EXPERIMENTAL STUDY RESULTS OF THE EFFECTIVENESS OF UNDERPINNING A STRIP FOUNDATION FRAGMENT USING A DRILL-AND-INJECTION ENLARGED PILE

Abstract

The article presents the results of static load tests of a strip foundation fragment (bearing plate) underpinned by a drill-and-injection pile with enlarged base. The static load tests were carried out in the summer of 2020 at the testing site in the city of Tyumen. A drill-and-injection pile with enlarged base is an injection pipe that has a rubber membrane-glass at its lower end. With the help of a hy-draulic packer, the solution is injected into the rubber membrane-glass. After the solution has hard-ened, an enlarged base of the injection pipe of the required size is formed. To assess the results ob-tained, static load tests are also carried out both for a strip foundation fragment not underpinned us-ing a drill-and-injection pile with enlarged base and a separately located drill-and-injection pile with enlarged base. Based on the data obtained during static load tests in the course of the experimental study, the following dependency graphs are formed: the graph of the settlement of a strip foundation fragment without underpinning and with underpinning by means of an enlarged pile depending on the pressure under its base; and the graph of the settlement of an enlarged drill-and-injection pile depending on a static pressed load. The results indicate that the use of an enlarged drill-and-injection pile to underpin a strip foundation fragment allows increasing the safe working pressure under the strip foundation fragment base by an average of 25% and reducing its settlement by an av-erage of 43 %.