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In the steep terrain of southwestern China, there are numerous complex strata characterized by thin overburden layers and well-behaved underlying bedrock, yet excavation poses significant challenges. This situation is unfavorable for the construction of transmission towers’ foundations. To address this issue, inclined anchor short-pile foundations have been proposed as foundations for transmission towers. These foundations not only reduce the depth and construction difficulty of excavation but also make full use of the load-bearing capacity of the bedrock. To investigate the influence of the anchor rods’ layout on the uplift resistance characteristics of inclined anchor short-pile foundations, numerical models were established using FLAC3D. The effects of the anchor rods’ position and the length of the free segment on the uplift resistance characteristics of inclined anchor short-pile foundations were explored. The results indicated that variations in the anchor rods’ position and the length of the free segment had minimal impact on the uplift resistance characteristics of inclined anchor short-pile foundations. The pile head displacements of short piles with different anchor rod positions were similar under both loading conditions. Under pure uplift loads, the maximum displacement before failure was approximately 13 mm, while under combined uplift and horizontal loads, the maximum displacement before failure was around 15 mm. Placing the anchor rod too low increased the difficulty of construction, while positioning it too high resulted in a shorter embedment length of the anchor rod in the pile’s body, leading to potential failure at the pile–anchor node. Therefore, it is recommended to position the anchor rod near the center of the short pile’s body. As the length of the free segment of the anchor rod decreased, there was a slight reduction in the displacement under the same uplift loading conditions, with an overall difference of less than 5%. However, if full-length anchoring was adopted, the anchor rod was prone to tensile shear failure. Compared with short-pile foundations of the same size, inclined anchor short-pile foundations demonstrated enhanced ultimate bearing capacity under uplift and combined uplift and horizontal loading. The improvement was more significant when horizontal loads were present. Under horizontal loading, the ultimate uplift bearing capacity of inclined anchor short-pile foundations decreased by only 14%, whereas that of single-pile foundations decreased by 24%.

Based on the upper bound theorem of limit analysis and variational principle, the uplift resistance of shallow horizontal anchor plates in heterogeneous soil and three-dimensional failure surface of overlying soil are investigated. The results calculated by the theoretical approach are compared with results of the existing solutions and numerical results obtained by software PLAXIS 3D to verify the validity of the variational analysis. Furthermore, the influence of the heterogeneity and nonlinearity on the uplift characteristics of shallow horizontal anchor plates is discussed. The results show that: (i) Increase in the uplift resistance and expansion of failure range are observed with decreasing nonlinear coefficient m and variation coefficient k t of soil uniaxial tensile strength as well as increasing variation coefficient k c of soil initial cohesion. (ii) Heterogeneity and nonlinearity jointly determine the shape of failure surface. This study enriches the analytical method of anchor plates and has great significance for stability and safety of anchor plates.

To enhance the stability and safety of marine aquaculture facilities by addressing the limited uplift resistance capacity and susceptibility to deflection of conventional straight-shafted piles, this study introduces an improved H-pile anchor and conducted laboratory experiments. The new anchor incorporates resized H-piles with wing plates added to both sides, optimized for area and placement, as well as an adjusted loading angle. The findings demonstrate a positive correlation between the uplift resistance capacity of the H-pile anchor and its length and width, indicating that while increased pile length significantly enhances resistance, widening has a minimal impact. Additionally, enlarging the wing plate area improves the resistance; however, efficiency (δ) decreases with the increase in the area, suggesting the existence of an optimal size. The optimal wing plate dimensions (L = 80 mm, W = 25 mm) improve uplift resistance by at least 10.6% compared to non-wing pile anchors. Furthermore, positioning the wing plates at the base of the pile anchor rather than the top enhances resistance by approximately 13.8%. Setting the anchor layout angle to 45° reduced the displacement under inclined loads. This research provides essential theoretical support and practical guidance for strengthening the safety and stability of marine aquaculture facilities.

Unlike traditional building structures, transmission tower foundations endure significant vertical and horizontal loads, with particularly high uplift resistance requirements in complex terrains. Moreover, challenges such as difficult material transport and low construction efficiency arise in these regions. This study, based on practical projects, proposes a novel high uplift resistance prestressed concrete prefabricated foundation (HURPCPF) tailored for transmission line systems in complex terrains. A refined finite element model is developed using ABAQUS to analyze its performance under uplift, compressive, and horizontal loads. Comparative studies with cast-in-situ concrete foundations evaluate the HURPCPF’s bearing capacity, while parametric analysis explores the impacts of foundation depth and dimensions. The results show that the proposed HURPCPF exhibits a linear load–displacement relationship, with uniform deformation and good integrity under compressive and uplift conditions. During overturning, the tilt angle is less than 1/500, meeting safety standards. The design of prestressed steel strands and internal reinforcement effectively distributes tensile stress, with a maximum stress of 290 MPa, well below the yield stress of 400 MPa. Compared to cast-in-situ concrete foundations, the displacement at the top of the HURPCPF’s column differs by less than 7%, indicating comparable bearing performance. As foundation depth and size increase, vertical displacement of the HURPCPF decreases, enhancing its uplift resistance.

A new type of static load test system and test method based on steel screw anchor pile is proposed. Through field uplift tests of single pile and pile group, the influence of soil properties, pile length and other factors on the uplift bearing capacity of steel screw pile is analyzed. The influence range of steel screw pile on the displacement of adjacent soil and pile foundation are revealed. The calculation method of ultimate uplift bearing capacity of single steel screw anchor pile is established. The reliability of the test method is verified by practical cases. The test results show that the uplift bearing capacity of steel screw pile is higher than that of straight rod pile. According to the properties and compactness of the soil, the coefficient of uplift side resistance improvement of steel screw piles can be taken as 1.2 – 1.6. The construction of steel screw pile is convenient and can be reused, without special treatment of the test site. The test method can save up to 70% of the cost compared with traditional surcharge test method, and greatly improve the safety of large-tonnage static load test.

The article presents the results of an experimental study on driven reinforced concrete piles with hybrid shaft, which incorporates several wedge-shaped elements with inclined side faces. A technology for the installing of these piles, involving the addition of loose materials to enhance soil compaction, is herein proposed. Field experiments were conducted to determine the energy intensity of driving and the uplift load resistance of these piles. It was found that the energy intensity of a driving hybrid pile with loose materials addition is 1.4–3.5 times greater compared to conventional driven piles. However, the uplift bearing capacity was 1.5–4.4 times higher than that of piles with a traditional shape. The efficiency of the experimental piles is attributed to an increase in the volume of wedge-shaped elements on the pile shaft and the incorporation of loose materials, such as gravel and sand. The uplift capacity of hybrid shaft piles improves with the increasing volume of the aforementioned parameters. The obtained correlation dependencies enable a reliable calculation of the energy intensity and uplift resistance of hybrid shaft piles installed with the addition of loose materials. These findings hold significant practical importance for foundation design using piles with non-traditional shaft shapes in variant design assessments.

This study investigated the uplift and penetration resistance of dual interfering pipelines buried in clay using advanced regression machine learning models, specifically the group method of data handling (GMDH), genetic programming (GP), extreme gradient boosting (XGBoost), and random forest (RF). The dataset comprises 256 numerical FELA data points for uplift conditions and 384 numerical FELA data points for penetration conditions, marking the first application of these models in this context. To train the models, three input parameters are considered: the spacing ratio ( S / D ), the embedded ratio ( w / D ), and the normalized unit weight and increasing strength ( γ / ρ ). The models predict two output parameters: the vertical uplift resistance ( q t ρ D ) and the vertical penetration resistance ( q c ρ D ). Performance metrics were employed to evaluate and compare the effectiveness of each model. The study revealed that the GP model is particularly effective in predicting the uplift and penetration resistance of pipelines. Both external validation and literature validation confirmed the predictive capabilities of the proposed models. Furthermore, the influence of each input parameter was analyzed, resulting in the development of empirical equations for both uplift and penetration conditions. The resulting empirical equations provide dimensionless output parameters, offering practical utility for design practitioners in real-world field conditions. Detailed study results, including comprehensive tables and empirical equations, are presented to facilitate practical applications and enhance the understanding of pipeline-soil interactions in clay environments. These contributions underscore the potential of advanced regression machine learning models in geotechnical engineering and pipeline design.

As a new type of transmission line foundation developed by the author, joint board cable foundation has obtained an invention patent and has a good application in the transmission tower foundation of thick collapsible loess regions. The research on the ultimate tensile strength of the base plate will be the key to carry on this design. In order to do a better job in the general design of the base plate, the author starts with the research on the uplift resistance theory of joint board cable foundation, who has put forward uplift resistance theory of joint board cable foundation formula, simplified the formula, and derived the calculation formula of the uplift stability of joint board cable foundation. The author has calculated dimensionless coefficient by self-compiled program and has studied on the rationality of the simplified calculation formula. The results from the study indicate that the calculation formula of the uplift stability of joint board cable foundation is easy to use, dimensionless coefficient can be derived through using chinese procedure, the formula reduces the computational difficulty of lower plate uplift resistance, the rationality and accuracy of the formula are proved through the research on the rationality of the simplified formula.

A pressure-resistant vessel is the core equipment of deep-diving equipment, which needs to have good pressure-resistant performance. In this paper, due to the problem that it is difficult to monitor the pressure-resistant vessel in the real diving process, we design a lightweight carbon fibre pressure-resistant vessel, construct a finite element model of the pressure-resistant vessel in deep diving, and carry out simulation and analysis, so as to provide a simulation test method for the real diving work. Specifically, the pressure-resistant vessel is subjected to finite element analysis at typical depths, and the floating process of the pressure-resistant vessel under different working conditions is simulated by using Computational Fluid Dynamics (CFD) simulation and orthogonal tests. Comparison of the CFD simulation results with the orthogonal test results proves that the selected pressure-resistant vessel can meet the working requirements under different working conditions.

This paper presents new numerical evaluations of the vertical uplift resistance of rectangular anchors located in heterogeneous and anisotropic clays obeying the Anisotropic Undrained Shear (AUS) failure criterion. The computation is based on the assumption that the anisotropic strengths of clays increase linearly with depth. To determine the uplift resistance of rectangular anchors, the uplift capacity factor F c serves as the standardized result parameter. This factor can be determined using the finite element limit analysis (FELA) technique and is set to relate to four dimensionless parameters: the ratio of embedment ratio ( H/B ), the shaped ratio ( L/B ), the increasing strength factor ( ρB/s uTC0 ), and the anisotropic ratio ( r e ). An analysis is carried out to explore the influence of dimensionless characteristics on developing failure mechanisms of rectangular anchors. Furthermore, this study explores the abilities of a machine learning model using the algorithm of the eXtreme Gradient Boosting (XGBoost), which has exceptional accuracy in forecasting the uplift capacity factor of rectangular anchors in heterogeneous and anisotropic clays.