Seepage Grouting Mechanism for Foundations in Goaf Sites considering Diffusion Paths

Wang, Hui; Li, You; Dun, Zhiyuan; Cheng, Jianwei; Dun, Zhilin; Wu, Chenxi

doi:10.1155/2022/8394811

Cited by 9 publications

(8 citation statements)

References 10 publications

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“…Based on this, some scholars have integrated the advantages and disadvantages of traditional solid backfilling, paste backfilling, and high-water backfilling techniques [14][15][16]. They proposed a new type of coal gangue slurry backfilling technology by combining caving zone grouting technology, long-distance pipeline transportation technology, and yellow mud grouting technology [17][18][19]. Coal gangue slurry backfilling technology utilizes the voids formed by the caving and fragmentation of overlying rocks as storage space for gangue, achieving in-situ, green, and harmless disposal of gangue.…”

Section: Introductionmentioning

confidence: 99%

Research and engineering practice on space characteristics of gangue slurry filling

Gu,

Yang,

Pan

et al. 2023

Preprint

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The macroscopic characteristics of the fractured space and the microscopic pore features are critical factors determining the effectiveness of gangue slurry backfilling. To identify the key areas for slurry backfilling, a combination of theoretical analysis, simulation experiments, and on-site industrial trials was used to reveal the movement laws of backfilling space overlying the fractured zone. The distribution characteristics of voids available for slurry backfilling within the fractured space were explored, and the interaction between gangue slurry and goaf voids was clarified. A formula for calculating the void ratio in the caved zone was derived, and a model for the distribution of voids in the slurry backfilling space was established. This model identified the main areas where slurry backfilling should be focused, namely the overlapping space between the free accumulation zone and the load-influenced zone. Experimental results demonstrated that the porosity of the collapsed rock mass within the goaf follows a negative logarithmic function along both the dip and strike directions, which was consistent with the theoretical calculations. Through in-situ grouting backfilling experiments on the ground, the feasibility of gangue slurry backfilling in the goaf was verified, and the process of interaction between gangue slurry and goaf voids was elaborated. This process generally involves three stages: initial flow, vertical upwelling, and horizontal diffusion, all of which are closely interconnected. Practical engineering applications of gangue slurry backfilling were carried out in the free accumulation zone and the load-influenced zone at the Huangling No.2 coal mine. The successful validation of underground gangue slurry backfilling technology demonstrated its feasibility and the correctness of the theoretical approach. This research provides new evidence for environmentally friendly disposal of gangue materials.

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Section: Introductionmentioning

confidence: 99%

Research and engineering practice on space characteristics of gangue slurry filling

Gu,

Yang,

Pan

et al. 2023

Preprint

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“…Yang et al 26 proposed a Bingham fluid column permeation and diffusion mechanism considering the effect of grout on groundwater displacement. Wang et al 27 derived the conventional permeation and diffusion mechanism of Bingham fluid in porous media based on the equation of seepage motion. Self-gravity is one of the key parameters to characterize the permeation and diffusion behavior of grout.…”

Section: Introductionmentioning

confidence: 99%

Simulation test study on filling flow law of gangue slurry in goaf

Shi,

Zhao,

Liang

et al. 2023

Sci Rep

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The disposal and utilization of solid waste of coal gangue is one of the main problems in coal mining in China. Injecting coal gangue into goaf in the form of slurry can effectively solve the problems of ground stacking and environmental pollution prevention. In order to obtain the flow law of gangue slurry in the void of the accumulated rock in the goaf, a visualization simulation test device for gangue slurry permeation grouting in the goaf was independently designed. The flow and diffusion characteristics, flow and diffusion velocity changes, void pressure changes, and viscosity changes of three mass concentrations (76%, 78%, 80%) of gangue slurry in the void between caved rock blocks in goaf were studied by visual grouting simulation test. The results show that: (1) The seepage process of gangue slurry in the goaf simulation test is divided into three diffusion forms, namely radial diffusion, axial diffusion, and bidirectional diffusion. The three diffusion forms are interrelated and inseparable. (2) The initial flow velocity of the slurry with different concentrations is different under the same permeation grouting pressure, and the higher the slurry concentration, the smaller the initial flow velocity of the slurry. The velocity of the slurry has a nonlinear relationship with the diffusion distance of the slurry. (3) With the permeation and diffusion of slurry, pressure sensors at different positions are subjected to pressure from bottom to top and enter the pressure boost stage, gradually forming stress peaks. When the slurry exceeds the position of the pressure sensor, the pressure on the pressure sensor is weakened and begins to enter the pressure relief stage, and the stress decline trend gradually becomes gentle with time. (4) The water loss effect occurs during slurry flow interaction with rock mass, resulting in slurry viscosity increasing. The viscosity of the slurry affects the difference in the amount of viscosity change. The research results can provide a certain theoretical basis for the goaf gangue slurry filling project.

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“…Wang et al proposed a modified theoretical formula for seepage grouting in goaf foundations that takes into account the fracture distribution characteristics and superposition effect of porous grouting. The formula was validated through laboratory tests and has great engineering significance, as it aids in designing optimal spacing between grouting holes to reduce residual deformation and activation deformation in goaf foundations [ 18 ]. When selecting grouting materials for reinforcement projects, it is important to consider their impact on the reinforcement effect and cost [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Study on Preparation and Performance of Foamed Lightweight Soil Grouting Material for Goaf Treatment

Zhao¹,

Chen²,

Zhang

et al. 2023

Materials

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The harm goafs and other underground cavities cause to roads, which could lead to secondary geological hazards, has attracted increased attention. This study focuses on developing and evaluating the effectiveness of foamed lightweight soil grouting material for goaf treatment. The study examines the foam stability of different foaming agent dilution ratios by analyzing foam density, foaming ratio, settlement distance, and bleeding volume. The results show that there is no significant variation in foam settlement distance for different dilution ratios, and the difference in foaming ratio does not exceed 0.4 times. However, the bleeding volume is positively correlated with the dilution ratio of the foaming agent. At a dilution ratio of 60×, the bleeding volume is about 1.5 times greater than that at 40×, which reduces foam stability. Furthermore, an appropriate amount of sodium dodecyl benzene sulfonate improves both the foaming ability of the foaming agent and the stability of the foam. Additionally, this study investigates how the water–solid ratio affects the basic physical properties, water absorption, and stability of foamed lightweight soil. Foamed lightweight soil with target volumetric weights of 6.0 kN/m3 and 7.0 kN/m3 meet the flow value requirement of 170~190 mm when the water–solid ratio ranges are set at 1:1.6~1:1.9 and 1:1.9~1:2.0, respectively. With an increasing proportion of solids in the water–solid ratio, the unconfined compressive strength initially increases and then decreases after 7 and 28 days, reaching its maximum value when the water–solid ratio is between 1:1.7 and 1:1.8. The values of unconfined compressive strength at 28 days are approximately 1.5–2 times higher than those at 7 days. When the water ratio is excessively high, the water absorption rate of foamed lightweight soil increases, resulting in the formation of connected pores inside the material. Therefore, the water–solid ratio should not be set at 1:1.6. During the dry–wet cycle test, the unconfined compressive strength of foamed lightweight soil decreases, but the rate of strength loss is relatively low. The prepared foamed lightweight soil meets the durability requirements during dry–wet cycles. The outcomes of this study may aid the development of enhanced approaches for goaf treatment using foamed lightweight soil grout material.

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Seepage Grouting Mechanism for Foundations in Goaf Sites considering Diffusion Paths

Cited by 9 publications

References 10 publications

Research and engineering practice on space characteristics of gangue slurry filling

Research and engineering practice on space characteristics of gangue slurry filling

Simulation test study on filling flow law of gangue slurry in goaf

Study on Preparation and Performance of Foamed Lightweight Soil Grouting Material for Goaf Treatment

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