Cap used for intermittent ventilation vacuum preloading drainage

Abstract

The invention relates to a cap used for intermittent ventilation vacuum preloading drainage. The cap is connected to the bottom of a lower drain board inserted into soil, two sides of the lower drain board are respectively provided with a sealed hollow pipeline (11), the bottom of the cap is a base plate (18), the inner part of the cap is provided with a connection board (19) of ventilation circular holes (13), a ventilation channel (16) is enclosed by the base plate (18) and the connection board (19), two sides of the cap are respectively provided with a ventilation connecting pipe (12) communicated with the ventilation channel (16), and after the cap is connected to the bottom of the lower drain board, the two ventilation connecting pipes (12) are respectively communicated with the corresponding sealed hollow pipelines (11) of the lower drain board. According to the cap, contributions can be made to independent operation of drainage pipeline network and ventilation pipeline network.

Description

technical field [0001] The invention relates to an intermittent ventilation vacuum preloading drainage system, which is mainly suitable for soft soil and super soft soil foundation treatment, and belongs to the vacuum preloading drainage consolidation technology in geotechnical engineering. Background technique [0002] The conventional vacuum preloading method is to lay a sand cushion on the surface of the soft ground, lay a plastic drainage board or a sand well, and then lay a sealing film to isolate the atmosphere. The four sides of the sealing film are buried in the soil, and the drainage pipes buried in the sand cushion Use a vacuum device to pump air, and under the action of vacuum negative pressure, the soil under the sealing film will generate a vacuum negative pressure; at this time, the water in the pores of the muddy soft soil around the drainage board will seepage due to the pressure difference, and the water will flow from the The silt soil flows into the vertic...

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Problems solved by technology

According to common sense, it is very difficult to drain the water in a water pipe that has been sealed at one end, but if the seal is opened, the water will be sucked out easily

[0004] In view of the shortcomings of the above-mentioned conventional vacuum preloading method, during the vacuuming process, gas is introduced into the drainage board extending into the muddy soil, so that the air pressure at the bottom is greater than the upper air pressure, and the airflow generated by the pressure difference will push the water in the drainage board. The precipitated water flows to the upper horizontal drainage channel

The method of introducing air into the drainage board can improve the drainage rate to a certain extent, but it is found that the drainage effect is not ideal at the end of the test.

Moreover, since the continuous and uninterrupted ventilation will always offset part of the vacuum degree, the vacuum degree in the drainage board will decrease, the vacuum negative pressure will decrease, and the drainage rate will decrease, which will increase the time for sludge consolidation and slow down the construction period; moreover, when the ventilation pressure When it is greater than the vacuum degree, especially when the vacuum degree at the bottom of the soil has a large attenuation, the method fails

[0005] In view of the low efficiency of conventional vacuum preloading drainage, poor consolidation effect, poor post-effect of ventilation vacuum preloading drainage and the inability to provide sufficient and stable vacuum negative pressure, the existing vacuum preloading drainage system is improved, and the working principle is designed as follows: figure 1 drainage system shown

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