Laserfiche WebLink
- 15 - <br />• <br />clastic. They show so,~e softening near the water table. Free water <br />was measured at depth 15 feet in the valley ~~ttom. The sandstone <br />bedreck contains an abundant anount of fines. Standard penetration <br />resistance and unconfined compressive strength tests indicate the <br />bedmek is compatent. Direct shear tests perforr~ed on the cmper clays <br />indicate they possess moderate strength. F.esults of direct shear tests <br />are shown on Figs. 21 and 22. <br />Stability Analysis: The relatively st^_ec valley crofile, approximately <br />133, requires the downstream slope of the °.mhank.:.ent to he as steep as <br />possible in order to li,:~it the area an~ quantity o° fill. The natural <br />,: <br />soils in the bottom of the valley are only of ;!xy3erate strength an~3 in <br />• their present condition could not adequately su^port a hinh dam with a <br />3:1 downstream sloce. In order to achieve a 2.5:1 downstream slope, <br />our analysis included rerioval of this raterial or. the downstream <br />section of the day and replacirxl it compacted si-~ilar to the enhanlc*,ient <br />material. 11s the natural soils arc very ;:gist, it e~ay be ire <br />expedient to stockpile their after removal and bac}:fill with importxl <br />drier soil. <br />Using this approach arx3 strength values obtained from the typical <br />borrow soils as well as the natural soils un•9erlying the site, slip <br />circles were analyzed. Results of these analyses are shown on Fi7. 7C. <br />They indicate satisfactory factors of safety for all conditions. <br />Settlement: Settlement shoulc] be fairly mall ar.:7 well within <br />. tolerable limits for this type construction providim the dor<mstrean <br />alluvial soils have !aeon re..oved and recompacted. t:e estimate final <br />'i <br /> <br />