Stability Analysis of Rock Slope with Multilayer Weak Interlayer

The existence of the weak interlayer of the rock slope changes its mechanical characteristics. To ensure the safety of the slope, it is necessary to analyze the overall stability of the slope. Taking the double-layer weak interlayer rock slope beside 318 National Road in Qiyue Mountain, Hubei Province, as an example, a slope model with a weak interlayer was established through GTS software, and the model was imported into FLAC3D for calculation, and the deformation of the slope by the double-layer soft interlayer was studied. The influence of characteristics and safety factors reveals the controlling effect of the double-layer weak interlayer on the stability of the slope and its failure mode. The potential sliding surface of the slope is determined to be the lower weak interlayer, and the weak interlayer after the anchor cable reinforcement is carried out. Numerical analysis shows that the reasonable application of anchor cables significantly improves slope stability. The research results can provide reference significance for slope stability analysis of similar projects.

Research progress in the mining technology of the slowly inclined, thin to medium thick phosphate rock transition from open-pit to underground mine

This paper takes the deep ore body of Yunnan Phosphate Group Co. Ltd, the largest open-pit chemical mining enterprise in China, as the research background, and systematically introduces the technical problems recognised by many Chinese researchers in the past eight years on the open-pit to underground mining of gently inclined thin to medium-thick ore bodies with a soft interlayer. It shows that the mining of open-pit transferred to underground is a complex engineering system, and the underground stope surrounding rock and overlying strata present a nonlinear failure process. Through mining process innovation, mining method innovation and improvement, research was undertaken on new processes and technologies for phosphorus mining under complex conditions. The relevant research results not only have important economic value and academic significance for Yunnan Phosphate Group Co. Ltd. but also have important guidance and impetus to the exploitation of a large number of similar phosphate resources in China.

Acoustic Emission Characteristics of Normal and Layered Concrete Blocks during Dilating/Static Fracture

Static fracturing technology is one of the most effective methods for localized breaking of rock and concrete. Layered concrete and rock structures are commonly seen in engineering applications such as breaking of concrete buildings, stone cutting, and excavation of rock in underground spaces. Therefore, it is essential to study the static fracturing characteristics of layered concrete to ensure the safety of engineering construction processes. In this paper, using acoustic emission (AE) technology and surface displacement monitoring, the deformation and fracturing of ordinary-strength concrete, concrete with a soft interlayer, and layered concrete (with strength decreasing successively by layer) were studied under the effect of a static (or soundless) cracking agent (SCA). The experimental results indicated that (1) AE activity of the two layered concrete test blocks during static fracturing showed a gradually increasing trend, while that of the ordinary-strength concrete tended to first increase and then decrease; (2) for the concrete test block with a soft interlayer sandwiched by high-strength layers, the AE events reached a maximum in the transfer of expansion pressure stage, which accounted for 47.11% of the total value in static cracking; the macroscopic damage to layered concrete test blocks comprising multiple interlaid layers with different strengths mainly occurred in the fracturing stage, during which the AE events and AE energy accounted for 76.22% and 66.94%, respectively, of those in the whole static fracturing process; and (3) the duration of static fracturing prolonged with the increase of the overall strength of the concrete test blocks. The results provide a useful experimental reference for the application of static fracturing technology in the breaking of layered concrete and rock.