Question

1. Soil can stand in vertical cuts only if it has cohesive strength. Even so, anyone can build a sand castle at the beach using clean fine-to-medium sand, and these castles can have vertical cuts. This appears to be a contradiction.
   1. Explain why sand castles can be built in this way.
   2. If no waves, thieves, rain, or wind disturb the castle, will the vertical cuts stand for a long time? Explain why or why not.

Please make your writing and numbers legible,

thank you

Answer 1

Part A

If the soil is moist we can built the sand castle.Near the beach the sand has moisture like cohesive soil and will have surface tension which will increase the effective stress(as there will be negative pore water pressure) and the shear strength increases.So the vertical cuts can be made in sand castle.

Part B

Beacuse the sand is exposed to the sun and the atmosphere, the pore water can evaporate reducing the effective stress as well as shear strength,so over the time the vertical cut can collapse and cannot stand.