Abstract: Deformation modulus is an important parameter of the geotechnical materials. The in--situ plate loading test is a direct as well as effective method measuring the deformation modulus. The sandstone rock mass was exposed after the upper reservoir slope excavation for the Zhanghewan PumpedStorage Power Station. The exposed sandstone rock mass might have an adverse impact on the deformation of slope with asphalt concrete facing. Extensive in--situ plate loading tests were performed on the sandstone bedrock with various degrees of weathering.

Key words: Deformation Modulus, Stabilized Settlement, In--Situ Testings