A Method for Dynamic Risk Assessment and Management of Rockbursts in Drill and Blast Tunnels

ere are a series of human or natural activities, including earthquakes, explosions, and rockbursts, which have caused a number of safety accidents in geotechnical engineering. is review paper summarized the theories and methods for dynamic stability analysis of rockmass. First, numerical simulation methods, including finite element method (FEM), discrete element method (DEM), finite difference method (FDM), boundary element method (BEM), discontinuous deformation analysis method (DDA), and numerical manifold method (NMM), are summarized. Second, the laboratory experiments, containing shaking table test, split-Hopkinson pressure bar test (SHPB), improved true-triaxial test, dynamic centrifugal model test, acoustic emission (AE) technique, and dynamic infrared monitoring, are considered. ird, the in situ tests including microseismic (MS) technique, velocity tomography, stress-strain monitoring, and electromagnetic radiation monitoring are considered. Finally, some comprehensive analysis methods based on statistical theories are also provided. It is pointed out that the study foundation for the dynamic stability of rockmass is weak to explain the mechanism. So, a set of general comprehensive theories integrating the different methods, including theoretical analysis, numerical methods, laboratory experiments, and in situ tests, should be completely established. is is the most effective way for further investigation.

Section: Some Comprehensive Analysis Methods Based On Statistical Thementioning

confidence: 99%

Dynamic Stability Analysis of Rockmass: A Review

Dong

Wang

et al. 2018

“…Especially in hard rock, the wear of cutting tools of the excavating equipment is severe and the removal and reinstallation of cutting tools takes a long time, so mechanized excavation in hard rock is uneconomic and time-consuming. Although drilling and blasting is a traditional excavation method, it still plays an important role in tunnel excavation on account of its good applicability and economy [3][4][5]. At present, the mainstream blasting method is controlled blasting, which includes directional blasting, smooth blasting, splitting blasting, and millisecond blasting [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Adjacent Hole on the Blast‐Induced Stress Concentration in Rock Blasting

Yang

Shao

Jing

et al. 2018

To investigate the effect of an adjacent hole on the blast-induced stress concentration in rock blasting, a rock blasting model with an adjacent hole is explored through theoretical analysis and numerical simulation. The commercial software LS-DYNA is utilized to simulate adjacent hole effect in rock blasting, in which the Johnson–Holmquist concrete material model is used to simulate rock and the high-explosive-burn-explosive and the equation of state of JWL are used to simulate explosive. Influences of the key parameters of adjacent hole effect in rock blasting, pitch of holes, adjacent hole diameter, and uncoupled medium in a blasting hole are extensively explored. According to the simulation results, when the explosion stress wave spreads to the adjacent hole wall, the tangential stress on the adjacent hole wall induced by the explosion stress wave is always greater than the radial stress. Adjacent hole diameter has a major effect on stress concentration, but with the adjacent hole diameter increasing, the stress concentration phenomenon weakens and the free surface effect of the adjacent hole plays a more important role.

“…Meanwhile, excavation methods implemented in deep-buried tunnel excavation have considerable influence on the rockburst evolution process. Most deep-buried tunnels have been excavated by drill-and-blast (D&B) method resulting in large amounts of studies on the evolution mechanism and prevention of rockbursts associated with blasting excavation [38][39][40][41][42]. Nevertheless, TBM has always been the preferred method to construct the deep-buried tunnels owing to its incomparable advantages.…”

Section: Introductionmentioning

confidence: 99%

Microseismic Monitoring of Energy Changes in Deep Tunnels during the TBM Tunneling of the Jinping II Hydropower Station

Zhuang

Tang

et al. 2018

e TBM tunneling at the Jinping II hydropower station in Southwest China has received extensive concerns around the world because of its large engineering scale and the high rockburst risks faced in the tunnel advancement. e associated energy changes of rockbursts and control method for safe TBM tunneling are to be further investigated. A movable microseismic (MS) monitoring system was established to capture the MS events and rockbursts when the TBM excavated the headrace tunnel #1 at the Jinping II hydropower station. e spatial and temporal patterns of the energy changes in the tunnel rock masses were studied. Meanwhile, the evolution of a rockburst encountered in front of the TBM excavation face was revealed, and the performance of the top pilot tunnel method on the reduction of the rockburst risks in the headrace tunnel #1 was evaluated based on the energy changes of the surrounding rock masses. It can be concluded that energy accumulation and energy release firstly occurred in the surrounding rock masses at the southern end of the top pilot tunnel section of the headrace tunnel #1. en, energy transference of the rock masses took place from the southern end to northwest of the top pilot tunnel giving rise to the occurrence of a moderate rockburst about 30 m in front of the tunnel. However, no rockbursts appeared when the TBM excavated through the top pilot tunnel section of the headrace tunnel #1. erefore, the top pilot tunnel method really works in reducing the risks of rockbursts during the TBM tunneling in deep tunnels.