Seite - 1417 - in Book of Full Papers - Symposium Hydro Engineering

limestone, 1 has been considered as 36° and C' as 115 Kpa, in stability calculations. 8. EXCAVATION GEOMETRY Invert elevation for the approach channel is 730 m.a.s.l. Excavation of trenches will start, with 11-1: 1.5V slope in two 8-m berm and after the first 8 meter, a 4-in berm will be excavated and then, the second 8-m wide berm will be excavated at El. 745 m.a.s.l. After that, the excavation slope will be 2H: 1V for complete excavation to minimize the failure surfaces. In other words, in the first 15 m, there is a 4-m berm at El. 738 m.a.s.l. and then, in a 15-m height, the 8-m berm with 2H: 1V slope will be complied with until excavation in soil is completed. The major excavations to be carried out belong to the approach channel, with a maximum depth of 42 m. However, crossing the approach channel or the access, the concrete flat-edge spillway and its chute will start, whose maximum excavation depth will not exceed 12 to18 m. Excavation for the spillway with its slope shown in the figures. 9. MECHANICAL AND GEO-MECHANICAL SPECIFICATIONS OF TRENCH MATERIALS FOR STABILITY ANALYSIS BH-22, BH-23 and BH-24 have been drilled at the right abutment and BH-25 and BH-26 at the left abutment, with following characteristics and pressure meter test has been taken into consideration in its different depths. Meanwhile, the in-situ plate loading test has also been carried out to control the in-situ strength and density of the soil and combination of the results. Mechanical and geo mechanical specifications of the materials have been entered into the calculations based on the pressure meter test results in different boreholes, as provided in table 1, which are totally based on the in-situ pressure meter tests carried out at the site. In depths beyond the values mentioned in table 1, the Lar limestone has been entered in the calculations with φ =36° and C=115 Kpa. Most of the concerned soft rocks have had strength more than the foreseen and selected values. 10. ASSUMPTIONS AND CALCULATION PROCEDURE Calculations have been carried out based on the mechanical and geo- mechanical parameters provided in table 1, limestone properties and drilling 1417