A Visual Measurement Method of Groundwater Level Under Negative Pressure

Abstract

The invention discloses a visual measurement device for underground water level under negative pressure conditions, which includes a permeable pipe, a floating block, a pulley, a high-definition camera with a light source, a wire, a fixed wire interface, an indicator needle, a top cover, a bottom cover, and external display equipment. , Geotechnical filter cloth. The invention also discloses the measurement method of the device. The floating block drives the high-definition camera with the light source to change freely up and down with the floating of the groundwater level. When measuring each time, the external display equipment located outside the permeable pipe passes through the wire and the high-definition camera. The camera is connected to shoot the scale position pointed by the indicator needle in the pipe, so as to obtain the groundwater level under the negative pressure condition. The invention can accurately measure the real groundwater level under the negative pressure condition, avoids the error of traditional open measurement, and has simple structure, easy manufacture, low cost, convenient use and wide application prospect.

Description

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

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Problems solved by technology

But it has the following disadvantages: (1) This device affects the change of the reading of the resistive water level gauge embedded in the water level pipe through the change of the water level, and indirectly calculates the change of the water level, and there will be a large error; 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 the measurement of the water level that 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 because it is not airtight

(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 affected inaccurately.

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