Mechanism Study And Testing Of New Technology For Dewatering And Curing Engineering Waste Slurry

The large-scale development of Chinese public transport infrastructure produces a large number of engineering waste slurry every year.How to deal with the waste slurry quickly has become an important task to alleviate our environmental problems.Engineering waste slurry often has high water content,high compressibility,basically no strength and other engineering characteristics.At present,vacuum preloading and electroosmosis technology is an efficient method,and has been proved in a lot of engineering practice.However,there are some problems in traditional vacuum preloading,such as uneven reinforcement effect,clogged drainage plate and slow consolidation rate.Later soil cracking and interfacial resistance increase affect the treatment effect in electro-osmosis.Through the model test analysis under vacuum thermal consolidation,the influence of different temperature and heat source on the dewatering and curing of engineering waste slurry was discussed.According to the temperature attenuation in radial direction,the influence of different dynamic tamping time on temperature was discussed.The effect of different tamping energy on electro-osmotic consolidation was studied.The conclusions of this paper are as follows:1.The experimental study of vacuum preloading combined with thermal consolidation method is carried out.The results show that the soil consolidation can be effectively promoted by increasing the temperature within a certain temperature range,but the attenuation of heat transfer in the soil will affect the reinforcement effect of the remote soil.The introduction of thermal consolidation method effectively alleviates the clogging problem of drainage plate existing in vacuum preloading method.The microscopic image of the treated soil mass shows that the pores between soil particles increase and the permeability of the soil mass improves with the increase of temperature,which reasonably explains the thermal expansion of the soil mass during the heating process.When the heating temperature was 80 ℃ and the radial distance between the heat source and PVD was 7cm,it had the most significant easing effect on the silting of the drainage plate and the soil consolidation effect was the best.2.In order to reduce the attenuation of heat in soil,the vacuum thermal consolidation method combined with dynamic compaction test was carried out.The results show that: The temperature of the soil far away from the heat source and the consolidation effect of the soil were significantly improved after the joint reinforcement,and there was an optimal dynamic consolidation opportunity in the process of vacuum thermal consolidation combined with dynamic compaction.Combined with the microscopic image analysis of the soil after reinforcement,the optimal dynamic compaction opportunity was set at 75℃ and the settlement rate was 4cm/3d.When the compaction time is too early,the improvement of the soil reinforcement effect is not obvious,but when the compaction time is too late,the soil reinforcement effect is reduced.3.In order to reduce energy consumption,a step-by-step pressure electroosmotic consolidation test was carried out.The results show that: Compared with the traditional electroosmosis method,the overall shear strength and uniformity of the soil after the stepwise pressure electroosmosis method are higher,and the reinforcement effect of the soil after the combination of the dynamic compaction method is further improved.Combined with energy consumption and shear strength,60 J is the best dynamic tamping energy,and further increasing the dynamic tamping energy on this basis will reduce the economy of the method.From the point of view of engineering reinforcement effect and economy,the combination of step by step pressure electroosmosis and dynamic compaction is more suitable for practical application.