复合地层盾构滚刀磨损风险等级模糊评判

针对盾构在复合地层隧道掘进过程中存在滚刀易磨损且不易判断磨损程度的施工难题,通过综合分析滚刀磨损的各种影响因素及其影响关系,总结提炼出4个磨损风险等级和五大类15个子项的关键影响指标。针对复合地层提出复合高度比和等效岩土强度的概念,综合运用两级模糊评判法和层次分析法建立了复合地层盾构滚刀磨损程度评判方法。通过对佛莞城际铁路长隆隧道复合地层段进行现场验证,证实了该方法在不进入盾构土仓的情况下,可对滚刀在盾构不同掘进距离下的磨损程度进行定性判断。

On the fuzzy assessment of the wear risk grade of the shield disc cutter in the complex strata

The given paper has analyzed various factors that are likely to influence the wearing loss of the disc cutter and the relations between the above mentioned factors. Based on the analysis of the specific features of the shield tunneling construction and the experience of the disc cutter utilization,it has then extracted the key influential indicators of the 4 wear risk levels and the 15 sub-constitutional factors of the 5 categories. What is more,it has also managed to determine the weights of each evaluation index of the wear risk so as to establish the wear extents as the target layer and the 2-level evaluation indexes as the intermediate analysis layers. The above said analytic hierarchical process( AHP) has thus been introduced into the AHP model whereas the corresponding digital scale values of each factor have been provided through comparing their relative significances at the same level. The assessment matrix of each factor can be built up with its eigenvector being worked out. And,so,through normalization,it can be determined as weight vector,with their weight being determined by the consistency approval. And,next,we have also brought about the concepts of the composite height ratio and the equivalent geotechnical strength for the composite strata.At this step,we have built up the assessment method of wear degree of the disc cutter via the 2-level fuzzy evaluation method.With the above said methods,it is necessary,first of all,to quantify the necessary discrete qualitative indexes by assigning the wear grades. And,then,it is also necessary to take the membership functions to work out the membership degrees of all the evaluation indexes,so as to give out the quantitative standards of the 4 wear risk levels. And,consequently,the above mentioned methods can also be taken to assess the wearing extents of the disc cutters in the composite strata of Changlong tunnel in the railway construction of Foshan-Dongguan intercity. The assessment results we have gained prove to be quite close to the testing results on the spot and therefore tends to be of great effectiveness and accuracy,thus,demonstrating that the approach we have taken can help to assess the wearing extents of the disc cutters qualitatively under the different shield tunneling distances with no need to enter the shield soil cabin.