Improved testing method for uniaxial swelling force of red-bed mudstone

Aim To address the problem of excessive gap between the rock specimens and the standard sleeve in conventional uniaxial swelling force test devices, this study improves the existing testing method by replacing the standard sleeve with an open sleeve and adopting a “preset-then-load” installation procedure.

Method Typical red mudstone (undisturbed sample and remolded sample) in Sichuan area was selected to carry out the comparative test of uniaxial swelling force of open sleeve and standard sleeve.

Results The uniaxial swelling force of the original open sleeve (214.0 kPa) is 1.44 times that of the standard sleeve (149.6 kPa), and the uniaxial swelling force of the reshaped open sleeve (159.2 kPa) is 1.27 times that of the standard sleeve (125.8 kPa), The test results show that the uniaxial swelling force of the open sleeve is greater than that of the standard sleeve.

Conclusions The improved design of open sleeve and installation method are reasonable and effective, improving the accuracy of the test results and making the rock uniaxial swelling force test device and method more perfect; The open sleeve has a wide application range and is applicable to the test requirements of different expansive rocks (mudstone, argillaceous siltstone, anhydrite, and marlstone) and different expansion grades (weak, medium and strong). Using the improved test method and device, the test results of rock uniaxial swelling force are more accurate, providing more reasonable parameters for engineering construction.