Page - 1408 - in Book of Full Papers - Symposium Hydro Engineering

Therefore, trench slope, berms wide and height elaborate and compared base on result of lab tests and “in-situ” test. The above-mentioned explanations belong to a natural case of cutting with trenches of different heights. To provide slope stability of trenches (with any type of weak materials) the simplest and the major way is to decrease the over burden pressure of the slope, if it is made of soil or eroded, weak rock. Indeed, the lower part will be stable for the required safety factor for all loading cases and various conditions. Fig.3. Geotechnical Longitudinal Section along Approach Channel of Spillway The geometry shape of trench of left and right banks of spillway approach channel was designed considering using appropriate geo-mechanically parameters from lab and “in-situ” tests and engineering judgment on the results, The main point is that to meet the desired width for spillway channel after cutting with trenches (different height) to provide stability of trenches. 2. PROJECT OVERVIEW In-situ as well as laboratory tests on the fine-grained materials were carried out and sample materials taken from exploration boreholes obtained from test pits for better understanding of Neogene formation materials in free spillway area of the Glevard dam. The Neogen formation consists of an intercalation of siltstone, mudstone, marlstone and sometimes local loose conglomerate and semi- intercalations of loose limestone. SPT test results of different layers had been used for primary estimation of C and φ parameters had in stability calculations. For more certainty, some "in-situ tests" were carried out to finalize geotechnical parameters of the soil materials of the approach channel and the spillway location, accordingly. 1408