Sleeve for static-load detection of bearing capacity of permanent pile foundation below bottom of foundation pit

The invention relates to a pile foundation detection sleeve used for eliminating pile side friction between a pile body from the natural ground to the top elevation of an engineering pile and a soil body before excavation of a building foundation pit. A sleeve for static-load detection of the bearing capacity of a permanent pile foundation below the bottom of a foundation pit comprises an inner sleeve body (1) and an outer sleeve body (2), wherein the upper end of the inner sleeve body and the upper end of the outer sleeve body are flush, a gap is formed between the inner sleeve body and the outer sleeve body, and the lower end of the inner sleeve body stretches out of the outer sleeve body by a certain length; and full-length longitudinal positioning steel bars (3) are evenly arranged onthe outer wall of the inner sleeve body. Waterstop belts (5) are arranged at the top end and the bottom end of the sleeve and fixed between the inner sleeve body and the outer sleeve body through transverse positioning steel