Abstract
The mud cake is easily formed during the tunnel boring machine (TBM) excavation in clay soils or rocks containing clay minerals. Mud cake will lead to soil disturbance of tunnel face, clogging cutterhead and even affect the construction efficiency and personnel safety. In this study, a discrimination method of mud cake formation based on cutterhead temperature was proposed. An online monitoring system was designed and installed on the slurry balance TBM. The results show that: (a) the cutterhead temperature data can be reliably detected and transmitted by the system; (b) in a tunneling cycle, the temperature at some positions of the cutterhead will increase first and then decrease; (c) during the field test, the temperature variation is around 2.5 °C under the normal condition, but the temperature variation will increase more than 50 °C due to the mud cake or geological change; (d) compared with the cooling rate, mud cake formation can be accurately discriminated.
Highlights
The mud cake is formed during the tunnel boring machine (TBM) excavation in clay soils or rocks containing clay minerals
Earth pressure balance (EPB) TBMs and slurry balance TBMs are mainly used for soft soil
The stability of the cutting surface of these TBMs needs to be ensured by the support fluid
Summary
The mud cake is formed during the tunnel boring machine (TBM) excavation in clay soils or rocks containing clay minerals. Mud cake will lead to soil disturbance of tunnel face, clogging cutterhead and even affect the construction efficiency and personnel safety. A discrimination method of mud cake formation based on cutterhead temperature was proposed. Thewes et al.[18,19] proposed a series of methods to prevent and relieve clogging and applied them to EPB shield TBMs. Zumsteg et al.[20,21] quantified and explained the limited efficiency of existing conditioning chemicals, by which an enhanced interaction mechanism is proposed to reduce soil viscosity. Few researchers paid attention to the monitoring of cutterhead temperature, and there was little data to analyze the formation of mud cake by temperature. The existing monitoring system can be used as the basis for designing the cutterhead temperature monitoring system
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