Study On The Mechanism And Disposal Measures Of Clay Clogging In TBM Cutter-head

Clay clogging in cutter-head is a phenomenon that the muck cut by the cutter-head stuck between the cutter-head and the tunnel face,and the muck to be solid or semisolid lump by extrusion of cutter-head,which causes clay adheres to the cutter-head and clog it.When the phenomenon occurs,the cutters on the cutter-head will gradually to be solidified,which leads to a reduction in the penetration of the cutters and the decrease on the tinnelling efficiency.If the clogging of the cutter-head has not been disposed properly,while the advance driving is continuous,the clogging-muck will be more and more dense and gradually consolidated into rock,which makes the driving parameters fluctuate and the slag temperature to be high,which greatly reduces the controllability risk during the tunnelling and poses a great threat to the safety of the tunnel boring machine(TBM).The difficult of clay clogging in cutter-head had been commonly encountered either in China or at abroad when TBM tunnelling in sticky soil ground,and experts have studied it for a long time.However,TBM tunnelling is still facing the challenge of clogging until now,which means the problem has not been solved well.In actual construction,the problem is still very serious,and it has gradually become a bottleneck that restricting the tunnelling efficiency.Based on the background,this research foucus on the mechanism and disposal measures of clogging in the cutter-head,and the research contents and achievements are summarized as follows:(1)Through analysis of the force mechanism of cutter-head and tunnel face during tunnelling and the observation shape of clogging in the actual engineering,two model named "bridge" and "clay muck landslide away from cutter-head" are established to explain the mechanism of the clay muck block cutter-head opening and how the clay muck is removed by tunnel face.The principle of mechanochemistry in material science is introduced to analyze the clogging of the cutter-head,and the mechanism of clogging muck to be hardening and diagenesis is explained.(2)The growing process of the clay clogging of the cutter-head is simulated through a shear adhesion test and an indoor tunnelling test.The influence of water content,kind of metal material,roughness of metal surface,opening rate of cutter-head and pressure forced by cabin on clogging was analyzed,and influence laws of the various parameters on the clogging were obtained,the applicability of "bridge" model and " clay muck landslide away from cutterhead" model in the analysis of clogging problem was verified.(3)The effect of foam on the soil conditioning to alleviate the cutter-head clogging is studied based on indoor tunnelling test.The applicability of common use disposal methods is explored by analysis of some engineering cases,and the implementation suggestions for the cutter-head design and the auxiliary measures for the construction are brought up.