Mechanical Properties Of Embedded Bolt Casing

This paper studies embedded bolt-casing technology, casing bolts embedded in prefabricated units. A variety of devices can be attached on prefabricated units by a screw bolt, which is screwed into the casing. Embedded bolt casing technology using in subway shield tunnel segment has high construction efficiency, low cost advantages. This article will through experiment, the finite element simulation of embedded bolt axis of casing specimen tensile and pull cutting compound stress through analyzing the two kinds of stress conditions.In test section, this paper studies the M16, M20, M24 three different types of embedded bolt casing specimen. For 21 embedded bolt casing of axial tensile specimen, embedment depth is studied on the influence of different types of embedded bolt casing specimen. For 21 composite tensile shear force embedded bolt-casing specimens, bolt-casing buried dip is studied. The pull-out tests of 42 embedded bolt-casing specimens were conducted, obtained each load-displacement curve of the specimens and related data of the failure pattern.In the finite element simulation part, using the display algorithm of ABAQUS, which is finite element software, analyzed the embedded bolt-casing specimen by the force of the quasi-static simulation. For finite element analysis of load-displacement curve and test results were compared, analysis the stress cloud of bolt casing and steel rob, the equivalent plastic strain distribution of cloud picture of concrete, and compare with the test of failure pattern.Through the study of the test results and finite element method, this paper obtained the following conclusions:1) The embedded bolt sleeve, stretched axially, mainly occur mixed failure with concrete cone pull out and bolt casing pull off; The composite tensile shear force embedded bolt-casing specimens mainly occur extrusion damage between concrete casing bolts and shear failure of thread;2) Increased the embedded depth and diameter of bolt-casing will help improve the ultimate bearing capacity, but the embedded inclination of bolt-casing has little effect on the ultimate bearing capacity;3) According to the results of the experimental study, deduce the formula of ultimate bearing capacity, applying to the mixed failure of bolt casing.