Foundation pit drainage sedimentation basin

A foundation pit drainage sedimentation basin belongs to the technical field of underground drainage structures and comprises a foundation pit sedimentation basin body, an inner cavity of the foundation pit sedimentation basin body is in an inverted pyramid frustum shape, drainage ditches are formed in the bottom end of the inner cavity of the foundation pit sedimentation basin body in an end-to-end communicating mode in the circumferential direction, and the lower surface of an inner cavity of each drainage ditch is arranged to be downhill in the clockwise direction from head to tail. Multiple layers of sediment blocking assemblies are arranged at the end-to-end communicating position of an inner cavity of the drainage ditch. By arranging the multi-stage sediment blocking assembly, sediment and water can be gradually separated, the water is discharged outwards through the U-shaped pipe and the drainage pipe in the inner cavity of the third separation tank, meanwhile, water on the liquid level of the top end