_GENERAL DOCUMENTS - C1981017 (244)

Home Browse Search

LABORATORY TESTING, PROGRA'-1 For purposes of laboratory tcsting, representative samples of the materials a`fecting slope stability were obtained in the field . Basically, only two materials warranted consideration : the excavated shale from. which the fill will be built, and the native material which the fill will be constructed . Shale samples were obtained from stockpiles of material_ previously excavated, while samples of the native material were obtained from test pits . A standard Proctor test with rock correction (MT1.1 D-698) was perforrr.ed on the shale cr:aterial, in order to deter,cine the maximum Proctor density and provide a curve for moisture-density relation. This test indicated a n:a;ci- mum. density of 131 . 2 pcf at 8. 8/ moisture. The moisture-densi''y relation curve is pr_ov�dcd with this report (Plate 2 ) . For the shale fill, it was felt that UP triaxial shear strength testing would provide the best information, since the compacted fill will probably behave as a clay. There- fore, the triaxial test was selected as preferable to the direct sheer: test, for purposes of deter:r:ini.ng co'_ esion and friction angle. Since the fill will be provided with drainage ditches upslope and at the toe, will maintain a positive gradient at all points, and is underlain by a relatively permeable strata, it- is unlikely '.:hat the fill itself will ever become sat0rated. Therefore, it was felt that a total-stress approach would be appropriate, and that an un- consolidated, undrained (UU) triaxial test would provide realistic information. The triaxial tests were performed using AOINI tj 1. 5 inch diameter remolded samples, which were remolded at approxi- mately 90;, of the maximum; standard Proctor density for the shale. This was done in order to simulate the strength cliaracteristics