Experimental Study on Dynamic Performance of Rock-Concrete Composite with Different Thickness Ratios

Abstract

In order to study the influence of different thickness ratios on the mechanical properties of rock-concrete composite, a 50 mm diameter split Hopkinson pressure bar device (SHPB) was used to conduct impact loading tests on ϕ 50 mm × 50 mm cylindrical composite with sandstone thickness of 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 mm. The results show that with the increase of the proportion of rock in the composite, the dynamic compressive strength increases gradually, and the dynamic elastic modulus increases linearly. When the rock thickness increases, the average strain rate decreases and the peak strain decreases. In dynamic loading combination behind the rock specimen with concrete cushion, absorb energy decrease with the increase of rock accounted concrete; when the rock is 25 mm, total absorption energy reached its lowest point; when the thickness of the rock is greater than the thickness of concrete, concrete and adjacent parts of rock joint cushion absorb the energy into a rising trend. With the increase of the proportion of rock, the degree of fragmentation of the composite specimens decreases gradually, and the fragments are mostly concrete with smaller particle size, which is correlated with the dynamic compressive strength. The rock-concrete interface is a weak surface relative to the materials on both sides.

Experimental Study on the Dynamic Fracture Characteristics of Mortar–Rock Interface Zones with Different Interface Inclinations and Shapes

“…The amount of energy absorbed is defined as the energy absorption density (w), which is a measure of the ability of concrete to resist breaking under impact loading. The energy absorption density can be calculated according to Equation (18).…”

“…Recently, some scholars have investigated the interface properties in concrete materials from experimental and analytical perspectives [15][16][17][18][19][20][21]. Kaplan [22] was the first to introduce the concept of fracture mechanics in the study of crack extension.…”