An associated evaluation methodology of initial stress level of coal-rock masses in steeply inclined coal seams, Urumchi coal field, China

Shan, Pengfei; Lai, Xingping

doi:10.1108/ec-07-2019-0325

Cited by 39 publications

(26 citation statements)

References 20 publications

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“…When the stress concentration area reaches the release limit under the influence of mining, the stress release will occur. Therefore, the rock mass in the stress release area will deflect to the free side of the floor without reinforced support under the influence of the released high stress, resulting in floor heave [21][22][23][24]. When the limit equilibrium state is reached, the active pressure P1 and passive pressure P2 under floor rock mass can be expressed as [25][26][27][28] With the continuous advance of the working face, the side of the roadway will produce the effect of load transfer to the floor.…”

Section: Theoretical Calculation Of Support Parameter Optimizationmentioning

confidence: 99%

Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

Lai

Shan

et al. 2020

Energies

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The stability of the surrounding rock is the key problem regarding the normal use of coal mine roadways, and the floor heave of roadways is one of the key factors that can restrict high-yield and high-efficiency mining. Based on the 1305 auxiliary transportation roadway geological conditions in the Dananhu No. 1 Coal Mine, Xinjiang, the mechanism of roadway floor heave was studied by field geological investigation, theoretical analysis, and numerical simulation. We think that the surrounding rock of the roadway presents asymmetrical shrinkage under the original support condition, and it is the extrusion flow type floor heave. The bottom without support and influence of mining are the important causes of floor heave. Therefore, the optimal support scheme is proposed and verified. The results show that the maximum damage depth of the roadway floor is 3.2 m, and the damage depth of the floor of roadway ribs is 3.05 m. The floor heave was decreased from 735 mm to 268 mm, and the force of the rib bolts was reduced from 309 kN to 90 kN after using the optimization supporting scheme. This scheme effectively alleviated the "squeeze" effect of the two ribs on the soft rock floor, and the surrounding rock system achieves long-term stability after optimized support. This provides scientific guidance for field safe mining.Energies 2020, 13, 381 2 of 14 the surrounding rock and the complexity of occurrence in the environment, the distribution law of floor heave deformation is very complex. In view of the mechanism of unsymmetrical floor heave of a mining roadway in a fully mechanized top coal caving face, we put forward corresponding countermeasures to ensure the normal operation and safety of the roadway.In recent years, many experts and scholars have carried out a series of research studies on the mechanism and control of roadway floor heave under different conditions. Sun et al. [9], based on Euler's formula, analyzed the deformation and failure mechanism of different layered rock roadways by the theory of pressure bar stability, Mohr-Coulomb strength criterion, and the deflection failure mechanical model. According to the flexibility of rock mass, he established new mechanical strength parameters to obtain the best support method by studying the change rule of strength parameters and making full use of the stability of the surrounding rock. Sungsoon Mo et al. [10] introduce some of the main floor heave events in the development of the Glencore Bulga Underground plant. Their study indicates that the high horizontal stress of the roadways surrounding rocks and certain types of floor lithology configuration are the reasons for the failures of floor strata. Zhai et al. [11] analyzed that the bottom depressurized trough can effectively control the floor heave, which is beneficial to the long-term stability of the roadway. The surrounding rock of the large deformation chamber is in a stable state after the excavation of the bottom floor decompression trough and the joint support of the bolt and jet. Gong et al. [12] establishe...

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Section: Theoretical Calculation Of Support Parameter Optimizationmentioning

confidence: 99%

Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

Lai

Shan

et al. 2020

Energies

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“…It is often used to simulate the fracture characteristics and movement laws of overlying strata. In this research, JSET command is used to generate vertical and horizontal joint groups, and CHANGE command is used to change the material properties of blocks and joints [44][45][46][47]. Because the tensile strength of rock is significantly lower than the compressive strength, the Mohr-Coulomb elastoplastic model is chosen as the block constitutive model.…”

Section: Numerical Simulationmentioning

confidence: 99%

The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

et al. 2020

Advances in Civil Engineering

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Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.

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“…Once the salt cavern leaks, it will lead to oil leakage, which may bring the risk of serious disasters such as cavity scrapping and ground subsidence, even causing major fires and activating regional faults [26][27][28]. Therefore, the porosity and permeability characteristics of the rock surrounding the caverns are important for evaluating its tightness [29][30][31][32]. Moreover, the essence of these macroscopic characteristics is the macroscopic embodiment of its microscopic pore structure.…”

Section: Introductionmentioning

confidence: 99%

Microscopic Pore Structure of Surrounding Rock for Underground Strategic Petroleum Reserve (SPR) Caverns in Bedded Rock Salt

et al. 2020

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Using salt caverns for an underground strategic petroleum reserve (SPR) is considered as an ideal approach due to the excellent characteristics of low porosity, low permeability, self-healing of damage, and strong plastic deformation ability of rock salt. Salt deposits in China are mostly layered rock salt structures, with the characteristics of many interlayers, bringing great challenges for the construction of SPR facilities. Studying the microscopic pore characteristics of the rock surrounding SPR salt caverns in different environments (with brine and crude oil erosion) is necessary because the essence of mechanical and permeability characteristics is the macroscopic embodiment of the microscopic pore structure. In this paper, XRD tests and SEM tests are carried out to determine the physical properties of storage media and surrounding rock. Gas adsorption tests and mercury intrusion tests are carried out to analyze the microscopic pore structure, specific surface area variation and total aperture distribution characteristics of SPR salt cavern host rock. Results show that: (1) Large numbers of cores in interlayer and caprock may provide favorable channels for the leakage of high-pressure crude oil and brine. (2) The blockage of pores by macromolecular organic matter (colloid and asphaltene) in crude oil will not significantly change the structural characteristics of the rock skeleton, which is beneficial to the long-term operation of the SPR salt cavern. (3) The water–rock interaction will bring obvious changes in the micro-pore structure of rock and increase the leakage risk of the storage medium. The results can provide theoretical bases and methods for the tightness analysis of China’s first underground SPR salt cavern.

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An associated evaluation methodology of initial stress level of coal-rock masses in steeply inclined coal seams, Urumchi coal field, China

Cited by 39 publications

References 20 publications

Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

Research on Mechanism and Control of Floor Heave of Mining-Influenced Roadway in Top Coal Caving Working Face

The Key Stratum Structure Morphology of Longwall Mechanized Top Coal Caving Mining in Extra‐Thick Coal Seams: A Typical Case Study

Microscopic Pore Structure of Surrounding Rock for Underground Strategic Petroleum Reserve (SPR) Caverns in Bedded Rock Salt

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