Evolution characteristics of mining fissures in overlying strata of stope after converting from open-pit to underground

2021 ◽  
Vol 14 (24) ◽  
Author(s):  
Xiaoshuang Li ◽  
Qihang Li ◽  
Yunjin Hu ◽  
Lin Teng ◽  
Shun Yang
Keyword(s):  
Open Pit ◽  
Evolution Characteristics ◽  
Overlying Strata

scholarly journals Research on the Evolution Characteristics of Rock Mass Response from Open-Pit to Underground Mining

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiabo Geng ◽  
Qihang Li ◽  
Xiaoshuang Li ◽  
Tao Zhou ◽  
Zhifang Liu ◽  
...  
Keyword(s):  
Underground Mining ◽  
Vertical Direction ◽  
Mining Area ◽  
Open Pit ◽  
Measuring Point ◽  
Deformation And Failure ◽  
Ore Body ◽  
Evolution Characteristics ◽  
The Impact ◽  
Overlying Strata

This study is based on the engineering background of pit no. 2 in Jinning Phosphate Mine, China. In order to systematically analyze the movement, deformation, and failure laws of surrounding rocks in underground stopes. The room and pillar method is used to excavate and stop the ore bodies in the mining area. Combined with the similar physical model experiments and discrete element MatDEM numerical simulations, it reveals the deformation and failure laws and evolution characteristics of the surrounding rock of the stope in the process of converting from open-pit to underground mining. The results show the following: (1) Along the inclination of the ore body, the farther the horizontal and vertical displacements are from the underground stope, the less the impact of mining stress. On the other hand, along the inclined vertical direction of the ore body, the farther the measuring point is from the stope, the smaller the range of mining influence will be. (2) In the process of ore body recovery, the rupture of the overlying strata of the stope has an obvious layered structure, with collapse zones, fissure penetrating zones, and microfracture loosen zones appearing from the bottom to top. In addition, the movement and destruction of the overlying strata of the entire stope is an “elliptical arch.” Therefore, the results of similar simulation experiments and numerical simulation are basically consistent.

scholarly journals Similar Physical Modeling of Roof Stress and Subsidence in Room and Pillar Mining of a Gently Inclined Medium-Thick Phosphate Rock

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Xiaoshuang Li ◽  
Zhifang Liu ◽  
Shun Yang
Keyword(s):  
Phosphate Rock ◽  
Yunnan Province ◽  
Room And Pillar Mining ◽  
Working Face ◽  
Evolution Characteristics ◽  
Failure Evolution ◽  
Phosphate Mine ◽  
Pillar Mining ◽  
Maximum Subsidence ◽  
Overlying Strata

Gently inclined medium-thick orebodies are generally recognized as the most difficult type of orebody to mine, using current available strategies (i.e., the room and pillar method). In the present study, a similar physical model was used to investigate the roof stress and subsidence for mining gently inclined medium-thick phosphate rock from the Jinning Phosphate Mine, Yunnan Province, China. The stress field, displacement field, and roof failure evolution characteristics of the surrounding rock with stope structures of 3 m, 5 m, or 8 m ore pillars were considered. The results showed that, after mining stopped, obvious pressure relief areas formed above the three stope structures, and pressure-bearing areas formed at the front of the roof. With extending the mining in the working face, the stress relief boundary also gradually increased, and the top of the roof tended to sink with a maximum subsidence of –14.58 mm, –4.67 mm, and –3.48 mm. Due to the mining activity, the overlying strata bent and subsided from top to bottom, creating bending subsidence, fracture, and caving zones.

scholarly journals Macro-Micro Response Characteristics of Surrounding Rock and Overlying Strata towards the Transition from Open-Pit to Underground Mining

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Xiaoshuang Li ◽  
Shun Yang ◽  
Yunmin Wang ◽  
Wen Nie ◽  
Zhifang Liu
Keyword(s):  
Stress Reduction ◽  
Underground Mining ◽  
Local Deformation ◽  
Linear Increase ◽  
Surrounding Rock ◽  
Open Pit ◽  
Measurement Technology ◽  
Pressure Relief ◽  
Important Relationship ◽  
Overlying Strata

The macro-micro mining response of the surrounding rock and overlying strata towards the transformation from open-pit to underground mining is examined in the present study, based on the engineering background of the Jinning phosphate mine (Yunnan Phosphate Chemical Group Co., Ltd.) via simulations involving similar materials, digital photographic measurement technology, and numerical simulation. The mining deformation of the surrounding rock underground, and of the overlying strata, is shown to develop in three stages, namely: (1) small and local deformation, (2) continuous linear increase, and (3) the violent nonlinear collapse of the entire system. The internal distribution of stress in the surrounding rock and adjacent overlying strata of the inclined mined-out area is complicated. The degrees of pressure increase and pressure relief have an important relationship with the size of the mining space. The pressure relief is more complete close to the mined area, and the stress reduction decreases with increasing distance. The cracks propagate in arc shapes and have a tendency to penetrate into the upper and lower ends of the stope. The size of the excavation space plays a key role in the generation, propagation, and penetration of the cracks. Due to the disturbance of the first mining level and the increase in excavation depth, the rate of damage to the surrounding and overlying rock increases in the second mining level. This process generates more cracks, which accelerate the instability of the surrounding rock and overlying strata.

Evolution Characteristics of Composite Pressure-Arch in Thin Bedrock of Overlying Strata During Shallow Coal Mining

2019 ◽  
Vol 11 (03) ◽  
pp. 1950030 ◽  
Author(s):  
S. R. Wang ◽  
X. G. Wu ◽  
Y. H. Zhao ◽  
P. Hagan ◽  
C. Cao
Keyword(s):  
Coal Mining ◽  
Structural Characteristics ◽  
In Situ Stress ◽  
Instability Criterion ◽  
Far Field ◽  
Mining Condition ◽  
Evolution Characteristics ◽  
Mechanical Models ◽  
Movement Rules ◽  
Overlying Strata

Under the shallow coal mining condition and based on the cracking and movement rules of the roof in different mining stages, the mechanical models of symmetrical pressure-arch, stepped pressure-arch, rotating-squeezed pressure-arch in the mining field were established. Then, the instability criterion of each pressure-arch structure was derived. Through the similarity material experiment and numerical simulation, the evolution characteristics of the composite pressure-arches in the near- and far-field were revealed. Results show that the stepped pressure-arch in broken blocks of the basic roof was formed when the horizontal principal stress was greater than the in-situ stress. The broken blocks’ sliding could induce roof cutting off and strong weighting load. The structural characteristics of the overlying strata were determined by the thickness of the bedrock. The upper broken rocks formed a symmetrical pressure-arch in the near- and a far-field pressure-arch formed in the mining field. The median periodic broken rocks formed the rotating-squeezed pressure-arch, bearing the load of the loose layers and protecting the mining panel. After all bedrocks breaking, the latter arch foot of the far-field pressure-arch was transferred to the compacted caving zone. This study can provide a theoretical reference for the similar mining engineering.

Analysis of Efficiency of Drilling of Large-Diameter Wells With a Profiled Wing Bit / Badania Efektywności Wiercenia Studni Wielkośrednicowych Świdrem Skrawającym z Profilowanymi Skrzydłami

2012 ◽  
Vol 57 (2) ◽  
pp. 363-373
Author(s):  
Jan Macuda
Keyword(s):  
Average Rate ◽  
Large Diameter ◽  
Open Pit ◽  
Mechanical Parameters ◽  
Drilling Rate ◽  
Geological Conditions ◽  
Rock Drillability ◽  
Drilling Technology ◽  
Weight On Bit ◽  
Rotary Speed

Abstract In Poland all lignite mines are dewatered with the use of large-diameter wells. Drilling of such wells is inefficient owing to the presence of loose Quaternary and Tertiary material and considerable dewatering of rock mass within the open pit area. Difficult geological conditions significantly elongate the time in which large-diameter dewatering wells are drilled, and various drilling complications and break-downs related to the caving may occur. Obtaining higher drilling rates in large-diameter wells can be achieved only when new cutter bits designs are worked out and rock drillability tests performed for optimum mechanical parameters of drilling technology. Those tests were performed for a bit ø 1.16 m in separated macroscopically homogeneous layers of similar drillability. Depending on the designed thickness of the drilled layer, there were determined measurement sections from 0.2 to 1.0 m long, and each of the sections was drilled at constant rotary speed and weight on bit values. Prior to drillability tests, accounting for the technical characteristic of the rig and strength of the string and the cutter bit, there were established limitations for mechanical parameters of drilling technology: P ∈ (Pmin; Pmax) n ∈ (nmin; nmax) where: Pmin; Pmax - lowest and highest values of weight on bit, nmin; nmax - lowest and highest values of rotary speed of bit, For finding the dependence of the rate of penetration on weight on bit and rotary speed of bit various regression models have been analyzed. The most satisfactory results were obtained for the exponential model illustrating the influence of weight on bit and rotary speed of bit on drilling rate. The regression coefficients and statistical parameters prove the good fit of the model to measurement data, presented in tables 4-6. The average drilling rate for a cutter bit with profiled wings has been described with the form: Vśr= Z ·Pa· nb where: Vśr- average drilling rate, Z - drillability coefficient, P - weight on bit, n - rotary speed of bit, a - coefficient of influence of weight on bit on drilling rate, b - coefficient of influence of rotary speed of bit on drilling rate. Industrial tests were performed for assessing the efficiency of drilling of large-diameter wells with a cutter bit having profiled wings ø 1.16 m according to elaborated model of average rate of drilling. The obtained values of average rate of drilling during industrial tests ranged from 8.33×10-4 to 1.94×10-3 m/s and were higher than the ones obtained so far, i.e. from 181.21 to 262.11%.

Management and engineering solutions to improve processing stock quality and reduce resource-intensity of mining

2018 ◽  
pp. 56-68
Author(s):  
V. V. Agafonov ◽  
V. Yu. Zalyadinov ◽  
M. E. Yusupov ◽  
N. S. Bikteeva
Keyword(s):  
Development Strategy ◽  
Open Pit ◽  
Mining Operations ◽  
High Concern ◽  
General Production ◽  
Resource Intensity ◽  
Product Output ◽  
And Control ◽  
A Company

Sustainability of mining companies is of of high concern. The problem is specifically acute at companies that are monotownor monosettlement-forming. Sustainability of a mine depends in many ways on product quality and production resource-intensity. This article discusses formation of mineral quality indexes in terms of an open pit chrysotile mine. The studies took into account specific features of operation procedures implemented by each structural division of the mine. The analysis has found managerial and technological inconsistencies which affect quality and marketable product output, as well as efficiency of the mine in whole. The background for efficiency enhancement at a company is, by the authors’ opinion, consolidation of personnel subject to the single development strategy, namely: improvement of production and control efficiency, as well as use of available reserves and resources by means of better setup for production. The proposed approaches to planning mining operations and forming mineral quality allow higher quality of processing stock. In addition, a new model proposed for interaction between structural divisions of a mining company ensures improvement of general production indexes.

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