Abstract: Field reconnaissance and engineering test results indicate that the properties of Qinghuai East River sandstone of Huangmaqing Formation (T2h) are critical to the stability of the proposed high cut rock slopes. The Xray Diffraction (XRD) tests indicates that high clay mineral contents exist in sandstone so that the rock will likely be softened when absorbing the water. Rock mass fractures could also be developed after the water infiltrating and connecting the microcracks. The targeted sandstone was categorized as soft rock by the unconfined compressive strength tests on intact rock samples. When exposed in the ambient atmosphere, the soft rock will be softened. The evaluation results indicate that the rock mass integrity index determined from the shear wave velocity is less than that of determined from the volumetric joint methods. It is also concluded that the water is a critical factor affecting the rock mass properties and the stability issue of the proposed slope excavation should pay attention to the effect of water.

Key words: qinhuaieast river, huangmaqing formation (T2h), sandstone, engineering geology