Interface Mechanical Model of Mineral Fiber-Resin Coated Sand

To further understand the enhancement mechanism of the fiber-resin coated sand control technique,the interfacial mechanical properties of fiber and resin coat were analyzed.The shear-lag model of fiber-reinforced composites was used to analyze the interfacial mechanics of single fiber-resin infinitesimal element.Then,this model was modified according to the characteristics of the mineral fiber-resin coated sand,into a shear-lag mechanical model that could quantify the compressive strength of the fiber-resin coated sand.SEM showed that there were a large number of micro-cracks and micro-pores resulting from resin shrinkage and pellet porous structure,which enabled the stress concentration in the sand body and made its compressive strength only 2.75 MPa(60 ℃)and 8.88 MPa(80 ℃).Point contact existed between mineral fiber and resin coated sand,with net bond length approximately 0.3 mm at each point.The compressive strength of the fiber-resin coated sand with 0.2% mineral fibers was 0.92 MPa higher than that of blank sample.The results proved that there was a hyperbolic tangent function relationship between the maximum shear stress and the effective bond length of fiber,and the effective bond length of fiber was equal to the radius of the resin coated sand.The modified model provided a more reasonable explanation of mechanism of the fiber-resin coated sand from the perspective of interface mechanics,and allowed the quantitative calculation of the compressive strength of fiber-resin coated sand with a appropriate fiber content in a small error range.