DIRECT RING SHEARING TEST FOR PIT BOTTOM

摘要

PURPOSE:To exactly perform a test on the shearing strength of stratum by touching a cylindrical test tube with the bottom of a pit by means of a piston and turning the cylindrical test tube by external moment in such a way as to cause shearing breakage in a soft stratum, e.g., sand layer, etc. in field test. CONSTITUTION:A cylindrical test tube 1 whose lower end is formed into a teeth or groove form 4 is pressed onto the bottom of a pit by means of a piston 11 operated by loading, hydraulic pressure, oil pressure, compression, etc. The cylindrical test tube 1 is turned by an external moment to cause a shearing breakage in a ring form in the bottom stratum of the pit. In this case, the pressing pressure is changed in a stepwise manner, torque value under each condition is measured by a breaking rotary torque meter 19, and the values of internal friction angle and adhesion as the shearing strength constant of the stratum are obtained from the relations of both the pressing pressure and the torque value. Thus, breaking shearing strength and residual shearing strength can be obtained.