In order to address the issue of hole collapse, which frequently arises when boring piles are being constructed in intricate marine strata, this paper discusses the influence of the slurry ratio on the slurry performance as well as the mechanism of slurry wall protection. It performs this by means of theoretical analysis, laboratory ratio testing, engineering analogies, numerical simulation, and field testing. Our findings demonstrate that adding sodium polyacrylate and sodium carboxymethyl cellulose can enhance mud’s viscosity, contribute to flocculation, and improve the connection between mud and soil layers. Refering similar engineering cases, three optimization schemes are proposed for achieving a mud ratio that offers wall protection in complex marine strata. Furthermore, the particle flow model of slurry viscous fluid is established. The collapse of holes in the sand layer is reflected in the uneven radial displacement of hole walls and the invasion of mud particles. Increasing the viscosity of mud gradually transforms the uneven radial deformation of pore walls in the sand layer into a uniform radial deformation, whereas increasing the proportion of mud significantly decreases the radial displacement of hole walls. Additionally, when the mud pressure in the hole is 300 kPa and 600 kPa, the wall protection effect is better, and there is no particle penetration by substances such as sand. It is found that a high mud pressure can promote the diffusion of mud particles into the sand layer, while low mud pressure cannot balance the pressure on deep soil. The results of the field tests show that the ratio of water–clay–bentonite–CMC-Na–sodium carbonate = 700:110:90:1.5:0.5 used (where the mass percentage of each material is 77.8% water, 12.2% clay, 10% bentonite, 0.16% CMC-Na, and 0.05% sodium carbonate) can effectively prevent hole collapse and reduce the thickness of the sand layer at the bottom of the hole by 50%.

：A series of experiments were conducted to study the damage response of rock-like specimens on the water content and the unloading rate of the incremental amplitude cyclic loading experiments. Under the conditions of five unloading rates and three water contents, the influence of the incremental amplitude cyclic loading on the rock-like specimens was analyzed. The damage characteristics of the rock-like specimens were discussed, and a damage model was proposed. The test results indicate that the rock-like specimens are sensitive to the water content and the unloading rate of the incremental amplitude cyclic loading. Compared to the monotonic uniaxial compression tests, the rock-like specimens’ elastic modulus and failure stress subjected to incremental amplitude cyclic loading are generally lower. As the unloading rate increases, the failure stress generally decreases, while the elastic modulus first decreases and then increases. Moreover, water can amplify the effect of the unloading rate on failure stress, elastic modulus, and damage variable of rock-like specimens. The influence of the unloading rate on the damage variable has a critical value. A lower unloading rate below the critical value has little effect on the damage variable. In contrast, an enormous unloading rate that exceeds the critical value will enhance the damage variable. The established damage model is suitable for describing and assessing the plastic strain damage variable and the energy damage variable of rocks with different water contents subjected to an incremental amplitude cyclic loading with different unloading rates.