An Inverted Step Shaft Structure and Blowout Reduction Method

Abstract

The invention relates to an inverted stepped shaft structure and a blowout reduction method thereof. The shaft is arranged on the top of an underground pipeline to communicate with the underground pipeline and the ground, and the well cover is arranged on the top of the shaft. The shape of one side of the shaft is stepped and mirrored along the axis of the hole. The width of the step is larger than that of the underground pipeline, and it can be integrally formed or assembled. The first step of the shaft step is flush with the ground, and a cylinder is dug out in the center, which is the shaft mouth; the last step is connected to the top of the underground pipeline, and the slope of the middle step is 30° to 60°; the backfill above the step and The ground is level. The present invention tans the driving pressure difference for blowout formation, the manhole cover is provided with ventilation holes to connect the underground pipeline and the ground atmosphere, balances the non-constant air pressure in the vertical shaft and underground pipeline, balances the air pressure in the pipeline in advance, and tansizes the driving pressure difference for the blowout phenomenon. value, effectively suppressing the formation of blowout conditions.

Description

technical field [0001] The invention belongs to the technical field of municipal engineering and water conservancy engineering, and in particular relates to an inverted stepped shaft structure and a blowout relief method thereof. Background technique [0002] In municipal engineering, the underground pipe network is criss-crossed, including sewage pipe network, cable pipe network, water supply pipe network, etc. Manhole covers are often provided on the street floor to block the entrance of the pipe network. The structure connecting the ground and underground pipe networks is often called It is a shaft, which usually has the functions of collecting water, ventilating, and passing people. Generally, these shafts are designed as a well-shaped pipe with a vertical wall, and the upper part is sealed with a manhole cover. [0003] In recent years, with the solidification of the underlying surface of the city, the drainage load of the urban drainage pipe network has increased. Ge...

AI Technical Summary

Problems solved by technology

To sum up, the reduction measures that have been proposed so far mainly include the following: (1) Increase the diameter of the vertical shaft. It is believed that increasing the diameter of the vertical shaft (to the same size as the main pipeline) can reduce the instantaneous extreme pressure when the blowout occurs, However, this method cannot avoid the possibility of blowout, and the diameter of the shaft cannot be increased indefinitely in practical applications; (2) A manhole cover with small holes is installed on the top of the shaft. The principle of this method is to reduce the extreme value of water flow pressure. Constrain the flux of the shaft to suppress the spraying of the water-steam mixture. However, this method often hinders the outflow of gas when the blowout intensity is high, and increases the pressure change in the pipeline, which cannot avoid the possibility of blowout; (3) Install it under the well cover Buffer structures, such as elastically supported rubber balls or baffles, etc., are designed to dissipate energy and separate water and air from jet streams, but they also bring troubles to shaft maintenance.

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