Jian Liu

A series of vertical loading tests on stone columns based on transparent soil were conducted to investigate the failure modes and bearing characteristics of stone columns in layered soils. The influences of different layer thicknesses, different layer distributions, and different aggregate gradations on the bearing capacity of stone columns were examined. Based on the experimental results, a bearing capacity calculation method is proposed for stone columns subjected to bulging failures in lower soft soils. This new calculation method incorporates the self-weight of both the column and the surrounding soil. Verification through an engineering case study shows that, compared with the existing calculation methods, the outcomes derived from the proposed approach exhibit superior agreement with field measurements.

Cohesive soil containing calcareous nodules (CSCN), as a regional special soil composed of fine‐grained soil and calcareous nodules, is widely distributed in northern Jiangsu and Huaibei area in China. The presence of calcareous nodules leads to significant differences in the physical and mechanical properties compared to cohesive soils and gravelly soils. Currently, the primary method for studying the physical and mechanical properties of CSCN is large size direct shear testing. However, the direct shear test has issues including fixed shear planes, a reducing shear area during testing and stress concentration, which may compromise the accuracy and representativeness of the results. In this study, conducted through medium‐scale triaxial tests, explore the effects of calcareous nodule particle size (2–5 mm, 5–10 mm, 10–20 mm) and water content (10%, 25%, and 30%) on CSCN strength characteristics under different confining pressures. Additionally, discrete element method (DEM) simulations of the medium‐scale triaxial tests were used to reveal the impact of calcareous nodules on soil’s mechanical properties from a microscopic perspective. The results show that stress–strain curves of CSCN samples basically exhibit hardening behavior. Under the same confining pressure, the shear strength of CSCN sample initially decreases and then increases with the increase in calcareous nodule particle size. With increasing water content, both the shear strength and the axial strain at peak values of the CSCN sample consistently decrease. The initial tangent modulus exhibits varying patterns with increasing calcareous nodule particle size under different confining pressures. In contrast, the initial shear modulus remains largely unaffected by water content below 25%, but significantly decreases at 30%. Numerical simulation results show that during the low strain stage, the calcareous nodules are surrounded by fine‐grained soil. The shear stresses are primarily carried by the fine‐grained soil. In the high‐strain stage, the calcareous nodules come into contact with each other to form a skeleton structure in samples to resist the shear.

Pre-tensioned H-type prestressed concrete revetment piles are a newly developed product dedicated to the protection of river, lake, and sea bank embankments, and their cross-section is H-shaped. In this study, a field test of H-type pile soil’s squeezing effect is carried out based on the second phase project of the HujiaShen Line. Pore water pressure, soil displacement, and other parameters of the H-type pile-driving process are monitored in real time. The test results show the following: (1) The influence range of the excess pore water pressure caused by the soil squeezing effect in the horizontal direction is about 14–15D, and in the vertical direction, the pore water pressure within a depth range of about 7D below the pile bottom increases rapidly. Its dissipation rate is fast at first and then slows down, and it completely dissipates 20 days after piling. (2) The excess pore water pressure caused by the soil squeezing effect does not decrease linearly in the radial direction. The soil around the construction pile can be divided into four areas: A, B, C, and D. Among them, A and B belong to the plastic zone, and C and D belong to the elastic zone. (3) The horizontal displacement of the soil occurs within the depth range of 5D from the surface of the pile to the bottom of the pile at the piling location, and the radial influence range is about 8–12D. From a vertical perspective, the main horizontal displacement of the soil occurs in the long section of the pile driven into the soil, showing a “U”-shaped distribution. (4) The dividing point between the vertical displacement uplift and the settlement of the soil appears within the range of 2–3 m from the construction pile, that is, between 5 and 7D. Settlement occurs after the piling is completed, and the settlement rate is fast at first and then slows down. The final settlement of the soil is stable on the 20th day. This research and experiment provide a design reference for the engineering application of pre-tensioned H-type prestressed concrete bank protection piles.

Jet grouted piles are widely used to reduce post-construction settlement of soft clay roadbeds. Nevertheless, it is easy to cause ground heave due to the jet grouted pile. According to the analytical method and numerical method, a sensitivity analysis of the factors affecting ground heave caused by a single jet grouted pile was performed. It is found that the influence of each parameter on ground heave is in the following order: grout pump pressure > embankment load > soil type (including the cohesion, friction angle, and Young’s modulus) > pile diameter > pile length. Considering the effect of the pump pressure on the ground heave is more significant, based on the analytical method of ground heave caused by a single jet grouted pile combined with the solution of small-deflection bending of a circular thin plate, the calculation method for the suggested limit grout pressure for construction under different embankment heights was established. Suggested values of theoretical grout pump pressure were given to prevent ground heave from harming the pavement of operating highways. This study provides some theoretical basis for the subsequent research on the jet grouted pile.

Rolling dynamic compaction (RDC) has been found to be useful for compaction soils and is now widely used globally. Because RDC is not often used in soft soils with poor engineering properties, field monitoring was used to study the soft clay embankment responses under RDC conditions in this study. Analysis of the monitoring data revealed that the response of the soil occurred mainly in the first 20 passes. Field monitoring revealed a strong correlation between settlement, horizontal displacement, and pore water pressure. The depth of impact of RDC on the soft soil embankment was between 3 and 3.5 m. Although settlement prediction is an important issue for construction, there is a lack of prediction methods for RDC-induced soil settlement. In this study, we used three different machine learning algorithms: random forest regression (RFR), multilayer perceptron (MLP), and extreme gradient boosting (XGBoost) to predict the total settlement and uneven settlement induced by RDC on the soft soil embankment. The three prediction models were compared, and the predictive accuracy of these models was assessed. This study analyzes and summarizes the effect of RDC application on a soft clay embankment and explores the machine learning method used for settlement prediction based on monitoring data, which provides some methods and ideas for research on the application of RDC on soft soil foundations.

Predicting soil deformation is critical for the success of building construction projects. The traditional methods used for this task, which rely on theoretical calculations and numerical simulations, require detailed information on soil characteristics and geological conditions. These essential details are often challenging to obtain in practical engineering, thereby limiting the accuracy of these methods in building construction contexts. Deep learning (DL) provides a direct approach for modeling soil deformation without having a detailed understanding of the soil properties and geological conditions. However, the existing DL algorithms mainly focus on modeling deformation directly. With advancements in monitoring technology, integrating diverse monitoring data has become crucial for accurately predicting deformation, a need often overlooked in current practices. This paper introduces a monitoring data fusion (MDF) model aimed at enhancing the utilization efficiency of diverse monitoring data. Validated against real-world engineering scenarios, this model significantly outperforms traditional single-feature and multi-feature long short-term memory (LSTM) models. It achieves a mean absolute percentage error (MAPE) of approximately 2.12%, representing reductions of 30% and 63%, and a root mean square error (RMSE) of around 12.5 mm, with reductions of 36% and 77%. Additionally, the DL interpretability method, Shapley additive explanations (SHAP), is utilized to elucidate how various model features contribute to generating predictions.

In response to the rapid urban expansion and the burgeoning number of landfill sites, managing water infiltration in these areas has become a critical challenge, especially in cities like Shenzhen, Hong Kong, and Singapore where traditional cover materials such as silt, clayey gravel, and sand are scarce. A three-layer (silt/gravelly sand/clay) capillary barrier cover system has been proposed to address this issue in humid climates. As an alternative to scarce traditional materials, using local soils and construction waste (CW) for this system presents a viable solution. However, the real-world performance of this adapted three-layer system, constructed with local soils and CW under natural rainfall conditions, remains to be fully evaluated. This paper presents a field test evaluating the water infiltration behavior of a three-layer capillary barrier landfill cover system under natural conditions. The tri-layered system is comprised of a 0.6 m loose local unscreened soil layer, covered by a 0.4 m CW layer and topped by a 0.8 m heavily compacted local screened soil layer. Monitoring findings reveal that, during the wet season, infiltration through the top two layers was staved off until the third rainfall, after which these layers retained moisture until 15 September 2016. The fluctuation in pore water pressure in the topmost layers showed each rainfall was contingent not only on the day’s precipitation but also the hydraulic state. Beyond the hydraulic state’s influence, a deeper tensiometer showed resulted in a diminished correlation between the surge in pore water pressure and daily rainfall. This declining correlation with depth can be attributed to the capillary effect and the reduced permeability of the screened soil layer. Rainfall patterns significantly affect percolation, with the combination of a short-duration, intense rainfall and prolonged weak rainfall resulting in a marked increase in percolation. In the foundational screened soil layer, the pore water pressure remained relatively low, with the cumulative percolation over six months (June to December) registering approximately 10 mm. These findings suggest a promising performance of the three-layer capillary barrier cover system, integrating local soils and CW, in the year of the study conducted in a humid environment.