Expeimental Study On Simulate Grouting Effect In Expansive Tuff

Based on drifting the tuff rock tunnels in the Langcang lead mine, this paper tries to present the idea of sealing the joint fissure by means of grouting epoxy resin into the tuff rocks. It could prevent the moisture from permeating while bonding the weak rock planes together at the same time. Fundamentally it would prevent the tuff from disintegrating and softening, and improve the integrity of rocks.Firstly, the paper introduces the physical geography and the geological background of the Lancang lead mine, and focuses on the analysis of the geological characteristics and stability of the tuff rock tunnel. Following the preliminary test, the physical and mechanical properties of the tuff, such as bulk density, dry apparent density, moisture content and the point load strength have been determined.Secondly, regarding the tuff as subject investigated, the grouting theory and the suitable grouting material are discussed. In the meanwhile it focuses on the constituents of epoxy resin grouting material, the properties of the constituents and the main technical parameters of the reagents. And the design ideas, principle, technical specifications of the self-made simulated grouting equipment are introduced in this paper.Thirdly, the following conclusions have been presented by means of the indoor simulated grouting test. A suitable amount of curing agent in epoxy resin system can improve the compressive strength of tuff and, when mixing the modified phenolic amine T-31 and low molecular polyamide 650 curing agent at the ratio of 2:1, it would be more suitable to control the total mass in 33%-38%(at weight ratio). Moreover, the accelerants can obviously shorten the gelation time, but the accelerants should be added carefully, especially if the formula of the epoxy resin has a high activity in general, lest the chemical reaction between them becomes too violent.The suitable incorporation for single epoxy reactive diluent should be 80g for per 100g epoxy resin. After grouting,the slake durability of tuff briquettes can obviously increase; XRD and SEM test results have show an obviously grouting effect for the epoxy resin.Finally, using the Finite Element Analysis (FEA) software, the stress distribution, deformation, plastic zone, strength coefficient and other indexes of tuff tunnel had been simulated before and after grouting. According to the simulated results, and after the tunnel excavation, anchor support and grouting can remarkably minimize the stress concentration of the surrounding rocks. Moreover, anchor support and grouting can also reduce the stress concentration of surrounding rocks, and help decrease the odds of tunnel displacements. Thus, due to the decrease of stress concentration, the main stress direction is spread evenly around the tunnel instead of being concentrated horizontally. Thanks to the anchor support and grouting, most of the plastic zones formed when excavating are now dropping out, so the strength coefficient of surrounding rocks has increased significantly.