| The full face rock tunnel boring machine,abbreviated TBM,belongs to the major equipment in China;and it is widely used in tunneling works.TBM machines are not only complex,but also expensive,a machine may cost a hundred million dollars.In the recent ten years,because our country has attached great importance to railway construction,and at the same time,our country is a mountainous country,so the demand for TBM is very big.But abroad technology blockade about some related designs of TBM is serious,the usage of TBM mostly comes from import in our country,and the core technologies often are under the control of foreign manufacturers;to break our country' technology blank in the field of high-end equipment manufacturing,so it is imperative to develop our country's domestic TBM.The cutter-head located at the front of a TBM,is one of TBM core components,and it plays a basic role in other parts' design of the machine.Domestic scholars do a lot of research on the rock cutting mechanism and mechanical characteristics of disc cutters,the layout optimization of cutters,the performance evaluation of the cutter-head,the life prediction for cutters and cutter-head,and so on.But there is still a certain distance between these studies and the engineering practice,and these problems remains to be further explored and improved.There are many defects in current layout design studies for cutters,such as the variable cutting depth character of gage disc cutters,the constraints of cutter-head welds,the coupling mechanism between the profile of the TBM cutter-head and the assembled radius layout of the disc cutters and so on,these are not considered and valued.For this reason,an adaptive design method of studying disc cutter layout based on the cutter-head profile and the constraint conditions of welding lines are proposed.Specific research works are as follows:(1)Based on the CSM model,taking the bearing stress of the outermost cutter as evaluation criteria,combining the characteristic parameters of cutter-head's edge zone including the shape and size,the design method of the profile for a flat cutter-head was determined.(2)The calculation formula of rock breaking amount for cutters with constant cross section and the formula of calculating wear extent for gage cutters based on its characteristic were derived.Using genetic algorithm and based on the principle of equal life,the assembled radiuses of center cutters and normal cutters were optimally designed;based on the principle of equal wear,a nonlinear mathematics model was established and the tilt angles of the gage cutters were optimally designed,too.(3)Boundary conditions of non-interference between the cutters,manholes,muck buckets and welding lines were given when a star layout pattern was used on cutters.The cutter-head comprehensive evaluation model was established with taking the cutter-head's unbalanced radial force,overturning moment and the cutter group's centroid shift as evaluation indexes;the layout design in circumferential direction was finished.And the strength and stiffness of the cutter-head were checked using FEM software ABAQUS.(4)Exemplifying the MB264-311-8030 mm tape TBM cutter-head,the calculations show that compared with the original layout scheme,among the 51 disc cutters,the largest gap of the cutters' assembled radiuses is only 25.8 mm,which is 0.64% of the cutter-head's radius and is negligible.The cutter-head's unbalanced radial force decreases by 62.41%,the overturning moment decreases by 33.22%,and the cutter group's centroid shift increases by only 18.48%.Each index is better than or approximately equal to the original cutter-head layout scheme,and the equivalent stress and deformation are both smaller;these results effectively verify the feasibility of the model. |
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