Investigation of Performance Improvement of Friction Piles with Two-Component Polymer Using Direct Shear Test

Mobilized shear strength in the interaction between various materials such as sand and steel plays a crucial role in geotechnical applications, particularly in the design and performance of friction piles. This study presents an innovative approach through polymer injection to enhance the mobilized shear strength between the pile and soil. To investigate this idea, a series of direct shear tests were conducted under three values of vertical stresses on both smooth and rough surfaces. Parameters such as the amount of inject-ed polymer, curing time, and the roughness of the steel surface were examined. The test results indicate that polymer injection significantly increases the mobilized shear strength at the sand- steel interface, even after a short period of about one-hour post-injection. An increase in the amount of injected polymer from 0% to 20% resulted in a nonlinear increase in shear strength. The test results show a remarkable increase in shear strength on smooth surfaces after injection compared to rough surfaces. Additionally, with more time, the mobilized shear strength also increased. Microscopic images of the injected area in the sand demonstrate the bonds formed between the grains by the polymer, which ultimately improves the injected soil.