Experimental Study On Reinforcement Technology Of High Water Content And Large Thickness Soda Residue Foundation

Soda residue is the waste residue of the soda production using the ammonia-soda process technology.Year after year,the residue has been piled up and becomes the "Soda Residue Hill".The #3 Soda Residue Hill is the largest soda residue storage yard in Tianjin Port,which is about 20 m high.It has hindered the development of Tianjin Port.Therefore,how to dispose of this hill is an urgent task.In recent years,the soda residue has been used in replacing the engineering soil,which brings about huge economic and social benefits.Due to the limitation of transportation conditions and the requirements of environmental protection,used the method of digging and filling to dill with the soda residue.The soil which is replaced can be used as engineering soil by a simple treatment,and landfill residue also can be used as container yard foundation after reinforcing.The soda residue's water content is very high,and the slag pit's depth is large,so forming the high water content and deep soda residue foundation after finished filling.Because of its high water content and large thickness,it is very important to find a suitable reinforcement method.The soda's water content is very high and the permeability is good,so it is suitable for reinforcing by using the method of preloading drainage.Preloading methods mainly include the vacuum preloading method,the stack preloading method,the well point precipitation method.Research and engineering practice shows that the soil skeleton stiffness formed by residue particles is large,after using single preloading method to reinforce,the water content is still very high,resulting in the soda foundation has great settlement after construction.This paper develops a set of test apparatus for simulating various consolidation preloading methods' mechanism,the strengthening mechanism and effect of various preloading methods and their combined effects are studied by laboratory experiments,and verifying the feasibility of reinforcement mechanism of preloading method for soda residue with high water content and the superposition of reinforcement effect.Secondly,according to Terzaghi's one-dimensional consolidation theory,deduced the analytical solution of the positive pressure alone(stack preloading),negative pressure alone(vacuum preloading)and positive and negative joint pressure(stack-vacuum combined preloading),and provided theoretical calculation method for reinforcing soda residue by preloading consolidation methods.In addition,making a large scale field experiment for reinforcing the soda residue,obtained the reinforcement effect and the feasibility of comparative analysis of graded stack preloading,vacuum preloading,well point precipitation,analyzing the changes of strength under different treatment methods influenced by the external environment,developed construction method of the high water content of soda foundation treatment.Results can provide a scientific theoretical basis and engineering demonstration for the development of strengthening technology of Tianjin port area high water content and deep soda residue.