Engineering Geological Investigations of a Nuclear Building Foundation – A Case Study from Atomic Power Project, India

Abstract

Engineering geological foundation investigations are essential for important civil structures to provide permanent data set for geological interpretations. At Rawatbhata, India, two units of 700 MW each Pressurized Heavy Water Reactor (PHWR) type Nuclear Reactors are being constructed adjacent to existing Rajasthan Atomic Power Project (RAPP) units 1 to 6. Engineering geological mapping on 1:100 scale was carried out for Nuclear Building-8 structures to evaluate the design basis foundation parameters. 1 m x 1 m grids were prepared for mapping of the floors and walls. Based on the field observations and evidences, it was found that the floor area consists of fine to medium grained, compact quartzitic sandstones. The floor region was seen to contain certain iron stained and fractured zone. No evidence of faulting was observed on the surface of the floor areas. However, there were some isolated patches of soft, weathered/altered rock and small fractures in the rocks. The intact rock properties at the foundation levels were evaluated considering the necessity in the overall context of the design requirements of the foundations. Geotechnical assessment of the foundations of RB-8, RAB-8 and ECCS north and south pits was done on the basis of detailed engineering geological mapping, geological drill holes logging data, rock mass permeability values, geophysical profiling and laboratory test results. Based on investigations recommendations for the treatment of foundations were given. Consolidation grouting up to 9 m depth in the foundation using primary at 6 m spacing and secondary holes at 3 m spacing was recommended. After detailed investigations it was found that, the foundation is suitable to locate a nuclear power plant.

Geotechnical Assessment of the Foundation of Housing Chamber of Yaragol Gravity Dam, Karnataka State, India

“…Foundation floor engineering geological mapping is essential for important civil structures to provide permanent data set for geological interpretations during construction and also it forms valuable documentation for post-construction stage (Naithani et al , 2017. For very important structure, the supporting foundation strata should be studied and documented to provide data for credible geologic interpretations (Harikumar, 2010).…”