| In view of the low early strength,brittle failure and other defects,meeting the needs of global environment protection,nergy conservation and emissions reduction,it is urgent to find a new kind of modified material to solve these problems.Enhancement type graphene,as a new nanomaterial,will become a new trail to be applied to cement soil because of its excellent mechanical properties.Based on the experimental research,this thesis discussed the modification mechanism of enhancement graphene with the microscopic experiments,which will provide a certain reference for modification of cemented soil with nanomaterial.(1)On the basis of summarizing the research status of nanomaterials in the field of civil engineering,combining with SEM test,EDS test and XRD test,the microstructure characteristics of enhanced graphene was analyzed.The results show that the particle size of reinforced graphene is extremely small,the surface atoms are incompletely coordinated,and it has high activity;based on the interaction mechanism of soil,water and cement paste in the enhanced graphene cement soil,the modification mechanism of graphene will be enhanced.Summarized as: filling effect,adsorption and cementation and active catalysis.(2)The influence of enhancement graphene content on the early strength of cement soil was discussed and investigated by unconfined compression strength tests and unconsolidated-undrained triaxial test.The test results show that the strength of cement soil is significantly improved by adding 0.05% of enhancement grapheme.According to the test results,the deformation characteristics and failure characteristics of cemented soil with enhancement graphene were analyzed.The results show that enhancement type graphene can limit the propagation of internal cracks in the sample to a certain extent and enhance the deformation resistance of cemented soil.(3)Finally,through the analysis of damage mechanism and damage performance,the macroscopic damage characteristics of cemented soil with enhancement graphen were analyzed.Then,the elasto-plastic damage correction model was established,and the damage evolution law was analyzed.The results show that,in damage phenomenon,the damage process is mainly divided into two parts: local damage and overall damage.Comparison of the calculated stress-strain curve with experimental curves suggests the damage variable and modified damage model proposed can well reflect the damage characteristics of cemented soil with enhancement graphene. |
