Behavior of Pop-up Structures in Thrust Wedges on the Right Pressure Shaft Collapse of SIAH BISHEH Dam, North IRAN
The Siah Bishe Pumped Storage Dam is located in the northern part of the Alborz mountain range in Iran. The investigation results and the effect of brittle deformation of two fault sets in the right pressure shaft of Siah Bisheh Dam are discussed in this paper. The shaft is arranged in sedimentary and volcanic highly jointed rocks of Triasic and Jurasic ages. The length of the shaft is 450m and its diameter is 6m with 65 degree inclination relatively south-north trend. The results of geoengineering surveys using boreholes and statistical joint-graphics of stereograms reveal at least two sets of faults in the rock mass. Several transversal sections along the shafts were studied in order to analyze the effect of faults in shaft collapse. The findings from the surface and underground mapping and investigation boreholes are described and interpreted in a geological map of pressure shaft slope including sections and stereograms. The site area and especially the area of the pressure shaft are characterized by the presence of three important thrust faults that cut through the whole stratigraphic series. The Main Thrust Fault (MTF), fault Nr. 2, both dipping to the north and fault Nr.3 that dips to the south. East of the site, faults 2 and 3 border a large ‘pop-up’ structure while the Main Thrust Fault occupies a lower tectonic position. The results show that the collapse could be a local occurrence which is limited to a critical, fractured and water-saturated rock zone at the boundary between MTF and fault 3. Stability of the shaft was analysed with Unwegde 3.0 software. Result of rock bolting of the shaft was not suitable because of depth of the tip wedges are longer than maximum allowable rock bolt length. The lowest safety factor occurred on wedge number 4 (SF=0.873). But using of shotcrete as a support shows that safety factor of the wedge is increased to 3.219, when shotcrete thickness is 20 cm.
H.Hassani H.Sarkheil Sh.Arshadnejad
Faculty of Mining, Metallurgical and Petroleum Engineering, Amirkabir University of Technology Mining Engineering Department, Mahallat Azad University
国际会议
香港
英文
1-3
2009-05-19（万方平台首次上网日期，不代表论文的发表时间）