Backfill grouting slurry diffusion device for simulating shield tail gap and test method

The invention discloses a backfill grouting slurry diffusion device for simulating the shield tail gap, wherein a test device is vertically placed on the ground, one end of an air compressor is communicated with the test device through a pressure gauge and a slurry return valve which are installed on a pipeline, and the other end of the air compressor is communicated with a slurry storage device through a grouting valve installed on the pipeline; on one hand, the device is used for considering the influence of a shield tail gap on backfill grouting in shield construction; on the other hand, the slurry distribution holes and the filter screen are arranged on the laminar flow cylinder, and therefore slurry can be uniformly injected into a test soil body; the change curve of the soil body pressure when the slurry is injected by adopting the test method of the device is basically the same as the change curve of the soil body pressure when the slurry is injected in actual engineering, meanwhile, the diffusion cond