Search Results (45)

On 23 April 2023, a rotational landslide occurred at El Florón III (Portoviejo, Ecuador), triggered by intense rainfall that increased saturation and water pressure in the pores of the colluvial materials. Therefore, the current research predominantly aimed to (i) characterize the geological, geophysical, and geotechnical conditions that controlled the instability, (ii) identify and validate the fault surface, and (iii) evaluate a stabilization alternative in accordance with the Ecuadorian Construction Standard (NEC-15). Additionally, a probabilistic analysis was conducted based on the post-landslide geotechnical characteristics of the material, obtained from direct shear tests, which served as the basis for the back-analysis that determined the parameters governing the soil’s behavior during the event. Based on the parameters obtained for the landslide analysis and the determination of safety factors in accordance with the guidelines of the Ecuadorian Construction Standard, a ground reinforcement configuration was proposed through the implementation of micropiles combined with terracing. This approach allowed for establishing a methodology applicable to landslide scenarios in equivalent environments, considering the specific geotechnical and climatic conditions of the area. Full article

Background: Chronic gastritis (CG) involves gastric mucosal imbalance, with H. pylori (>90% cases), acid-pepsin imbalance, and bile reflux as druggable mechanisms. FDA-approved drugs show limited efficacy against antibiotic-resistant strains and fail to target undruggable pathways (e.g., inflammation, autoimmune atrophy). Traditional Chinese Medicine (TCM), particularly Qing-Wei-Zhi-Tong micro-pills (QWZT), offers multi-target advantages, though its mechanisms remain poorly understood. Methods: The dual-algorithm integration framework predicts QWZT’s pharmacological effects to treat gastritis. For druggable processes (pathways targeted by existing drugs), the structure–target–pathway similarity algorithm quantifies QWZT similar activities to FDA drugs, validated by gastrointestinal smooth muscle experiments. For undruggable processes (novel biological mechanisms not addressed by current therapies), the multi-target perturbation algorithm predicts QWZT’s unique capacity to undruggable processes and is validated via LPS-induced inflammation in RAW264.7 and GES-1 cells. Results: Structure–target–pathway similarity algorithm identified QWZT compounds sharing prokinetic mechanisms with FDA drugs, validated by dopamine-induced relaxations and acetylcholine-induced contractions in gastrointestinal smooth muscle. Multi-target perturbation algorithm quantified QWZT’s superior disruption of undruggable immune/inflammation networks, confirmed by restored cell viability in LPS-injured GES-1 cells and significantly reduced the expression of NO, IL-6, and TNF-α in RAW264.7 cells via key compounds (paeoniflorin and berberine). Conclusions: QWZT may exert its regulatory effects on gastrointestinal smooth muscle by mediating muscarinic and dopamine receptor D2 (DRD2), and reduce the expression of NO, IL-6, and TNF-α to achieve anti-inflammatory effects, thereby effectively treating CG. The integration strategy that integrates algorithms and experiments to reveal the common and distinct mechanisms of QWZT compared to FDA-approved drugs, offering a novel approach for studying Traditional Chinese Medicine mechanisms. Full article

This study investigates the development of axial force in micro anti-slide piles under soil movement during slope stabilization. Axial force arises from two primary mechanisms: axial soil displacement ($z_{\mathrm{s}}$) and pile kinematics. The former plays a dominant role, producing either tensile or compressive axial force depending on the direction of $z_{\mathrm{s}}$, while the kinematically induced component remains consistently tensile. A sliding angle of $\alpha =5°$ represents an approximate transition point where these two effects balance each other. Furthermore, the two mechanisms exhibit distinct mobilization behaviors: $z_{\mathrm{s}}$-induced axial force mobilizes earlier than both bending moment and shear force, whereas kinematically induced axial force mobilizes significantly later. The study reveals two distinct pile–soil interaction mechanisms depending on proximity to the slip surface: away from the slip surface, axial soil resistance is governed by rigid cross-section translation, whereas near the slip surface, rotation-dominated displacement accompanied by soil–pile separation introduces significant complexity in predicting both the magnitude and direction of axial friction. A hyperbolic formulation was adopted to model both the lateral soil resistance relative to lateral pile–soil displacement (p-y behavior) and the axial frictional resistance relative to axial pile–soil displacement (t-z behavior). Soil resistance equations were derived to explicitly incorporate the effects of cross-sectional rotation and pile–soil separation. A novel beam-spring finite element method (BSFEM) that incorporates both geometric and material nonlinearities of the pile behavior was developed, using a soil displacement-driven solution algorithm. Validation against both numerical simulations and field monitoring data from an engineering application demonstrates the model’s effectiveness in capturing the distribution and evolution of axial deformation and axial force in micropiles under varying soil movement conditions. Full article

This study investigates an innovative and sustainable hybrid approach combining enzyme-induced carbonate precipitation (EICP) with inclined micropile reinforcement systems for improving the soil bearing capacity of existing footings. The research evaluated two distinct EICP implementation methods across eleven experimental configurations, including three micropile inclination angles (90°, 105°, and 120°) for improving the bearing capacity of a square footing. The first method (method M1) involved injecting 150 mL of EICP solution through each of the eight perforated micropiles with a 21-day curing period, while the second method (method M2) employed staged injections around the footing totaling 1200 mL over two days with a 21–22-day curing period. Results demonstrated that the micropile-confined system combined with the EICP treatment significantly enhanced bearing capacity, with effectiveness increasing proportionally to pile inclination angles. While the EICP injection method M1 caused a 32% to 83% increase, method M2 exhibited 66% to 125% enhancement in bearing capacity for different micropile inclinations. Based on experimental validation, an analytical procedure was developed for predicting the bearing capacity of footings. This hybrid technique not only ensures structural effectiveness but also represents a sustainable, eco-friendly alternative to conventional ground improvement methods by reducing reliance on energy-intensive or chemically hazardous processes. Full article

To address the issue of structural tilting caused by uneven foundation settlement in soft soil areas, this study combined a specific engineering case to conduct numerical simulations of the rectification process for an inclined reinforced concrete building using ABAQUS finite element software. Micropile-raft combined jacking technology was employed, applying staged jacking forces (2400 kN for Axis A, 2200 kN for Axis B, and 1700 kN for Axis C) with precise control through 20 incremental steps. The results demonstrate that this technology effectively halted structural tilting, reducing the maximum inclination rate from 0.51% to 0.05%, significantly below the standard limit. Post-rectification, the peak structural stress decreased by 42%, and displacements were markedly reduced. However, the jacking process led to a notable increase in the column axial forces and directional changes in beam bending moments, reflecting the dynamic redistribution of internal forces. The study confirms that micropile-raft combined jacking technology offers both controllability and safety, while optimized counterforce pile layouts enhance the long-term stability of the rectification system. Based on stress and displacement cloud analysis, a monitoring scheme is proposed, forming an integrated “rectification-monitoring-reinforcement” solution, which provides a technical framework for building rectification in soft soil regions. Full article

This study investigates the excavation of the cataclastic loose rock slope at the mixing plant on the right bank of the BDa Hydropower Station, which is situated in the upper reaches of Lancang River. The dominant structural plane of the cataclastic loose rock mass was obtained using unmanned aerial vehicle tilt photography and 3D point cloud technology. The actual 3D numerical model of the study area was developed using the 3DEC discrete element numerical simulation software. The excavation response characteristics and overall stability of the cataclastic loose rock slope were analyzed. The support effect was evaluated considering the preliminary shaft micropile and Macintosh reinforced mat as slope support measures, and the stability was assessed by applying seismic waves. The results showed the main deformation and failure area after slope cleaning excavation at the junction of the cataclastic loose rock mass and Q^edl deposits in the shallow surface of the excavation face. Moreover, the maximum total displacement could reach 18.3 cm. Subsequently, the overall displacement of the slope was significantly reduced, and the maximum total displacement decreased to 2.78 cm. The support effect was significant. Under an earthquake load, the slope with support exhibited considerable displacement in the shallow surface of the excavation slope, with collapse deformation primarily occurring through shear failure. Full article

In this contribution, the classical Cauchy first-gradient elastic theory is used to solve the equilibrium problem of a bidimensional (2D) reinforced elastic structure under small displacements and strains. Such a 2D first-gradient continuum is embedded with a reinforcement, which is modeled as a zero-thickness interface endowed with the elastic properties of an extensional Euler–Bernoulli 1D beam. Modeling the reinforcement as an interface eliminates the need for a full geometric representation of the reinforcing bar with finite thickness in the 2D model, and the associated mesh discretization for numerical analysis. Thus, the effects of the 1D beam-like reinforcements are described through proper and generalized boundary conditions prescribed to contiguous continuum regions, deduced from a standard variational approach. The novelty of this work lies in the formulation of an interface model coupling 1D and 2D continua, based on weak formulation and variational derivation, capable of accurately capturing stress distributions without requiring full geometric resolution of the reinforcement. The proposed framework is therefore illustrated by computing, with finite element simulations, the response of the reinforced structural element under uniform bending. Numerical results reveal the presence of jumps for some stress components in the vicinity of the reinforcement tips and demonstrate convergence under mesh refinement. Although the reinforcement beams possess only axial stiffness, they significantly influence the equilibrium configuration by causing a redistribution of stress and enhancing stress transfer throughout the structure. These findings offer a new perspective on the effective modeling of fiber-reinforced structures, which are of significant interest in engineering applications such as micropiles in foundations, fiber-reinforced concrete, and advanced composite materials. In these systems, stress localization and stability play a critical role. Full article

As environmentally friendly pile foundations with small diameters and higher slenderness ratios, micropiles are widely used in fields such as transmission line engineering and building reinforcement. However, the available research has primarily focused on their bearing performance under compressive and horizontal loads, and there is insufficient research on predicting the uplift capacity of micropiles. This study investigated the load transfer mechanism and the behavior of the surrounding soil using model tests and finite element simulations. The ultimate uplift capacities and load distributions of micropiles with different slenderness ratios were analyzed. The results show that as the slenderness ratio increases, the ultimate uplift capacity of a pile gradually increases. However, this rate of increase diminishes gradually. Additionally, the restraining effect and range of the surrounding soil at the lower part of the pile are enhanced. The critical embedment depth of the micropiles shifts further away from the pile tip as the slenderness ratio increases. Finally, this study proposed a novel modification to Shanker’s model of incorporating variations in the critical embedment depth based on the slenderness ratios. Subsequently, a modified model for the ultimate uplift capacity of micropiles was proposed and validated using a model test. The proposed model effectively predicts the uplift bearing capacity of micropiles with high slenderness ratios, which is practical for engineering applications. Full article

Unstable sandy soils pose significant challenges for buried pipelines due to soil–infrastructure interaction, leading to settlement that increases the risk of displacement and stress-induced fractures. In earthquake-prone regions, seismic-induced ground deformation further threatens underground infrastructure. Fiber-reinforced polymer (FRP) composites have emerged as a sustainable alternative to conventional piling materials, addressing durability issues in deep foundations. This paper introduces novel explicit models for predicting the maximum settlement of oil pipelines supported by concrete or polymer micropiles under seismic loading. Using genetic programming (GP), this study develops closed-form expressions based on simplified input parameters—micropile dimensions, pile spacing, soil properties, and peak ground acceleration—improving the models’ practicality for engineering applications. The models were evaluated using a dataset of 610 data points and demonstrated good accuracy across different conditions, achieving coefficients of determination (R²) as high as 0.92, among good values for other evaluation metrics. These findings contribute to a robust, practical tool for mitigating seismic risks in pipeline design, highlighting the potential of FRP micropiles for enhancing infrastructure resilience under challenging geotechnical scenarios. Full article

This study systematically investigates the plastic deformation behavior and load-bearing mechanisms of micropiles through integrated scaled physical modeling and nonlinear finite element analysis, with particular emphasis on quantifying plastic hinge characteristics. The development of plastic deformation in laterally loaded micropiles was analytically described using plastic hinge theory, complemented by experimental-numerical validation. The key findings demonstrate the following points. (1) Existing empirical formulas for plastic hinge length, based on sectional parameters, show significant discrepancies, with experimental calibration establishing an optimized length of 2D. (2) Parametric FEM studies of three diameter groups (3–7% longitudinal reinforcement ratio) reveal that cross-sectional geometry and reinforcement configuration collectively govern nonlinear ultimate capacity, where ≤0.1% reinforcement ratio variation induces <5% bearing capacity deviation. (3) Square sections exhibit 12–18% higher capacity than circular equivalents of the equivalent dimensions, with this advantage amplifying with increasing pile size. (4) While excessive reinforcement ratios (>6%) impair structural performance, emergent scale effects effectively mitigate associated capacity reduction. These findings provide critical insights for optimizing micropile design in geotechnical applications through coordinated consideration of geometric, material, and scale parameters. Full article

The traditional design of foundations in soft clay often relies on large-diameter piles, which, although effective, are costly and impractical for low- to medium-rise buildings. Micropiles have emerged as a cost-effective alternative, offering an efficient solution to these challenges. To advance the adoption of micropiles in geotechnical practice, this study employs a multi-objective genetic algorithm-based evolutionary polynomial regression (EPR-MOGA), a hybrid artificial intelligence method, to develop a robust and straightforward model for predicting the load–settlement response of micropiled rafts in cohesive soils under vertical loads. The model was created using an extensive database comprising 458 data points derived from field tests, centrifuge experiments, laboratory studies, and numerical simulations reported in the literature. This comprehensive database covers a wide range of scenarios by varying key parameters of micropiles within a group, including their length, diameter, number, spacing, construction method, and raft thickness. The proposed EPR model could deliver accurate predictions, providing a practical approach for geotechnical applications. In addition, the predictions of the model could support the conclusion that pressure-grouted micropiles are more efficient than gravity-grouted ones in enhancing the performance of micropiled rafts. Full article

To enhance the uplift resistance of micropiles used in soil slope reinforcement and ensure the stability and safety of slope structures, a novel micropile incorporating a small-scale pneumatic device and anchorage components was developed, and its uplift performance was evaluated. Through field uplift tests, the uplift load–vertical displacement relationship of the new micropile and conventional micropile in silty clay strata was compared. Numerical simulations were also conducted to reveal the uplift mechanism and analyze the influence of an anchorage component layout on the micropile’s uplift resistance. The field tests showed that the ultimate uplift capacity of a 3 m long novel micropile increased by 161.7% compared to that of a conventional micropile, with a 14.7% reduction in displacement. When the anchorage components were deployed without grouting, the novel micropile achieved 70.7% of the uplift capacity of a conventional micropile, indicating a certain level of uplift resistance. Numerical simulation results indicated that the novel micropile altered the stress state of the surrounding soil, and the anchorage components changed the load transfer mechanism during micropile uplift from vertical interfacial friction to a combination of anchorage pressure and soil friction, significantly enhancing uplift resistance. For an 8 m long micropile without anchorage components, the ultimate uplift capacity was 489.9 kN. With the addition of 1 m of anchorage length, the capacity increased to 661.5 kN, a 35.0% improvement. Subsequently, each additional meter of anchorage length increased the micropile’s capacity by 10.9% to 16.0%, with a cost increase of only 5.7%. The research findings provide valuable scientific references for the design and remediation of soil slope reinforcement. Full article

Micropiles are a new type of retaining structure widely used in slope engineering due to their small footprint, low vibration and noise emissions, and simple construction process. This study aims to investigate the dynamic response and failure mechanisms of micropiles used in retaining accumulation landslides under seismic loading through shaking table tests and numerical simulation. The failure process, observed phenomena, and bending moments of micropiles in the test were discussed, and the shear force distribution of micropiles was thoroughly analyzed based on numerical simulation. The findings reveal that the natural frequency of the entire landslide system exhibits a gradual decrease and tends to stabilize under sustained earthquake excitation. The bending moment of micropiles follows an “S” shape, with a larger magnitude at the top and a smaller one at the bottom. Additionally, the shear force distribution exhibits a “W-shaped” pattern. Damage to micropiles mainly includes the flexural shear combination failure at the load-bearing section (which occurs within 1.4–3.6 times the pile diameter above the sliding surface) and the shear failure near the sliding surface. This study provides significant insights into the strengthening mechanisms of micropiles under seismic action and offers valuable guidance for the design of slope support. Full article

Micropiles, small-diameter-drilled and grouted piles, are often used to provide foundation support in challenging ground conditions. This research seeks to understand the behavior of Type D micropiles (pressure-grouted) within layered soil profiles. Layered soils frequently create complexity because of differences in stiffness, strength, and permeability, which impact load transfer and the interaction between the micropiles and the surrounding soil. Type D micropiles use pressure injection, which results in enhanced skin friction, better grout–soil contact, and a greater capacity to carry loads. A set of numerical simulations was conducted to analyze the behavior of the micropile Type D under axial loading, which was evaluated by considering factors such as micropile diameter, spacing, and inclination. The results indicated that increasing the diameter of a micropile significantly improves its performance by enhancing load transfer and structural stiffness, as well as reducing soil deformation and settlement. In addition, for vertical micropiles and those with inclination angles of 10° and 20°, stiffness increased with diameter, while axial displacement remained constant at a 45° inclination. Furthermore, larger diameters reduced lateral displacements up to 20° inclination angles by increasing stiffness, but lateral deflection increased at 45° due to greater lateral load components. The bending moment increased with inclination angle, driven by higher horizontal loads and increased eccentricity, while spacing had little effect for angles greater than 20° due to effective load redistribution. Full article

Micropiles were first used to repair the damaged structures of “Scuola Angiulli” in Naples after World War II. They are known as small versions of regular piles, with a diameter of less than 30 cm, and are made of high-strength, steel casing and/or threaded bars, produce minimal noise and vibration during installation, and use lightweight machinery. They are capable to withstand axial loads and moderate lateral loads. They are used for underpinning existing foundations and to restore historical buildings and to support moderate structures. In the literature, several reports can be found dealing with micropiles, yet little has been reported on Micropiled-Raft Foundations (MPR). This technology did not receive the recognition it deserved until the 1970s when its technical and economic benefits were noted. A series of laboratory tests and numerical modeling were developed to examine the parameters governing the performance of MPR, including the relative density of the sand, the micropile spacing, and the rigidity of the raft. The numerical model, after being validated with the present experimental results, was used to generate data for a wide range of governing parameters. The theory developed by Poulos (2001) (PDR) to predict the capacity of pile-raft foundations was adopted for the design of MPR. The PDR method is widely used by geotechnical engineers because of its simplicity. Full article