软弱地层管棚法施工中管棚作用空间分析

针对软弱地层管棚法施工过程,从棚架体系视角,建立了可用来分析管棚作用的空间分析模型。该模型可考虑施工过程、管棚与支护之间相互作用以及网喷混凝土早期弹性模量随时间逐渐变化特性等。以上海地铁某车站出入口工程作为实例,对管棚防止掌子面坍塌和控制地层沉降的作用机理进行了分析。计算表明:在棚架体系分析中,考虑网喷混凝土早期特性是必要的。管棚防止坍塌和控制沉降主要是通过注浆,以及棚架体系在纵向和横向对开挖释放荷载重新分布和调节来实现的。

3D analysis of function of piperoof applied in soft ground

Based on the concept of piperoof-support system, a 3D analysis model was developed for the insight to the function of piperoof applied in underground engineering of soft ground. The factors of construction procedure, interaction between the piperoof and support, in addition to the the stiffness and strength properties of shotcrete at early ages, could be taken into account in the 3D analysis model. Taking a subway of a metro station located in Shanghai as an example, the function of piperoof used to prevent the collapse of face and to control the ground settlement was analyzed. It was demonstrated that it was necessary to take the time effect of shotcrete at early ages into account, and the function of piperoof was implemented by redistribution of the released load by excavation in longitudinal and transversal direction, in addition to the grouting.