Transient characters of energy changes induced by blasting excavation of deep-buried tunnels. (June 2015)

• Record Type: Journal Article
• Authors: Fan, Y.; Lu, W.B.; Yan, P.; Chen, M.; Zhang, Y.Z.
• Is Part Of: Tunnelling and underground space technology. Volume 49(2015)
• Page Start: 9
• Page End: 17
• Publication Date: 2015-06
• Subjects: Energy change -- Quasi-static unloading of in-situ stress (QSUIS) -- Transient release of in-situ stress (TRIS) -- Damage range -- Excavation; Tunneling -- Periodicals; Underground construction -- Periodicals; Tunnels -- Periodicals; Underground areas -- Periodicals; 624.193
• DOI: 10.1016/j.tust.2015.04.003
• Languages: English
• ISSNs: 0886-7798

Abstract

Graphical Abstract: Highlights: Energy changes induced by quasi-static unloading of in-situ stress were analyzed. Transient characters of energy changes induced by dynamic unloading were studied. Effects of transient changes of energy on the damage range were represented. Abstract: As energy release plays an important role in engineering disasters such as rockburst, seismicity induced by deep rock mass excavation via drill and blast, energy changes caused by excavation have been studied for a long time. However, previous studies ignored the time factor and took the unloading of in-situ stress on the excavation boundary as a quasi-static process. In this paper, energy changes induced by quasi-static unloading of in-situ stress (QSUIS) and transient release of in-situ stress (TRIS) were analyzed for the case of circular excavation under the condition of in-situ hydrostatic stress. Results show that, different from energy changes caused by QSUIS, the dynamic adjustment of strain energy induced by TRIS which first decreases and then increases, is a transient process. With the propagation of the unloading stress wave from the excavation boundary to the far surrounding rock masses, energy is transmitted by the way of radial stress doing work from the far surrounding rock masses to the near ones which causes the transient aggregation of strain energy. Comparison based on the effects of energy changes on the damage range indicates that higher aggregation degree of strain energy causes larger damage range induced by TRIS than that induced by QSUIS. In addition, a practical application in Jinping II hydropower project was presented as a verification.