Material | Confining Pressure (PSI) | Regression Equation | Coefficient of Determination | Standard Error of Estimate |
Single variable regression equations | ||||
Sand | 5 10 15 | σd = 41.3 − 12.8 PR σd = 100.4 − 23.4 PR σd = 149.6 − 12.7 PR | 0.998 0.998 0.978 | 0.3 0.5 0.9 |
Sandy gravel | 5 10 15 | σd = 51.3 − 13.6 PR σd = 62.9 − 3.6 PR σd = 90.7 − 5.8 PR | 0.992 0.997 0.975 | 1.9 0.3 1.5 |
Multiple linear variable regression equations | ||||
Dense Graded Materials | 5 10 15 | σd = 2777 − 105.7 PR − 18.0 e + 1.6 γ − 1575 Cu σd = 4474 − 148.7 PR − 29.1 e + 1.8 γ − 2411 Cu σd = 5392 − 179.9 PR – 34.8 e + 2.2 γ −2983 Cu | 0.859 0.893 0.941 | 18.1 22.7 21.2 |