ICS 93.020                         CED 48

New Standard from Last Update.

1 SCOPE

1.1 This standard covers the determination of modulus of deformation of rock mass by borehole jack test at different depths and directions in NX size drillhole of 76.2 mm diameter. The stress is applied through two curved steel platens covering a 90° sector over a length of 203 mm. The applied stress and resulting deformations of rock mass are used for the determination of modulus of deformation of rock mass using appropriate elastic theory. The modulus of deformation of rock mass depends on the applied stress level and thus, it is not a constant parameter which means it cannot be characterised by a unique value. The modulus of deformation of rock mass is recommended based on the stress levels anticipated on account of the proposed structure and thus becomes an engineering judgement.

1.2 Creep characteristics may be studied keeping the uniform stress level for a specified period and then deformation versus time curve is plotted to analyse behaviour of rock mass under sustained loading.

1.3 Anisotropy can also be determined by application of stress level in desired directions in relation to the bedding or any other prominent joint or the design requirements suiting the proposed structure.

2 REFERENCES

The standard listed below contain provisions which, through references in the text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below:

4464 : 1985 Code of practice for presentation of drilling information and core description in foundation investigation