In situ calibrating device for soil pressure box and method therefor

Abstract

The invention discloses an original position calibrating device for a soil pressure cell and a method thereof, relating to the application technology of soil pressure cells. The device is structured as: in a round calibrating pit, a reinforced concrete floor (3), a soil pressure cell (1) covered by a rubber bag (5), medium and coarse sands (11), undisturbed soil (4), a rubber pad (10), a load steel plate (2), a jack (6) and a reaction frame (7) are arranged and connected in turn from bottom to top; the reaction frame(7) and a ground anchor(8) buried in the anchorage hole of the round calibrating pit are vertical to each other and connected by a coak (9). The method is mainly as follows: step one, the soil pressure cell (1) is connected with a steel string frequency tester to measure the initial reading of the soil pressure cell (1) under the condition of bearing no load; step two, the soil pressure cell (1) is positioned in the original position calibrating device for the soil pressure cell; step three, gradual loading is carried out and calibrating test is started; and step four, quantitative relation between the pressure input quantity and the frequency output quantity is calibrated. The device is applicable to the calibration of the soil pressure cell.

Description

technical field [0001] The invention relates to an application technology of an earth pressure cell when monitoring earth pressure in civil engineering risk assessment and control, in particular to an earth pressure cell in-situ calibration device and method thereof. Background technique [0002] In the construction of urban subway stations or high-rise buildings, the site is narrow and the environmental boundary conditions are complex and diverse. The excavation of deep foundation pit directly affects the safety quality, construction period and cost of the whole project, especially the destruction of undisturbed soil outside the foundation pit causes damage to surrounding buildings and the safe use of various pipelines. The change of earth pressure at different depths of the retaining structure and pit wall interface is a must-measure item for risk assessment and control of engineering projects, and is generally directly measured by an earth pressure cell. However, the har...

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Problems solved by technology

[0004] The earth pressure cell is generally calibrated by air pressure (gas scale), liquid calibration (oil standard) and soil medium calibration (sand standard) before leaving the factory and before use; the calibration environment is inconsistent with the environment and temperature of the actual measuring point: indoor calibration tests are often applied Uniform pressure, but in its application, due to the influence of shear action and arch effect distribution, the actual earth pressure has a larger deviation than the earth pressure calculated by indoor calibration

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