Study On Solidification Treatment And Application Of Engineering Waste Mud

A large amount of waste mud will be produced in pile foundation,underground continuous wall and tunnel shield,which is characterized by high water content,many viscous particles and certain pollution.For the disposal of waste mud,long-term storage needs to occupy a large number of construction sites.In-situ burial will pollute groundwater and harden the land.The transportation distance is long and the cost is high.Based on the actual situation that it is difficult to dispose of waste mud,this paper combines the construction site of Fujiayao to Kushui highway.From the perspective of environmental protection,waste utilization and capital saving,the waste mud is first flocculated and dehydrated,and then the bottom soil is solidified.The feasibility of using it as the subbase of pavement is discussed,which can provide reference for similar projects.The main research contents and results are as follows :(1)Remove 500 ml waste mud,its moisture content is 85 %.Two kinds of flocculant,polyaluminum chloride and polyacrylamide,were selected to carry out flocculation dehydration test by single mixing and double mixing.On the basis of comparing the key indexes such as flocculation efficiency,floc size and supernatant p H value,the optimum dosage of flocculant was 3.5g polyaluminum chloride and 22 ml polyacrylamide.(2)For the dehydrated subsoil,the high-strength environment-friendly CG-T1 curing agent and cement were selected to solidify it.According to the three categories of CG-T1 curing agent,cement and CG-T1 curing agent + cement curing,a total of 12 groups of samples were tested.After compaction test,7-day unconfined compressive strength and California bearing ratio test,SN-5(cement 5 %)and ISSN4(4 % cement + 0.02 % CG-T1 curing agent)were determined to be reasonable curing agent dosage under the condition of meeting the ’ Highway Asphalt Pavement Design Specification ’(JTG D50-2017).(3)In order to further study the durability of solidified subsoil,the dry-wet cycle and freeze-thaw cycle tests were carried out on SN-5 and ISSN4 samples.The strength and mass loss of the samples after multiple cycles were used as the evaluation criteria,and the durability of ISSN4 samples was better.At the same time,the results of nuclear magnetic resonance test showed that the porosity of ISSN4 sample was significantly lower than that of SN-5 sample,and ISSN4 was determined as the optimal curing agent.(4)In order to explore the feasibility of solidified sub-soil for pavement subbase,ABAQUS finite element software is used to establish subgrade and pavement model.All the subbase of the pavement is filled with solidified sub-soil,and the thickness is 10 cm,20 cm and30 cm respectively.The uneven settlement of the pavement,the vertical displacement of the subgrade,the vertical stress and the tensile stress at the bottom of the subbase layer of different subbase thickness models are calculated and analyzed.From the perspective of meeting the requirements of the specification and economy,the solidified sub-soil is used for the pavement.When the thickness of the subbase is 20 cm,the road effect is good.