Analysis On Dynamic Abrasion Of Earth Pressure Balance Shield Cutters

The main types of shield machine used recently in tunnel construction are earth pressure balance(EPB)shield and slurry shield. In order to reduce shield cutters wear, the advancement parameter in shield construction process should be rational. This is fundamentally critical to ensure the shield to advance distantly in sandy cobble stratum. When tunneling in sandy cobble stratum, shield cutters wear is serious, meanwhile the shield cutters are easily chip and scale. If such situations occur, the shield will unable to construct and people are compelled to open the chamber, which will easily cause the cutting face landslip, not only bring great influence to construction time limit and cost for the project, but put people's life into peril as well. Therefore, research how to reduce EPB shield cutters wear in sandy cobble stratum and find out how long can EPB shield advance in sandy cobble stratum without changing shield cutters is of great significance.Based on researching relevant theoretical achievements and engineering practice, on the engineering background of Beijing metro line 4 EPB shield tunneling, from soil and machine two aspects, the shield cutters wear in sandy cobble stratum was researched. a series of achievements were obtained.Firstly, the principle of work, the abrasion reasons and influencing factors of all kinds of EPB shield cutters were analyzed.Secondly, EPB shield cutter wear with ultrasonic supervisory gear for abrasion was researched in sandy cobble stratum. The design of test is rational and the result of test is true.Thirdly, With abrasion coefficient as dependent variable, advancement rate, total thrust, cutter-head rotation speed and cutter torque as independent variables respectively, four regression expressions were established and eight regression graph were drawn. Based on the regression expressions and graph, the rational range of advancement parameters was proposed and the fitting expression of abrasion of shield cutters to advancement distance was established. Which may provide theory basis for reducing abrasion of shield cutters in practical engineering, and estimate the longest advancement distance in similar stratum and cutter structure.Fourthly, Based on the fitting expression of abrasion of shield cutters to advancement, the longest advancement distance is 1.S4 km in similar stratum and cutter structure.Fifthly, shield machine model was designed, and the test operating procedure was devised according to similarity theory.