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This study investigates the simultaneous influence of particle shape and initial suction on the hydromechanical behavior of unsaturated sandy soils. Anisotropic loading-unloading tests at constant water content conditions were conducted on three sands with distinct shapes (Firoozkooh-most angular, Babolsar-Subangular, and Mesr-roundest) using a direct shear apparatus. Particle shapes were quantified in terms of sphericity, roundness, and regularity using the results of scanning electron microscopy (SEM) tests. In addition, a coupled hydromechanical model based on elasto-viscoplasticity was developed and validated against the experimental results first. The model was then employed to conduct a parametric study (compressibility, pore water pressure, and permeability) with an emphasis on the role of particle morphology and shape. The findings revealed rounder particles (higher regularity) experienced higher volumetric strain (epsilon v) under lower suction but less epsilon vwith increasing suction compared to angular sands. Moreover, the rate of permeability reduction during loading in Mesr sand was 1.5 times and 2.4 times higher than that of Babolsar and Firoozkooh sands at near-saturation condition. However, this amount decreased with increasing suction. Pore water pressure (PWP) generation was highest in the most angular sand due to its retention characteristics. The relationship between void ratio and PWP was independent of loading cycles and exhibited a linear dependence. Particle shape significantly impacted this relationship, with rounder sands showing a higher rate of void ratio change per unit change in PWP.

期刊论文 2025-05-01 DOI: 10.1016/j.trgeo.2025.101560 ISSN: 2214-3912

To investigate the unloading mechanical properties of deeply buried silty soil in dam foundation cover layers, a series of consolidated drained triaxial compression tests along multi-stage loading-unloading path were performed on both undisturbed samples (including horizontally and vertically oriented samples) and remolded samples. The test results demonstrate that: (1) the vertically oriented soil samples exhibit strain softening under low confining pressures (100, 200, and 400 kPa), transitioning to strain hardening at high confining pressures (800 and 1600 kPa). In contrast, the horizontally oriented specimens consistently exhibit strain softening across all confining pressures, whereas the remolded samples display strain hardening under all confining conditions; (2) the strength of vertically oriented soil specimens is significantly higher than that of horizontally oriented specimens, ranging from 1.18 to 1.43 times greater. Remolded samples, however, remolded samples are slightly weaker than horizontally oriented specimens under low confining pressures (100, 200, and 400 kPa), while at high confining pressures (800 and 1600 kPa), their strength approaches that of horizontally oriented specimens; (3) the deeply buried silty soil also exhibits pronounced unloading-induced volume contraction characteristics, which increase with the initial axial strain at the beginning of unloading and diminish as confining pressure increases; (4) the unloading modulus is obviously higher than the initial loading modulus, with the ratio of the unloading modulus to the initial loading modulus ranging from 1.4 to 3.6. This ratio increases with increasing confining pressure but decreases with increasing axial strain at the onset of unloading.

期刊论文 2025-04-01 DOI: 10.1007/s40999-024-01058-w ISSN: 1735-0522

The new type of support disc-type anchor is an expanded body anchor with broad application prospects, and its load-bearing performance is significantly better than that of traditional anchors. However, there is a problem of premature shear damage in traditional support disc-type anchors. In order to solve this problem, this paper improves the traditional support disk anchor. It conducts cyclic loading tests on the new type of support disc-type anchors with different support disc diameters, support disc thicknesses, anchoring diameters, and anchoring lengths so as to simulate the repeated loads that the anchors are subjected to in actual projects. The function model suitable for predicting the bearing capacity of the new type of support disc-type anchors was derived by nonlinear fitting of some data using the function model and verified by comparing it with the measured data. A functional model predicts the bearing capacity of the new type of support disc-type anchors through nonlinear fitting of the data, validating the model against measured results. The study reveals that factors such as support disc diameter and anchoring length have the most significant impact on pullout bearing capacity. In contrast, increasing the anchoring diameter and shortening the anchoring length may lower the pullout bearing capacity. The Q-s curve divides into five stages, where the lateral friction force between the anchoring and the soil, along with the bulb resistance at the supported disc, collectively generates the bearing capacity of the new type of support disc-type anchor. The Belehradek function model proves most effective in describing the Q-s curve for these anchors during testing, demonstrating high accuracy and strong engineering practicality.

期刊论文 2025-01-02 DOI: 10.1038/s41598-024-84639-y ISSN: 2045-2322

In this study, six rock-socketed bored piles were tested in the field to investigate the bearing characteristics of rock-socketed bored piles in silty clay formations in coastal areas, and the model piles were simulated and optimized using the finite element (FE) method. The results showed that the lateral resistance of the piles in the clay layer is less than 50 kPa, and the lateral resistance of the rock-embedded portion is within 136.2-166.4 kPa. Compared with increasing the rock-embedded depth, increasing the diameter of the test piles can improve their vertical bearing capacity more effectively. The average horizontal critical load (Hcr) increased by 84.54 %, and the average horizontal ultimate load (Hu) increased by 50.3 % for the 800 mm diameter piles compared to the 600 mm diameter piles. Also, at the end of the test, the 600 mm diameter test piles showed severe damage at 6-9.5 D below the mud surface and were more susceptible to instability damage than the 800 mm diameter test piles. In soft clay strata, the 'm' values converged rapidly with increasing horizontal displacement and stabilized when the displacement exceeded 10 mm. The FE simulations confirmed that the horizontal displacement of the pile mainly occurs at 4 m depth below the mud surface, and the displacement of the test pile can be effectively reduced by reinforcing the soil around the pile. The silt at the bottom of the pile is one of the critical factors causing the uneven settlement of the test pile, severely affecting the vertical bearing capacity of the pile foundation.

期刊论文 2025-01-01 DOI: 10.1016/j.apor.2024.104336 ISSN: 0141-1187

Venice, the enchanting Italian city built on a lagoonal environment, faces ongoing geotechnical challenges due to natural processes and anthropogenic influences. Over the past century, extensive geotechnical investigations have been conducted to characterize the unique stratigraphy of Venice's soils. Some key locations, representative of the city's diverse soil profiles, have undergone in-depth analysis, with investigations reaching depths of tens of meters. Three key sites-Malamocco, Treporti, and La Grisa-were strategically selected to study the complex mechanical properties of Venetian soils. In this study, we present a comprehensive synthesis of the most significant findings from the geotechnical investigations conducted throughout the Venetian lagoon over recent decades, focusing on methodologies for the evaluation of stiffness parameters in highly heterogeneous soil layers. These results enhance the understanding of geological and geotechnical behaviour of Venice's subsoil and provide crucial data for developing resilient engineering solutions.

期刊论文 2025-01-01 DOI: 10.3934/geosci.2025013 ISSN: 2471-2132

When constructing temporary roads for disaster recovery, it is necessary to improve the ground or replace the soil with high-quality soil when the ground conditions at the site are not good. However, it may be difficult to procure and transport a sufficient quantity of high-quality soil for replacement at some sites. In addition, when using cement to improve the ground, for example, the high strength of the ground can be maintained for a long period of time, but disadvantages are also encountered with its use. A ground improved by the addition of cement cannot be restored to its original condition. Moreover, cement is relatively expensive and has a negative impact on the environment. The use of soil bags, known as donou in Japan, is one of the effective methods for constructing temporary roads. The advantages of soil bags are that the strength of the ground can be improved more easily and quickly without the need for heavy machinery or modification by cement, and that the damaged areas can be repaired by replacing damaged soil bags with new soil bags. Thus, a roadbed can be simply removed and rapidly restored to its original condition. The loading characteristics of soil bags arranged as a stacked structure need to be understood. In the present study, in order to evaluate the loading characteristics of soil bags, cyclic plate-loading tests were conducted to investigate the pressure transfer among the soil bags and from the soil bags to the lower roadbed layer. It was found from the experiments that the earth pressure was distributed over a wider area in the structure with the staggered stacking of the soil bags than in the structure with the flat stacking of the soil bags.

期刊论文 2025-01-01 DOI: 10.1007/978-981-97-8241-3_8 ISSN: 2366-2557

This study aims to thoroughly analyze the lateral loads that impact tubular steel piles, which are extensively employed in the construction of coastal structures. The ASTM D 3966 standard was followed for conducting field tests on test piles installed at the Mersin International Port. The time-displacement and load-displacement curves were obtained from the cyclic loading test of the laterally loaded piles at the construction site. The finite elements models of the tests conducted on the construction site with the same parameters was built to perform numerical analysis. At the end of the analysis, it was determined that the numerical model's results were highly consistent with those obtained from the field test. After verifying the field experiments with numerical models, a parametric study was conducted. Parametric studies were conducted to compare the lateral displacements of tubular steel piles with variations in pile diameter, wall thickness, and load application height effect. The relationship between pile head displacements and these parameters appears to be almost linear. It is noteworthy that a change of approximately 10 percent in these parameters shows a correlation with changes of up to 3 percent in deformations.

期刊论文 2024-11-01 DOI: 10.1016/j.oceaneng.2024.118774 ISSN: 0029-8018

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and costeffectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with inplane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The loadcarrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of inplane seismic performance and yield displacement of HCS panels was proposed.

期刊论文 2024-05-01 DOI: 10.1016/j.istruc.2024.106478 ISSN: 2352-0124

Surrounding rocks at different locations are generally subjected to different stress paths during the process of deep hard rock excavation. In this study, to reveal the mechanical parameters of deep surrounding rock under different stress paths, a new cyclic loading and unloading test method for controlled true triaxial loading and unloading and principal stress direction interchange was proposed, and the evolution of mechanical parameters of Shuangjiangkou granite under different stress paths was studied, including the deformation modulus, elastic deformation increment ratios, fracture degree, cohesion and internal friction angle. Additionally, stress path coefficient was defined to characterize different stress paths, and the functional relationships among the stress path coefficient, rock fracture degree difference coefficient, cohesion and internal friction angle were obtained. The results show that during the true triaxial cyclic loading and unloading process, the deformation modulus and cohesion gradually decrease, while the internal friction angle gradually increases with increasing equivalent crack strain. The stress path coefficient is exponentially related to the rock fracture degree difference coefficient. As the stress path coefficient increases, the degrees of cohesion weakening and internal friction angle strengthening decrease linearly. During cyclic loading and unloading under true triaxial principal stress direction interchange, the direction of crack development changes, and the deformation modulus increases, while the cohesion and internal friction angle decrease slightly, indicating that the principal stress direction interchange has a strengthening effect on the surrounding rocks. Finally, the influences of the principal stress interchange direction on the stabilities of deep engineering excavation projects are discussed. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting 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/).

期刊论文 2024-04-01 DOI: 10.1016/j.jrmge.2023.09.005 ISSN: 1674-7755

Traditional wooden structures are characterized by the presence of a column base that seems to be floated above the foundation stone. This study used pseudo-static experiments to assess the seismic performance of flat pendulum floating resting columns, focusing on the decay and repair of the wood frame (WF). First, an artificial method was used to simulate fungal decay damage of column-foot joints, and filling reinforcement was applied to the decayed column-foot joints, and second, according to the design method in the Sung dynasty architecture, the Ying-tsaofa-shih (building standards). This study presents the findings of pseudo-static tests that were conducted at Yangzhou University. Three 1:3.52 scaled specimen WFs with flat-pendulum-floating-shelf (FPFS)-typed (Ping-bai-fu-ge) columns, i.e., non-damaged WF (named after NT), considering the damaged WF (named after DF) and strengthening damaged WF (named after DR) with one-way straight mortise-tenon joints (OWSMT) joints were made and subjected to cyclic lateral loads during testing. The properties of the WFs with FPFS columns, such as the failure mode, hysteretic and envelope curves, strength and stiffness deterioration, and energy dissipation, have been studied. Finally, the effects of additional damage and reinforcement measures on the seismic performance of WFs are analyzed and compared with the finite element numerical simulation results. This research shows that damage to the column foot decreases the WF's seismic performance, although filler reinforcement may increase it. The foot and mortise joints are interconnected and interact in the wood frame's seismic stressing mechanism. Foot decay reduces the seismic performance of the foot joint, hence increasing the seismic energy dissipation activity of the mortise joints.

期刊论文 2024-02-01 DOI: 10.1002/tal.2082 ISSN: 1541-7794
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