THE PRACTICAL REMEDIAL MEASURES TO DEAL WITH RED BOLE DURING LOCATION OF FOUNDATIONS FOR STRUCTURES

V T LONDHE JULY 1979–OCTOBER 1980

Bole beds occur as prominent horizons composed of fine-grained clayey or earthy material having colors in shades of red to chocolate brown, green, purple or gray, often marking the flow contacts of Deccan basalt, which date to approximately 65 Ma. Bole beds preserved between two successive lava flows can be studied relative to soils developed into the same basalt during the Holocene. The bole beds have significantly lower electrical conductivity values and organic matter contents compared to modern soils. Results indicate that the bole beds may not have been subjected to intense weathering but nonetheless formed under uniform rainfall with surface runoff exceeding evaporation. The trace elements in red and green boles do not all show similar behavior with increasing weathering during their formation. Trace elements from the red and green boles inter trapped between the Deccan basalt have been studied to understand their mobility as they are characterized by distinct coloration. They have been correlated with the analysis of four underlying and nine overlying basalt and seventy two basalt occurring elsewhere in the Deccan Volcanic. During the formation of rocks like trap or basalt, the lava flows from the volcanoes spread on the available surface of the earth and settles for quite long geological years. Over a period of long time the lava flow recedes. The earth’s crust then gets deposited over lava flows (already got converted into either trap or basalt) before the next lava flows. During this long gap the earth’s crust gets converted into the so called Red or Green Bole depending upon the color they take up. Now the practical remedial measure is as follows:

• Excavate the foundation of the igneous rock say e.g. the trap or basalt.
• You may meet inter trapped bole of any color either red or green.
• Check the quality and color of the bole layer
• Excavate the entire quantity of red bole from the entire foundation area.
• Now measure the thickness of the full bole layer.
• Excavate the rock further below up to a depth equal to twice the thickness of the bole layer
• Finally check the geological and physical qualities with soundness of the parent foundation rock.
• Check for all other tests for foundation approval.
• The foundation area is then ready for taking any further action.