Dynamic compression performance of carbon fiber reinforced grout and its numerical simulation
In order to study a large number of fine fractures in sand layer,the graded gravel was selected as the injected material,and carbon fiber modified superfine cement grout was used as grouting material,which was tested in laboratory.The grouted cemented body(GCB)was used as a research object.Dynamic compressive mechanical properties of grouting samples and toughening mechanism of carbon fiber(CF)of different strain rate were studied with the help of split Hopkinson pressure bar(SHPB)impact test and scanning electron microscope(SEM)test.The research conclusions are as follows:With the increase of strain rate,the dy-namic compression enhancement effect of 1％CF gradually becomes larger,the number of bro-ken pieces of GCB gradually increases,but the scale of broken pieces gradually decreases.Basi-cally,LS-DYNA simulated results are consistent with the SHPB test results of GCB,the ener-gy dissipation rate of GCB under dynamic compression shows no relation with the strain rate,and fluctuation range is about 40％.The energy dissipation of cement slurry accounts for more than 85％of the total energy dissipation,besides,the energy dissipation rate of 1％CF-GCB is slightly higher than that of 0 CF-GCB.According to the SEM images,the failure modes of car-bon fiber are mainly debounding failure and a few are damage failure.Carbon fibers can absorb energy by debounding or damaging failure from the grouting sample and prevent its failure,and change the path of microcrack growth,so as to improve the overall mechanical properties of the grouting sample.The numerical model of carbon fibers that are randomly distributed is established by MATLAB,and the carbon fibers in different positions and angles in the GCB grouting samples are subjected to large differences of axial stresses.With the increase of the an-gle between the fibers and the impact direction,main bearing mode of the carbon fibers gradu-ally changes from compression status to tension status.
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