Abstract: Long-term researches have now indicated that the roadbed project is one of the key factors of the Qinghai-Tibet Railway which have close relationship with whether the project successful or not; frozen soils are the key problem of the roadbed project in cold regions. In order to protect the permafrost under the railway roadbed, prevent the inhomogeneous deformations induced by frost heaving and thaw collapsing of the frozen soils under the roadbed, we carried out the embankment filling grading and reconstructing local experiment research, embedded the frozen soil settlement drill monitoring instrument. We have accomplished the plate loading test to study the bearing capacity of the grading and reconstructing local experiment roadbed and the reliability of the inbuilt settlement monitoring instrument. Results show that it is reasonable to regard the soil of the experiment as isotropic, continuum and elastic substance. Based on this mothod, the calculated settlement of the experiment roadbed is in accord with the monitoring result, high quality and reliability of the settlement drill monitoring instrument had now been testified.

Key words: Qinghai-Tibet Railway, plate loading test, settlement monitoring, reliability verification