| On the basis of in situ stress measuring at engineer site, indoor experimentation analysis and simulative calculation, exerting multidisciplinary theory, for example, engineering geology, rock body mechanics and so on, this dissertation, combining with practical tunnel project, studies the many problems of deep-long tunnels at the north Tianshan mountain of JINGYIHUO railway, Sinkiang. For instance, the in-situ stress field of tunnel area, project stability, geological hazards etc. It is on the base of collecting and analyzing predecessor's studying fruits.By view of researching of area tectonic at tunnel region, geological model is established on the basis of researching theory and related experiment. The stress state of the tunnel site is qualitatively analyzed, including size, orientation and distribution regularity by simulation analyzing. At the same time, the country rock stability of tunnel is discussed and the geological hazard (for example, rock burst) after tunnel excavating is forecasted by resulting of in-situ stress measurement and analyzing of finite-element simulation at in-situ stress field on the basis of on-the-spot in situ stress measured by hydraulic fracturing at the tunnel site of north TIANSHAN mountain of JINGYIHUO railway and simulated results. It gives emphasis to four points as follows. First, geological environment of tunnel area is valuated by geological survey at on-the-spot site. Second, the distribution principle of surrounding rock stress site is studied by measuring in-situ stress with hydraulic fracturing at the north TIANSHAN tunnel area of JINGYIHUO railway. Third, on the basis of simulating the tectonic stress field and the tunnel crossing rifts by three-dimensional finite element analog simulation technology, the stress field of tunnel area is researched, the distributed character of tunnel surrounding rock is analyzed and the best form of tunnel section is chose. Last, Rock blasting is studied during the constructing of the north Tianshan mountain tunnel, for example, rock burst probability, types, levels and places. On the basis of past two years' researching, some progress and conclusion are obtained as follows: Firstly, geological environment of tunnel area is valuated by collecting predecessor's data. It shows that geological condition is complicated at tunnel area and characteristic of tunnel is deep (about 1000m) and long (13.62km). There are two active rifts in the region (the northern and southern rifts of KE LUO BO NU SHAN Mountain). There are two rifts which effect directly on the tunnel (F15 and F18). F18 is a active rift among them. And it has effected greatly on the construction of tunnel, because it still activates at present.Secondly, In-situ stress is measured by hydraulic fracturing method at 3 drill holes of tunnel site. Measuring results and analysis of regional present stress field shows:①Present area stress field plays a leading role in the SN direction extrusion, and intersects at big angle with railway tunnel of NE direction, which is disadvantageous to the tunnels' stability, because it is bigger about the difference value of the maximum and minimum main stress.②The present maximal compressive principal stress value increases along with the deepness increasing. In the range of 100 meter of the earth's surface, the value ranges from 0 to 12MPa. In the range from 100 to 400 meter, the value is not more than 21MPa.③Horizontal stress is dominant in the present area stress field of tunnel site. Stress state belongs to the contrary rift pattern. And difference value of maximal and minimal principal stress ranges from 2.70 to 15.24MPa. Moreover, their ratio value ranges from 1.44 to 6.49. Namely, rock body of tunnel wall rock has some shearing stress.④the principle stress direction of tunnel area is basically conform to the direction of earthquake focus mechanism solution.Thirdly, on the basis of measurement, experiment data and geological tectonic characteristic, geological model is established by making use of ANSYS software. On the basis of analyzing model, the simulation of in-situ stress site is finished at the great longer and deeper tunnel area. Numerical value simulation results shows:①Present area stress field is main in the NNW direction extrusion, and intersects at big angle with railway tunnel of NE direction. In-situ stress direction has some variety because of suffering from terrain affection at the middle part and shallow position of the tunnel.②The present maximal compressive principal stress value is conform to the measurement value. In the range from 0 to 400 meter of the earth's surface, the simulation value is compatible very much with measurement data.③The rise and fall of contour line of maximal main stress on section is conformed basically to the variety of topography.④It is obvious specially that rift zone effects on the distribution of maximal main stress. And it shows obviously that contour lines go down along rift zone.For choosing rational tunnel section, the tunnel segment crossing 15th rift is analyzed by finite element method. It shows that the stress state of round and straight wall and semicircle-shaped tunnel is almost large. Moreover, they are all stability state. Straight wall and semicircle shaped section is fit to the tunnel on the basis of making fully use of sectional space, analyzing the stress state of wall rock and exacting the cubic meter of earth. Therefore, Straight wall and semicircle shaped is chose in the tunnel.Lastly, Using basal theory of engineering geo-mechanics, theoretical mechanics, elastic-plastic mechanics etc. and regarding concrete project as example, thinking and method of deep-long tunnels' main geological hazards prediction have been put forward preliminarily. The dividing method of rock burst type is summed systemically and overall up. On the basis of systemically analyzing eight influencing factors of rock burst occurrence, the ratio of rock single axial compressive strength Rc to maximal principal stressσ1 is regarded as the standard of distinguishing rock burst occurrence at the north Tianshan extra long tunnel of the JIYIHUO railway project. The intensity rank and position of rock burst occurrence is predicted emphatically at the north Tianshan tunnel. According to all sorts of rock bursting criterions, it shows that rock burst occurrences has some possibility at the north Tianshan tunnel. At the same time, geological hazards are predicted during the constructing of the north Tianshan tunnel.
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