Creep characteristics of ultra-soft mudstone and creep-slip analysis of Gaomiao landslide

The creep-slip behavior of creeping landslides is closely related to the creep characteristics of slope rock. This study analyzed the creep behavior of ultra-soft mudstone from the Gaomiao landslide in Haidong City, Qinghai Province, China. Uniaxial creep tests were carried out on ultra-soft mudstone with various moisture contents. The test results indicated that the creep duration of the rock sample with a natural moisture content of 9% is 2400 times longer than that of the sample with a natural moisture content of 13%, while its accumulated strain is 70% of the latter. For the rock sample with a natural moisture content of 9.80%, the creep duration under 0.5 MPa load is 80% of that under 0.25 MPa load, yet the accumulated strain is 1.4 times greater. Additionally, porosity significantly influences the creep behavior of mudstone. Analysis of the cause of the Gaomiao landslide and field monitoring data indicates that the instability of the Gaomiao landslide is related to the moisture content of the landslip mass and external forces. The creep-slip curves of landslides and the creep deformation curves of rocks share a common trend. Precisely identifying the moment when the shift occurs from steady state creep to accelerated creep is critical for comprehending slope instability and rock failure. Moreover, this study delves deeper into the issue of the consistency between landslide creep and rock deformation.