Time-dependent deformation and fracture evolution around underground excavations

Fu, Teng Fei; Xu, Tao; Wasantha, P. L. P.; Yang, Tao; Nara, Yoshitaka; Heng, Zhen

doi:10.1080/19475705.2020.1856202

Cited by 15 publications

(5 citation statements)

References 43 publications

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“…Convergence deformation is one of the severe effects of excavations which can be spectacular. It evolves as time increase owing to the time-dependent behavior of rocks [116,4]. Convergence is inevitable, as revealed by Kontogianni et al [117], since it is part of tunnels deformations mechanisms.…”

Section: Convergence Deformationmentioning

confidence: 99%

“…It is quite obvious that, when excavating deep rocks tunnels, the virgin rock mass properties are modified [1,2], and there are disturbances or alteration of the existing stresses in the rock massifs [3,4]. There is then an imbalance in the stresses state of rocks which mainly surround the generated openings.…”

mentioning

confidence: 99%

“…The red Sandstone samples was initially immersed in water at different durations like 2 days, 4 days, 6 days and 8 days. In the figure, the symbol "d" refers to days, the times are multiplied by 4 10 s , the creep strain rates are multiplied by 5 10 1 s . s refers to second.…”

mentioning

confidence: 99%

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Long-term degradation, damage and fracture in deep rock tunnels: A review on the effect of excavation methods

Frenelus

Peng

Zhang

2021

Frattura Ed Integrità Strutturale

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Rocks are frequently host materials for underground structures, particularly for deep Tunnels. Their behavior plays a fundamental role in the overall stability of these structures. In fact, the erection of deep tunnels imposes rocks excavations around the defined routes. These excavations are generally carried out by various methods of which the most used are Drill-and-Blast (DB) and Tunnel Boring Machine (TBM). However, regardless of the tunnelling method used, the impacts such as the perturbation of the initial stress field in rocks and the release of the stored energy are always significant. The impacts produce damage, fractures and deformations which are generally time-dependent and influence the long-term stability of deep tunnels built in rocks. Thus, by considering the aforementioned excavation methods, this paper identifies, reviews and describes the relevant factors generated during and after rock excavations. Interestingly, such factors directly or indirectly influence the long-term stability and therefore the structural integrity of deep rock tunnels. In addition, some recommendations and proposals for future works are presented. This paper can provide useful references in understanding the degradations, damage and fractures generated by tunnelling methods and facilitate suitable actions to ensure long-term stability of deep underground structures.

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Section: Convergence Deformationmentioning

confidence: 99%

mentioning

confidence: 99%

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Long-term degradation, damage and fracture in deep rock tunnels: A review on the effect of excavation methods

Frenelus

Peng

Zhang

2021

Frattura Ed Integrità Strutturale

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“…Sun et al (2015) conducted a detailed analysis of the deformation and stress characteristics of surrounding rock from the perspective of rheological properties. Time-dependent deformation and fracture evolution around underground excavation with different shapes were numerical studied by stress corrosion theory from the view of the rheological model (Fu et al 2020). Keawsawasvong and Ukritchon (2020) proposed a new design method for stability analyses of shallow buried tunnels with no liner, considering the generalized Hoek-Brown failure criterion.…”

Section: Introductionmentioning

confidence: 99%

The failure characteristics around shallow buried tunnels under rainfall conditions

Wang

Zheng

et al. 2021

Geomatics, Natural Hazards and Risk

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The instability of weak surrounding rock around shallow buried tunnels induced by rainfall is a challenge for tunnel engineering and threatens construction safety. To reveal the influence of rainfall on the rock surrounding a tunnel, the results of experiments on the failure of surrounding rock under different rainfall intensities and durations using a self-developed test system are presented. First, the stress and seepage behaviors of the surrounding rock under rainfall were analysed, and the results showed that the stress increased while the pore water pressure decreased as the rainfall intensity decreased. It was more difficult to maintain vault collapse as rainfall intensity increased, and the particle erosion in the model intensified as the rainfall duration increased. The change in pore water pressure was greater than the change in stress, but the stress and pore water pressures influenced each other during rainfall. The influence of rainfall on the rock at the top of the tunnel was greater than that at the two sides of the tunnel because the seepage channels at the top of the tunnel were more developed and collapsed more easily due to smaller stresses. According to the phenomena of the surrounding rock observed during the test, the evolution of progressive failure under rainfall was roughly divided into eight stages: stability, water drop, continuous water flow, partial collapse, mud and water mixture, vault collapse, throughgoing collapse, and massive water and mud gushing. Furthermore, the final failure pattern of the surrounding rock consists of an excavation disturbance zone, vault damage zone and collapse failure zone. This research helps to reveal the progressive failure of surrounding rock around tunnels under rainfall conditions and can be used as a reference for designing disaster prevention strategies in practical engineering.

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“…It is proved that the radar antenna with high frequency is effective for the detection of the EDZ (Excavation Damage Zone) (Silvast and Wiljanen 2008). Other scholars (Siren et al 2015;Xu et al 2017Xu et al , 2021Fu et al 2020) have compared and analyzed the URL's EDZs in ASPO (locates in Sweden) and in ONKALO (locates in Finland). Mostly are about the blasting effect, attenuation of vibration law and the damage of surrounding rock caused by blasting.…”

Section: Introductionmentioning

confidence: 99%

Rock blasting vibration velocity and excavation damaged zone for the high-level radioactive waste geological disposal

Man

Liu

Song

2021

Geomatics, Natural Hazards and Risk

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Based on Beishan Exploration Tunnel (BET), the blasting test has been carried out and studied deeply, especially the blasting vibration velocity and excavation damaged zone (EDZ) have been monitored immediately along the blasting cycles. It has obtained that the maximum blasting vibration velocity ranged from 4 cm/s to 60 cm/s. Meanwhile, the EDZ tested by the radar system is ranged from 17 cm to 24 cm. Furthermore, as the cutting method, surrounding hole distance and specific charge are different, the maximum blasting vibration velocity and EDZ are also diverse caused by the blasting energy release, distribution, absorbing, and transfer. Finally, the controlling method with rock damaged depth using the maximum blasting vibration velocity at the distance 10 m is proposed. Through the blasting vibration velocity attenuation law and rock damaged characteristic, the threshold of the maximum blasting vibration velocity at the distance 10 m has been confirmed, i.e. when the maximum blasting vibration velocity is under 100 cm/s, the rock damaged depth could be controlled within 30 cm. Then the blasting damaged zone could be ensured and confirmed. The research and theoretical knowledge could be applied to the blasting and excavation of the deep geoengineering and the HLW geo-disposal.

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Time-dependent deformation and fracture evolution around underground excavations

Cited by 15 publications

References 43 publications

Long-term degradation, damage and fracture in deep rock tunnels: A review on the effect of excavation methods

Long-term degradation, damage and fracture in deep rock tunnels: A review on the effect of excavation methods

The failure characteristics around shallow buried tunnels under rainfall conditions

Rock blasting vibration velocity and excavation damaged zone for the high-level radioactive waste geological disposal

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