As transmission lines extend into mountainous regions, engineering practices must address the challenging geological conditions of soil-over-weathered-rock strata and the complex loads imposed by extreme climates. This study introduces a novel perimeter anchor pier composite foundation designed specifically for soil-weathered rock strata, aimed at optimizing the mechanical performance of piles and anchors. Initially, material pretests were conducted to determine the appropriate proportions and mechanical properties for scaled models. Subsequently, tension-compression-bending loading tests were performed to investigate the deformation and failure patterns of the novel foundation. Finally, by analyzing the deformation and failure characteristics of the piles and test data, load-displacement-failure curves for the composite structure were derived. The results show that under compression-bending loads, cracks penetrate the pier, causing splitting failure of the pier body and shearing failure of the short piles at the base. Under tension-bending loads, the base short piles experience tensile rupture without damaging the rock mass, while the anchor undergoes significant deformation. The study also reveals that the load-bearing capacity of the base rock mass is not fully utilized, and it recommends enhancing pile strength to improve the overall bearing capacity of the perimeter anchor pier composite foundation.

Clay deposits typically exhibit significant degrees of heterogeneity and anisotropy in their strength and stiffness properties. Such non-monotonic responses can significantly impact the stability analysis and design of overlying shallow foundations. In this study, the undrained bearing capacity of shallow foundations resting on inhomogeneous and anisotropic clay layers subjected to oblique-eccentric combined loading is investigated through a comprehensive series of finite element limit analysis (FELA) based on the well-established lower-bound theorem and second-order cone programming (SOCP). The heterogeneity of normally consolidated (NC) clays is simulated by adopting a well-known general model of undrained shear strength increasing linearly with depth. In contrast, for overconsolidated (OC) clays, the variation of undrained shear strength with depth is considered to follow a bilinear trend. Furthermore, the inherent anisotropy is accounted for by adopting different values of undrained shear strength along different directions within the soil medium, employing an iterative-based algorithm. The results of numerical simulations are utilized to investigate the influences of natural soil heterogeneity and inherent anisotropy on the ultimate bearing capacity, failure envelope, and failure mechanism of shallow foundations subjected to the various combinations of vertical-horizontal (V-H) and vertical-moment (V-M) loads. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Energy piles, as innovative energy underground structure, serve the dual purpose of shallow extracting geothermal energy while bearing the upper building load. There are few studies on the thermomechanical properties of energy piles under combined horizontal and vertical loads. The temperature change of pile body under combined horizontal and vertical loads will result in variations in pile bending moment, horizontal and vertical displacement, etc. This paper investigated the deformation characteristics of energy piles under combined vertical and horizontal loads through model tests with 10 heating-cooling cycles applied to the piles. The results showed that the heating-cooling cycles under combined load led to further increase in the pile bending moment, particularly affecting the middle of the pile, with the maximum increase in pile bending moment reaching 117%. Additionally, the heating-cooling cycles caused cumulative displacement at the top of the pile. The vertical displacement of the test pile increased by 0.201 mm, and the increase in horizontal displacement due to the thermal cycles reached 1.46% D (D is the diameter of the pile). Simultaneously, the heating -cooling cycles induced a forward tilt of the pile, with the tilt angle reached 1.88x10(-3) rad after 10 heating-cooling cycles and gradually increasing with the number of thermal cycles. Moreover, the soil pressure in front of the pile decreased during heating, while increased during cooling.