Experimental Study On The Performance Of Flowable Engineering Soil Based On Muck

The muck in this study is mainly the engineering abandoned soil generated by underground engineering excavation,foundation pit excavation and subway construction.With the development and construction of the city,the amount of muck increases rapidly.Improper disposal of muck can have a significant impact on the environment.Therefore,the utilization of waste soil resources is particularly important for building a green and conservation-oriented society.In this paper,28 kinds of ratio design were carried out with muck,cement,rosin type plant blowing agent and activated magnesium oxide as raw materials.To optimize the performance of fluid engineering soil,obtain both fluidity and strength of fluid engineering soil.In order to improve the fluidity and mechanical properties of fluid engineering soil,the influence of different proportions on the performance of fluid engineering soil was analyzed.The contents are as follows:（1）According to the fluidity test method,the fluidity test of the modified fluid engineering soil with foam agent and active magnesium oxide was carried out,including the time loss of mobility,bleeding rate and the density change of the solidified sample.From the perspective of analyzing the fluidity of the improved fluid engineering soil,the fluidity of the mixed liquid soil with different proportions was compared.It is proved that adding appropriate amount of foam can improve the fluidity and water retention of the mixture and reduce the density of the solidified sample.When the foam content is 3%,the fluidity loss of the mixture is the smallest and the water retention is the best.The fitting formula is obtained by fitting the flow time loss curve:Y=a X^5.0+b.According to the fitting formula,it is predicted that the fluidity of the fluid engineering soil mixture tends to be stable after 3 h.（2）The stress-strain curve of solidified sample of modified fluid engineering soil was obtained by triaxial compression test.From the perspective of analyzing the strength characteristics of solidified samples of fluid engineering soil,get the ratio of solidified specimen under stress-strain curve and curing strength,combined with the fluidity of the changing law of proportion of recommendations.Compared with the sample without active magnesia,the failure strain of the solidified sample with 3%active magnesia content is the largest,and the solidified strength of the sample at 28 days can reach 1.20 MPa,which increases by 26.7%.（3）The strain field nephogram was drawn by the triaxial image measuring system,and the local and global failure characteristics of the sample were analyzed combined with the apparent failure characteristics of the sample.By comparing the samples before and after failure,it can be seen that the samples affected by water-cement ratio and foam content have three different failure modes.When the foam content is 0,the splitting failure occurs;when the foam content is 3%and 5%,the shear failure occurs;when the foam content is 7%,the compression failure occurs.With the increase of foam content,the failure mode of the sample changes from splitting failure to shear failure,and then to compression failure.In summary,the optimal mix ratio of the mixture was analyzed.The ratio of cement to soil is 15%,the content of 3%and 5%foam and 3%activated magnesium oxide are the best to improve the fluidity and mechanical properties of the mixture.Therefore,by adjusting the ratio of cement to soil,the amount of foam,and the amount of active magnesium oxide,the fluid engineering soil with fluidity between 180 mm and 320 mm,bleeding rate within 5%,and 28-day curing strength between 0.6 MPa and 1.2 MPa can be obtained.It is of great significance to improve the application range of muck engineering and optimize the allocation of resources.