A theoretical study of the load deformation characteristics of a soil nail during performance tests based on elastic theories

摘要

In most soil-nailed slope works, there are normally two basic types of tests [BSI. BS EN 14490:2010. Execution of special geotechnical works - soil nailing; 2010]: sacrificial nail tests and production nail tests. In Hong Kong, Geoguide 7 [GEO. Guide to soil nail design and construction (Geoguide 7). Hong Kong: Geotechnical Engineering Office, Civil Engineering and Development Department; 2008] has only a pullout test, which is a sacrificial test to verify the design assumptions. Alternatively, Architectural Services Department (ArchSD) requires all soil nail works to carry out performance tests (i.e. production nail tests) after their construction, in addition to pullout tests. In existing ArchSD soil nail works, the acceptance criteria for soil nail head movement in performance tests is based on that in pullout tests. Nevertheless, the theoretical basis for this is not too strong. On the other hand, the BSI [BS EN 14490: 2010. Execution of special geotechnical works - soil nailing; 2010] acceptance criterion also cannot be applied as their soil nails have a de-bonded zone, not fully bonded. Accordingly, it is the purpose of the present paper to carry out a theoretical study of the load deformation characteristics of a soil nail during performance tests based on elastic theories in order to establish a more rational acceptance criterion. Based on present theoretical analyses, together with load deformation data from pullout tests, it is possible to calculate from the theoretical solutions thus obtained the maximum soil nail head movement that can be allowed in a performance test so as to compare it with the actual measured values.