*Paper presented by the Central Water and Power Research Station, Poona at the 28th Annual Research Committee Meeting of C.B.I&P held at Srinagar in June 1958.
In connection with foundation problems at Kotah Barrage site, a detciled investigation has been carried out on ike following lines :—
(i) Exact nature of foundation material in the river bed and their permeability characteristics. (ii) Nature of silt covered terrace on the right bank. (iii) A laboratory study on the clay-cement grouting for the foundation treatment.
The size of the boulder and gravels has necessitated non-conventional methods of investigation. Ordinary sampling methods to determine the insitu characteristics of the foundation failed and so a big box pile pit was driven into the boulder formation and the properties were determined by ex-cavation and visual observation in the pit.
Similarly, standard methods of permeability determination could not be followed, and so a combination of field tests and three dimensional electrical analogy tests in the laboratory were carried out to determine the permeability of the foundation.
The deposit on the tarrace is of two types:
(i) top pale brown soil of permeability 60 ft/yr,, followed by (ii) light yellow soil of permeability 9 ft/yr.
These layers rest on 10 ft-15 ft thick boulder fissured rock formation, of permeability of 150-200 ft/yr., followed by continuous rock.
The practice of clay grouting is not much in vogue in India, though it is an economical and desirable method of treatment for alluvial foundation. A study has been made in the laboratory on the various aspects that determine the feasibility of clay-cement grouting, with special reference to the conditions met with at Kotah Barrage site. Some interesting results have been obtained and a trial grouting test can be made with the day-cement grout developed in the laboratory.
