Excavation-induced relaxation effects and hydraulic conductivity variations in the surrounding rocks of a large-scale underground powerhouse cavern system

Chen, Yifeng; Zheng, Hua-Kang; Wang, Min; Hong, Jia-Min; Zhou, Chuangbing

doi:10.1016/j.tust.2015.05.007

Cited by 44 publications

(17 citation statements)

References 36 publications

(44 reference statements)

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“…Thus, the correlations between the ranges of the EDZs, the evolution characteristics of crack formation and development, and the construction progress can be observed. For example, the research and applications of digital borehole TV technology have focused mainly on the fields of engineering and geological exploration, including the investigations of the formation and evolution characteristics of EDZs in deep underground excavation (Li et al 2011;Ramulu et al 2009;Chen et al 2015) and rock slope deformation (Chigira et al 2013 for evaluating the rock mass damage and reinforcement of underground caverns. Various typical borehole TV images were selected for comparison with the multi-point extensometer and acoustic wave testing results discussed above.…”

Section: Borehole Tv Test Resultsmentioning

confidence: 99%

Comprehensive evaluation of excavation-damaged zones in the deep underground caverns of the Houziyan hydropower station, Southwest China

Dai

et al. 2016

Bull Eng Geol Environ

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The disturbance of a rock mass by blasting or stress redistribution can significantly influence the overall performance of an underground excavation. The characteristics of excavation-damaged zones (EDZs) during the excavation of underground caverns at the Houziyan hydropower station in Sichuan Province, China, were investigated using various in situ tests. This study presents a comprehensive evaluation of the evolution of EDZs in the surrounding rock mass in the underground powerhouse caverns using microseismic (MS) monitoring and conventional testing methods, including multi-point extensometers, acoustic wave testing and borehole TV. First, by analyzing a series of conventional testing and MS monitoring results, the deformation and failure characteristics of the surrounding rock mass were determined. Next, the formation mechanisms of fractures in the surrounding rock mass subjected to excavation-induced unloading in the underground powerhouse caverns were determined. The relationships between the EDZs of the surrounding rock mass, crack evolution and construction status were then analyzed to investigate the crack formation, development and coalescence processes. Finally, the thicknesses of the EDZs were quantitatively determined, the relationships between the fracture evolution and construction progress were established, and the EDZ formation and evolution mechanisms were evaluated. The results not only provide direct data for geological exploration but also contribute to optimizing excavation design and support for analyzing the deformation behaviors of underground powerhouse caverns.

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Section: Borehole Tv Test Resultsmentioning

confidence: 99%

Comprehensive evaluation of excavation-damaged zones in the deep underground caverns of the Houziyan hydropower station, Southwest China

Dai

et al. 2016

Bull Eng Geol Environ

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“…The higher the damage degree of a rock mass, the lower its acoustic velocity 43 . As shown in Figure 14, borehole nos.…”

Section: Verification Via Field Monitoring Datamentioning

confidence: 98%

Transfer and dissipation of strain energy in surrounding rock of deep roadway considering strain softening and dilatancy

Liu

Lü

et al. 2020

Energy Science & Engineering

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In this study, the transfer and dissipation of strain energy in the surrounding rock of a deep roadway were analyzed, considering the objective strain softening and dilatancy behaviors. The strain energy increment was decomposed, and its variation was analyzed based on the incremental plastic flow theory; then, a numerical simulation was conducted for verification and further analysis. The results were verified by the field monitoring data of a coal mine gateway. The results show that in the elastic stage, the volumetric elastic strain energy density Uev decreases, while the shear elastic strain energy density Ues increases. In the plastic stage, both Uev and Ues decrease. The volumetric plastic strain energy density Upv is negative, and its absolute value increases, leading to strain energy accumulation. In contrast, the shear plastic strain energy density Ups is positive and increases, leading to strain energy dissipation. Considering strain softening, the elastic strain energy decreases, the plastic strain energy increases, and the region of strain energy dissipation expands. Considering dilatancy, the plastic strain energy varies more significantly, and the effect of strain softening is amplified. The strain energy is transferred from the deep part to the shallow part of the elastic zone and then to the plastic zone. The preexisting and input strain energies in the plastic zone are transformed into considerable amounts of plastic strain energy and then dissipated. Thereafter, a significant plastic strain appears, leading to the large deformation of the surrounding rock.

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“…En la caverna de la central hidroeléctrica Jinping se mostraron valores significativamente mayores para el área perturbada mediante cálculos numéricos y mediciones relacionadas con el avance en roca metamórfica epizonal [Chen, Y.-F., et al (2015)]. El ancho del área en los macizos influenciadas por la excavación fue de 6 a 17 m. La permeabilidad hidráulica del macizo aumentó de 2 a 3 órdenes de magnitud.…”

Section: Aumento Involuntario De La Permeabilidadunclassified

Hydrogeology of Crystal Rocks in the Planning and Construction of Underground Structures

Höfer‐Öllinger

2021

J. min. eng. res.

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Underground excavations usually have a significant impact on hydrogeological runoff. Water seepage affects underground construction and the long-term behaviour of the structure. The flow paths can be altered by underground activity and the spring areas can become infiltration zones. Concerning the healthy massif, permeabilities near a cavity can increase or decrease. The increase in permeability through excavations in an environment of shear stress and associated water inlets, have a lapse, which can lead to problems in mechanized tunnels when falling below a critical feed rate. When a rock mass is drained, deformations occur, which are reflected in surface settlements; the drainage of the massif causes changes in the physical parameters and the chemical composition of the groundwater. The characteristics of the leaks found in tunnels and drains do not reflect the state of the unaffected groundwater. Numerous parameters in the forecast can lead to over- or underestimations of the actual flow rates of water seepage. In addition to a forecast, it is recommended to carry out sensitivity and risk analyses, in particular to exceeding the value of the forecast and when assessing environmental compatibility, the worst possible scenario

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Excavation-induced relaxation effects and hydraulic conductivity variations in the surrounding rocks of a large-scale underground powerhouse cavern system

Cited by 44 publications

References 36 publications

Comprehensive evaluation of excavation-damaged zones in the deep underground caverns of the Houziyan hydropower station, Southwest China

Comprehensive evaluation of excavation-damaged zones in the deep underground caverns of the Houziyan hydropower station, Southwest China

Transfer and dissipation of strain energy in surrounding rock of deep roadway considering strain softening and dilatancy

Hydrogeology of Crystal Rocks in the Planning and Construction of Underground Structures

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