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<br />Introduction <br /> <br />Design Guideline 2 <br /> <br />Soil Cement <br /> <br />In areas where high quality rock is scarce, the use of soil cement can provide a practical <br />countermeasure alternative for channel stability and scour protection. Soil cement has been <br />used to construct drop structures and armor embankments, dikes, levees, channels, and <br />coastal shorelines. Soil cement is frequently used in the southwestern United States <br />because the limited supply of rock makes it impractical to use riprap for large channel <br />protection projects. <br /> <br />Design Guidelines <br /> <br />The following design guidelines <br />reflect guidance in information <br />provided by the Pima County <br />Department of Transportation in <br />Tucson, Arizona and the <br />Portland Cement Association. <br />Typically, soil cement is <br />constructed in a stair-step <br />configuration by placing and <br />compacting the soil cement in <br />horizontal layers (see Figure <br />2.1). However, soil cement can <br />be placed parallel to the face of <br />an embankment slope rather <br />than in horizontal layers. This <br />technique is known as plating. <br /> <br /> <br />Figure 2.1 Stair step facing on Bonny Reservoir, <br />Colorado after 30 years (PCA). <br /> <br />1. Facing Dimensions for Slope Protection using Stair-Step Method <br /> <br />In stair-step installations soil cement is typically placed in 2.4-m-wide horizontal layers. The <br />width should provide sufficient working area to accommodate equipment. The relationship <br />between the horizontal layer width (W), slope of facing (S), thickness of compacted <br />horizontal layer (v), and minimum facing thickness measured normal to the slope (tn) is <br />quantified by the following equation and is shown graphically in Figure 2.2: <br /> <br />W = tn.JS2 +1 +Sv <br /> <br />(PCA) <br /> <br />As illustrated in Figure 2.3, for a working width of 2.4 m, a side slope of 1V:3H, and <br />individual layers of 150 mm thick, the resulting minimum thickness of facing would be 620 <br />mm measured normal to the slope. Bank stabilization along major rivers in Pima County, <br />Arizona is constructed by using 150 mm lifts of soil cement that are 2.4 m in width and <br />placed on a 1 V: 1 H face slope. <br /> <br />2.3 <br />