|
Abstract During slurry shield tunnelling in silty sands during construction of Hangzhou Canal Tunnel，the cutter head of shield was trapped by sand adhesion. Due to the additional torque imposed by adherent sands，the cutter head stopped to rotate. The reasons for trap of shield?s cutter head were analyzed，and the measures taken to relieve the cutter head were described. Based on experiences and lessons learned from this case study，measures to avoid trap of slurry shield?s cutter head by adhesion of sands in silty sands were presented. In order to relieve the trapped cutter head，a pit was excavated at the front ground，and then high-pressure water jetting was used to clear sands adhered to the cutter head. Practice shows that the measures taken in this case were safe and effective for relieving the trapped shield?s cutter head. Attention should be paid to ensure the safety of surrounding environments，especially the completed tunnel nearby when the pit is excavated. To avoid the cutter head of slurry shield being trapped by sands while tunnelling in silty sands，unobstructed and continuous slurry circulation should be maintained，high-quality slurry should be guaranteed to balance the excavating face，the ability to sweep away sands should be enhanced，and the cutter head should be rotated at set intervals when the shield stops to assemble the segmental linings.
|
|
Received: 19 August 2011
|
|
|
|
2013, Vol. 32 
