# Method to Control the Deformation of Anti-Slide Piles in Zhenzilin Landslide
## 1 Introduction  
During the construction of the Sichuan-Tibet highway, many roadbed slopes were constructed via excavation and dumping. Several backfill slopes slide along the original surface of the Sichuan-Tibet Highway in the southwest Sichuan province of China. This area is mainly characterized by Silurian strata, comprising medium-thick-layered limestone intercalated with mudstone [1]. Anti-slide piles are used in this bedrock to maintain landslide stability [2]. The pile heads often undergo lateral displacement [3, 4]. If the pile head deformation is too large, cracks form in the landslide body behind the pile, which provide a channel for surface water infiltration and increase the risk of landslides [5, 6]. Many recent studies have investigated the mechanism of pile deformation. In foundation engineering, the deformation behavior of piles is related to the section shape and slenderness ratio of piles [6]. In landslide prevention and control projects, anti-slide piles play an important role and coordinate deformation with the surrounding soil to improve stability of the entire slope [7, 8, 9, 10, 11]. The deformation of the pile head in a slope is related to the slope angle [12, 13]. The excavation and increasing driving force of landslides behind piles will lead to pile deformation and even pile damage [14, 15, 16]. The deflection of the pile head is affected by the lateral load pattern, and the rectangularlateral load pattern has a greater influence on the deflection of the pile head than the trapezoidal load pattern [17; 18]. When the driving force of the landslide, stratum properties, and relative stiffness of the pile are determined, the embedded depth of the anti-slide pile will directly affect the internal force and displacement of the piles [19; 20]. The effective embedded length of anti-slide piles used for reinforcing slopes is analyzed via numerical simulations, theoretical calculations and experimental modeling. [PERSON] [21] presented an approach for the design of piles to reinforce slopes. [PERSON] and [PERSON] [22] and [PERSON] and [PERSON] [23] conducted experimental investigation into the response of vertically loaded free head single piles subjected to lateral soil movement. [PERSON] and [PERSON] [24] adopted an analytical method for calculating the response of flexible piles under the laterally linear movement of the sliding layer in landslides. [PERSON] and [PERSON] [25] adopted strength reduction to study the reinforcement of a row of piles on a slope. [PERSON] et al. [26] studied the way in which expansive power and embedded pile length affected the deformation of the pile in an expansive soil region. [PERSON] et al. [27] studied the effect of the embedded pile length on the factors of safety and pile behavior. [PERSON] and [PERSON] [28] and [PERSON] et al. [29] investigated the effects of pile spacing and pile-head conditions on the critical pile length. As observed, the critical pile length increases with decreasing pile spacing. [PERSON] et al. [30] studied the minimum socketed length in the upper-middle region of the slope, the factor of safety remaining constant. [PERSON] et al. [31] and [PERSON] et al. [32] studied the mechanism of pile deformation in multilayered bedrock. The above researchers have studied the mechanism of pile deformation with a single rock layer and investigated the influence of pile length on slope stability with a multilayered stratum. However, in backfill landslides with multilayer bedrock, studies on large horizontal displacements of piles after the implementation of anti-slide piles are limited. Such excessive displacements will affect the stability of the landslide. Hence, the interaction mechanism between the deformation behavior of anti-slide piles in multilayered bedrock, and the corresponding approaches to alleviate this deformation are crucial. Using the case of the Zhenzilin landslide in Luding county located at southwest of the Sichuan province in China, the objective of this study is to investigate possible factors influencing the pile deformation.