Abstract: Rock point load test is a test method to quickly obtain the mechanical properties of rock.However,there are some problems in the existing point load equipment,such as inconvenient carrying and difficult constant loading rate.There fore,a new point load tester is developed through the following ideas:the deceleration motor is used to improve the loading pump oil circuit,and the ability of stable loading and adjustable rate under controllable weight and volume is realized.The em bedded data acquisition unit is integrated to synchronously record the point load value and displacement,and eliminate the manual recording error.In order to verify the improvement effect,the green sandstone is selected to carry out the indoor test, and the test results are compared with the traditional point load equipment.The results show that the discrete coefficient of the rock point load strength index measured by the hydraulic servo point load tester is reduced by 35%,and the failure mode of the sample is more stable.The linear fitting analysis of the measured point load strength and uniaxial compressive strength shows that the relationship between the two is highly positively correlated,which verifies the reliability and superiority of the perform ance of the new hydraulic servo point load tester.

Key words: 　point load apparatus,hydraulic servo,rock debris,mode of failure