Downhole standard penetrometer

Abstract

The invention discloses a downhole standard penetrometer which consists of a standard penetration head, a hammer gasket mechanism, a heavy hammer mechanism, a griping, discharging, lifting and leading mechanism and a guide mechanism; the heavy hammer mechanism and the griping, discharging, lifting and leading mechanism are encapsulated in a sealed conduit; the hammer gasket mechanism is arranged onthen the inner side of the bottom of the sealed conduit; the heavy hammer mechanism is lifted by the griping, discharging, lifting and leading mechanism, automatically discharged, then do free falling motion in the sealed conduit and finally acts on the hammer gasket mechanism vertically; the griping, discharging, lifting and leading mechanism consists of a pull rod running through the sealed conduit from top to bottom and an automatic gripping and discharging device fixed on the bottom of the pull rod; the standard penetration head is arranged in the outside of the bottom of the sealed conduit; the guide mechanism is a drill rod arranged on the pull rod; and the drill rod, the griping, discharging, lifting and leading mechanism, the standard penetration head, the hammer gasket mechanism and the heavy hammer mechanism are positioned on the same straight line in turn from top to bottom. The downhole standard penetrometer removes the consumption of the drill rod to the impact energy of the drop hammer, can carry out effective test in the deep stratum and reduce the length of the rod and the requirement of correcting the underground water level.

Description

technical field [0001] The invention relates to the technical field of geotechnical engineering investigation, in particular to a downhole standard penetrometer suitable for standard penetration tests. Background technique [0002] In the field of geotechnical engineering investigation technology, the standard penetration test is a very convenient and effective in-situ test method, which is suitable for testing in the sandy soil where the original sample cannot be taken. Through this test, the sand in the foundation can be determined indirectly. The density, deformation modulus, bearing capacity and other parameters of the soil layer. In addition, this test can also be used to judge the liquefaction of sandy soil. The standard penetrometer is the most commonly used in-situ test equipment in geotechnical engineering investigation, and the standard penetration test (SPT) is suitable for application in cohesive soil and sand layer; and in the standard penetration test, the hamm...

AI Technical Summary

Problems solved by technology

[0004] To sum up, the effective depth of the existing standard penetration tests is all within 20m, and for the hole depth below 20m, because the length-to-diameter ratio of the drill pipe used to transmit the impact energy is too large, most of the energy is lost in the deformation of the drill pipe and The friction consumption between the drill pipe and the hole wall makes the standard penetration test impractical

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