The wellpoint pipes are arranged at regular intervals around the foundation pit. The bottom of the wellpoint pipe is arranged with a water filter pipe inserted into the permeable layer, and the upper hose is connected to the water collecting main pipe. The Φ40 suction pipe mouth, and then the water in the collecting pipe is pumped out by the vacuum suction pump, so as to achieve the effect of lowering the groundwater level around the foundation pit and ensure that the base is dry and water-free. Generally, each group is 60m, but the current equipment is very poor. The length of the main pipe is generally 50m, and the maximum is not more than 55m. The precipitation of light wells must be calculated. Generally, there is a suction pipe at a distance of 2.5 to 3m.
The main pipe is discharged first, and then the well point is buried. The well point pipe is connected with the main pipe by the curved pipe, and then the pumping equipment is installed. Here, the burying of the well point pipe is a key work. The well point pipe is buried by the water flushing method, which is divided into two processes: punching and burying the pipe. When punching, first connect the high-pressure water pump with the high-pressure rubber hose to connect the hole, and the punching pipe is lifted with the lifting equipment and inserted into the well point. At the position of the punching pipe, high-pressure water (1.8N/mm2) is used to wash the soil with a rapid jet through the water spray holes in the head of the main punching pipe, and at the same time, the punching pipe is rotated up and down, left and right, and sinks while flushing. , so as to gradually form holes in the soil. After the well hole is formed, pull out the punching pipe, insert the well point pipe immediately, and fill the sand filter layer between the well point pipe and the hole wall in time to prevent the hole wall from collapsing.
It is the key to ensure the smooth pumping of the well point and reduce the groundwater. At the same time, it should be noted that during the punching process, the hole must be kept vertical, the hole diameter is generally 300mm, and the hole should be 300mm below the hole. Consistently, the punching depth should be about 0.5m lower than the filter tube, so as to prevent part of the soil from being backfilled and touching the bottom of the filter tube when the punching tube is pulled out, the sand filter layer should be coarse sand. So as not to block the mesh of the filter tube, fill it to 1.0-1.5m on the top of the filter tube. After the sand filter layer is filled, within the depth of 0.5-1.0m from the ground, use clay sealing to prevent air leakage. After all the well point systems are installed, a sampling test is required to check whether there is air leakage.
When the well point is used for precipitation, water should generally be pumped continuously, and the pumping should be stopped at times. The filter screen is easy to block the effluent turbidity, and cause the nearby buildings to settle and crack due to the loss of soil particles. In the process of pumping and other accidents, the water outlet valve of the centrifugal pump should be adjusted to control the water volume to keep the suction and drainage uniform. The normal water discharge rule is “big first, then small, first muddy and then clear”, and the vacuum degree of the vacuum pump is used to judge the well point. Whether the system is in good working condition, it must be checked frequently and measures must be taken. During the pumping process, it should also be checked for blockage of “dead wells” (well pipes that work normally, when touched by hand, should be warm in winter and cool in summer) If there are too many dead wells, which seriously affect the precipitation effect, they should be repeatedly washed with high-pressure water one by one, pulled out and reburied.
Post time: Jun-17-2022