To investigate the distribution of radial expansion compressive stress along the direction of hole depth in static crushing process and explore the influences of hole diameter

hole depth

and constraint degree on radial expansion compressive stress

the radial expansion compressive stress of 21 specimens during static crushing process was measured by means of resistance strain gauge method by using seamless steel pipe to simulate drilling. According to the theory of hoop of concrete filled steel tubular

the ratio of sectional area of steel tube to sectional area of static crushing agent was defined as constraint degree. Experimental results show that the radial expansion compressive stress produced by static crushing agent was not uniformly distributed along the direction of the hole depth

and the expansion compressive stress in the middle and bottom of the hole was generally greater than that in the top. With the increase of the hole size

the difference between the radial expansion compressive stress at the bottom of the hole and the upper part was more significant

the expansion compressive stress at the middle and bottom of the hole in the same time became larger

and more crushing agent overflowed the orifice. Hole depth and constraint degree had little influence on the expansion compressive stress

and the expansion compressive stress generated by static crushing agent in the middle and bottom of the hole increased with the increase of hole depth or constraint degree. The selection of suitable hole depth and larger hole size is more conducive to static crushing agents for developing their expansion potential.