Abstract:
To solve the problem of difficult high-strength bonding between ordinary resin anchoring agents and surrounding rocks under conditions such as soft and fractured rock mass and geological structures, this study proposes a method of adding expansion agents to anchoring agents. The aim is to enhance the bonding properties of the resin anchors with the surrounding rocks by inducing the expansion effect of the resin anchors, and ultimately improve the overall anchoring effect. Three kinds of expansion systems were selected, including polymethylene polyphenyl isocyanate, alum and sodium bicarbonate, aluminum sulfate and sodium bicarbonate. Through the expansion rate test and performance test of resin anchorage agent, the expansion rate of each expansion system and the related performance data of expansive resin anchorage agent with aluminum sulfate and sodium bicarbonate as expansion agent were obtained. The results show that the expansion system of polymethylene polyphenyl isocyanate, alum and sodium bicarbonate only has obvious expansion effect on the medium-speed anchorage agent, while the expansion system of aluminum sulfate and sodium bicarbonate has obvious expansion effect on all kinds of anchorage agents. The addition of aluminum sulfate and sodium bicarbonate has little effect on the gelation time of resin anchorage agent. In the range of 0%-20% expansion rate, the compressive strength is negatively correlated with the mass fraction of aluminum sulfate and sodium bicarbonate, but all can reach the minimum standard of compressive strength, while the anchorage force is positively correlated with the mass fraction of aluminum sulfate and sodium bicarbonate. In mudstone without cracks, the anchoring force can be increased by up to 82.9%, and the anchoring force after exchanging the installation sequence of anchoring agents is higher than that of the original installation sequence; in fractured mudstone, the anchoring force of 20% expansion rate anchoring agent can be increased by 104% compared with that of non-expansion anchoring agent.