Calculation Sheet
Design of Pump House
Sheet No PH/4
Additional resistance to uplift Additional resistance to uplift is given by friction between the soils and the walls, Td Rd = Td Verification of stability against Uplift Limit State (UPL) Vdst;d ≤
Gstb;d
+
Rd
Use calculated values of structure self-weight and hydraulic uplift force to determine the minimum value of Rd required in order that stability is achieved. BS EN 1997-1 Table A.NA.15
Partial factors on Actions for UPL limit state γG;dst = 1.1 γG;stb = 0.9 Rd Td
≥ ≥ ≥
Vdst;d – Gstb;d 1.1 × 2330 – 0.9 × 2171 2563 – 1954
=
609 kN
To determine minimum friction (δd) required between soil and walls in order to generate sufficient friction force (Td) to achieve stability, must first determine lateral earth pressure distribution on walls. Characteristic soil properties (assumed) γ = 18 kN/m³ φ′k = 30° BS EN 1997-1 Table A.NA.16
To obtain design soil properties, use partial factors on soil parameters for UPL limit state γφ′ φ′d
BS EN 1997-1 Eqn 9.1
= 1.25 _ = tan 1 [tan φ′k / γφ′] _ = tan 1 [tan 30° / 1.25]
=
24.7°
Coefficient of Lateral Earth Pressure ‘At Rest’ K0 = 1 – sin φ′d = 1 – sin 24.7 = 0.58
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