Laserfiche WebLink
general the more plastic the clay, the lower will be the maxim um dry <br />• <br />density and the higher the optimum moisture content. There are a number <br />of items that can be influenced by compaction and % moisture. In the <br />case of Haul Road G, those more noteworthy relationships would be in the <br />shrink-swell potential of the clay. Compaction has the fo llowing <br />influence on shrink and swell characteristics. <br />1. A soil's potential for swell is increased as density increases. <br />2. A soil's potential for swell increases with decreasing <br />compaction moisture content. <br />3. A soil's potential for shrinkage increases with increasing <br />compaction moisture content. <br />Summary of Test Results <br />The soils in and around the Haul Road G construction area are classified <br />as clay (CL) according to where the PI and LL plot on the plasticity <br />chart. These clays approach the CS-S clay which are also called "fat" <br />clays. They tend to be more compressible, less permeable, tend to swell <br />and have a high cation or base exchange capacity. <br />Their use as a construction material, especially embarilanents, under the <br />right moisture and compaction is generally acceptable. They have a <br />relatively high compressive strength and shear strerxfth, they conyxct <br />well and are very low in permeability. <br />• Construction of a road cut through this material can result in some <br />detrimental effects, especially if they are not anticipated. The <br />Standard Penetration Tests indicate that the clay is hard. This also <br />means that the clay is more dense (high lbs/c.f.) which adds more weight <br />to the slope. Under ideal conditions this characteristic doesn't present <br />a problem. Adding water to the material and increasing the slope (or <br />undercutting the slope) will add to instability problems. The other <br />problem with this material is that its swelling potential is quite high. <br />The addition of water to the slope could cause revealing of the slope. <br />STABILITY ANALYSIS <br />The computer slope stability program called SB-SNPE by VonGunten <br />Engineering Software was used to predict slope stability. In order to <br />set up the slope model a number of preliminary steps were taken. <br />Cross-sections of the road were plotted from Sta. 29+00 to 74+00 with the <br />aid of DCA Computer Software (engineering program that runs using <br />Autocad). Visual observations, along with comments regarding stability <br />from CMCRD were the basis for "typical" cross-section selection for <br />stability analysis. The two main areas selected for analysis were <br />between Stas. 48+00 to 54+00 (sidehill) and Stas. 56+00 to 64+00 <br />(unstable drainage). Representative cross-sections were then chosen as <br />51+00 and 60+00. Please refer to Attachment 1S for results. <br />Stability at Station 51+00 <br />The road cross-section, including the uphill and downhill profiles, were <br />used to analyze the stability. A distributed load, simulating a parked <br />haul truck, was also added to the section. The triaxial test conducted <br />4 <br />