Constant rigidity boundary hydraulic fracturing test device

The invention provides a constant-rigidity boundary hydraulic fracturing test device which comprises a confining pressure loading system, an axial pressure loading system, a water pressure loading system, a confining pressure monitoring system, an axial pressure monitoring system, a water pressure monitoring system, a lateral deformation measuring system, an axial deformation measuring system, a rock test piece and a computer control system. The principle for realizing the constant-rigidity boundary hydraulic fracturing test is as follows: in the process of applying water pressure, a computer control system calculates confining pressure required for keeping the constant rigidity according to the monitored lateral deformation of a rock test piece, and then the confining pressure is continuously corrected through automatic control, so that the constant-rigidity boundary is realized; and the test piece is fractured. The hydraulic fracturing indoor simulation test under the constant rigidity boundary condition is