Quantitative Analysis Of The Morphological Characteristics Of Pea-Gravel And Its Simulation Test Of Backfill Grouting

In the TBM tunnel project,pea-gravel is a natural pebble or crushed gravel filler with a 5~10mm particle size.In engineering,pea-gravel backfill grouting is one of the keys to the success of TBM construction.The compressive strength of pea-gravel backfill grouting solidified-body was found to be lower than that of design intensity.Based on the Water Source Construction Project of Lanzhou City,taking the morphological characteristics of pea-gravel as the research object,specifically for the time period from the beginning of pea-gravel filling to backfill grouting,combining with the factors affecting such as over-low size and rock dust content,simulated test of backfill grouting with pea-gravel sample,determining the effect of the quantitative index of the shape characteristics of pea-gravel and the porosity fraction of the accumulated body on the compressive strength of backfill grouting solidified-body,exploring the quality control of pea-gravel,in order to improve the grouting quality and strength of solidified-body by changing the distribution of pea-gravel material.(1)Quantitative indicators of particle morphology of pea-gravel were divided into three parts: particle size,three-dimensional particle shape index and angular index.Through the correlational analysis of the morphological characteristics and the porosity accumulation of pea-gravel,for pea-gravel this single particle size aggregate,the porosity of the accumulation is more sensitive to the Elongation and Angular Parameters,and the two are positively correlated.(2)Simulation test of pea-gravel backfill grouting: Using the PFC particle flow analysis software,the simulation of the gravel filling movement was carried out to understand the movement of the particles in the gap between the segments and the surrounding rock;Reference to engineering site construction technology,independently designing simulation tests for slurry perfusion simulation and realizing pressure grouting.The compressive strength of pea-gravel solidified-body with different configuration of pea-gravel was obtained by uniaxial compression experiment on core coring.(3)The single variable analysis of the compressive strength of pea-gravel solidified-body: Particle size,Elongation and Angular Parameters are proportional to the strength of solidified-body;The porosity of the gravel accumulation of pea-gravel has a great correlation with the compressive strength of pea-gravel solidified-body,the regression curves of the two are parabola-like,and this regression equation can be used to estimate the strength of solidified-body at known voidages.(4)Multivariate analysis of the compressive strength of pea-gravel solidified-body was carried out,and the Elongation and Angular Parameters in the morphological characteristics of pea-gravel were selected as regression analysis,and this can be used to estimate the strength of pea-gravel solidified-body under the known pea-gravel morphology index.According to the two points,pea-gravel quality control was performed.