When estimating excavation in ordinary clay, what slope is typically used?

When estimating excavation in ordinary clay, a slope of 1:2 is commonly used to ensure stability and safety during excavation activities. This ratio indicates that for every vertical unit of depth, the slope extends two horizontal units away from the edge. This is important because ordinary clay tends to have cohesive properties that can lead to collapses if the excavated walls are too steep.

Using a 1:2 slope allows for adequate support of the excavated soil, reducing the risk of cave-ins. It also complies with various safety standards and regulations that govern excavation practices. A more gradual slope not only enhances the safety of workers but also facilitates the movement of equipment and materials, reducing potential hazards in the excavation area.

In contrast, other slopes such as 1:1 or 2:1 are generally steeper and do not provide the same level of safety in clay soils. A slope of 3:1 could be used for more stable soils, but is not typically recommended for ordinary clay because the increased angle of repose may not adequately prevent collapses. Therefore, a 1:2 slope is the most appropriate choice for excavation in ordinary clay.