Analysis of Fractured Rock Permeability Evolution Under Unloading Conditions by the Model of Elastoplastic Contact Between Rough Surfaces

Zhao, Yu; Wang, C. L.; Bi, Jing

doi:10.1007/s00603-020-02224-x

Cited by 100 publications

(42 citation statements)

References 37 publications

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“…As for the seepage tests of the heat-treated sandstones, steady method has been used to measure the rock permeability [12,13]. For this seepage testing procedure, the permeability of the samples can be calculated by measuring the fluid volume from the pump in a period of time and written by [14],…”

Section: The Seepage Tests Of the Heat-treated Sandstonesmentioning

confidence: 99%

The Thermal Effect on the Physical Properties and Corresponding Permeability Evolution of the Heat-Treated Sandstones

Liu

et al. 2020

Geofluids

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The complex high temperature and high stress are commonly encountered in the hot dry rock for geothermal energy development; the thermal effect on the rock properties and corresponding thermal-hydromechanical coupling process has attracted much more attentions in the field of the energy. Taking the sandstones in Chongqing as a case study, the physical and mechanical experiments of the heat-treated sandstones and corresponding permeability tests under triaxial loading conditions have been widely conducted. It can be seen that the quality, porosity, uniaxial compression strength, and elastic modulus of the heated sandstones vary differently with different heat-treated temperature. As for the permeability tests in the process of gradual failure under triaxial loading conditions, the permeability variation divided by four variation stages is the same as that under room temperature condition, and the initial permeability, minimum permeability, and maximum permeability have been characterized with temperature variation, showing that the permeability variation in a certain temperature range from 400°C to 600°C presents more obvious than that in other temperature ranges. Furthermore, the relationship between the permeability and the crack volumetric strain of the heat-treated sandstones is further analyzed to prove the mechanism of the permeability evolution. In addition, a damage model has been proposed to deeply determine the correlation of the permeability and damage variables, indicating that gradual damage variation has caused obvious cracks to form flow paths and abruptly change the permeability variation, revealing that the damage can describe the permeability evolution of the heat-treated sandstones considering different temperature and loading conditions.

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Section: The Seepage Tests Of the Heat-treated Sandstonesmentioning

confidence: 99%

The Thermal Effect on the Physical Properties and Corresponding Permeability Evolution of the Heat-Treated Sandstones

Liu

et al. 2020

Geofluids

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“…is study was designed to investigate the stress and displacement laws of a gently inclined medium-thick phosphate rock and the rock surrounding a stope in room and pillar mining after continuous excavations. It is well known that the experiment/test is the most reliable way to study mechanical problems [24][25][26][27][28][29][30][31][32][33][34][35][36][37]; therefore, in this paper, a similar physical model was adopted with a stope structure consisting of a size of 10 × 10 m room with 3 × 3 m, 5 × 5 m, and 8 × 8 m pillars, respectively. e stress distribution of the surrounding rock, the change in the subsidence displacement of the overlying rock mass, and the roof deformation and failure laws were explored.…”

Section: Engineering Backgroundmentioning

confidence: 99%

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

Liu

Shuang-suo

2021

Advances in Civil Engineering

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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.

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“…As a green, environmental, safe, and sustainable mining method, two-step mining is usually involved in backfill mining [1][2][3][4][5]. Due to the many advantages of the technology of filling goaf, when the ore is being mined, the stress of the original rock can be redistributed, and the stress of the rock is relatively complex at this stage, in order to prepare for it [6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Sampling and Mechanical Testing of Backfill in Large Mined-Out Area

Deng

Jiang²,

Duan

2021

Geofluids

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To investigate the physicomechanical properties of stope backfill and to explore the mining conditions for an adjacent pillar, four boreholes, namely, GZK1, GZK2, GZK3, and GZK4, were constructed for taking the backfill core in the test stope. During borehole sampling, it is found that the strength of backfill is usually lower than that of the rock and ordinary concrete, and its resistance to tensile and compressive loads is limited. Therefore, the drilling speed should not be too fast, and a small amount of water is needed to continue drilling smoothly. For backfill with high strength, the sampling process is relatively smooth, and the backfill samples are relatively complete. GZK1 is located on the upper part of the stope near the footwall of the orebody, and the test results show that the backfill quality of this part is poor; thus, a complete backfill core cannot be obtained. GZK2 is located at the bottom of the stope close to the footwall of the orebody, GZK3 is located at the bottom of the stope close to the hanging wall of the orebody, and GZK4 is located at the top of the stope close to the hanging wall of the orebody. The average compressive strength and average tensile strength of the backfill samples obtained from the three boreholes, namely, GZK2, GZK3, and GZK4, are 2.928 to 3.583 MPa and 0.328 to 0.523 MPa, respectively, indicating that the backfill near the upper part and bottom close to the hanging wall of the orebody is good, while the backfill near the upper part close to the footwall of the orebody is poor. Special attention should be paid to the backfill with the range of GZK1 in the future second-step pillar mining process, and the sublevel method can be adopted to ensure the safety of the mining process. The backfill samples in the large goaf of No.17 room were obtained by geological drilling. Segregation occurred in the upper part of the No.17 room near the area of the footwall. The concentration and flow rate of the filling slurry were reasonably adjusted and controlled with the improvement of backfill quality. Therefore, the backfill strength of the No.17 room is generally good, which can meet the requirements of pillar mining, and also creates a good condition for the resource utilization of waste tailings of Caolou Iron Mine.

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Analysis of Fractured Rock Permeability Evolution Under Unloading Conditions by the Model of Elastoplastic Contact Between Rough Surfaces

Cited by 100 publications

References 37 publications

The Thermal Effect on the Physical Properties and Corresponding Permeability Evolution of the Heat-Treated Sandstones

The Thermal Effect on the Physical Properties and Corresponding Permeability Evolution of the Heat-Treated Sandstones

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

Sampling and Mechanical Testing of Backfill in Large Mined-Out Area

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