Abstract:

Dehydration technology is the main method of shield tunnel spoil reduction, and it is of great significance to analyze and summarize various dehydration technologies of shield tunnel spoil at the present stage. Based on the nature of shield tunnel spoil and its water retention mechanism, five indicators for evaluating spoil dehydration performance, including specific resistance to filtration, capillary suction time, sedimentation rate, permeability coefficient, and water content are summarized. Three main types of dehydration technologies are expounded emphatically, namely, mechanical dehydration, drying dehydration, and seepage dehydration. Furthermore, the dehydration effects, applicability, and limitations of various methods are analyzed. The mechanical dehydration technology is relatively mature for shield tunnel spoil with low clay content. Highefficiency conditioners shall be added to enhance dehydration performance for shield tunnel spoil with high clay content. Currently, the high cost and pollution treatment of conditioners are urgent issues that must be solved. Natural drying evidently falls short of meeting the requirements on efficiency and environmental sustainability. Although dehydration by heat drying has a wide range of applications and is relatively complete, it has the disadvantages of high energy consumption and cost. In the seepage dehydration technology, the geotextile tube bag method and the vacuum preloading method exhibit superior dehydration effects for spoil with high permeability. The electroosmosis method can be applied to lowpermeability clay. However, its drawbacks, such as high power consumption and susceptibility of electrode corrosion, can hardly be avoided. Currently, the main issues in dehydration of shield tunnel spoil include insufficient equipment adaptability, high energy consumption, difficulty in operation and maintenance, low utilization rate of spoil resources, challenges in promotion and application of new technologies, and incomplete treatment standards. In the future, emphasis should be placed on the intelligentization, modularity, and integrated and scaled development of dehydration equipment. Meanwhile, efficient utilization of spoil resources should be achieved. Unified dehydration standards should be established, and efforts should be made to encourage engineering application and promotion of new dehydration technologies.