Experimental study on attitude control of shield machine in soft and hard uneven strata

The soft and hard uneven stratum is one of the bad geology often encountered in the process of shield construction. When the shield machine is excavating the soft and hard uneven stratum, the uneven force of the cutterhead can easily lead to the change of the attitude of the shield machine, which leads to the deviation of the shield tunnel from the design axis. In order to study the relationship between the force of the cutterhead and the attitude change of the shield machine when the shield machine is tunneling in the soft and hard uneven strata, a 1 : 10 model shield excavation construction model test was designed. The force condition of the shield machine in the soft and hard uneven strata was analyzed, and the attitude of the shield machine during the test construction was monitored and analyzed. The analysis of the test results shows that : ( 1 ) When the shield machine excavates the soft and hard uneven stratum, the soil reaction force of the excavation surface when the cutter head excavates the hard soil layer is greater than the soil reaction force of the excavation surface when the cutter head excavates the soft soil layer, and the cutter head will be subjected to additional excavation surface torque, which leads to the increase of the cutter head torque of the shield machine. ( 2 ) When the shield method is used to construct the upper soft and lower hard strata, the cutterhead of the shield machine rotates counterclockwise. When the contact hard soil area on the right side of the cutterhead is greater than, less than or equal to the left side, the cutterhead of the shield machine is subjected to the overall resultant force of the excavation face reaction force to the lower left, upper left and left respectively. When the cutterhead of the shield machine rotates clockwise, the force direction is opposite. ( 3 ) When the shield machine excavates the soft and hard uneven strata, the cutterhead should be changed frequently, and the positive and negative rotations are alternately excavated. ( 4 ) The attitude change of the shield machine in the stratum is affected by its inherent attitude and the force of the shield machine.