In recent years, experimental and numerical researches on the effect of blasting pressure stability existing tunnels was widely obtained. However, during excavation a new tunnel or expansion old an has disadvantages still unclear. Some were carried out to study relationship observed Peak Particle Velocity (PPV) lining areas along direction, due either lack in situ test data difficulty co...

Some of the geotechnical parameters used in the analysis may not be accurately measured directly from laboratory tests due to effects of sample disturbance and errors of tests. The back analysis or the observational method are thus often applied to determine the representative and/or dominant strength parameters based on field observations in practice. Based on the Hoek-Brown failure criterion,...

the rock masses in a construction site of underground cavern are generally not continuous, due to the presence of discontinuities, such as bedding, joints, faults, and fractures. the performance of an underground cavern is principally ruled by the mechanical behaviors of the discontinuities in the vicinity of the cavern. during underground excavation, many surrounding rock failures have close r...

Based on real-time monitoring data of harmful gasses during blasting and excavation Yuelongmen Tunnel Chengdu–Lanzhou Railway, this study summarized laws distribution characteristics gas escape intensified by the excavation, effectiveness shotcreting grouting for water blocking to inhibit is verified. Then, taking water-containing gas-containing voids as carriers, considering influence differen...

Seeking the law of through-crack in double hole shaped charge can help reveal rock failure mechanism directional controlled blasting. Using LS-DYNA numerical simulation analysis, dynamic mechanical behaviors double-hole crack development and penetration elliptical bipolar linear-shaped blasting ordinary were compared studied. The results showed that it was difficult to form a straight line thro...

the paper is concerned with the hydrogeological appraisal of the proposed mining operations in thethar lignite field in sindh, pakistan. the thar coalfield covers an area of approximately 9000km2 andcontains three lignite seams lying at depth of 130m to 250 m. in the thar lignite field, the presence ofthree main aquifers induces pore pressure in the rock mass surrounding the lignite seams and m...

We present a new set of spectroscopic and photometric data extending the observations of SN 1997D to over 400 days after the explosion. These observations confirm the peculiar properties of SN 1997D, such as the very low abundance of Co (0.002 M⊙) and the low expansion velocity of the ejecta (∼ 1000 km s ). We discuss the implications of these observations for the character of the progenitor an...

Metal-free stars are assumed to evolve at constant mass because of the very low stellar winds. This leads to large CO-core mass at the end of the evolution, so primordial stars with an initial mass between 25 and 85 M are expected to end as direct black holes, the explosion energy being too weak to remove the full envelope. We show that when rotation enters into play, some mass is lost because ...

 Preparing to manage weapons of mass destruction events challenges emergency services systems neighboring Syria every day. Understanding injury from explosives is essential for all providers of emergency care in both civilian and military settings. In this case, the authors present a 22-year-old man who was admitted to the emergency department with displaced skull fracture, epidural hemorrhage ...

Measuring the elastic modulus of in-situ rock masses over scales of tens of meters remains an important challenge in experimental rock mechanics. We present a new approach using ambient resonance measurements of freestanding rock masses to identify vibrational modes, which are then matched with numerical models implementing bulk, globally representative material properties. The result is an exp...