Slopes

B. Material B is cohesive.

C. I could tell by looking at the different y-intercepts of my graphs. Material A has a y-intercept of almost 0.

D. The cohesion value of Material B is 3947.8 according to my graph.

E. Material A - 2843 pascals. Material B - 6816 pascals. To figure this out I plugged my numbers into the formula s = c+σ tanφ. s is shear strength, c is cohesion, σ (sigma) is the normal force, and φ (phi) is the angle of internal friction. For the angle of internal friction of Material A I got 34.8 degrees. For the angle of internal friction of Material B I got 34.99 which I rounded up to 35.

F. These graphs and data describe the strength of each material, and the likelihood that that it will fail based on other parameters. The basic equation that covers those parameters is s = c+σ tanφ. Sigma is the variable that covers normal stress, which varies based on saturation of the slab, and cohesion.

The formula for Material A is, s = C+σ(tan(34.8))

The formula for Material B is, s= C+σ(tan(35))

Riverside Ave. Parameters.

• Dry density :1800 kg/m³

• Wet density :2000 kg/m³

• Gravity : 9.8 m s^-2

• Phi angle : 30 degrees

• Failure plane angle (alpha) : 30-35 degrees

• Slab thickness (h) : 1.0-1.5 meters

• Cohesion (c) : 0 - 10000

• Saturation depth (h') : 0-1 meters

In the case of this Riverside Ave. landslide there were many factors causing the failure. The fact that so much rain had come down raised the saturation of the bank. The fact that the top of the bank is paved could also send more runoff down the hill. The hill was most likely topped off with a lot of non-compacted fill as well. The cohesion of this is very low. Low cohesion mixed with a lot of water, leads to a very saturated slab. This combination is very bad, and can lead to slope failure like it did on Riverside. Based on the excel model, the slope barely needed any water saturation to fail. A large rainstorm was more than enough to cause failure. Leaving this area forested, and not dumping on it would help keep it stable in the future. Adding root cohesion, and keeping the soil cohesion high could do a lot for Riverside Avenue.