TABLE 1.—Pressures on Typical Structures Under Varying Assumed Conditions.

h = exterior height, l = exterior width, δ = depth of cover, that is, D_E = earth, and D_W = water depth,
φ = angle of repose, and, for tunnels D_W > D_E a depth

W_E = weight of 1 cu. ft. of earth = 90 lb.; W_W = weight of 1 cu. ft. of water = 62½ lb.

Conditions: 1 = normal sand, 2 = dry sand, 3 = supersaturated firm sand with 40% of voids, 4 = supersaturated semi-aqueous material, 60% aqueous, that is, 60% water and aqueous material.

Combined assumed conditions.	h	l	φ	D_E	Combined assumed conditions.	h	l	φ	D_E	D_W
I₁	20	30	45°	40	I₃	20	30	50°	40	60
I₂	20	30	30°	40	I₄	20	30	40°	40	60
II₁	15	15	45°	40	II₃	15	15	50°	40	60
II₂	15	15	30°	40	II₄	15	15	40°	40	60
III₁	15		45°	15	III₃	15		50°	15	15
III₂	15		30°	15	III₄	15		40°	15	15
IV₁	30		45°	30	IV₃	30		50°	30	30
IV₂	30		30°	30	IV₄	30		40°	30	30

Approximate Pressures on Tunnels, per Square Foot.

Pressure per square foot, at	I₁ Earth.	I₃ Earth.	I₃ Water.	I₃ Comb- ined.	I₂ Earth.	I₄ Earth.	I₄ Water.	I₄ Com- bined.	II₁ Earth.	II₃ Earth.	II₃ Water.	II₃ Com- bined.	II₂ Earth.	II₄ Earth.	II₄ Water.	II₄ Com- bined.
A	3,240	3,690	1,500	5,190	2,325	2,880	2,250	5,130	1,485	1,755	1,500	3,255	1,035	1,305	2,250	3,555
B	2,745	3,105	1,500	4,605	1,845	2,385	2,250	4,635	1,305	1,485	1,500	2,985	945	1,170	2,250	3,420
C	2,160	2,475	1,500	3,975	1,350	1,800	2,250	4,050	1,125	1,215	1,500	2,715	810	990	2,250	3,240
D	450	540	1,500	2,040	450	450	2,250	2,700	405	405	1,500	1,905	540	450	2,250	2,700
E	360	360	1,625	1,985	450	450	2,438	2,888	405	405	1,625	2,030	540	450	2,438	2,888
F	270	270	1,750	2,025	450	360	2,626	2,986	360	360	1,750	2,110	540	450	2,626	3,076
G	225	225	1,875	2,100	360	270	2,814	3,084	315	315	1,875	2,190	360	360	2,814	3,174
H									180	225	2,000	2,225	180	180	3,000	3,180
I									90	110	2,175	2,285	135	135	3,188	3,323

Approximate Pressures on Sheeted Trench Faces or Walls

Pressure per square foot at	III₁ Earth.	III₃ Earth.	III₃ Water.	III₃ Total earth and water.	III₂ Earth.	III₄ Earth.	III₄ Water.	III₄ Total earth and water.	IV₁ Earth.	IV₃ Earth.	IV₃ Water.	IV₃ Total earth and water.	IV₂ Earth.	IV₄ Earth.	IV₄ Water.	IV₄ Total earth and water.
A	575	510	100	610	1,350	810	140	950	1,370	1,210	100	1,310	3,175	1,910	150	2,060
B	400	350	190	540	900	540	260	800	1,170	1,030	200	1,230	2,700	1,610	290	1,900
C	200	175	280	455	450	270	380	650	970	855	290	1,145	2,250	1,355	430	1,785
D									775	680	370	1,050	1,800	1,100	570	1,670
E									590	515	460	975	1,350	820	710	1,530
F									400	350	560	910	900	540	860	1,400
G									190	170	650	820	450	275	1,000	1,275