Mechanism And Efficiency Of "Physicochemical Composite Method"-Based Treatment Technology For Recycling Slurry-like Mud As Filling Material

Slurry-like mud produced by various ecological engineering and capital construction projects generally has high environmental pollution risk and poor engineering mechanical properties.Conventional landfill methods and yard disposal schemes show obvious inapplicability and outstanding limitations,so it has become an urgent need to realize the recycling of slurry-like mud.At present,an ideal resource disposal way is to realize filling utilization through mud modification treatment.However,facing the engineering demand of high-performance filler,it is severely limited due to the sharp increase of disposal cost.In view of this,In order to solve the problem of high cost when slurry-like mud is modified into high-performance filler,based on chemical solidification and flocculation dehydration,this paper creatively incorporated vacuum preloading technology and put forward a set of physical and chemical composite disposal method for filling disposal and utilization of slurry-like mud:vacuum preloading-flocculation-solidification combined method(VP-FSCM).At present,the existing indoor research results have fully demonstrated the feasibility and advantages of the VP-FSCM,but the applicability for large-scale field application is not clear.In order to extend this technology to practical projects,this paper studies the reasonable formula and dosage of additives through a series of indoor model tests,and demonstrates its technical advantages and spatial distribution of strength combined with field test projects.Then,based on the benefit evaluation,the comprehensive benefit and economic rationality of the resource disposal technology of physical and chemical compound method(VP-FSCM)are quantitatively explored.The specific experimental work and related conclusions are as follows:(1)Based on mechanical model test and vacuum preloading model test,the influence law of additive formula and dosage on the strength of slurry-like mud treated by physical and chemical composite method was explored,and the suitable ratio and dosage of additive were determined.The results show that the cement excitation blast furnace slag(GGBS)is better than that of lime(Ca O),and the reasonable excitation ratio of lime(Ca O)or cement(OPC)to activate blast furnace slag(GGBS)is Ca O/GGBS=0.6(GLM)and OPC/GGBS=1.0(GCM),respectively;The dosage of PAM(w_f)in Ca O-PAM composite flocculant has a critical value range for the gain effect of undrained shear strength of the sample,and the reasonable dosage range is about 0.16%～0.20%.(2)Based on the field test of the mud disposal project,the technical advantages and strength spatial distribution law of the VP-FSCM are explored to reveal the applicability of its practical engineering application.The results show that the unconfined compressive strength of VP-FSCM treated mud can be increased by 1.44～2.54 times compared with FSCM under the condition of large-scale field test.After the VP-FSCM,the mechanical properties of the slurry-like mud increase with the spatial distance of the drainage plates narrowing,and the corresponding water content gradually decreases.Under the significant influence of vacuum loading on the surface layer of the test section,the strength of the slurry-like mud also increases to a certain extent as compared with other areas.(3)Based on the overall estimated cost of the actual mud disposal project,evaluate the economic and social benefits of resource disposal technology of physical and chemical compound method,quantitatively reveal its comprehensive benefits and verify its economic rationality.The results show that the total workload cost of the site construction unit is about RMB 72.09/m~3.Compared with the conventional yard disposal scheme and the traditional cement solidification scheme,the unit workload benefit can reach RMB12.91/m~3and RMB 14.91/m~3respectively,with significant economic and social benefits.