Abstract: It is generally recognized that the difficulties in borehole advancement in the installation of prestressed ground anchors in talus formations and broken rock masses. The downhole hammer with a casing immediately followed method is an effective way to advance boreholes in complicated subsurface conditions, such as, broken rock, loose soil and running sand conditions. This paper discusses the potential difficulties of apply down hole hammer in the talus and broken rock mass formations through trial tests. The parameters such as, air entry pressure, drill bit pressure, and pump pressures, are also discussed under different subsurface conditions. 

Key words: Talus Formation, Broken Rock Mass, Air Pressures, Drill Bit Pressures