Filter cake is critical to maintaining the stability of the excavation face of an underwater shield tunnel in a high-permeability stratum. In a high-permeability formation. generating an effective filter cake on the excavation face is difficult with a pure bentonite slurry. which penetrates the ground and may not achieve the required suspension pressure. https://www.countryscenesaddleryandpetsuppliers.shop/product-category/tough1-cactus-saddle-bag/