Continuous, undisturbed sampling by rotational boring in non-plastic granular tills

Claim 2

A boring apparatus to obtain continuous undisturbed sampling from heterogeneous non-cohesive granular till soils, said apparatus comprising a hollow drill rod having a coring bit of preselected diameter secured at a boring end thereof, drive means for rotating said drill rod at a predetermined speed and down pressure dependent on the coring bit diameter to impart rotation to said coring bit for the penetration of said drill rod in said soil at a predetermined rate, said coring bit having an annular drilling head, a plurality of fluid convection channels of preselected diameter in said annular drilling head, convection means to provide for a pressurized flow of a mud drill fluid in said hollow drill rod at a predetermined flow rate, an outer casing positioned about said drill rod and spaced therefrom to define a mud circulation annulus between said drill rod and outer casing, said drill fluid being convected to said drilling head by passage of said mud through said channels in said annular drilling head and out through said circulation annulus when said drill rod is rotated whereby said mud flow is away from said coring bit avoiding contact with the granular till projecting into said annular drilling head so as not to disturb the granular till core, said mud having a viscosity of at least 70 seconds as measured with a Marsh funnel, said mud in said drilling head being pressurized to about 140 to 175 KPa, a retractable soil sample receiving tube for insertion and retraction from said coring bit and dimensioned for receiving in close fit therein an undisturbed sample of said granular till soil and capable of retracting said sample from said hollow drill rod in an undisturbed form, and an outer soil stabilizing tube positioned about said outer casing and extending in a top portion of said soil whereby to prevent wash away about a bore drilled by said boring apparatus.

Claim 3

An apparatus as claimed in claim 1 wherein said coring bit is a cylindrical casing, said crown shaped drilling head being formed on a free end of said casing and defined by an inner abrading ring having a convexly curved outer abrading surface and an outer rearward circumferential tapered abrading surface, said fluid convection channels extending from said abrading surfaces to an inside wall of said cylindrical casing.

Claim 4

An apparatus as claimed in claim 2 wherein said fluid convection channels extend from an area intermediate said curved outer abrading surface and tapered abrading surface to lubricate said surfaces and to convect fine particles in the path of said drilling head.

Claim 5

An apparatus as claimed in claim 3 wherein said cylindrical casing is provided with an inner thread portion adjacent a connecting end thereof to receive said drill rod working end in threaded engagement therein.

Claim 6

An apparatus as claimed in claim 3 wherein there are eight fluid convection channels equidistantly spaced about said crown shaped drilling head, said outer abrading surfaces being provided with industrial diamonds having a size of about 60 to 90 stones per carat.

Claim 7

An apparatus as claimed in claim 1 wherein said mud drill fluid is a bentonite mud of high viscosity whereby not to wash away silt and sand particles of said soil.

Claim 8

An apparatus as claimed in claim 1 wherein said soil sample receiving means is a triple tube wire line core barrel having an open bottom end and a connecting top end, means to secure said top end to a retracting cable, said top end having evacuating ports to provide for the evacuation of mud fluid from within said cylindrical tube when said tube is inserted downwardly in said hollow drill rod.

Claim 9

An apparatus as claimed in claim 7 wherein said means to secure said top end to a retracting cable comprises a connecting element coupled to said top end and having an engageable knob at a top end thereof, said cable having a gripping jaw at a lower end for automatic engagement with said knob.

Claim 10

An apparatus as claimed in claim 1 wherein said coring bit has an inner diameter of about 80-85 mm, said speed of rotation of said drill rod being about 150-200 rpm with said mud drill fluid having a flow rate of about 18 to 23 liters/min.

Claim 11

A boring apparatus to obtain continuous undisturbed sampling from heterogeneous non-cohesive granular till soils, said apparatus comprising a hollow drill rod having a coring bit of preselected diameter secured at a boring end thereof, drive means for rotating said drill rod at a predetermined speed and down pressure dependent on the coring bit diameter to impart rotation to said coring bit for the penetration of said drill rod in said soil at a predetermined rate, said coring bit having an annular drilling head, a plurality of fluid convection channels of preselected diameter in said annular drilling head, convection means to provide for a pressurized flow of a mud drill fluid in said hollow drill rod at a predetermined flow rate, an outer casing positioned about said drill rod and spaced therefrom to define a mud circulation annulus between said drill rod and outer casing, said drill fluid being convected to said drilling head by passage of said mud through said channels in said annular drilling head and out through said circulation annulus when said drill rod is rotated whereby said mud flow is away from said coring bit avoiding contact with the granular till projecting into said annular drilling head so as not to disturb the granular till core, said mud having a viscosity of at least 70 seconds as measured with a Marsh funnel, said mud in said drilling head being pressurized to about 140 to 175 KPa, a retractable soil sample receiving tube for insertion and retraction from said coring bit and dimensioned for receiving in close fit therein an undisturbed sample of said granular till soil and capable of retracting said sample from said hollow drill rod in an undisturbed form, means to advance said outer casing in said soil behind said drill rod and coring bit, a mud drill fluid reservoir being provided about an outer circumferential edge of said outer casing and said drill rod, means to remove soil particles from said mud and for convection of said mud into said hollow drill rod, a centrifugal pump being associated with said reservoir to filter fine particles of soil from said mud fluid.

Claim 12

A boring apparatus to obtain continuous undisturbed sampling from heterogeneous non-cohesive granular till soils, said apparatus comprising a hollow drill rod having a coring bit of preselected diameter secured at a boring end thereof, drive means for rotating said drill rod at a predetermined speed and down pressure dependent on the coring bit diameter to impart rotation to said coring bit for the penetration of said drill rod in said soil at a predetermined rate, said coring bit having an annular drilling head, a plurality of fluid convection channels of preselected diameter in said annular drilling head, convection means to provide for a pressurized flow of a mud drill fluid in said hollow drill rod at a predetermined flow rate, an outer casing positioned about said drill rod and spaced therefrom to define a mud circulation annulus between said drill rod and outer casing, said drill fluid being convected to said drilling head by passage of said mud through said channels in said annular drilling head and out through said circulation annulus when said drill rod is rotated whereby said mud flow is away from said coring bit avoiding contact with the granular till projecting into said annular drilling head so as not to disturb the granular till core, said mud having a viscosity of at least 70 seconds as measured with a Marsh funnel, said mud in said drilling head being pressurized to about 140 to 175 KPa, a retractable soil sample receiving tube for insertion and retraction from said coring bit and dimensioned for receiving in close fit therein an undisturbed sample of said granular till soil and capable of retracting said sample from said hollow drill rod in an undisturbed form, means to advance said outer casing in said soil behind said drill rod and coring bit, a mud drill fluid reservoir being provided about an outer circumferential edge of said outer casing and said drill rod, means to remove soil particles from said mud and for convection of said mud into said hollow drill rod, a centrifugal pump being associated with said reservoir to filter fine particles of soil from said mud fluid.

Claim 13

An apparatus as claimed in claim 10 wherein said means to advance said outer casing is said drive means for rotating said drill rod.

Claim 16

A method as claimed in claim 12 wherein said step (ii) comprises injecting said mud drill fluid over said drilling head under a pressure of about 140 to 175 KPa.

Claim 17

A method as claimed in claim 12 wherein said step (vi) comprises simultaneously injecting said mud drill fluid under pressure in said circulation annulus formed between said drill rod and an outer casing spaced thereabout to cause said mud to rise in said hollow drill rod without disturbing said sample, and retracting said core barrel at the same rate as said speed of displacement of said mud in said hollow drill rod.

Claim 18

A method as claimed in claim 13 or 14 wherein there is further provided the step of filtering fine particles from said mud drill fluid by means of said pressure pump, said pump being a centrifugal pump.

Claim 19

A method as claimed in claim 14 wherein said mud drill fluid is injected at a pressure of about 140 to 175 KPa.

Claim 20

A method as claimed in claim 14 wherein said step (i) comprises rotating said drill rod and said outer casing, alternately.