Structure Restrengthening Process and Mechanical Properties of Damaged Weakly Cemented Mudstone

The stable surrounding rock is the key to ensuring tunnel availability in weakly cemented strata. In recent years, the joint support scheme of “steel beam + anchor net rope + grouting” was proposed based on numerical analysis, laboratory tests, and field tests, which was efficient in the short term. However, the effect of time and environment on the support structure was neglected. The weakly cemented mudstone was sensitive to water, with disintegration soaking up water and consolidation losing water. In this paper, analogy-based remolded soil puts forward the structural restrengthening of damaged mudstone. It was believed that when the clay content of a rock mass exceeded the critical proportion, the restrengthened structure could be regained under certain conditions of consolidation stress and water content. On the one hand, the residual strength of broken mudstone can be improved; on the other hand, pores and cracks are filled with minerals, restraining further water absorption. The structural strengthening feasibility of damaged mudstone was verified based on the geological characteristics and microscopic and strength tests. It is found that restrengthening specimens form cementation on the contacts of broken blocks. The greater the consolidation stress and moisture content, the denser the structure and the higher the strength. The research contributes to supporting the construction of weakly cemented mudstone.