Farmland vegetation is commonly cultivated with uniform planting spacing and heights. The effect of these features on resistance to hydraulic erosion is unclear. Hydraulic model experiments with the angle between the crop rows and the water flow direction set at 15°, 30°, 45° or 90° were conducted to analyze variation in the law of water flow resistance under partial or complete submergence of the crop. Cultivation can impact the flow resistance on slopes and this effect was greater when the crop was partially submerged. When planting spacing, slope, and water depth were constant, the change of the water flow Darcy-Weisbach resistance coefficient f with crop row-water flow angle was f 15° > f 30° > f 45° > f 90°. This suggests that flow resistance of farmland vegetation is anisotropic. The water flow resistance coefficient of crops that were partly submerged increased with water depth, but decreased with water depth when the crop was completely submerged. At the critical change from partial submergence to complete submergence, the water flow resistance coefficient was the highest when water depth was equal to crop height. These results may be useful for optimizing farmland planting and soil and water conservation.

No abstract

The anchor bolt is a key point of tunnel design in bedded rock mass. The previous theory of anchorage support falls does not fulfil engineering requirements, and the stability of bedded rock must be addressed by empirical methods. To investigate the bolt anchoring performance for bedded rock mass under different anchoring methods, the rock failure mode under shear and tensile stresses in bedded rock was examined in this paper. The results showed that bolt anchoring for rock is achieved mainly through the bonded restoration of surrounding rock near the drill holes by means of an anchoring agent and the supporting resistance provided by the bolt body. It was observed that the strength parameters of bedded rock were increased under the anchoring effect. Full anchoring bolts were especially effective. In addition, it was observed that, in the absence of bolts, the failure form changed from shear to split. In the case of bolting, the failure plane occurred parallel to the bolt’s axis. The shearing began along the interface between the hard and soft rock bedding. Compared to end bolt anchoring, full-length bolt anchoring was more capable of offering an anchoring effect. The latter offered a greater increase in the strength and greater shear-bearing capacity of the rock, which ultimately enabled the rock to bear more load.

No abstract