110:
as the hole gets deeper. The core sample is carried by an inner tube locked in place in contact with the drilling head, To recover the core, the drive system is disconnected, opening the top of the uppermost drill rod. A tool called an overshot assembly is lowered at the end of a wire and pumped down the string with water pressure. When it reaches the sample tube, it locks onto the top, and using the retraction winch to apply tension to the wire unlocks the sample tube from the drill head and retracts it and the core sample within it to the open top end of the drill string, where it can be removed before returning the sample tube down the drill string to lock back onto the cutting head. This is particularly useful for drill holes more than 30 ft deep as otherwise the whole string of rods had to be removed to recover the core, then re-inserted to drill deeper, and repeated. Removing all the rods every 30 feet to recover the core was time consuming for deep holes required for mining and mineral exploration, some of which may be 1,000 ft deep or more. This method greatly reduced the time required to drill a hole, and thus its cost, which increased the use of drilling and decreased the use of shaft sinking as a means of mineral exploration. It is also quite useful if there is a high risk of the hole walls collapsing when the drill tube is retracted, so it is suitable for most soil types, and to depths of 1000 m. Several diameters are available.
86:
597:
450:
496:
409:
397:
508:
118:
559:
484:
385:
20:
532:
585:
573:
609:
520:
633:
549:
472:
373:
621:
421:
50:. Core drills used for concrete and hard rock generally use industrial diamond grit as the abrasive material and may be electrical, pneumatic or hydraulic powered. Core drills are commonly water cooled, and the water also carries away the fine waste as a slurry. For drilling masonry, carbide core drills can be used, but diamond is more successful when cutting through rebar.
109:
Wireline core drilling is a technique used to extract the core without having to retrieve the entire drill string of rods, which generally only needs to be retracted when the hole is finished or the drill bit must be replaced. Drill rod extensions are added at the top as required to extend the string
97:
Before the start of World War Two, John
Branner Newsom, a California mining engineer, invented and patented a core drill that could take out large diameter cores (>5 ft.) up to 10 feet in length for mining shafts. This type of shaft-sinking drill is no longer in use as it was cumbersome, prone
81:
may be several hundred to several thousand feet in length. The core samples are recovered and examined by geologists for mineral percentages and stratigraphic contact points. This gives exploration companies the information necessary to begin or abandon mining operations in a particular area.
61:
is often referred to as a corer), or where drilling can be done more rapidly since much less material needs to be removed than with a standard bit. This is the reason that diamond-tipped core drills are commonly used in construction to create holes for pipes, manholes, and other large-diameter
98:
to jamming with cuttings, thus slow compared to conventional shaft sinking techniques, and only worked effectively in soft rock formations. Modern shaft-sinking technology accomplishes the same faster and at a much cheaper cost.
400:
511:
487:
57:, invented in 3000 BC. Core drills are used for many applications, either where the core needs to be preserved (the drilling apparatus used in obtaining a
263:
535:
321:
588:
101:
Core drills come with several power choices including electric, pneumatic, and hydraulic (all of which require power sources, such as a generator).
475:
1467:
1286:
1331:
314:
246:
1457:
741:
339:
307:
194:
989:
870:
412:
1462:
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174:
85:
74:
1302:
902:
347:
1205:
600:
1281:
1271:
1143:
1133:
963:
701:
499:
330:
1121:
1096:
1036:
716:
657:
129:
1384:
1195:
1009:
845:
820:
671:
650:
542:
1071:
880:
388:
1424:
1276:
1233:
1126:
1051:
434:
8:
1200:
1190:
746:
731:
691:
664:
439:
429:
1151:
860:
643:
562:
1248:
994:
885:
855:
706:
242:
54:
1298:
1185:
1076:
1041:
1016:
875:
696:
523:
1414:
1238:
1156:
1091:
1086:
984:
850:
721:
576:
281:
1361:
1253:
1170:
974:
736:
726:
612:
164:
158:
154:
93:, commonly used when analyzing cores for contacts and other structural features
67:
47:
1291:
216:
1446:
1389:
1228:
1106:
1101:
1056:
825:
596:
449:
1409:
1404:
1394:
1374:
1061:
1004:
835:
552:
495:
408:
299:
169:
78:
32:
461:
396:
1419:
1116:
999:
938:
507:
128: with: Sectional diagram of the core removal system. You can help by
58:
558:
483:
384:
117:
1243:
1223:
1111:
923:
918:
840:
830:
711:
456:
90:
1399:
1379:
1265:
1081:
1066:
682:
624:
424:
19:
35:
specifically designed to remove a cylinder of material, much like a
1429:
1316:
1046:
1021:
948:
865:
531:
63:
36:
584:
572:
1369:
1341:
1026:
953:
943:
933:
928:
636:
608:
519:
1351:
1346:
1336:
1326:
1258:
1031:
979:
789:
632:
548:
471:
39:. The material left inside the drill bit is referred to as the
372:
804:
620:
420:
16:
Drill specifically designed to remove a cylinder of material
799:
794:
784:
779:
774:
759:
239:
The
Handbook of Groundwater Engineering, Second Edition
236:
1444:
241:. Taylor & Francis. p. 7 in chapter 2.
53:The earliest core drills were those used by the
315:
329:
322:
308:
104:
195:"Diamond Core Bits vs Carbide Core Bits"
84:
18:
274:
237:Jacques W. Delleur (12 December 2010).
1445:
230:
303:
261:
46:Core drills used in metal are called
112:
1468:In situ geotechnical investigations
73:Core drills are used frequently in
13:
262:Boone, Andrew R. (December 1943).
14:
1479:
340:Offshore geotechnical engineering
631:
619:
607:
595:
583:
571:
557:
547:
530:
518:
506:
494:
482:
470:
448:
419:
407:
395:
383:
371:
116:
255:
209:
187:
1:
990:Mechanically stabilized earth
180:
742:Hydraulic conductivity tests
217:"Concrete Drilling Tutorial"
175:Exploration diamond drilling
7:
1458:Ancient Egyptian technology
1303:Stress distribution in soil
148:
10:
1484:
453:Pore pressure measurement
1360:
1315:
1214:
1206:Preconsolidation pressure
1178:
1169:
1142:
962:
911:
898:
813:
767:
758:
681:
601:Standard penetration test
359:
346:
337:
702:California bearing ratio
500:Rotary-pressure sounding
331:Geotechnical engineering
23:Truck-mounted core drill
1122:Geosynthetic clay liner
1097:Expanded clay aggregate
717:Proctor compaction test
658:Crosshole sonic logging
644:Nuclear densometer test
401:Geo-electrical sounding
264:"He Bores Bigger Holes"
1385:Earthquake engineering
1196:Lateral earth pressure
821:Hydraulic conductivity
672:Wave equation analysis
651:Exploration geophysics
543:Deformation monitoring
512:Rotary weight sounding
105:Wireline core drilling
94:
24:
563:Settlement recordings
488:Rock control drilling
389:Cone penetration test
88:
22:
1425:Agricultural science
1127:Cellular confinement
1463:Egyptian inventions
1453:Drilling technology
1317:Numerical analysis
1201:Overburden pressure
1191:Pore water pressure
971:Shoring structures
846:Reynolds' dilatancy
747:Water content tests
732:Triaxial shear test
692:Soil classification
665:Pile integrity test
161:for metal drilling)
75:mineral exploration
1292:Slab stabilisation
1272:Stability analysis
197:. 10 December 2012
95:
25:
1440:
1439:
1311:
1310:
1287:Sliding criterion
1249:Response spectrum
1165:
1164:
995:Pressure grouting
894:
893:
754:
753:
707:Direct shear test
413:Permeability test
282:"Wireline coring"
248:978-0-8493-4316-2
146:
145:
89:An oriented core
55:ancient Egyptians
1475:
1299:Bearing capacity
1186:Effective stress
1176:
1175:
1077:Land reclamation
1017:Land development
912:Natural features
909:
908:
876:Specific storage
765:
764:
697:Atterberg limits
635:
623:
611:
599:
587:
575:
561:
551:
536:Screw plate test
534:
522:
510:
498:
486:
474:
452:
423:
411:
399:
387:
375:
357:
356:
324:
317:
310:
301:
300:
294:
293:
291:
289:
278:
272:
271:
259:
253:
252:
234:
228:
227:
225:
223:
213:
207:
206:
204:
202:
191:
141:
138:
120:
113:
62:penetrations in
1483:
1482:
1478:
1477:
1476:
1474:
1473:
1472:
1443:
1442:
1441:
1436:
1415:Earth materials
1356:
1318:
1307:
1216:
1210:
1161:
1138:
1092:Earth structure
1087:Erosion control
985:Ground freezing
975:Retaining walls
958:
900:
890:
851:Angle of repose
809:
750:
684:
677:
676:
637:Visible bedrock
589:Simple sounding
577:Shear vane test
353:instrumentation
352:
350:
342:
333:
328:
298:
297:
287:
285:
280:
279:
275:
268:Popular Science
260:
256:
249:
235:
231:
221:
219:
215:
214:
210:
200:
198:
193:
192:
188:
183:
159:annular cutters
151:
142:
136:
133:
126:needs expansion
107:
48:annular cutters
17:
12:
11:
5:
1481:
1471:
1470:
1465:
1460:
1455:
1438:
1437:
1435:
1434:
1433:
1432:
1422:
1417:
1412:
1407:
1402:
1397:
1392:
1387:
1382:
1377:
1372:
1366:
1364:
1362:Related fields
1358:
1357:
1355:
1354:
1349:
1344:
1339:
1334:
1329:
1323:
1321:
1313:
1312:
1309:
1308:
1306:
1305:
1296:
1295:
1294:
1289:
1284:
1282:Classification
1279:
1274:
1263:
1262:
1261:
1256:
1254:Seismic hazard
1251:
1241:
1236:
1231:
1226:
1220:
1218:
1212:
1211:
1209:
1208:
1203:
1198:
1193:
1188:
1182:
1180:
1173:
1167:
1166:
1163:
1162:
1160:
1159:
1154:
1148:
1146:
1140:
1139:
1137:
1136:
1131:
1130:
1129:
1124:
1119:
1114:
1104:
1099:
1094:
1089:
1084:
1079:
1074:
1069:
1064:
1059:
1054:
1049:
1044:
1039:
1034:
1029:
1024:
1019:
1014:
1013:
1012:
1007:
1002:
997:
992:
987:
982:
977:
968:
966:
960:
959:
957:
956:
951:
946:
941:
936:
931:
926:
921:
915:
913:
906:
896:
895:
892:
891:
889:
888:
883:
881:Shear strength
878:
873:
868:
863:
858:
856:Friction angle
853:
848:
843:
838:
833:
828:
823:
817:
815:
811:
810:
808:
807:
802:
797:
792:
787:
782:
777:
771:
769:
762:
756:
755:
752:
751:
749:
744:
739:
737:Oedometer test
734:
729:
727:Sieve analysis
724:
719:
714:
709:
704:
699:
694:
689:
687:
679:
678:
675:
674:
668:
667:
661:
660:
654:
653:
647:
646:
640:
639:
628:
627:
616:
615:
613:Total sounding
604:
603:
592:
591:
580:
579:
568:
567:
566:
565:
555:
539:
538:
527:
526:
515:
514:
503:
502:
491:
490:
479:
478:
467:
466:
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464:
459:
445:
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443:
442:
437:
432:
416:
415:
404:
403:
392:
391:
380:
379:
368:
367:
365:
354:
344:
343:
338:
335:
334:
327:
326:
319:
312:
304:
296:
295:
284:. Parma, Italy
273:
254:
247:
229:
208:
185:
184:
182:
179:
178:
177:
172:
167:
165:Drilling fluid
162:
150:
147:
144:
143:
123:
121:
106:
103:
15:
9:
6:
4:
3:
2:
1480:
1469:
1466:
1464:
1461:
1459:
1456:
1454:
1451:
1450:
1448:
1431:
1428:
1427:
1426:
1423:
1421:
1418:
1416:
1413:
1411:
1408:
1406:
1403:
1401:
1398:
1396:
1393:
1391:
1390:Geomorphology
1388:
1386:
1383:
1381:
1378:
1376:
1373:
1371:
1368:
1367:
1365:
1363:
1359:
1353:
1350:
1348:
1345:
1343:
1340:
1338:
1335:
1333:
1330:
1328:
1325:
1324:
1322:
1320:
1314:
1304:
1300:
1297:
1293:
1290:
1288:
1285:
1283:
1280:
1278:
1275:
1273:
1270:
1269:
1267:
1264:
1260:
1257:
1255:
1252:
1250:
1247:
1246:
1245:
1242:
1240:
1237:
1235:
1234:Consolidation
1232:
1230:
1229:Frost heaving
1227:
1225:
1222:
1221:
1219:
1213:
1207:
1204:
1202:
1199:
1197:
1194:
1192:
1189:
1187:
1184:
1183:
1181:
1177:
1174:
1172:
1168:
1158:
1155:
1153:
1150:
1149:
1147:
1145:
1141:
1135:
1132:
1128:
1125:
1123:
1120:
1118:
1115:
1113:
1110:
1109:
1108:
1107:Geosynthetics
1105:
1103:
1102:Crushed stone
1100:
1098:
1095:
1093:
1090:
1088:
1085:
1083:
1080:
1078:
1075:
1073:
1070:
1068:
1065:
1063:
1060:
1058:
1057:Cut-and-cover
1055:
1053:
1050:
1048:
1045:
1043:
1040:
1038:
1035:
1033:
1030:
1028:
1025:
1023:
1020:
1018:
1015:
1011:
1008:
1006:
1003:
1001:
998:
996:
993:
991:
988:
986:
983:
981:
978:
976:
973:
972:
970:
969:
967:
965:
961:
955:
952:
950:
947:
945:
942:
940:
937:
935:
932:
930:
927:
925:
922:
920:
917:
916:
914:
910:
907:
904:
897:
887:
884:
882:
879:
877:
874:
872:
869:
867:
864:
862:
859:
857:
854:
852:
849:
847:
844:
842:
839:
837:
834:
832:
829:
827:
826:Water content
824:
822:
819:
818:
816:
812:
806:
803:
801:
798:
796:
793:
791:
788:
786:
783:
781:
778:
776:
773:
772:
770:
766:
763:
761:
757:
748:
745:
743:
740:
738:
735:
733:
730:
728:
725:
723:
720:
718:
715:
713:
710:
708:
705:
703:
700:
698:
695:
693:
690:
688:
686:
680:
673:
670:
669:
666:
663:
662:
659:
656:
655:
652:
649:
648:
645:
642:
641:
638:
634:
630:
629:
626:
622:
618:
617:
614:
610:
606:
605:
602:
598:
594:
593:
590:
586:
582:
581:
578:
574:
570:
569:
564:
560:
556:
554:
550:
546:
545:
544:
541:
540:
537:
533:
529:
528:
525:
524:Sample series
521:
517:
516:
513:
509:
505:
504:
501:
497:
493:
492:
489:
485:
481:
480:
477:
473:
469:
468:
463:
460:
458:
455:
454:
451:
447:
446:
441:
438:
436:
433:
431:
428:
427:
426:
422:
418:
417:
414:
410:
406:
405:
402:
398:
394:
393:
390:
386:
382:
381:
378:
374:
370:
369:
366:
363:
358:
355:
349:
348:Investigation
345:
341:
336:
332:
325:
320:
318:
313:
311:
306:
305:
302:
283:
277:
269:
265:
258:
250:
244:
240:
233:
218:
212:
196:
190:
186:
176:
173:
171:
168:
166:
163:
160:
156:
153:
152:
140:
131:
127:
124:This section
122:
119:
115:
114:
111:
102:
99:
92:
87:
83:
80:
76:
71:
69:
65:
60:
56:
51:
49:
44:
42:
38:
34:
30:
21:
1410:Biogeography
1405:Hydrogeology
1395:Soil science
1375:Geochemistry
1134:Infiltration
1062:Cut and fill
1005:Soil nailing
871:Permeability
836:Bulk density
553:Inclinometer
476:Ram sounding
376:
361:
286:. Retrieved
276:
267:
257:
238:
232:
220:. Retrieved
211:
199:. Retrieved
189:
170:Drilling rig
134:
130:adding to it
125:
108:
100:
96:
79:drill string
72:
52:
45:
40:
28:
26:
1420:Archaeology
1144:Foundations
1117:Geomembrane
1000:Slurry wall
939:Water table
903:Interaction
899:Structures
886:Sensitivity
683:Laboratory
155:Core drills
59:core sample
1447:Categories
1277:Mitigation
1259:Shear wave
1244:Earthquake
1239:Compaction
1224:Permafrost
1215:Phenomena/
1112:Geotextile
1037:Embankment
1027:Excavation
964:Earthworks
924:Vegetation
919:Topography
841:Thixotropy
831:Void ratio
814:Properties
712:Hydrometer
457:Piezometer
377:Core drill
270:: 104–107.
181:References
137:March 2022
91:goniometer
77:where the
29:core drill
27:A modern
1400:Hydrology
1380:Petrology
1268:analysis
1266:Landslide
1171:Mechanics
1082:Track bed
1067:Fill dirt
1052:Terracing
625:Trial pit
440:Statnamic
425:Load test
1430:Agrology
1319:software
1217:problems
1047:Causeway
1022:Landfill
949:Subgrade
866:Porosity
861:Cohesion
288:17 March
222:4 August
201:4 August
149:See also
64:concrete
37:hole saw
1370:Geology
1342:SVSlope
1152:Shallow
1072:Grading
1010:Tieback
954:Subsoil
944:Bedrock
934:Topsoil
929:Terrain
722:R-value
685:testing
435:Dynamic
362:in situ
360:Field (
1352:Plaxis
1347:UTEXAS
1337:SVFlux
1327:SEEP2D
1179:Forces
1032:Trench
980:Gabion
790:Gravel
430:Static
245:
1332:STABL
805:Loess
768:Types
68:stone
33:drill
31:is a
1157:Deep
800:Loam
795:Peat
785:Sand
780:Silt
775:Clay
760:Soil
462:Well
290:2022
243:ISBN
224:2014
203:2014
41:core
1042:Cut
351:and
132:.
66:or
1449::
1301:*
266:.
70:.
43:.
905:)
901:(
364:)
323:e
316:t
309:v
292:.
251:.
226:.
205:.
157:(
139:)
135:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
