软岩地层泥水盾构掘进刀盘堵塞现象研究

Study on Clogging Phenomenon on Cutterhead of Slurry Shield Machine Tunneling Under Soft Rock

软岩地层(黏性矿物含量高)泥水盾构掘进刀盘堵塞现象(刀盘结泥饼)时有发生,不仅影响施工进度和质量,而且开舱处理风险较大,可能会导致人身伤亡或工程事故。为了探明刀盘堵塞现象及其影响因素,实现对刀盘堵塞的有效预防和治理,研发了一套软岩地层泥水盾构掘进模型试验装置。在自行设计、制作的模型试验平台上,选用以膨润土、高岭土、石英砂、水泥和水为原材料制备的人工软岩模拟实际工程中的软岩地层,分别采用不同人工软岩类型、盾构掘进速度、刀具突起高度及形式和泥水(清水)冲刷流量等进行盾构掘进模拟,实现刀盘堵塞现象的室内再现。通过分析盾构扭矩、推力和掘进距离间的关系,提出以扭矩指数和扭矩指数在盾构掘进距离上的增长率为指标的盾构掘进期刀盘堵塞现象发生的判断依据。试验结果表明:当模型盾构扭矩指数为0.10 m,且增长率达到0.40时,刀盘即发生堵塞;盾构掘进速度的增大,容易导致刀盘堵塞现象的发生;而刀具突起高度的降低和在刀盘面板中心设置泥水冲刷装置,对防止盾构刀盘堵塞具有较好的效果,需要说明的是,当采用泥水冲刷刀盘面板时,冲刷流量需足够大,才能确保其可对黏附在刀盘面板上的渣土进行有效剥离和输运。

The clogging phenomenon occurred frequently on the cutterhead of a slurry shield when it tunnelling under soft rock,which contains a large amount of clay minerals.This phenomenon not only delays the construction schedule and lowers the project quality,but also has a higher risk of opening the chamber,and even causing personal injury or engineering accidents.To investigate the clogging phenomenon of the cutterhead of a slurry shield machine and its influencing factors under soft rock,which contains a mass of clay mineral,a model test apparatus was designed to simulate the process of slurry shield tunnelling under soft rock.Artificial soft rock was prepared from bentonite,kaolin,quartz sand,cement,and water.The test was conducted under different conditions of artificial soft rock,driving velocity,cutter length and type,and slurry(or water)washout flux.The clogging phenomenon of the cutterhead could be observed in the tests.The torque,trust,and driving distance of the shield machine were analyzed,and it was found that the torque index and its change rate on the driving distance can be used as double indicators to judge the clogging of the cutterhead during shield tunnelling.The test results show that when the torque index and its increase rate were more than 0.10 and 0.40,respectively,the clogging phenomenon occurred.In addition,an increase in the driving velocity of the shield makes the clogging phenomenon more likely and it was also determined that decreasing the length of the cutters and the slurry washout device has a high effect in preventing the clogging phenomenon of the cutterhead.It is important to note that the washout flux needs to be large enough to ensure that the muck is stripped and carried out from the cutterhead plate.