AREMA - Apparent Earth Pressure Diagram
AREMA - Apparent Earth Pressure Diagram
(OP)
I am trying to apply the "Apparent Earth Pressure Diagram" in Figure 8-28-2 of the AREMA Manual for Railway Engineering. The diagram is a trapazoidal shaped pressure diagram for a multi prop temporary wall. The diagram has a formula "F(H+SC)" to define the maximum pressure of the trapazoid. They give some values of F (psf), H is defined as height and SC is surcharge. I think this formula has an error or this diagram is just a schematic representation. Can anyone confirm this please?





RE: AREMA - Apparent Earth Pressure Diagram
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RE: AREMA - Apparent Earth Pressure Diagram
RE: AREMA - Apparent Earth Pressure Diagram
RE: AREMA - Apparent Earth Pressure Diagram
AREMA Figure 8-28-2 basically shows the active earth pressure is 18H (or H') to 36H (or H'). For softer soils Schnabel will use more than 25H or H'. 25H = (0.8 x gamma x Ka) x H. If you use properly matched unit weights and phi angles, the magnitude of the trapezoid should be approximately 25H(psf) and the total earth load per LF of wall should be approximately 20H^2(plf). The problem is that engineers almost always use an extra high unit weight with an extra low phi angle. Therefore, they can easily wind up with an earth pressure magnitude of 35H to 40H.
In nature, granular soils with higher unit weights usually also have higher phi angles. Therefore, as unit weight increases, phi usually increases and Ka usually decreases. The net result is that you still will have about 25H(psf) and 20H^2(plf) unless you have a very soft cohesive soil. See attached comparison.
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RE: AREMA - Apparent Earth Pressure Diagram
RE: AREMA - Apparent Earth Pressure Diagram
www.PeirceEngineering.com
RE: AREMA - Apparent Earth Pressure Diagram
RE: AREMA - Apparent Earth Pressure Diagram
www.PeirceEngineering.com
RE: AREMA - Apparent Earth Pressure Diagram
RE: AREMA - Apparent Earth Pressure Diagram
www.PeirceEngineering.com