Research On Applicability Of Physicochemical Composite Method In Solidification Treatment Of Mud(Slurry)

The dredged mud(slurry)produced by water environment treatment projects often has problems such as ultra-high water content,low strength,poor permeability and heavy metal element pollution,which cannot be directly used.At present,an ideal way to absorb this kind of dredged mud(slurry)is to make resource utilization after treatment in the dumping sites.However,due to the poor effect of direct solidification modification of the dredged mud slurry at extra high water content(referred to as EHW-MS from hereon),it is difficult to make resource utilization.In this regard,our research group proposed two forms of physicochemical composite methods: flocculation-solidification combined method(referred to as FSCM from hereon)and vacuum preloading-flocculation-solidification combined method(referred to as VP-FSCM from hereon).The former aims to promote the rapid formation of a hard shell working platform on the surface of the EHW-MS dumping sites,while the latter aims to realize EHW-MS of the dumping sites efficient modification utilization as engineering fillers.At present,the existing achievements of our research group have well demonstrated the feasibility of the two methods under specific conditions,but the understanding of their respective scope and laws of application is not in-depth,which restricts the process of popularization and application.In view of this,this paper deeply discusses the applicability of the two methods through a series of geotechnical tests.The specific work content and main conclusions are as follows:(1)Based on laboratory cylinder sedimentation tests and mechanical model tests,the influence of the Atterberg limits indexs on the self-weight sedimentation and mechanical properties of EHW-MS treated by FSCM was studied,and the applicable law of FSCM in EHW-MS treatment with different Atterberg limits indexes was obtained.Results indicate that: the higher Atterberg limits index of EHW-MS is,the more significant the treatment efficiency advantage of FSCM is compared with pure cement solidification(referred to as PCSM from hereon);in the case of cement,EHW-MS and flocculant types selected in this paper,"plastic limit is more than 10.60%,liquid limit is more than 17.54%" can be used as a reasonable Atterberg limits range for FSCM treatment EHW-MS(in this range,the solidification efficiency of FSCM is more than 1.20 times that of PCSM).(2)Based on laboratory cylinder sedimentation tests and mechanical model tests,the influence of the equivalent initial water content on the self-weight sedimentation and mechanical properties of EHW-MS treated by FSCM was studied,and the applicable law of FSCM in EHW-MS treatment with different equivalent initial water content was obtained.Results indicate that: the higher equivalent initial water content of EHW-MS is,the more significant the treatment efficiency advantage of FSCM is compared with PCSM;in the case of cement,EHW-MS and flocculant types in this paper,"equivalent initial water content is more than 279.65%" can be regarded as the reasonable equivalent initial water content range applicable to FSCM.(3)Based on laboratory vacuum preloading model test,the influence of equivalent initial water content on the sedimentation consolidation and mechanical properties of EHWMS treated by VP-FSCM was studied,and the applicable law of VP-FSCM in EHW-MS treatment with different equivalent initial water content was obtained.Results indicate that: the higher equivalent initial water content of EHW-MS is,the more significant the treatment efficiency advantage of VP-FSCM is compared with vacuum preloading-pure cement solidification(VP-PCSM);in the case of cement,EHW-MS and flocculant types in this paper,"equivalent initial water content is more than 148.71%" can be regarded as the reasonable equivalent initial water content range applicable to VP-FSCM.