Predicting rockburst tendency based on fuzzy matter–element model
基于模糊物元模型的岩爆倾向性预测
International Journal of Rock Mechanics and Mining Sciences, Volume 75, April 2015, Pages 224-232
Abstract: Rockburst is a dynamic phenomenon caused by multiple factors associated with mining excavations and activities. It is very hard to make predictions accurately. In this study, a multi-index model, based on fuzzy matter–element theory, information entropy theory and closeness degree rules, are established to predict rockburst tendency. The basic evaluation indices introduced in this model include the rock brittleness coefficient B, the strength/stress ratio Rc/σ1, the impact energy tendency WCF, and the rock integrity coefficient Kv. Ore body 10 of Huize Lead–Zinc Mine in China is selected as a case study for the establishment of the model, while the C1b and ore straum served for the model verification. In different rock strata, this model is compared with the origin methods for predicting the rockburst tendency. The results are compared with those obtained by other traditional methods. The cases verified that the proposed model can predict rockburst in a reliable mode; this is a meaningful discovery for predicting rockburst tendency.
Microseismic multi-parameter characteristics of rockburst hazard induced by hard roof fall and high stress concentration
坚硬顶板垮落和高应力集中诱发的岩爆灾害的微震多参数特征
International Journal of Rock Mechanics and Mining Sciences, Volume 76, June 2015, Pages 18-32
Highlights: •Before rockburst, the sudden rise of MS energy and the lower level of event count.
•When rockburst, peak value of fault total area, the lower b value, and |Z||Z|>2.
•When rockburst, the largest energy ratio in the dominant low-frequency band.
•Before rockburst, abnormal cluster of sources and high-energy events congregation.
•Prior to rockburst, the sudden drop of EME amplitude indicating macro-fracture.
A new method to test rock abrasiveness based on physico-mechanical and structural properties of rocks
基于岩石物理力学和结构特性的岩石腐蚀性测试新方法
Journal of Rock Mechanics and Geotechnical Engineering, In Press, Accepted Manuscript, Available online 12 March 2015
Abstract: A new method to test rock abrasiveness is proposed based upon the dependence of rock abrasiveness on their structural and physico-mechanical properties. The article describes the procedure of presentation of properties that govern rock abrasiveness on a canonical scale by dimensionless components, and the integrated estimation of the properties by a generalized index. The obtained results are compared with the known classifications of rock abrasiveness.
Microseismic monitoring and stability evaluation for the large scale underground caverns at the Houziyan hydropower station in Southwest China
中国西南猴子岩水电站超大型地下洞室微震监测与稳定性评估
Engineering Geology, Volume 188, 7 April 2015, Pages 48-67
Abstract: The stability of underground caverns and the excavatability of rock masses are important for geotechnical engineering practices during the design and construction stages. The risks associated with underground caverns at the Houziyan hydropower station in Southwest China are growing due to excavation-induced unloading. To assess the instability of underground caverns and resolve the complex subsurface conditions of the highly fractured rock mass, a high-resolution microseismic monitoring system was established in deep underground caverns. This system was used to determine the relationship between the measured microseismic activities and the excavation damage zones of the surrounding rock mass. The excavation damage zones and potential risk regions in the underground caverns were identified by analyzing the tempo-spatial distribution of microseismic activities. In addition, the correlation between microseismic activities and pre-existing geological structures was determined, and traditional monitoring results were analyzed. To validate the correlation between seismicity and the excavation damaged zones of the underground caverns, a numerical model was employed to further evaluate the deformation and stability of the surrounding rock mass. The monitoring results demonstrate that microseismic events mainly occurred in high-stress-concentration regions, corresponding with the results obtained from the numerical analysis. Therefore, this comprehensive method, which incorporates microseismic monitoring, numerical analysis, traditional monitoring and field observations, is promising for predicting the deformation and instability of surrounding rock masses in the underground caverns subjected to excavation.
Automated coal seam detection using a modulated specific energy measure in a monitor-while-drilling context
钻井监测环境下应用调制比能方法进行自动化煤层检测
International Journal of Rock Mechanics and Mining Sciences, Volume 75, April 2015, Pages 196-209
Abstract: This paper describes a novel measure called Modulated Specific Energy (SEM) which has been developed for the purpose of characterizing drilled material in open-pit coal mining. In Monitor-While-Drilling (MWD), the information available for coal detection are limited to a small set of drilling parameters that can be measured on a rotary drill rig. Despite this constraint, our analysis shows that MWD can still detect the top of the coal seam consistently without relying on geophysical data — such as bulk density and natural gamma — by using the SEM measure. The proposal utilizes a hypothesized link between a derived drill performance indicator (the rotation-to-thrust power ratio) and geomechanical properties of sedimentary rock strata (shear and compressive strengths) to increase the coal discriminative power of SEM relative to Teale׳s specific energy measure. Its efficacy is demonstrated using mutual information, a simple threshold strategy and an artificial neural network. The results show the SEM can detect the coal seam interface consistently with a greater margin for error, and overcome the problems of low specificity and high variability observed in existing MWD approaches. By reducing the detection uncertainty, the SEM is able to provide consistent feedback while drilling and eliminate trial-and-error. This makes coal mining processes more integrated and reliable, which in turn improves operational effectiveness and efficiency in coal recovery.
A short review on basalt fiber reinforced polymer composites
玄武岩纤维增强聚合物基复合材料研究进展
Composites Part B: Engineering, Volume 73, May 2015, Pages 166-180
Abstract: A recent increase in the use of ecofriendly, natural fibers as reinforcement for the fabrication of lightweight, low cost polymer composites can be seen globally. One such material of interest currently being extensively used is basalt fiber, which is cost-effective and offers exceptional properties over glass fibers. The prominent advantages of these composites include high specific mechano-physico-chemical properties, biodegradability, and non-abrasive qualities to name a few. This article presents a short review on basalt fibers used as a reinforcement material for composites and discusses them as an alternative to the use of glass fibers. The paper also discusses the basics of basalt chemistry and its classification. Apart from this, an attempt to showcase the increasing trend in research publications and activity in the area of basalt fibers is also covered. Further sections discuss the improvement in mechanical, thermal and chemical resistant properties achieved for applications in specific industries.
Numerical study of pressure on dams in a backfilled mining shaft based on PFC3D code
基于PFC3D的回填矿井坝压数值研究
Computers and Geotechnics, Volume 66, May 2015, Pages 230-244
Abstract: In all EU countries, the number of actively operational coal mines continues to decrease. This decrease requires the closure of unnecessary shafts, which is a very complicated task. Currently, the most commonly used method of shaft closure involves building dams and locking plugs in the area of insets and subsequently backfilling with a granular material. The design of the dams and locking plug should take into account the horizontal and vertical pressure in the backfilled shaft. This paper presents a comparison of the results obtained from the analytical (Janssen’s theory) and numerical calculations, as well as an analysis of the changes in the load of the dams, depending on their location relative to the shaft. The numerical approach was developed using the method of discrete elements implemented in the commercial software PFC3D (Particle Flow Code in 3D). The analysis was performed in the framework of the “MISSTER” project (RFCR-CT-2010-00014: Mine Shafts: Improving Security and New Tools for the Evaluation of Risks).
