Abstract：Nine groups of hydraulic fracturing tests of thirty thick-wall cylinder samples are performed；and the experimental results are analyzed. The analytical methods reported in some studies based on Lame¢s formula of the thick-wall cylinder are incorrect. Infiltration theory of hydraulic fracturing is presented. Based on elasticity mechanics and mathematics，an analytic distribution result of thick-wall cylinder under stable infiltration is put forward and it is verified by commercial software. A rigorous theory foundation is established for the research of hydraulic fracturing of rock masses. Failure condition of thick-wall cylinder on hydraulic fracturing is discussed. And a semi-empirical formulation on critical stress of hydraulic fracturing is presented.
