Disturbance analysis of shield tunneling in clay and limestone composite strata using EDEM simulation

With the mass implementation of rail transit engineering, the tunnel constructed by the shield method will inevitably pass through increasingly complex strata. Compared with single formation, studying the disturbance rule of shield tunneling in composite formation is more difficult. This paper takes the shield section of Jinan Metro Line R3 from Olympic Center West Station to Dingjiadong Station as an example, adopts EDEM simulation to simulate the shield tunneling process of clay-limestone composite formation, and studies the transverse and longitudinal settlement of composite formation under different stratification coefficients. Based on Peck's empirical formula, an improved Peck formula suitable for the surface settlement prediction of composite formation is proposed. The disturbance law of clay-limestone composite stratum caused by shield tunneling is revealed. The results show that the horizontal and longitudinal settlement increases with the increase of the stratification coefficient. When the delamination coefficient increases from 0.2 to 0.8, the maximum lateral displacement increases by 1.03 times, and the maximum longitudinal displacement increases by 0.99 times. The maximum transverse settlement occurs at the central axis of the tunnel. The longitudinal settlement increases gradually with the arrival, passing, and departure processes of the shield machine. The calculation result of the modified Peck formula accords with the law of practical measurement and numerical simulation. The relevant research can provide theoretical support for similar shield construction and has important reference significance for shield tunnel construction under similar geological conditions in China.