砂卵石地层盾构刀具动态磨损分析

ANALYSIS OF DYNAMIC ABRASION OF SHIELD CUTTERS IN SANDY COBBLE STRATUM

减小盾构刀具磨损,是保证土压平衡盾构长距离掘进的重要措施。砂卵石地层是一种典型的力学不稳定地层,盾构在此种地层条件下掘进,盾构刀具磨损严重。采用最新动态监测装置,对北京地铁四号线四标角门北路站～北京南站区间隧道盾构刀具进行磨损监测,利用最小二乘法对监测数据进行回归分析。以刀具磨损系数为因变量,以千斤顶掘进速度v、千斤顶推力F、刀盘转速n以及刀盘扭矩T等掘进参数为自变量分别建立回归表达式,在此基础上提出掘进参数的合理选择范围,并建立刀具磨损量与掘进距离的拟合表达式,为工程实际中减小刀具磨损及预测盾构在类似地层条件下的最长掘进距离等提供理论依据。研究结论对于类似地质条件下盾构选型和实际施工有一定的指导价值。

The main types of shield machines used recently in tunnel construction are earth pressure balance（EPB） shield tunneling and slurry shield tunneling.In order to reduce shield cutters wear,the parameter in shield construction advancing should be rational.This is fundamentally critical to ensure the shield to advance distantly in sandy cobble stratum.Sandy cobble is a typically unstable stratum and its mechanical properties are unfavorable for force transitivity and spread.Sandy cobble is also of unfavorable plasticity and fluidity,which will bring serious abrasion to shield cutters.By employing the latest dynamic supervisory gear,the abrasion of shield cutters used in shield tunnel section of Jiaomen Northern Load station to Beijing Southern station of Beijing metro line 4 was monitored;and the monitoring data were analyzed with the least square method.With abrasion coefficient as dependent variable,and advancement ratet,otal thrust,cutter-head rotation speed and cutter torque as independent variables,four regression expressions were established and eight regression graphs were drawn.Based on the regression expressions and graphs,the rational range of advancing parameters was proposed;and the fitting expression of abrasion of shield cutters to advancing distance was established,which may provide theoretical basis for reducing cutter abrasion in practical engineering,and for estimating the longest advancement distance in similar stratum.Based on the fitting expression of abrasion of shield cutters to tunnel advancing,the longest advancement distance is found to be 1.84 km in this stratum.The research conclusion is helpful for shield selection and engineering construction with similar geotechnical conditions.