Abstract Method and apparatus for installing a benchmark in an arctic region to provide an accurate, reliable reference point even after prolonged periods of exposure. To install the benchmark, a hole is formed through the active layer and into the underlying layer. An alignment jig mounts a marker element in a casing and both are positioned into the hole. A leveling clamp on the casing is used to plump and adjust the marker element to a known elevation. The marker element extends to the bottom of the hole while the casing terminates at a depth which is above the bottom of the hole but below the bottom of the active layer. A settable material, e.g. sand-water slurry which will freeze at ambient conditions, is poured into the hole to a point just above the lower end of the casing and is allowed to set after which the remainder of the hole around the casing is filled. The annulus within the casing around the marker element is filled with fluidic material which will not freeze under ambient conditions, e.g. grease. Since the marker element does not directly contact any part of the active layer, the marker element is effectively isolated from contact therewith so that the thawing and refreezing of the active layer do not disturb the position or elevation of the benchmark. Temperature sensors, positioned along the marker element, provides temperature readings for which expansion coefficients are known which, in turn, are used to correct the actual elevational readings taken during a survey.
Inventors
👤 Roy B. Hurlbut
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-04 20:35
CPC Classifications
G; G01; G01C; G01C15/00; G01C15/02; G01C15/04
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
104 words
A benchmark for an arctic region having an active surface layer which partially thaws and then refreezes over prolonged periods, said benchmark comprising: a casing set through said active layer and into the layer underlying said active layer; a marker element extending completely through said casing and into said underlying layer, said marker element comprising: a length of pipe; and a reference element mounted on the upper end of said pipe; and fluidic material in said casing around at least that portion of said marker element that pass through said active layer, said fluidic material being material which does not freeze under ambient conditions.
Claim 2
Dependent Claim
104 words
A benchmark for an arctic region having an active surface layer which partially thaws and then refreezes over prolonged periods, said benchmark comprising: a casing set through said active layer and into the layer underlying said active layer; a marker element extending completely through said casing and into said underlying layer, said marker element comprising: a length of pipe; and a reference element mounted on the upper end of said pipe; and fluidic material in said casing around at least that portion of said marker element that pass through said active layer, said fluidic material being material which does not freeze under ambient conditions.
Claim 3
Dependent Claim
28 words
The benchmark of claim 1 wherein said reference element comprises: a plug threaded on the upper end of said pipe; and a spherical-shaped knob mounted on said plug.
Claim 4
Dependent Claim
21 words
The benchmark of claim 2 including: a conduit attached to said pipe; and means for sensing temperature positioned within said conduit.
Claim 5
Dependent Claim
26 words
The benchmark of claim 3 including: a plate secured to the lower end of said pipe to aid in securing said pipe in said underlying layer.