Rectangular pipe jacking jacking preparation analysis analysis construction scheme, determine the appropriate precipitation scheme in the presence of wet soil, do a good job of waterproofing work, avoid water jacking, if the subgrade does not contain groundwater then jacking construction will be more convenient. Under the condition of no water, the jacking of the pipe jacking machine requires digging to prevent digging. The pipe can be hollowed out first. The depth of digging should be determined by the soil on site.
When the pipeline stops the mud-water balance pipe jacking machine to push the jack out, this support effect disappears, because the bentonite pressure method is also stopped accordingly, so when the pipe re-pipe jacking machine is jacked, as the first measure, This support must be restored. Before starting the main pressure station and the intermediate pressure station of the dual-use pipe jacking machine, the entire pipeline must first be injected with the bentonite suspension for a sufficient time. The time needs to be long enough because the suspension can only flow slowly between the surface of the pipe and the surrounding soil layer under normal flow limits.
After a long pause, it is better to use a suspension with a lower flow limit when restarting the top pressure pipe of the earth pressure balance pipe jacking, that is, the content of bentonite is lower than the content corresponding to the standard particle size . In order to enable the suspension to reach the injection nozzle quickly without first squeezing the hardened substance in the bentonite pipe with a high pressure, it is better to empty the bentonite pipe before a long pause.
In order to prevent the working face from collapsing, the depth of each excavation must not exceed 0.3m. When the pipeline stops jacking, do not dig more before the pipe. Excavate when encountering unstable soil such as sand or sand pebble. Steel plate shield, and then excavate the soil inside the steel plate shield. Do not dig soil in front of the shield.
After evacuating, it is inevitable that pengrun mud will be everywhere. In order to play the same role as emptying the pipeline without causing the trouble of soiling the pipeline, you can pump fresh water into the pipeline before shutting down the bentonite pressure delivery system. The amount of water should be exactly as accurate as the pipeline Volume. When the pipe jacking machine is lifted, the water stored in the pipe must be discharged with a small pressure until the suspension flows out.
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