Experimental and theoretical investigation on hydraulic fracturing in cement mortar exposed to sulfate attack

Zhang, Hongwei; Shen, Zhenzhong; Xu, Liqun; Liu, Gan; Liu, Detan; Wu, Qiong; Tan, Jiacheng; Sun, Yongjun; Ma, Zekai

doi:10.1016/j.matdes.2022.111226

Cited by 3 publications

(2 citation statements)

References 94 publications

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“…Cracks emerged in the dam heel upon its 1978 commissioning, resulting in substantial leakage (200 L/s) at reservoir water levels reaching 158 m. Diverse measures, including freezing, grouting, and innovative anti-seepage interventions, failed to mitigate the issue. As a result, a downstream multifaceted support arch was introduced to enhance stress distribution and restore operational stability [5]. Drawing insights from the Kölnbrein experience, Austria's Zillergrundl arch dam (182 m high) incorporated a bottom joint and pre-dam heel apron in its design.…”

Section: Introductionmentioning

confidence: 99%

Investigation on Hydraulic Fracturing and Flexible Anti-Hydrofracturing Solution for Xiaowan Arch Dam

Jia

Yang

et al. 2023

Applied Sciences

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Understanding hydraulic fracturing in concrete super-high arch dams is vital for the implementation of safety measures on the bearing surface. In this study, we conducted tests on hydraulic fracturing for the Xiaowan arch dam (294.5 m) to analyze concrete behavior at cracks under various stress conditions. The risk of hydraulic fracturing near the dam heel was identified without compressive stress. Addressing this, we propose a flexible anti-hydrofracturing system using GB sealing material and a spray polyurea coating. Simulation tests on three schemes: ‘3 mm GB plate + 4 mm polyurea’, ‘1 mm GB glue + 5 mm polyurea’, and ‘7 mm polyurea’ showed effective prevention of hydrofracturing at concrete crack openings of 5 mm, 8 mm, or 10 mm under 300 m water pressure. Field tests supported ‘3 mm GB plate + 4 mm polyurea’ and ‘7 mm polyurea’ as optimal solutions for dam sections. Implementation involves a protective block layout with ‘3 mm GB plate + 4 mm polyurea’ on blocks and ‘7 mm polyurea’ in interval zones and corners. Since 2008, maximum leakage, including rock foundation, has remained minimal at 2.78 L/s under regular water levels. These insights aid similar concrete dams in optimizing safety systems.

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Section: Introductionmentioning

confidence: 99%

Investigation on Hydraulic Fracturing and Flexible Anti-Hydrofracturing Solution for Xiaowan Arch Dam

Jia

Yang

et al. 2023

Applied Sciences

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“…An external sulfate attack on concrete structures is one of the primary causes of structural deterioration [1][2][3][4][5]. Infiltrations of sulfate into concrete constructions produce expansion products such as ettringite and gypsum when it reacts with the hydration products produced by the cement [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Concrete Attacked by Sulfate under Drying–Wetting Cycles Coupled with Alternating Loads

Guan

Zhang

Wang³

et al. 2022

Buildings

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Concrete structures such as rigid pavements, tunnels, and runways at airports are usually subject to fatigue traffic loading during their service life. Research on the aftereffects of drying–wetting cycles coupled with alternating loads on concrete erosion in saline–alkali and coastal areas is of considerable practical importance. For this study, we utilized specimens of dimensions 100 mm × 100 mm × 400 mm with strength ratios of C30, C40, and C50. We incubated the concrete samples in a 24 h/24 h drying–wetting cycle with sodium sulfate solutions of different concentrations as we applied alternating loads. We conducted ultrasonic wave velocity tests every 30 days from the 60th day of the experiment to determine the change in the sound velocity of the concrete over the course of 360 days. In addition, we examined the invasion depth of SO42− with time. Based on the change in sound velocity, we developed the damage degree function, and we modified the diffusion coefficient of SO42− in concrete in accordance with the coupling of drying–wetting cycles and alternating loads. We conducted a simulation on SO42− penetration depth, and the results were in reasonable agreement with those obtained by experimental testing.

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Effect of initial pore pressure on the hydraulic fracturing of tight sandstone: an experimental study

Yin

et al. 2023

Geomech. Geophys. Geo-energ. Geo-resour.

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Pore pressure is a crucial factor affecting reservoir stimulation, especially in unconventional reservoirs, because it can control crack initiation and propagation. However, studies on the effect of initial pore pressure on hydraulic fracturing in low-permeability reservoirs are lacking, and fracturing mechanism remains unclear. Therefore, we conducted hydraulic fracturing tests under initial pore pressure, and proposed an improved fracturing initiation criterion to elucidate the fracturing mechanism of tight sandstone. The results demonstrated that the breakdown pressure increased with the initial pore pressure by 8 to 24%, and its evolution was identified approximately by the improved initiation criterion, which resulted in the complicated, invisible and intense features of the macroscopic fracture morphology and microscopic crack. The finding was mainly due to the viscous stress induced by fracturing disturbance under initial pore pressure and represented the dual interaction between rock structure and work fluid viscosity. As a result, the change in microporous diameter in micropores and a high pressure to failure can be obtained. Accordingly, the initial pore pressure in tight sandstone may not only induce n effective stress on the skeleton but also be responsible for the double effect on the fracturing mechanism with high pressure and intense failure features, which should be given attention in unconventional reservoir stimulation.

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Experimental and theoretical investigation on hydraulic fracturing in cement mortar exposed to sulfate attack

Cited by 3 publications

References 94 publications

Investigation on Hydraulic Fracturing and Flexible Anti-Hydrofracturing Solution for Xiaowan Arch Dam

Investigation on Hydraulic Fracturing and Flexible Anti-Hydrofracturing Solution for Xiaowan Arch Dam

Numerical Simulation of Concrete Attacked by Sulfate under Drying–Wetting Cycles Coupled with Alternating Loads

Effect of initial pore pressure on the hydraulic fracturing of tight sandstone: an experimental study

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