The experimental studies have been conducted upon the deformability of the dividing-pier rockmass of ship-locks of a hydrauclic project in China using the borehole elastic modulus test, which determines the spatial distribution of the rockmass's damaged areas and gives the elastic moduli of both damaged area and country rocks in the present paper. All this lays a foundation for establishing the valid model for the numerical analysis of the dividing-pier stability and thus offers the parameters essential for computation. And meanwhile, the seismic wave method has been used to determine the damaged areas inside the dividing-pier rockmass, the results being coincident with the tests of the borehole elastic modulus method (BEMM). However, the seismic sounding can only ascertain the distribution of damaged areas qualitatively but is unable to obtain the deformation parameters of the rockmass that are of paramount importance in the stability analysis.
The dividing-pier of ship-locks is the man-made slope of a special kind that is great in height and steep in dip. It is one of the most important tasks to understand the mechanical behavior of the dividing- pier rockmass when man conducts stability analysis and makes reinforcing design. The dividing-pier is the production of the excavating activities in a natural rock mountain. In the course of formation of the dividing-pier, the damaged zones of large areas due to tension and shearing result gradually in the rockmass from the effects of such factors as initial geostress field, excavation unloading and blasting in construction etc. Thus two problems arise: How large is the real range in the rockmass that is subjected to tension and shear damages and what are the differences between the damaged rockmass and the country rocks in their mechanical properties? To tackle these two problems perfectly is the prerequisite for the establishment of valid computation model and reasonable computing parameters for stability analysis as well as for the application of reliable reinforcing measure and the selection of technological indexes while making design. Traditionally, the damaged zones in a rockmass is determined using the seismic wave method in which the damage extent of the rockmass is evaluated according to the variation of the velocity and amplitudes of waves as they penetrate through the rockmass and to the correlation that exists between the velocity and amplitude of waves and the density of the rockmass fissures. However, this method is unable to understand and much less to distinguish the behavior of the damaged and the country rockmass although it can ascertain rather accurate spacial distribution of the damaged zones in the rockmass. To counteract the inadequcy of the seismic wave method, we have made, first in China, attempts to conduct the borehole elastic modulus tests for determination of the rockmass's damaged zones of a certain large-scale hydraulic project. The results have shown that this borehole elastic modulus method (BEMM) can solve the above mentioned problems perfectly.
2.1 Measuring principle
