| With the continuous development of urban construction in China,the amount of engineering sludge generated by various types of engineering construction is increasing day by day.However,traditional treatment methods have low utilization efficiency and high costs,and the accumulation of a large amount of muddy soil not only occupies land,but also causes environmental pollution.In the field of road engineering,roadbed filling requires a large amount of high-quality fill soil.The solidification treatment of muddy soil can be applied to roadbed filling,which can not only fill the gap in raw materials of the roadbed,reduce the damage to the ecological environment caused by soil excavation,but also reduce carbon emissions caused by soil excavation and transportation,thereby promoting the achievement of the "dual carbon" strategic goal.This dissertation took the resource utilization of muddy soil as the background,used composite curing agents to solidify marine muddy soil,and used response surface methodology to optimize the ratio of composite curing agents to prepare premixed fluidized solidified soil that meets construction requirements.Conducted research on the flowability and mechanical properties of premixed fluidized solidified soil through flowability test,unconfined compressive strength test,and CBR test;The durability of premixed fluidized solidified soil was explored through tests such as dry shrinkage,dry wet cycling,and seawater immersion.The strength formation mechanism of premixed fluidized solidified soil was also analyzed using SEM and XRD.On this basis,a self-developed large-scale treatment equipment for muddy soil was used to study the construction process of premixed fluidized solidified soil,verify the outdoor mixing effect,and fill the experimental road section.The main research conclusions of this article are as follows:(1)The response surface method was used to determine the optimal mix ratio of cement,slag powder,and sodium silicate as 5%: 11%: 1% of dry soil mass.It was also demonstrated that there was an interaction between water glass,cement,and slag powder during the strength formation process of premixed fluidized solidified soil,and the interaction with slag powder was more obvious.(2)The flow expansion of premixed fluidized solidified soil decreases with the increase of the amount of solidified agent,and increases with the increase of initial moisture content.For muddy soil with an initial moisture content higher than 100%,adding an appropriate amount of curing agent can make the premixed fluidized solidified soil meets the requirements of pumping construction.(3)The compressive strength of premixed fluidized solidified soil increases with the addition of curing agent.After standard curing for 7 days,the compressive strength reached0.78 MPa,and after 28 days,the compressive strength reached 1.52 MPa.Curve fitting proved that the compressive strength of premixed fluidized solidified soil increases logarithmically with age.(4)The initial moisture content of the original sludge soil and the amount of curing agent will have an impact on the dry shrinkage characteristics of the premixed fluidized solidified soil,and the changes in early dry shrinkage strain and dry shrinkage coefficient were first rapidly increasing and then gradually slowing down;The compressive strength of premixed fluidized solidified soil gradually decreased with the increase of the number of dry-wet cycles.And there was a significant decrease after the first wet and dry cycle;The seawater immersion environment has a significant impact on the experimental group with less slag powder content;The construction process of self-developed sludge disposal equipment proves the feasibility of on-site construction of premixed fluidized solidified soil. |
