Resistance-free load test device and method for upper extension section of foundation pile

Abstract

The invention discloses a resistance-free load test device and a resistance-free load test method for an upper extension section of a foundation pile, relates to the technical field of engineering pile foundation, and solves the technical problem that a test result has low reality in the prior art. The resistance-free load test device comprises an inner tube and an outer tube, wherein the inner tube is coaxially inserted into the outer tube, and the upper ends of the inner and outer tubes are flush; a coaxial protection sleeve is sleeved on the lower part of the inner tube; the upper end of the protection sleeve is connected with the lower end of the outer tube in a flange mode; the lower end of the inner tube extends out of the lower ends of the outer tube and the protection sleeve; a vertical waterproof sealing gasket is arranged between the lower end of the protection sleeve and the outer wall surface of the inner tube; the lower end of the outer tube is provided with a horizontal annular plate of the outer tube; the lower end of the inner tube is provided with a horizontal annular plate of the inner tube; a planar sealing gasket is used for waterproof seal of the horizontal annular plates of the inner and outer tubes; a plurality of groups of limit plates are arranged between the inner and outer tubes axially and are used for limiting the centering of the inner tube. The resistance-free load test device provided by the invention can improve the reality of the test result data.

Description

technical field [0001] The present invention relates to the technology of engineering pile foundations, in particular to a non-conductive method for measuring and reading the actual vertical limit resistance of the pile body below the design pile top of the cast-in-situ pile test pile (i.e. the upper extension of the foundation pile). Technology of resistance load test device and its test method. Background technique [0002] At present, the static load test of pile foundation is widely used in the test due to its mature technology, intuitive results and high reliability of the test value, but the test value includes the lateral resistance of the top extension of the test pile , so that the test value is higher than its actual value. With the increase of the design depth of the pile top (the design depth of the pile top is basically the same as the depth of the foundation pit of the building), the actual vertical value measured by this traditional static load test method Th...

AI Technical Summary

Problems solved by technology

[0005] 1) Affected by the diameter deviation of the inner and outer tubes, the roundness of the tube diameter often does not reach the required accuracy, so that the O-shaped rubber sealing ring will have an uneven state of relaxation or excessive extrusion in different directions. (that is, there will be gaps in some parts), because the O-shaped rubber sealing ring does not have the ability to fill the gaps, making the mortar in the mud or concrete easy to enter the annular space between the inner and outer pipes from these weak links, once the cement mortar Entering the annular space and solidifying, it will cause the resistance of the outer wall of the inner tube to increase during the load test, thus affecting the authenticity of the test results. This hidden danger becomes more obvious as the diameter of the test pile increases (the test pile The increase of the diameter means the increase of the diameter of the inner and outer pipes and the increase of the uncontrollable degree of the radial clearance deviation of the annular space);

[0006] 2) The setting of multiple O-shaped rubber sealing rings (with small spacing and high density) is not only expensive, but also increases resistance when the inner tube is inserted into the outer tube; at the same time, the O-shaped rubber sealing ring During the assembly process of the tube, there is a high probability of being squeezed away from the installation position, or even being squeezed, damaged or even broken, which makes the sealing effect somewhat uncertain;

[0007] 3) To achieve high-precision machining of the roundness of the inner and outer tubes, it needs to be customized by a professional manufacturer, and the wall thickness of the inner and outer tubes and the diameter of the sealing ring must also be increased to make up for the inevitable inner and outer tubes to a limited extent. The above-mentioned disadvantages caused by the inhomogeneity of the tube gap, so that the material and processing costs of the test device are very high, and additional costs such as freight are required

Images