Experiment And Theoretical Research On Vacuum Dehydration Of Waste Mud

With the acceleration of urbanization in China,the construction of urban rail transit has developed rapidly.The development of urban rail transit brings convenience to people’s life,but also brings new environmental pollution problems.At present,shield tunneling is mostly used in the construction of urban rail transit.Shield tunneling will produce a lot of waste mud.The generation,transportation and storage of waste mud will have a great impact on the urban environment.How to dehydrate and cure it effectively is the key to reduce environmental pollution during transportation or storage.At present,many scholars have studied the dewatering technology of waste mud,but due to the differences of geological conditions in different areas,the dewatering technology of waste mud is not systematic enough.In view of this,based on model test,theoretical analysis,numerical simulation and parameter analysis,the dewatering effect of two typical waste clay mud and silty clay mud produced by shield tunneling under different loading conditions is studied in this paper.Secondly,the variation regularities of settling volume and settling rate,pore water pressure,water content in layers of residual mud and drainage volume of the two waste muds during dewatering are analyzed.Finally,the dewatering effects of waste mud under different loading modes are compared.The main research contents are as follows:(1)A vacuum dewatering test device for waste mud has been developed,which can carry out indoor model test on the dewatering process of waste mud in different combination of self-weight,self-weight and bottom vacuum.(2)Based on the above theoretical model,the parameters of the dehydration process of waste mud are analyzed,and the influence of the change of initial height on the dehydration effect of waste mud is studied;The feasibility of deep dehydration of waste mud treated by the best dehydration method by overlying load is further analyzed.The results show that the settlement increases with the increase of the initial height of waste mud;The application of overlying load has a deep dehydration effect on the waste mud after staged loading and dehydration treatment.(3)Based on the idea of piecewise linearization,the one-dimensional dewatering theoretical analysis model of waste slurry is established,and the corresponding FORTRAN program is written to simulate the mud-water interface settlement and pore water pressure changes of the two waste slurries during dewatering process.The validity of the theoretical model is verified by comparing the numerical simulation results with the experimental results.(4)Based on the above theoretical model,the parameter analysis of the dewatering process of waste mud is carried out and the influence of initial height change on the dewatering effect of waste mud is studied.The feasibility of deep dewatering of waste mud treated by the best dewatering method by overlying load is further analyzed.The results show that with the increase of the initial height of waste mud,the settlement will also increase.The application of overlying load has a deep dewatering effect on waste mud treated by the best dewatering method.