This study utilizes a combined approach of Finite Element Method (FEM) simulation and Artificial Neural Network (ANN) modeling to analyze and predict the load-displacement relationship of bored piles in clayey sand. FEM is applied to simulate the nonlinear relationship between load and vertical displacement, with input parameters including load and the mechanical properties of the soil. The results obtained from FEM are used as input data for the ANN model, enabling accurate predictions of vertical displacement based on these parameters. The findings of this study show that the predicted ultimate bearing capacity of the bored piles is highly accurate, with negligible error when compared to field experiments. The ANN model achieved a high level of accuracy, as reflected by an R2 value of 0.9992, demonstrating the feasibility of applying machine learning in pile load analysis. This research provides a novel, efficient, and feasible approach for analyzing and predicting the bearing capacity of bored piles, while also paving the way for the application of machine learning in geotechnical engineering and foundation design. The integration of FEM and ANN not only minimizes errors compared to traditional methods but also significantly reduces time and costs when compared to field experiments.

Tower foundation plays an important role in transmission line engineering, but the traditional tower foundation has low bearing capacity against uplift and is damaging to the environment. In this regard, this paper proposes a new type of foundation structure, vertical-inclined combined high-pressure rotary piles, and its bearing performance and force mechanism are studied through modeling experiments. (1) The inclined pile inclination angles of 10 degrees and 20 degrees for vertical-inclined combined high-pressure rotary piles increased the ultimate bearing capacity of uplift resistance by 16.29% and 60.31% than that of corresponding vertical piles. (2) After changing the vertical piles into inclined piles, the vertical-inclined combined high-pressure rotary pile foundation can mobilize more soil to resist the vertical load, thus increasing the uplift capacity. (3) Having proposed a formula for calculating the uplift bearing capacity of a vertical-inclined combined high-pressure rotary piles foundation, model test results are also used to verify the formula's accuracy.

Corrugated steel-plate culverts, particularly in horizontal ellipse form, are commonly used in large-span projects. Despite the guidelines on plate radius ratios, the impact of these ratios on mechanical properties remains unexplored. This gap highlights the need for research to guide utility tunnel design because existing studies mainly focus on round culverts compressed into elliptical shapes. Therefore, this study conducted backfill, simulated vehicle live load, and ultimate-load tests on two horizontal-ellipse corrugated steel utility tunnel structures with different top-side plate ratios to examine their response characteristics under various load conditions. Moreover, they were compared with those of existing design methods to offer new insights for the design analysis of soil-steel structures. The results demonstrated that the ratio significantly influenced bending moment distribution, and the critical was concentrated beneath the loading pad for live loads. The ultimate capacity varied with the ratio, with the higher ratio specimen reaching approximately 92.5 % of the capacity of its counterpart. Both specimens failed via tri-plastic hinge mechanisms, with reduced capacity as corrugations flattened. The Canadian Highway Bridge Design Code, which considers thrust force and bending moment, accurately predicted bearing capacity than the other methods in this study. These findings are vital for optimising design and ensuring safety in horizontal-ellipse corrugated steel utility tunnels.

In order to further analyze the mechanical and deformation characteristics of geogrid-reinforced soil retaining wall in the high backfill road section, this study experimentally investigates the effects of retaining wall slope, reinforcement layers, and reinforcement position on the bearing capacity and deformation characteristics of geogrid-reinforced soil retaining walls. The distribution of earth pressure in the reinforced soil retaining wall is also analyzed. The test results indicate that the ultimate bearing capacity of the retaining wall can be effectively improved by increasing the geogrid layers. The overall stability of the retaining wall decreases as the slope increases. When the number of reinforcement layers is consistent, the arrangement of geogrid in the upper part of the retaining wall can better control the deformation of the retaining wall and enhance the overall stability of the retaining wall. Under the vertical load, the horizontal displacement of the upper part of the wall is larger than that of the lower part, and the maximum horizontal displacement of the wall occurs at the top of the wall. The vertical earth pressure is not completely transmitted along the vertical direction but is transmitted downward along a certain diffusion angle. The growth rate of the upper earth pressure decreases gradually compared to that of the lower earth pressure as the load increases.

Rotary penetration test is a newly developed in-situ testing technology in recent years, which combines the advantages of large drilling depth and continuous, intuitive, good repeatability, fast testing speed, and economy of cone penetration testing data. It uses static pressure and rotational torque to penetrate the soil stratum at a constant speed by standard conical double helix probe, recording the penetration resistance of the probe during the process of uniform penetration, the resistance torque, and water pressure during the process of soil damage. It is a new in-situ testing method for testing and studying the physical and mechanical properties of soil stratum. Through the analysis of mechanism and a large number of field tests, the results of the rotary penetration test (RPT) were analyzed by comparing with data of cone penetration test (CPT), drilling test, field pile test, and others; the characteristic indexes of rotary penetration as well as a series of analysis method and empirical formula were proposed, i.e. how the rotary penetration test results were applied to classify the strata, judge the soil category, determine the basic bearing capacity of the ground and the ultimate bearing capacity of the concrete bored pile. The research results were of great significance to enrich the in situ test method and promote the application and popularization of the rotary penetration technology.