Abstract: The shield muck dehydration has disadvantages such as long processing time, low efficiency, and environmental pollution caused by chemicals. Therefore, a novel material composed of liquid dimethyl ether and triguaiacyl phosphite(DMETTFP) is developed to dehydrate shield muck using phase change method, and the influence of different DMETTFP amount and reaction time on dehydration effect is examined. The composition, particle size distribution, and morphology of shield muck before and after dehydration are characterized by Xray diffraction, Xray fluorescence spectroscopy, scanning electron microscopy, and specific surface area analysis, respectively, and the moisture morphological variations of the shield muck during dehydration process is analyzed. The results demonstrate the following: (1) The amount of DMETTFP incorporation and treatment time considerably affect the dehydration of shield muck. The moisture content decreases with increasing amount of liquid DMETTFP incorporation and treatment time. (2) The moisture content of the muck can be stabilized at approximately 23% when the mass ratio of liquid DMETTFP to moisture in the muck is set at 8 with a dehydration time of 1520 min, resulting in an optimal dehydration state. (3) The particle size distribution of the muck after dehydration is relatively constant, and DMETTFP cannot be found in muck, which exhibits favorable reusability and weak contribution to the composition of the shield muck. (4) The free water would preferentially be detached during early stage of dehydration, and almost completely disengaged in the middle and later stages. Then partial bound water could be gradually detached, and the removal efficiency of bound water attained more than 35%.

Key words: tunnel, shield, muck dehydration, phase change, clean production