Dynamic Behavior and Energy Evolution Characteristic of Deep Roadway Sandstone Containing Weakly Filled Joint at Various Angles

Abstract

Dynamic impact tests were carried out by implying split-Hopkinson pressure bar (SHPB) apparatus under three-dimensional stress state to investigate the influences of weakly filled joint at seven kinds of angles on dynamic behavior and energy evolution characteristic of deep roadway sandstone (985 m below the surface). The results indicated that rebound strain phenomenon was obvious and the growth rate of stress was in two kinds of phased variations. Dynamic peak strain was inversely proportional to joint angle under three different strain rates. Dynamic compressive strength, elastic deformation modulus, and plastic deformation modulus were in similar variable tendencies with incremental joint angles, showing firstly decrease to minimum value at joint angle of 45° and then increase to maximum value at joint angle of 90°. Moreover, the sensitivity of plastic deformation modulus to joint angle was obviously inferior to that of elastic deformation modulus when joint angle increased from 0° to 45°. Furthermore, both elastic deformation modulus and plastic deformation modulus were independent of strain rate, which was contrary to dynamic compressive strength and dynamic peak strain. Additionally, absorption energy release rate was introduced and defined to describe energy release and conversion characteristics of joint specimens. The changed trend of energy reflection coefficient was completely opposite to that of energy transmission coefficient and absorbed energy release rate. Absorbed energy density was linearly decreased with incremental joint angle and was increased with the increase of strain rate.

Strength Recovery Effect of Bisphenol A Epoxy Resin E44 on Rock Masses with Various Crack Widths

“…To better explore the repair efect on rock masses with diferent crack widths, artifcial fractures need to be prepared in laboratory tests [9,21]. Standard rock samples of Φ50 * h100 (mm) were cut at the middle position along a line at 45 °with respect to the horizontal direction [55], with a total length of 70.7 mm. Te cracks along the height direction were 1 mm, 3 mm, 5 mm, and 7 mm in size.…”

Review of SHPB Dynamic Load Impact Test Characteristics and Energy Analysis Methods

“…The principle of the special-shaped impact bar method is to change the shape of the impact bar so as to change the shape of the incident wave. Generally, spindle-shaped impact bars and tapered impact bars are used [61][62][63][64][65][66][67]. Figure 4 shows the different types of impact bars.…”

“…The principle of the special-shaped impact bar method is to change the shape of the impact bar so as to change the shape of the incident wave. Generally, spindle-shaped impact bars and tapered impact bars are used [61][62][63][64][65][66][67]. In view of the current situation of the research and application of the pulse-shaping technique, the relevant domestic and international literature was analyzed.…”