Micro static pressure gauge for subsidence monitoring of expressway soft soil subgrade

Abstract

The invention discloses a miniature static pressure meter for subsidence monitoring of expressway soft soil roadbed. The casing is a closed metal cylindrical cavity, the pressure ring is fixed at the center of the top cover of the casing, and the disc-shaped membrane is transversely partitioned on the upper part of the casing. And its center is fixed to the bottom of the pressurizing ring. The part of the shell above the disc-shaped membrane is connected to the bellows for water injection. The part below the disc-shaped membrane is provided with a frequency measurement system connected to the disc-shaped membrane. The frequency measurement system includes steel strings , exciter, cable and frequency measuring instrument, the top of the steel string is connected to the center of the dish-shaped membrane, and the exciter on one side of the steel string is connected to the frequency measuring instrument on the ground through the side wall of the shell through the cable; The arc-shaped curved surface and large membrane surface characteristics of the disc-shaped membrane of the present invention ensure that it will undergo significant deformation under slight pressure, thereby causing a significant change in the vibration frequency of the steel string, and the water pressure can be accurately measured by measuring the change in the vibration frequency of the steel string The change of the ground and the settlement of the foundation are calculated. The instrument has good stability, high measurement accuracy, and easy on-site installation.

Description

technical field [0001] The invention relates to a static pressure gauge, in particular to a static pressure gauge for monitoring foundation settlement. Background technique [0002] The settlement observation of the foundation is a key issue in the construction and operation of expressways. At present, there are three main methods for the settlement observation of the foundation: the settlement plate method, the section settlement tube method and the observation method based on the principle of liquid level difference (hydrostatic pressure difference). [0003] The device of the settling plate method is composed of a settling plate, a metal measuring rod and a protective casing. The settlement is observed by observing the elevation change of the metal measuring rod, but this method is easy to damage the metal measuring rod during the construction process, and the road near the settling plate should be separated. Construction, and the observation process and roadbed construct...

AI Technical Summary

Problems solved by technology

[0003] The device of the settling plate method is composed of a settling plate, a metal measuring rod and a protective casing. The settlement is observed by observing the elevation change of the metal measuring rod, but this method is easy to damage the metal measuring rod during the construction process, and the road near the settling plate should be separated. Construction, and the observation process and roadbed construction interfere with each other, increasing the workload and prolonging the construction period

[0004] The device of the profile settlement tube method is composed of an inclinometer, a horizontally placed inclinometer tube and a digital display. The inclination angle change of the position can be measured by the inclinometer to convert the settlement amount of the position. The disadvantage of this method is that the settlement When the inclinometer is large, the inclinometer tube is easy to break, and the guide groove with a fixed inclination direction in the inclinometer tube is prone to deflection when the roadbed is deformed, and the direction measured by the inclinometer will change accordingly, resulting in obvious errors. At the same time, the observation workload of this method Large and expensive to observe

However, judging from the existing use experience, since the subsidence of the foundation is often small, the water pressure transmitted to the embedded pressure sensor is also very small. It is difficult for conventional instruments to accurately measure the water pressure, and the observation error is large If high-sensitivity instruments are used to observe, not only the cost is high, but also the obtained data is prone to drift due to various accidental factors. These problems limit the use of the liquid level difference method in actual engineering

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