Causes and Control Measures of Shield Drift in an Upper Soft and Lower Hard Strata
When the shield machine is tunneling in the upper soft and lower hard strata composed of gravel soil and mudstone,it is difficult to control the attitude of the shield machine and the segment.Excessive deviation of the shield attitude can easily lead to the deviation of the shield tunnel from the design axis,resulting in greater safety hazards.How to correct the deviation quickly and safely is very important.Based on a subway shield tunnel project,this study analyzes the reasons for the large amount of shield attitude drift during shield tunneling.In order to reduce the influence of shield attitude deviation on the segment,a method of advanced soil extraction by shield machine is proposed.The drilling equipment is used to extract the soil under the front shield of the shield machine to form a certain size cavity.With the jack zoning control measures,the attitude drift of the shield machine is successfully adjusted to the specified range,and the maximum correction amount is 120 mm.The research results can provide reference for similar shield machine attitude drift control.
shield tunnelupper soft and lower hard stratashield posturedriftrectify deviation
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