## 1 Introduction  
With advancements in foundation reinforcement technology, microbially induced carbonate precipitation (MICP) [1; 2] has garnered significant attention due to its environmental benefits, its low energy consumption, and the fact that it generates minimal pollution. Traditional methods, such as the use of cement and chemicals, are costly, especially for large-scale applications. Unlike traditional methods such as vacuum preloading and chemical grouting, MICP technology utilizes naturally occurring soil microorganisms. These microorganisms adsorb Cs\({}^{2+}\) from environmental solutions onto their cell surfaces, decompose urea, and subsequently produce CO\({}_{3}\)\({}^{2-}\) and NH\({}_{4}\)\({}^{+}\) through urease activity. The Ca\({}^{2+}\) then reacts with CO\({}_{3}\)\({}^{2-}\) to form substantial amounts of calcium carbonate crystals on the cell surfaces. Moreover, bacteria present in geotechnical materials produce large quantities of calcium carbonate, which bonds with microparticles in the soil, filling internal pores and fissures [3]. This process enhances soil strength, reduces soil permeability, and improves soil compressibility [4; 5]. Construction methods that involve MICP generate minimal chemical pollution in surrounding soil and water environments and produce almost no toxic or harmful substances. These methods are not only simple and cost-effective but also offer substantial advantages over traditional soil-reinforcement techniques in terms of cost efficiency, operational efficiency, and environmental impact across various soil types [6; 7]. MICP technology was initially applied to treat sandy soil [8; 9; 10]. Researchers such as [PERSON] et al. [9] and [PERSON] et al. [11] utilized the MICP method to treat sandy soil, resulting in significant improvements in cementing properties and anti-permeability. Rather than using traditional grouting, [PERSON] et al. [12] mixed urease and cementation liquid with silty soil, followed by compaction and storage, which yielded effective reinforcement outcomes. Extensive research has been conducted on sandy and silty soils [13], but there are relatively few studies on the use of the MICP method for the reinforcement of soft clay. [PERSON] et al. [14] employed MICP to improve sand-clay mixtures, and they found that the addition of kaolin clay inhibits the urease activity of bacteria. [PERSON] et al. [15] applied the slip casting method to consolidate organic clay, demonstrating significant improvements in unconfined strength and permeability coefficients. However, their study only focused on the relationship between calcium ion or ammonia nitrogen concentrations and the number of grouting applications, without considering the effects on strength, the permeability coefficient, or other characteristics over time. [PERSON] et al. [16] investigated Bacillus-pasteurii-induced carbonate precipitation in organic soft soil, revealing that bacterial treatment effectively enhances the compression performance and shear strength of the soil. Compared to sandy soil, soft soil has a low permeability coefficient and small pore diameters, which significantly affect the migration of microorganisms within the soil [17]. MICP excels in sand reinforcement, enhancing soil strength, stiffness, erosion resistance, and permeability by binding loose sand particles into a cohesive whole with bio-cement. For different soil types, such as those incorporating the use of rubber particles for reinforcing calcareous sand [18] and the addition of activated carbon in red clay [19], the reinforcement effect is improved. In recent years, the incorporation of glass fibers, basalt fibers, and carbon fibers, combined with MICP, has led to sand samples having unconfined compressive strength (UCS) values that are 4.5 times, 7 times, and 11 times that of samples without fibers, respectively [20]. [PERSON] et al. [21] also compared the effects of several fibers on MICP-treated samples, finding that carbon fibers performed the best, while basalt fibers were the most cost-effective.