Failure characteristics of coarse and fine sandstone containing two parallel fissures subjected to true triaxial stresses

Zhou, Xiaoping; Peng, Sen‐Lin; Zhang, Jianzhi; Berto, Filippo

doi:10.1016/j.tafmec.2021.102932

Cited by 23 publications

(3 citation statements)

References 53 publications

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“…It was found that as the depth increased, the specific surface area would be raised; the average pore diameter would decrease accordingly and the other parameters displayed the downward and upward trend. The total porosity of the three samples varied from 14.89% to 19.88%, which was consisted with the general coarse sandstone, and higher than the general tight/fine sandstone (Qi et al, 2022; Zhou et al, 2021). Through the accumulation calculation of the proportion for pore diameter over 10 μm as shown in Figure 5, the valid porosity for mine water storage in BCS was 1.36% to 3.46%, with the average being 2.52%.…”

Section: Resultsmentioning

confidence: 99%

Hydrogeological feasibility of mine water deep geological storage in Baotashan coarse sandstone: A case study in Ordos Basin

Chen

Sun

et al. 2022

Deep Underground Science and Engineering

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For the sake of mine water drainage and sustainable groundwater protection, the new approach of mine water deep geological storage (MWDGS) is highly necessary to save water resources in the semi-arid region of China. However, up to now, little academic research has been done on mine water geological storage. Given this situation, the hydrogeological feasibility of MWDGS was explored in Baotashan coarse sandstone (BCS) of Jurassic measure in Ordos Basin. The results show that the white-gray BCS with a fragile skeleton of quartz (41.4%), feldspar (21.1%), and clay minerals (16.4%) provides the potential variable-void for mine water; and its hydro-chemical type of BCS aquifer is CO 3 -Na and Cl-Na. As the burial depth increases, the strong alkaline groundwater is in stagnant and poor recharge-runoff-discharge condition. The lab test shows that the pores whose diameter is over 10 μm could be treated as the main storage of mine water; and the effective porosity varies from 1.36% to 3.46%. When mine water is injected, the strong hydrodynamics of mine water storage would change the permeability significantly and about 0.201% soluble solids would be dissolved. Partial clay minerals obstruct the pores and induce the saturated phase of high permeability to evolve into steady phase of lower permeability. Under the condition of nonhydraulic fracturing during continuous storage, the heterogeneous anisotropic medium obtained by Transition PRObability GeoStatistics (TPROGS) shows that the capacity of BCS aquifer is 0.455 to 1.226 Mm 3 for 1 km 2 in the study area. The simulation shows that the groundwater mound in well-scale and mine-scale would be formed. The groundwater quality characteristics of "Three Zone" would occur around and gradually drop to approximate the original brine within 10 years. The hydrogeological feasibility reveals that this approach is useful for the well design and groundwater environment management during the mine water deep geological storage project in the Ordos basin.

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Section: Resultsmentioning

confidence: 99%

Hydrogeological feasibility of mine water deep geological storage in Baotashan coarse sandstone: A case study in Ordos Basin

Chen

Sun

et al. 2022

Deep Underground Science and Engineering

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“…Li studied the failure mechanism of rock with prefabricated cracks by conducting compression failure tests on rock with prefabricated fractures under different true triaxial conditions [5]. Zhou conducted the true triaxial compressive tests on coarse and fine sandstone specimens containing two parallel fissures, and the failure characteristics were studied [6]. Liu conducted triaxial pulling tests on sandstone rock specimens, which contained a single fissure, and studied the influence of the fissure parameters on the strength of the specimens [7].…”

Section: Introductionmentioning

confidence: 99%

Triaxial Compression Strength Prediction of Fissured Rocks in Deep-Buried Coal Mines Based on an Improved Back Propagation Neural Network Model

et al. 2023

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In deep coal mine strata, characterized by high ground stress and extensive fracturing, predicting the strength of fractured rock masses is crucial for stability analysis of the surrounding rock in coal mine strata. In this study, rock samples were obtained from construction sites in deep coal mine strata and intact, as well as fissured, rock specimens were prepared and subjected to triaxial compression tests. A numerical model based on the discrete element method was then established and the micro-parameters were calibrated. A total of 288 triaxial compression tests on the rock specimens under different conditions of confining pressure, loading rate, fissure dip angle, and fissure length, were conducted to obtain the triaxial compressive strength of the fractured rock specimens under different conditions. To address the limitations of traditional back propagation (BP) neural networks in solving stochastic problems, a modified BP neural network model was developed using a random factor and an interlayer mean square error corrected network model evaluation function. The traditional and modified BP neural network models were then employed to predict the triaxial compressive strength of the fractured rock specimens. Through comparative analysis, it was found that the modified BP neural network prediction model exhibited smaller errors and significantly reduced overfitting, making it an effective tool for predicting the strength of fractured rocks in deep coal mine strata.

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“…Studies [19] have monitored borehole collapse, overburden damage, etc., by the drilling flushing fluid method. Studies [20][21][22][23][24][25][26] have used the acoustic method to analyze the morphology and effective radius of peripore fractures. Studies [27][28][29] have investigated borehole stability by observing peripore fracture development through the borehole peephole method.…”

Section: Introductionmentioning

confidence: 99%

Research on Hole Collapse Monitoring Technology of Coal Seam Gas Extraction Boreholes

et al. 2023

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It is difficult to monitor the collapse position of a gas extraction borehole in a coal seam. In order to solve this problem, a fiber-optic grating collapse monitoring technology was proposed. Five kinds of grating arrangements (0°, 45°, 90°, 135°, 180°) were examined to simulate the hole collapse. The relationship model between the center wavelength offset and the amount of collapsed coal and extraction flow was constructed to obtain the distribution curve of the hole collapse position and quality along the length of the hole, and flow decay rates of 80% and 50% were used as the critical values to classify the three levels of hole collapse. The results show that the hole collapse monitoring accuracy is the highest with the grating measurement points located below the substrate material arrangement. Finally, the effectiveness of fiber-optic grating monitoring technology was verified in the 2202 working face of the Changcun coal mine of the Lu’an Group, and the pure amount of gas extraction from the repaired borehole after monitoring was increased by 62.6% compared with that before the repair.

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Failure characteristics of coarse and fine sandstone containing two parallel fissures subjected to true triaxial stresses

Cited by 23 publications

References 53 publications

Hydrogeological feasibility of mine water deep geological storage in Baotashan coarse sandstone: A case study in Ordos Basin

Hydrogeological feasibility of mine water deep geological storage in Baotashan coarse sandstone: A case study in Ordos Basin

Triaxial Compression Strength Prediction of Fissured Rocks in Deep-Buried Coal Mines Based on an Improved Back Propagation Neural Network Model

Research on Hole Collapse Monitoring Technology of Coal Seam Gas Extraction Boreholes

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