Study Of AE And Seeping Characteristics Of Limestone Destructive Process

Subsea tunnel in Dalian Bay, metro Line 1 and 2 in Dalian City are being built now, all these are typical underground engineering items, geologic survey results show that, projects above all go through limestone rock formation. Dalian is coastal water-rich region, tunnel construction here is with comparatively complex stress path, what takes attention is wall rock destroy and water bursting risk under construction. Theory of wall rock injury and rock fracture seepage is far from mature, it is of far reaching importance to carry out correlation studies. It is expected to supply theoretical basis for safe work practices and prevention and cure of water inflow and seepage in the above or similar engineering by the study as follows in the text. Research content and conclusion is as follows:(1) The impacts of water to the stability of engineering rock mass are chemical and mechanical actions. In aspect of mechanical action, it proceeds fracture seepage tests, results of which indicate that, the impact of head pressure to seepage is obvious, and this text also analyze its relation with strain, which proves the relation above further though the increase of axial deformation. In chemical action aspect, it proceeds creeping tests in the text, the results indicates that, each grade of loading would bring immediate strain, which takes up 20～70%in proper. It is indicative of obvious creeping phenomena under chemical etching in each loading step. Which comparing with experiment without chemical etching, saves time, shows us the acceleration effect of rock creep by chemical etching.(2) Acoustic Emission(AE) test indicates that:①When the cover load of rock arrives at 70%of its peak stress, load-unload response ratio Y tends to 1, so it is feasible to take rock crippling premonition as ratio Y approach to 1.②Variance ratio r of power-low and linear fitting curve, and parameter z, are all much less than 1, which explains that AE energy accelerate release phenomena during cracking is obvious.(3) RFPA2D simulation indicates that:accelerating energy release reflects the characteristic of interior micro-crack spread, the results reappearance microscopic behavior during rock bursting.