Damage assessment of basaltic rock mass due to repeated blasting in a railway tunnelling project – A case study

Ramulu, M.; Chakraborty, A.K.; Sitharam, T. G.

doi:10.1016/j.tust.2008.08.002

Cited by 108 publications

(33 citation statements)

References 9 publications

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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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“…Under such repeated blast loading, cracks are propagated in quantity and extent or connected gradually to be main cracks or collective cracks. It means the repeated blast loading causes damage accumulation in rock masses, and in general leads to relatively excessive damage than a single fold (Villaescusa et al 2004;Ramulu et al 2009). At present, investigation of the cumulative damage due to repeated blast loading and its effects is mostly implemented by scaled or full size experiments, which are very expensive, and timeconsuming, and sometimes is impossible because of the presence of the stress redistribution-induced damage.…”

Section: List Of Symbolsmentioning

confidence: 99%

Numerical Simulation of Rock Mass Damage Evolution During Deep-Buried Tunnel Excavation by Drill and Blast

Yang

et al. 2014

Rock Mech Rock Eng

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Presence of an excavation damage zone (EDZ) around a tunnel perimeter is of significant concern with regard to safety, stability, costs and overall performance of the tunnel. For deep-buried tunnel excavation by drill and blast, it is generally accepted that a combination of effects of stress redistribution and blasting is mainly responsible for development of the EDZ. However, few open literatures can be found to use numerical methods to investigate the behavior of rock damage induced by the combined effects, and it is still far from full understanding how, when and to what degree the blasting affects the behavior of the EDZ during excavation. By implementing a statistical damage evolution law based on stress criterion into the commercial software LS-DYNA through its user-subroutines, this paper presents a 3D numerical simulation of the rock damage evolution of a deep-buried tunnel excavation, with a special emphasis on the combined effects of the stress redistribution of surrounding rock masses and the blasting-induced damage. Influence of repeated blast loadings on the damage extension for practical millisecond delay blasting is investigated in the present analysis. Accompanying explosive detonation and secession of rock fragments from their initial locations, in situ stress in the immediate vicinity of the excavation face is suddenly released. The transient characteristics of the in situ stress release and induced dynamic responses in the surrounding rock masses are also highlighted. From the simulation results, some instructive conclusions are drawn with respect to the rock damage mechanism and evolution during deep-buried tunnel excavation by drill and blast.

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“…Many scholars, based on PPV, focused on the study of the blasting damage threshold [9][10][11][12] and prediction of the blasting damage range [13][14][15][16][17][18][19]. Meanwhile, such methods as the SDOF method [20], the borehole extensometer measurement [21], the borehole TV observation [21], the plastic zone observation [22], the maximum plastic strain identification [22], and the effective strain identification [23] are combined to verify and complement each other. In addition, Hu et al [24] studied the distribution characteristics of PPV near the blasting source and the correspondence between PPV and the damage degree.…”

Section: Introductionmentioning

confidence: 99%

Study on Distribution Characteristics of Damage Range along Smooth Blasting Hole Based on PPV

Pan

Zhang

Shuangying

2020

Mathematical Problems in Engineering

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The damage range of surrounding rock has an important influence on optimization of blasting parameters. This study, based on the vibration attenuation law near the blasting source and the characteristics of the load acting on the wall of the smooth blasting hole, derives the distribution formulas of the damage range along the borehole during the expansion and quasistatic processes of detonation gas, respectively. More importantly, the quantitative relationship between the damage range and the charge weight of the single borehole is established. The experimental data are used to verify the correctness of the theoretical formulas. The results show that the damage range during the expansion process of detonation gas presents a continuous saddle-shaped distribution along the borehole and the maximum damage range is near the charge segment. The damage range during the quasistatic process of detonation gas is uniformly distributed along the borehole and can be more conservatively used to the practical prediction after corrected. The theoretical formulas are applicable to the perimeter hole with the radial and axial decoupled charge structure, which can provide a theoretical support for controlling the damage range of surrounding rock according to the charge weight.

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Damage assessment of basaltic rock mass due to repeated blasting in a railway tunnelling project – A case study

Cited by 108 publications

References 9 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

Numerical Simulation of Rock Mass Damage Evolution During Deep-Buried Tunnel Excavation by Drill and Blast

Study on Distribution Characteristics of Damage Range along Smooth Blasting Hole Based on PPV

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