Prediction and Analysis of Earth Pressure Balance Shield Machine Advancing Speed in Limestone Stratum

Objective The advancing speed of shield machine is crucial not only for the tunnel excavation pace but also for the predicting construction schedule and cost. Therefore, it is necessary to predict and analyze the advancing speed of the shield machine. Method Taking the full-section limestone stratum of Longao Station-Olympic Sports Center West Station interval on Jinan Metro Line 3 as research object, data from shield machine excavation are collected and preprocessed using methods such as zero-push value, outlier removal, and data denoising. To improve prediction accuracy, the dataset is divided into training and validation sets. A model for predicting thrust speed is established from linear regression based on cutterhead torque and total thrust, and the influence law of excavation load on advancing speed is analyzed. Result & Conclusion In limestone stratum, the linear regression prediction accuracy of three advancing speed prediction models all exceeds 0.70, indicating that advancing speed can be accurately predicted based on cutterhead torque and total thrust. During excavation with the earth pressure balance shield machine, fluctuations in cutterhead rotation speed and advancing speed are minimal. As the cutterhead rotation speed increases, the cutterhead torque gradually decreases. Cutterhead torque positively influences the advancing speed; the greater the cutterhead torque, the higher the advancing speed. Under the same stratum and excavation conditions, due to the soil extrusion action of cutterhead, merely increasing the total thrust is not conducive to improving advancing speed, calling for the necessity of simultaneously increasing cutterhead rotation speed.