apparent earth pressure for layered soil 2

[HanStrulo]

Hi Everyone.

I am designing a shoring shaft with sheet wall and I thought it will be straight forward.

My soil profile is layered 50/50. the top half is sand (fill) and the bottom half is clay.

how can i get the apparent earth pressure to design the struts? is there a specific way to use for layered soil?

Thank you.

 

[SlideRuleEra]

1) Pressure from sand is calculated the normal way.

2) Sand is considered a surcharge on the clay - use phi for clay to compute the surcharge.

3) Pressure from clay is calculated the normal way.

http://www.SlideRuleEra.net

 

[PEinc]

HanStrulo, SRE has it right for the theoretical earth pressure. However, you mention "apparent earth pressure." If you have a braced or tiedback sheeting/shoring wall, the apparent earth pressure diagram may be trapezoidal or possibly rectangular. Therefore, you will need to convert the theoretical pressure diagram to a rectangular or trapezoidal diagram. Calculate the total area (load per LF of wall) under the theoretical diagram and increase it by 20% to 30% (I use 30% per AASHTO). Then, form an apparent pressure diagram that has the increased, total area (load).

http://www.PeirceEngineering.com