112
basins. Multiple regression analyses similar to those for Ex prediction
equations were performed to develop equations suitable for the predic
tion of E2. The results of these analyses indicated the following two
equations provided the best overall accuracy for the range in variables
used in the study.
Case 1. For 150.0 < E < 300.0 ksi, 1.5 < t < 6.0 in.,
1 l
42.5 < E < 170.0 ksi, 30.0 < E < 60.0 ksi,
2 3
and 10.0 < E < 40.0 ksi,
4
log (El
2
2.9271 0.109 t + 0.5104 log (t ) 0.3997 log (D )
+ 4.213 log (D D ) 17.149 log (D D )
12 14
+ 12.295 log (D D )
(N = 240, and R2 = 0.962)
Eqn. 4.21
Case 2. For 1.5 < t < 8.0 in., 5.0 < E < 40.0 ksi, and others as
1 4
listed for Equation 4.21,
log (E ) = 3.06546 0.08134 t 0.1256 D + 0.2793 D 0.19322 D
2 1 1 2 5
+ 0.2998 log t + 3.5381 log (D )
+ 2.1045 log (D ) 2.4614 log (D )
5 8
+ 6.76643 log (D D ) 11.0912 log (D D )
13 14
Eqn. 4.22
(N = 400, and R2
0.953)