## 1 Introduction  
Double-row skid-resistant pile structures have the advantages of high stiffness, low deformation, and being able to provide larger skid-resistant force than single-row piles, which have been widely used in large-scale landslide management projects [1]. However, the calculation method of internal force of double-row skid piles is not uniform, which leads to some limitations in its engineering application [2, 3]. In recent years, scholars at home and abroad have conducted a lot of research on the pile-soil action mechanism [4, 5, 6] and have designed calculation methods [7, 8, 9] for double-row skidding piles. Theoretically, the internal force analysis methods of double-row skidding piles mainly include the ultimate foundation reaction method [10], elastic foundation reaction method [11], composite foundation reaction method [12, 13], etc. [PERSON] et al. [14] proposed a calculation model of landslide thrust of double-row piles based on the soil arch theory and the limit equilibrium theory. [PERSON] et al. [15] proposed a non-limit state double-row without connecting beams based on the soil strength theory and the soil arch theory. [PERSON] et al. [16] established the internal force and deformation formula of double-row skidding piles by using the theory of elastic foundation beams and verified it by engineering examples. [PERSON] et al. [17] established the internal force calculation model of double-row piles with connecting beams based on the elastic foundation beams of Winkler and regarded the soil pressure and constraints between the piles as springs. [PERSON] et al. [18] based on the soil displacement around the pile and the elastic foundation beam method, established an internal force calculation model of double-row skidding piles with a connecting beam. In a numerical simulation,Tang et al. [19] used Coulomb GEO5 numerical simulation software to study the effect of pile row spacing on the pile body. [PERSON] et al. [20] investigated the deformation of double-row piles and the damage characteristics of the pile force through model tests and finally verified the accuracy of the model test results by using ABQUS numerical simulation software. [PERSON] [21] used MIDAS numerical simulation software to study the effect of structural dimensional parameters of double-row piles on the internal force and horizontal displacement. [PERSON] [22] used simulation software and on-site monitoring to study the force and deformation law of double-row piles. In summary, the existing double-row skidding pile internal force calculation is based on the limit equilibrium theory and elastic foundation beam theory, i.e., through the empirical assumptions of the front and rear pile thrust sharing ratio and soil pressure distribution pattern in front of and behind the pile, combined with the structural mechanics model or numerical method for the calculation of skidding pile internal force. This method has not yet formed a unified theoretical system for the distribution of landslide thrust on double-row skid resistant piles and the nonlinear distribution characteristics of soil pressure in front of and behind the piles, and it lacks effective tests and verification. For this reason, our group carried out a series of experimental and theoretical studies under the support of the key research and development program of Shaanxi Province. In this paper, the pressure distribution form and damage mode of pile body of the fully embedded double-row skidding piles without connecting beams were obtained through the analysis of the experimental results, and then a new method of dividing the pile body was put forward, i.e., depending on the plastic hinges above the sliding surface of the pile body as a directional support and assuming that the shear force is zero, the pile body was divided into two parts for the internal force distribution, namely, the part above the zero point of shear force and the part below the zero point of shear force.