南宁地铁一号线土建五标盾构区间地层以圆砾为主，多次发生刀盘被困及螺旋输送机被卡的现象。在盾构机脱困过程中多次出现沉降过大，甚至产生塌方风险。为解决上述问题，经反复研究、实践，通过向盾构机土仓内添加一定比例的渣土改良溶液，起到增加渣土细颗粒，悬浮圆砾的作用，同时也可防止圆砾大量堆积在土仓内，造成刀盘被困或螺旋输送机被卡。配合渣土改良优化掘进控制技术，解决了盾构机在圆砾地层掘进过程中的诸多难题。%Nanning Metro Line 1 No.5 Section is mainly covered with round gravel layer,the cutting wheel is often trapped and the screw conveyor is jammed during construction.Some risks such as excessive settlement and collapse are occurred frequently when the shield machine escaping from difficulty.In order to solve the above problems,the project is researched and practiced repeatedly,it is concluded that soil improvement is the key to solve the problem.Round gravel layer is im-proved by adding a certain proportion improving agent in it,it plays a part in increasing fine particles and suspend round gravel,preventing round gravel piling in the soil chamber and trapping the cutting wheel or jamming screw conveyor.By u-sing optimized soil excavation control technology,the improved soil can be transported smoothly in the process of shield ex-cavation.
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