 
   positioning the gripper assemblies in the extended position wherein the gripper assemblies engage the tunnel wall to impart axial movement to the main cutterhead assembly and to react to boring forces of the tunnel boring machine;   excavating a circular main cutterhead boring area of the tunnel by rotating and simultaneously thrusting the main cutterhead assembly into a tunneling substrate; and   excavating lower side portions of the tunnel by rotating and simultaneously thrusting the secondary cutterhead assemblies into the tunneling substrate.   
     
     
         20 . The method of  claim 19 , further comprising:
 collecting primary muck created by the main cutterhead assembly during excavation and transporting the primary muck rearward with a backup conveyor extending along the main support beam;   collecting secondary muck created by the secondary cutterhead assemblies during excavation and transporting the secondary muck rearward with peripheral conveyors positioned adjacent to the secondary cutterhead assemblies; and   depositing the secondary muck on the peripheral conveyors to a common dump station above the backup conveyor such that the secondary muck combines with the primary muck for removal from the tunnel.   
     
     
         21 . The method of  claim 19 , wherein the secondary cutterhead assemblies create secondary cutterhead boring areas that have substantially vertical sidewalls and flat bottom portions. 
     
     
         22 . The method of  claim 19 , wherein the main support beam has an upper portion aligned with the primary axis and a lower portion having an elongate slot, wherein the pair of secondary cutterhead assemblies engage the elongate slots to permit the secondary cutterhead assemblies to move longitudinally with respect to the main support beam.