Strong Motion Studies in the Mines of Kolar Gold Fields
Abstract
Rockbursts are common phenomenon in mines during mining operations. A network of geophones was used to locate and assess the stability of mine workings. The important parameters needed to assess the damage potential and severity of a rockburst is its Richter's local magnitude. It was not possible from the records of geophone due to saturation effect. A strong-motion accelerograph has been installed and has recorded many rockbursts after closure of the mines. The Strong-motion accelerograms recorded due to rockbursts are therefore used to obtain a Wood- Anderson synthetic seismogram for getting accurate and reliable values of the local magnitudes. Using 100 typical strong motion accelerograms of rockburst in the mines of Kolar Gold Fields, the magnitudes have been computed. The maximum magnitude obtained from several rockbursts during the period has been found to be 4.29. Attenuation relationships for peak horizontal ground acceleration for short distances and low magnitudes have been used for the development of the attenuation relationship. Two step multi regressions have been made by analyzing the decay of individual magnitude classes with distance using it with the whole data set. The models used in the present study is log(A)=C1+C2 M-C4blog(X+ e(c/3/M)) where A is the peak ground acceleration, X is the hypocentral distance, M is the local magnitude M(L) and C(i)'s are regression coefficients. The discussions of the attenuation characteristics of the ground motion at shorter distances and low magnitudes have been discussed. The comparison of strong ground motion at similar distances using relationships developed from higher magnitudes reveals the difference in the observed peak ground horizontal accelerations with respect to the strain levels involved in the generation of the respective earthquakes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2008
- Accession Number
- ADA516108
Entities
People
- C. Sivakumar
- C. Srinivasan
- Yesurathernam A. Willy