Experimental Study on Local Scour and Related Mechanical Effects at River-Crossing Underwater Oil and Gas Pipelines

Table 3

Test conditions.

Embedment ratio (G)	Clay		Fine sand		Medium sand 1		Medium sand 2
	Test groups	Flow velocity (m·s^−1)	Test groups	Flow velocity (m·s^−1)	Test groups	Flow velocity (m·s^−1)	Test groups	Flow velocity (m·s^−1)
−2	1−1	0.408	2−1	0.383	3−1	0.417	4−1	0.413
−1.5	1−2	0.429	2−2	0.385	3−2	0.432	4−2	0.397
−1	1−3	0.417	2−3	0.419	3−3	0.385	4−3	0.398
−0.5	1−4	0.396	2−4	0.405	3−4	0.398	4−4	0.389
0	1−5	0.394	2−5	0.408	3−5	0.411	4−5	0.387
0.5	1−6	0.423	2−6	0.391	3−6	0.413	4−6	0.397
1	1−7	0.398	2−7	0.407	3−7	0.399	4−7	0.419
	Coarse sand		Very coarse sand		Very fine pebble
Embedment ratio (G)	Test groups	Flow velocity (m·s^−1)	Test groups	Flow velocity (m·s^−1)	Test groups	Flow velocity (m·s^−1)
−2	5−1	0.384	6−1	0.398	7−1	0.395
−1.5	5−2	0.384	6−2	0.423	7−2	0.422
−1	5−3	0.397	6−3	0.392	7−3	0.397
−0.5	5−4	0.391	6−4	0.423	7−4	0.395
0	5−5	0.416	6−5	0.387	7−5	0.387
0.5	5−6	0.385	6−6	0.404	7−6	0.414
1	5−7	0.411	6−7	0.406	7−7	0.404