Predicting the Function of the Dissolution Rate with Depth Using Drilling Data from Shallow Strata at Karst Sites

Abstract

The degree of dissolution in building foundations has been proven to be an exponentially decaying function of depth, which can be characterized by the dissolution rate depth distribution function obtained from survey drilling data. If the dissolution rate depth distribution function can be predicted using shallow drilling data, it would reduce the workload and cost of surveying, and have positive engineering significance. In this study, in the context of the Liuzhou Style Harbor project in Liuzhou City, the dissolution rate depth distribution prediction curve was obtained using drilling data above elevations H30, H40, and H50 (corresponding to dissolution rates of 30%, 40%, and 50%, respectively). The prediction accuracy of the curve was thoroughly analyzed in terms of curve deviation and parameters of the intensive dissolution layer. The conclusion has also been verified by more engineering practices. The results showed that the predicted dissolution rate depth distribution function curve obtained from survey data above elevation H30 was very close to the actual curve, and sometimes matched it. The dissolution rate deviation within the range of the intensive dissolution layer was generally less than 10%, and the deviation in the boundary elevation of the intensive dissolution layer was generally less than 1.0 m. The predicted function was highly reliable, and the prediction deviation met the requirements of engineering practice. Therefore, it is recommended that elevation H30 be used as one of the controlling conditions for the depth of survey drilling in karst building foundation investigations. These research findings can provide a basis for optimizing a karst foundation investigation plan.