| Located in the north of Chaohu Lake,Hefei Binhu New Area is distributed with lacustrine soft soil layer,which contains a large number of muddy soil and silt with high moisture content and low strength.If engineering construction is to be carried out on this kind of soft soil,it must be solidified.Cement solidified soil has been widely used in engineering construction,but the carbon dioxide emitted in the process of cement production seriously exceeds the standard,which is not conducive to the realization of China’s"double carbon"goal and consumes serious energy.Therefore,it is necessary to choose low-carbon and low-energy green soft soil curing agent to replace cement for soft soil curing treatment.Ground Granulated Blast furnace（GGBS）is the industrial waste slag discharged from the Blast furnace of iron making.Its composition is similar to cement and it has potential hydration activity.It not only has lower energy consumption and carbon emissions in the production process than,but also can be reused as industrial waste slag at a lower cost than cement.Therefore,it belongs to the green soft soil curing agent.In this paper,the green soft soil curing agent GGBS is used to study the curing treatment of lacustrine soft soil in the Hefei area.The second-order model of solidified soil strength was established based on the box-behnken design method,and the optimal ratio of the solidifying agent was determined by variance analysis of the second-order model.Through unconfined compressive strength and dry-wet cycling tests,the influence of various factors and dry-wet cycling on the mechanical properties of solidified soil was studied.The main research contents and conclusions are as follows:（1）GGBS was used as the main curing agent,calcium carbide slag and sodium sulfate（Na2SO4）were used as the activator,and the dosage range of each additive was determined preliminarily through the single doping test,which was 8%～14%,0.5%～2.5%and 2%～6%,respectively.（2）Based on the box-behnken design method for experimental Design,Design-Expert software was used to establish a second-order model with three additives,taking the amount GGBS,calcium carbide slag and sodium sulfate as impact factors,unconfined compressive strength of 7days and 28days ages GGBS solidified soil as target response values.Through analysis of variance,single factor effect,interaction and internal mechanism,the optimal ratio of GGBS,calcium carbide slag and sodium sulfate is determined as 12.18%,2.30%,5.31%.（3）It is believed that different curing agent ratios,curing age and initial water content make much difference to the strength of GGBS cured soil,the effects were analyzed using unconfined compressive strength test.It was showed that,the different proportion of curing agent will affect the hydration activity of GGBS.Only under the optimal proportion,the hydration reaction of GGBS is the most sufficient and the strength of solidified soil reaches the maximum;the strength of solidified soil increases with the increase of curing age;with the increase of the initial water content of soil,the strength of solidified soil generally increases first and then decreases,and the strength of solidified soil reaches the maximum when the initial water content of soil is 44%.（4）By studying the stress-strain characteristics of solidified soil under different curing agent ratio,curing age and initial water content of soil,it is obtained that the stress-strain curves of solidified soil show a change trend of first rising and then falling,and all include plastic stage,failure stage and residual stage.When the ratio of curing agent is the best,the failure strain of solidified soil is the smallest and the peak stress is the largest;with the increase of curing age,the plastic stage of stress-strain curve of solidified soil gradually shortens;when the initial water content is low,the stress-strain curve of solidified soil shows the characteristics of strain softening,and when the initial water content is high,it shows the characteristics of plastic failure.（5）It was analyzed what the mechanical properties of GGBS solidified soil would be under the condition of drying-wetting cycle,using the method of the drying-wetting cycle test.It was showed that the more the drying-wetting cycle was,the worse the quality of solidified soil would be,with the quality gradually stabilized after three times of drying-wetting cycles,and the better the strength of solidified soil.What’s more,the stress-strain curves of solidified soil all took on a characteristic of strain softening.Figure[39]Table[16]Reference[77]... |
