Cutting depth of pile materials subjected to the abrasive waterjet and its prediction model

摘要

Very limited study is available on the use of the abrasive waterjet in cutting the civil engineering structures such as the piles as compared to the use in rocks or metal. In this study pre-cutting of the reinforced concrete (RC) retaining piles by the abrasive waterjet is proposed to guarantee the operation of both the existing station and shield tunnel. The shield tunnel of Shenyang Metro Line 4 which has to underpass the existing metro station and needs to cut 37 RC retaining piles is taken into consideration in this study. Experiments of reinforced pile materials (i.e., rebar and concrete) subjected to the abrasive waterjet are carried out, which indicates that the cutting depth of the rebar increases with the decrease of the traverse speed. When the standoff distance (SOD) is within 30 mm, the effect of SOD on the cutting depth of the rebar can be ignored. However, when SOD is in the range of 30-100 mm, the cutting depth of the rebar decreases dramatically with the increase of SOD; when SOD is beyond 300 mm, abrasive particles are ineffective in cutting. The cutting behaviour of the concrete is heavily dependent on the coarse aggregate on its cutting path. Finally, the prediction model of the cutting depth of the rebar is proposed, which helps the determination of the optimal cutting number and provides some theoretical basis for the construction of shield tunnelling when encountering RC piles.