Long-term erosion resistance of grouting curtain in coastal karst fracture area

Abstract

To study the long-term erosion resistance of grouting curtain in coastal karst fracture areas, a long-term erosion resistance test is performed using a self-designed grouting curtain accelerated erosion test system at different accelerated erosion ages in a specific water pressure environment. Results show that the ion-diffusion depth in grouting-reinforced bodies follows the exponential function growth law with increasing erosion age. The grouting curtain deterioration in coastal karst areas occurs within 1–1.5 years. The damage pattern of grouting-reinforced bodies shows a brittle–ductile–brittle transformation trend. The compressive strength, elastic modulus, and peak strain of the grout curtain show a trend of first increasing and then decreasing, conforming to the normal distribution law. In addition, analyses of the pore structure, hydration products, and cementation characteristics of the slurry–rock interface reveal that the erosion products, Friedel salt, AFt, and CaSO4·2H2O, change the slurry microstructure. This shows the effect of filling and compacting in the early stage, swelling and cracking damage in the later stage. In particular, the porosity and proportion of harmful pores in the slurry first decrease and then increase, and cracks form and expand at the slurry and slurry–rock cementation surface.