Study On Evaluation For Stability And Control Technique Of High-Steep Slope During Turning Open Pit Into Underground Mining

Along with the continuous growth of scale and strength of state project construction, the stability problem of rocky high slope is inevitable in the engineering for hydroelectric work, railway, highway and mining construction. The stability directly connect the safety of construction and operation, especially the slope of transition from open pit to underground in high-steep hill area, which not only concerned the stability of open slope in the mining condition, but also assures the safety in the course of operation. Obviously, the study on evaluation for stability and control technique of slope during turning open pit into underground mining in high-steep area is more important.The slope stability is still hotspot and difficult according to complex nature of mechanical properties in geotechnical media and related to many subjects about rock and soil, geology, environment, structure etc. Taken the open-pit slope at certain Lead-zinc Mine as objects, a series of research work of slope stability during turning open-pit into under mining were done, and the research includes:Carrying out the research on slope stability, which showed stress change caused by mining work brings displacement of slope and surface in main area. Commonly the movement is divided into global and local forms, and horizontal movement and subsidence in nearby surface is represented in global change, while collapse and fall-roll of slope rock is repressed in local.Based on the analysis of geological data, the deformation mechanism of open slope in turning underground is immortal summarized. Stability of slope is calculated according to Blasting Scheme in mining, the result shows that underground production blasts inflect the whole stable open slope, especially bad to weak rock groups of west and south slope. Mathematic model about distortion of west open slope in the Lead-zinc mine is built, and the genetic programming theory is used to predict the global stability of slope, and then contrasts with existing date. The result proved the method offering good prediction accuracy and its average relative error is lower than 8%.Occurrence mechanism formation condition of collapse rockfall was analyzed and determinate the loose petrofabric in north side of west slope and the west strict of F₁₅ fault of North Slope probably take place collapse. Combining Pseudo Random technique and probability statistics principle to analyze and model route, bounce height, energy distribution and rest points of rockfall in typical section. The result shows that the influence scope of rockfall is 60-80m and jumping height and kinetic energy variations are relatively small. Finally protection of rockfall is provided according to the statistical results.The particle flow theory is used to establish model of protective wall about high slope rockfall, numerical simulation and dynamic analysis of stress and strain of protective wall, got that the 30MPa protective strength is enough for require, thus the design of protection can be optimize. At last, based on the knowledge of mainly slope, data mining system is constructed according to rough set theory, which is used in the case of slope stability of risk assessment.