Maximum Likelihood Estimation of Model Uncertainty in Predicting Soil Nail Loads Using Default and Modified FHWA Simplified Methods
Table 1
Summary of wall geometry, soil properties, and nail arrangement for soil nail walls reported in the source documents (after [9]and source data from [6–8]).
Wall
Soil type
Wall geometry
Number of data points
Soil strength properties
Surcharge, (kPa)
Nail
Wall height, (m)
Face batter angle (°)
Back slope angle (°)
Soil friction angle, (°)
Soil cohesion, (kPa)
Soil unit weight, (kN/m3)
Nail length, (m)
Horizontal spacing, (m)
Vertical spacing, (m)
Nail diameter (mm)
Steel bar diameter (mm)
Nail inclination angle (°)
W1
Medium dense, poorly graded sand
5.3
0
0
5
33
4.8
18.0
55
6.4
1.4
1.0
127
29
15−25
W2
Silty sand, clayey silt
5.6
0
27
5
33
4.8
18.0
0
5.2
1.4
1.0
127
29
15−25
W3
Glacial sand, gravel
16.8
0
0
5
40
9.5
21.0
0
10.7
1.8
1.8
229
36
15−20
W4
Silty sand, stiff clay
11.0
20
0
3
30
0
20.0
0
6.0−7.0
1.5−1.75
1.5
127
25
20
W5
Clayey silty sand
20.0
20
0
5
34
5.0
20.0
0
10.0
1.5
1.25
115
25
20
W6
Soft to very soft clay
5.2
0
0
6
0
13.4
18.9
0
6.1
0.75
0.75
152
19
5
W7
Soft to very soft clay
4.3
0
0
5
0
13.4
18.9
75
6.1
0.75
0.75
152
19
5
W8
Silty, gravelly sand
7.6
6
5
8
34*
7.2
17.3
0
6.7
1.5
1.5
203
25
12
W9
Residual soil and weathered rock
7.9
7
33
6
40
7.2
18.9
0
13.4
1.5
1.2
114
29
15
W10
Colluvium and highly weathered rock
12.2
14
33
8
39
0
20.0
0
6.1−9.2
1.5
1.5
89
25−32
10
Note. W1 = Swift-Delta S1; W2 = Swift-Delta S2; W3 = Polyclinic; W4 = Peasmarsh; W5 = Guernsey; W6 = IH30 R-SA; W7 = IH30 R-SB; W8 = San Bernadino Left and Right; W9 = Cumberland Gap 1988; W10 = I-78 Allentown G24 and G33. results indicated = 34° to 42° [7, 8]. In this study, is conservatively taken as 34°.
