Visual measurement device for underground water level under negative pressure condition and measurement method

Abstract

The invention discloses a visual measurement device for an underground water level under a negative pressure condition. The device comprises a permeable pipe, a floating block, pulleys, a high-definition camera with a light source, a wire, a fixed wire connector, an indicator pin, a top cover, a bottom cover, external display equipment and soil engineering filter cloth. The invention discloses a measurement method of the device. The floating block drives the high-definition camera with the light source to freely change the up-down displacement with the float of the underground water level; during each measurement, the external display equipment on the outer side of the permeable pipe is connected with the high-definition camera through the wire, and a scale position indicated by the indicator pin in the pipe is photographed, so that the underground water level under the negative pressure condition can be obtained. The real underground water level under the negative pressure condition can be accurately measured, and the error of the conventional open measurement is avoided; the device has the advantages of simple structure, easiness in manufacturing, low cost, convenience in use and broad application prospect.

Description

technical field [0001] The invention relates to a groundwater level testing tool and method, in particular to a visual measuring device and a measuring method for groundwater level under negative pressure conditions. Background technique [0002] In the field of geotechnical engineering, the measurement of groundwater level is of irreplaceable importance. On the one hand, the change of groundwater level reflects the progress of foundation reinforcement, and on the other hand, it reflects the pros and cons of reinforcement methods. Therefore, the real and accurate groundwater level measurement technology It is particularly important. The test method used in engineering for groundwater level mostly adopts the conventional open-type pipe measuring method, and the measured water level change reflects the average value of the water level drawdown at each point of the water level pipe filter pipe section under the action of atmospheric pressure. For the measurement of the groundw...

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Problems solved by technology

But it has the following disadvantages: (1) This device affects the reading change of the resistive water level gauge buried in the water level tube through the change of the water level, and indirectly calculates the change of the water level, which will have a large error; (2) The water level tube changes from The range from the nozzle to the 2m below the sand cushion is not connected to the surrounding soil, so it is difficult to ensure that the vacuum degree inside and outside the water level pipe is consistent, resulting in measurement errors

This device avoids the expensive water level sensor and reduces the cost, but the device also has the following problems: (1) The device causes the change of the imaging area through the distance between the camera and the float, and indirectly measures the change of the water level. The water level error will be greater than the error of direct measurement, and it will increase the measurement error when calculating the area

(2) For measuring the water level which is always changing, the device needs a certain period of time to calculate, which may cause data delay and is not suitable for real-time measurement

(3) For a sudden and large change in water level, the camera area of ​​the float will also change greatly, and the large change in data will cause the calculation error to increase, so that the result error of indirect calculation of water level will also increase

(4) For the measurement of groundwater level under negative pressure conditions, the device cannot be applied due to lack of airtightness

(5) The measurement of the device is carried out on the basis of the water level tube. When the float rises and falls greatly, because there is no lighting equipment in the tube, the camera effect will be affected, and the calculation of the area will also be inaccurately affected.

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