大断面矩形顶管施工地层变形及顶进参数控制研究

Study on Stratum Deformation Caused by Large-section Rectangular Pipe Jacking and Jacking Parameter Control

以武汉地铁7号线顶管工程为依托,建立顶进施工地表沉降数值模型,分析顶进力与地层变形之间的关系。对比不同顶管施工过程中的土压、推力及地层沉降数据,总结埋深与地质条件对顶进参数的影响规律。研究结果表明:(1)顶管施工时,土体扰动引起地表沉降或隆起,并导致管道下方2D~4D范围内的土体隆起(D为管道高度);(2)掌子面前方地表在附加顶进力的作用下出现隆起,后方土体由于开挖卸荷作用产生沉降;(3)在机头正前方1H(H为埋深)处地面出现隆起峰值,掌子面后方5 m范围内地表沉降变化较快;(4)随着附加顶进力的增大,机头正上方地表沉降减小,当顶进力大于20 000 kN时变化值逐渐变小,变化幅度不大。

Based on the pipe jacking works of Wuhan Metro Line 7, a numerical model for ground settlement during jacking construction was established to analyze the relationship between the jacking force and the stratum deformation. The data of earth pressure, thrust and stratum settlement during the construction of different pipe jacking works were compared, and the law of the influence of burial depth and geological conditions on jacking parameters was summarized. The study shows that(1) during pipe jacking, soil disturbance causes ground settlement or uplift and also leads to soil uplift within the range of 2D~4D below the pipe(D is the pipe height);(2) the surface in front of the tunnel face uplifts by the action of additional jacking force, while the soil behind the tunnel face settles by the action of excavation unloading;(3) the uplift peak appears on the ground 1H(H is the burial depth) right in front of the head of pipe-jacking machine, and ground settlement changes quickly within 5 m behind the tunnel face;(4) as the additional jacking force increases, ground settlement right above the head of pipe-jacking machine is reduced, and when the jacking force is greater than 20 000 kN, the variation gradually decreases and the amplitude of variation is relatively small.