Acta Geotechnica最新文献

{"title":"Lateral capacity and failure mechanisms of skirted foundation resting on slopes","authors":"Khalid Bashir,&nbsp;Ravi S. Jakka","doi":"10.1007/s11440-024-02486-7","DOIUrl":"10.1007/s11440-024-02486-7","url":null,"abstract":"<div><p>While the effect of combined loading on the load carrying capacity of skirted foundations on horizontal ground surfaces is well documented in the literature, comprehensive studies for skirted footings situated on or near slopes remain lacking. This study aims to investigate the influence of various factors, including slope angle (<i>β</i>), angle of internal friction (<i>ϕ</i>), setback distance (<i>B′</i>/<i>B</i>), and skirt length (<i>L</i>/<i>B</i>), on failure loads and capacity envelopes for skirted foundations. The performance of a skirted footing system under combined vertical and lateral loadings in cohesionless soils was analysed using finite-element limit analysis (FELA) and small-scale experimental tests. The results indicate that the optimal skirt length depends on the specific conditions of the slope and setback distances. As the setback distance increases, the optimal skirt length tends to decrease, while an increase in slope steepness corresponds to an increase in the optimal skirt length. Furthermore, this study presents integrated capacity envelopes that incorporate a wide range of realistic soil slopes. The calculated capacity envelopes are subsequently compared to those on flat ground, highlighting that the unique characteristics of these envelopes are based on different combinations of vertical load (<i>V</i>) and combined vertical and lateral load (VH). Skirted footings on slopes exhibit distinct behaviour compared to those on level ground, with multiple factors influencing their capacity envelopes. Specifically, skirted foundations demonstrate lower capacity than equivalent block foundations, particularly when placed near steep slopes due to the formation of an inverted circular scoop failure surface for larger <i>L</i>/<i>B</i> ratios. In contrast, the formation of an inverted circular scoop is less pronounced for moderate slopes and footings with a smaller <i>L</i>/<i>B</i> ratio. The numerical study provides a comprehensive explanation of the failure mechanisms associated with the design of skirted footings located in close proximity to slopes, especially when subjected to lateral loads. Based on the results obtained, capacity envelope diagrams are proposed for estimating the capacity of skirted footings on slopes. Small-scale experiments were also conducted to explore the effects of varying skirt lengths placed on both level and sloping ground within a testing tank. The outcomes of this study yield valuable insights into the behaviour of skirted foundations on slopes, as well as their overall response to both vertical and lateral loadings.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":"89 - 117"},"PeriodicalIF":5.6,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142963054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Undrained SHPB experiments on calcareous sand with different saturation degrees","authors":"Yuchen Su,&nbsp;Yuan Wang,&nbsp;Yaru Lv,&nbsp;Pengfei Li","doi":"10.1007/s11440-024-02478-7","DOIUrl":"10.1007/s11440-024-02478-7","url":null,"abstract":"<div><p>Extensive research has been conducted on the impact behavior of unsaturated sand at high strain rates. However, achieving the undrained boundary condition remains a persistent challenge, leading to an inconsistent understanding of the dynamic responses of sand with varying saturation degrees. In this study, a novel sleeve designed to conduct split Hopkinson pressure bar (SHPB) tests under undrained boundary conditions. Furthermore, drained SHPB tests were carried out by using the conventional steel sleeve as references. The absolute particle crushing distributions within various size ranges were investigated by utilization of dyed calcareous sand. Results revealed that, for the conventional drained sleeve, the locking-up phenomenon of full saturation sand was only observed at strain rate of 750 s⁻¹. However, locking-up occurs at all strain rates for undrained sleeve. The locking-up stiffness at strain rate of 1000 s⁻¹ was 1.6 times larger compared to that at strain rate of 500 s⁻¹ and 750 s⁻¹, respectively. It means that the locking-up stiffness increases with strain rates under the fully undrained boundary conditions. Furthermore, for the drained sleeve, negligible reductions up to 10.8% were observed in measured <i>B</i>_r if saturation degrees change from 0 to 100%. In contrast, for the undrained sleeve, the maximum reduction on <i>B</i>_r was 47.6% and increases rapidly with increasing strain rates. The particle crushing was more sensitive to saturation degree at higher loading strain rates under undrained boundary conditions. Meanwhile, the particle crushing probability <span>({P}_{text{c}})</span> of medium-sized (1.0–1.5 mm) particles decreases with decreasing saturation degrees and increasing strain rate. It leads that the probabilities of particle crushing across various size ranges become more uniformly distributed with lower saturation degree and higher strain rates.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":"287 - 302"},"PeriodicalIF":5.6,"publicationDate":"2024-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142963034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined study of creep and ageing under deviatoric loading in granular materials","authors":"Belinda Anna-Maria Jessen,&nbsp;Stefan Vogt,&nbsp;Roberto Cudmani","doi":"10.1007/s11440-024-02476-9","DOIUrl":"10.1007/s11440-024-02476-9","url":null,"abstract":"<div><p>Granular soils creep and age. Previous findings on the time-dependent phenomena under deviatoric stress are summarized and extended with the results of an experimental investigation. Multi-stage triaxial compression tests with creep phases at different deviatoric loading on medium-dense and dense samples of a uniformly graded silica sand confirm an increase in stiffness after creep phases. Contact maturing, contact homogenization, and stabilization of the soil structure are known causes for ageing reported in the literature. As other results found in the literature, the volumetric creep behavior can be dilatant, contractant or of negligible strain close to zero and depends on the trend of the volumetric strain resulting from deviatoric loading at the beginning of creep. By the triaxial tests it is shown that dilatant creep results in an increase of the radial strain due to grain rearrangements. The axial strain rates during creep and changes of the small-strain shear modulus (ageing) follow a power law with time. According to the experiments, the exponent of the proposed power law describing the development of strain and shear modulus at small strain during creep is independent of the density and stress state. The small-strain shear stiffness and the associated soil structure at the onset of creep determine the subsequent ageing behavior. A linear dependency was found between the related ageing rates and axial strain rates during creep, which can be used to predict ageing of granular materials in combination with rate-dependent constitutive models.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 4","pages":"1831 - 1845"},"PeriodicalIF":5.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11440-024-02476-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resistive force modeling for shallow cone penetration into dry and wet granular layers","authors":"Naoki Iikawa,&nbsp;Hiroaki Katsuragi","doi":"10.1007/s11440-024-02456-z","DOIUrl":"10.1007/s11440-024-02456-z","url":null,"abstract":"<div><p>Estimating penetration resistive forces on granular materials is important for applications in various research fields. This paper investigates resistive forces into dry and wet granular layers through theoretical analysis and discrete element simulations. Theoretical model is derived from slip line field theory by assuming materials with cohesion and inter-particle friction. This model indicates that penetration resistive forces are composed of the sum of the buoyancy-like force proportional to the penetration volume and the cohesion-derived force proportional to the penetration cross-sectional area. The model is compared with the simulation results of various cones shallowly penetrating into granular layers with/without liquid-bridge forces between particles. For cohesion-derived force, the simulated resistive forces agree with the theoretical model within a factor of two. For buoyancy-like force, on the other hand, the simulated resistive forces deviate from the theoretical model by up to five times as the cone-tip angle increased. To solve the discrepancy, this paper introduces the correction factor depending on the relationship between stagnant zone and cone shape. As a result, a maximum difference between the proposed model and simulated force are reduced to twice. Thereby, it turns out that the proposed model can compute penetration resistive forces on granular layers in a wide range of cone-tip angles and water content conditions.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 3","pages":"1279 - 1295"},"PeriodicalIF":5.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11440-024-02456-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143570925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Machine learning-aided selection of CPT-based transformation models using field monitoring data from a specific project","authors":"Hua-Ming Tian,&nbsp;Yu Wang,&nbsp;Chao Shi","doi":"10.1007/s11440-024-02475-w","DOIUrl":"10.1007/s11440-024-02475-w","url":null,"abstract":"<div><p>Transformation models have been widely used in geotechnical engineering to relate data from lab or field tests (e.g., cone penetration tests, CPT) to design parameters required in geotechnical analysis and design. Proper selection of transformation models is crucial but challenging for accurate prediction of geotechnical responses (e.g., reclamation-induced settlement) in practice. This study proposes a general machine learning framework that accommodates a wide variety of existing CPT-based transformation models and uses field monitoring data (e.g., settlement data observed from a specific project) to select suitable transformation models for improving prediction of spatiotemporally varying reclamation-induced settlement. The proposed approach takes advantage of sparse dictionary learning (SDL) and achieves prediction of settlement by a linear weighted sum of dictionary atoms that are constructed using outputs from finite element models (FEM) of reclamation-induced consolidation. Input parameters of the FEM models are determined using existing transformation models in literature. A transformation model database that relates multiple soil consolidation parameters with CPT data is also compiled for consolidation analysis and dictionary construction in SDL. The proposed approach is illustrated using a real reclamation project in Hong Kong. Results show that the proposed approach provides an effective and transparent vehicle to leverage existing abundant transformation models, identify appropriate transformation models using field monitoring data, and improve prediction of spatiotemporally varying reclamation-induced settlement, with greatly reduced prediction uncertainty. The transformation model selection and settlement prediction are also improved continuously as more field monitoring data are obtained.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":"439 - 459"},"PeriodicalIF":5.6,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11440-024-02475-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A machine learning-based drag model for sand particles in transition flow aided by spherical harmonic analysis and resolved CFD-DEM","authors":"Gaoyang Hu,&nbsp;Bo Zhou,&nbsp;Wenbo Zheng,&nbsp;Changheng Li,&nbsp;Huabin Wang","doi":"10.1007/s11440-024-02472-z","DOIUrl":"10.1007/s11440-024-02472-z","url":null,"abstract":"<div><p>Given the importance of drag model in solving fluid–particle interactions in unresolved numerical methods, this study proposed a machine learning (ML)-based drag model for irregular sand particles in transition flow, aided by spherical harmonic (SH) analysis and a resolved computational fluid dynamics-discrete element method (CFD-DEM). Initially, realistic particle shapes were reconstructed by the SH function, and their multi-scale shape features were quantified by the energy spectrums of SH frequencies. A developed fictitious domain method, particularly for irregularly shaped clumps, was proposed to solve fluid–solid interactions within resolved CFD-DEM. Subsequently, the fluid flow past a fixed particle test was repetitively simulated by the resolved CFD-DEM for 270 realistic sand particles, and a dataset consisting of 4220 drag coefficients was finally established. A classic ML algorithm, namely the multi-layer perceptron (MLP) neural network, was then utilized to train a drag model associated with the multi-scale shape features, particle orientations, and flow conditions. Compared with the results from the resolved CFD-DEM, the trained MLP model demonstrates both efficiency and accuracy in predicting the drag coefficients of natural sand particles with irregular shapes. This work provides a more reliable drag model for granular soils and shows its potential for application in large-scale modeling using the unresolved CFD-DEM framework.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":"461 - 474"},"PeriodicalIF":5.6,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering anomalous dielectric traits of nanoconfined water and its roles in modeling crystalline swelling of bentonite","authors":"Wen-jie Dai,&nbsp;Yong-gui Chen,&nbsp;Yu-cheng Li,&nbsp;Wei-min Ye,&nbsp;Qiong Wang,&nbsp;Dong-bei Wu","doi":"10.1007/s11440-024-02474-x","DOIUrl":"10.1007/s11440-024-02474-x","url":null,"abstract":"<div><p>The physicochemical properties of Na-montmorillonite (Na-Mt) determine the intrinsic behaviors of bentonite, which are of great significance for its application in high-level radioactive waste disposal. The dielectric behavior of water under nanoconfinement has been the subject of numerous conjectures due to the difficulties associated with experimental investigation. Na-Mt is modeled via molecular dynamics (MD) simulations at the nanoscale, and the dielectric responses as a function of the basal spacing and water density are studied. The results showed a heterogeneous dielectric profile of interlayer water and an unexpected local dielectric enhancement closed to Mt surface. The morphological characteristics of dielectric constant (<span>(upvarepsilon)</span>) was consistent with the layered structure of interlayer water. The hydrogen bonding network was strengthened near the interface, resulting in a local density augmentation and dipolar mobility decline of interlayer water. This anomalous dielectric behavior was mainly derived from the interfacial effect, rather than the physical field in Na-Mt interlayer. Introducing the MD simulations results into crystalline swelling model, and a significant improvement in accuracy was observed. These results provide a clear insight into the dielectric behavior of interlayer water in Na-Mt.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 4","pages":"1571 - 1583"},"PeriodicalIF":5.6,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability analysis of the slopes composed of heterogeneous and anisotropic clay","authors":"M. H. Bozorgpour,&nbsp;S. M. Binesh,&nbsp;H. Fathipour","doi":"10.1007/s11440-024-02468-9","DOIUrl":"10.1007/s11440-024-02468-9","url":null,"abstract":"<div><p>It is well perceived that the shear strength properties of natural soil stratum are inherently anisotropic and spatially heterogeneous due to the depositional, geological and environmental factors. In this study, the concurrent effect of inherent anisotropy and spatial heterogeneity of undrained shear strength of clay on stability of sloped ground is examined by using a numerical lower bound limit analysis approach. The inherent anisotropy of the undrained shear strength of clay is incorporated into the numerical model by the application of an iterative process, and the random field technique is utilized to account for clay’s spatial variability. The numerical tool for slope’s safety factor determination is based on the combination of lower bound theory, finite element method, second-order conic optimization and the strength reduction method. Probabilistic analyses of slopes with/without external tractions showed a remarkable effect of concurrent consideration of anisotropy and heterogeneity of soil on the evaluated safety factor of slope.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 1","pages":"69 - 87"},"PeriodicalIF":5.6,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of energy evolution process of rock mass during deep tunnel excavation based on elasto-viscoplastic damage model and time-dependent energy indices","authors":"Yaoru Liu,&nbsp;Rujiu Zhang,&nbsp;Shaokang Hou,&nbsp;Ling Zhu,&nbsp;Zhiyong Pang,&nbsp;Wenyu Zhuang","doi":"10.1007/s11440-024-02485-8","DOIUrl":"10.1007/s11440-024-02485-8","url":null,"abstract":"<div><p>Understanding the energy evolution process of rock mass during tunnel excavation is crucial for revealing the potential of deep geological hazards. A series of numerical simulations for continuous tunneling were conducted based on an elasto-viscoplastic damage model, and time-dependent energy indices, strain energy density (SED) and energy dissipation rate (EDR) were introduced to analyze the spatio-temporal evolutionary process of energy accumulation and release. Several new insights on rockburst and large squeezing deformation were subsequently proposed from an energy perspective. The influences of excavation rate and pilot tunnel on energy evolution were further discussed. Results indicate that deep tunnel excavation generally involves an energy accumulation process (a SED peak) and two energy release processes (two EDR peaks); the energy of rock mass exhibits a temporal evolution pattern of \"release-accumulation-re-release\" and a spatial migration pattern of \"deep-shallow-deep.\" Initial energy release, energy accumulation, and secondary energy release are induced by excavation unloading effect, elastic stress redistribution, and viscoplastic strain accumulation. Rockbursts exhibit different spatio-temporal characteristics; two EDR peaks appear shortly before and after excavation, indicating the potential of instantaneous rockbursts at excavation face and delayed rockbursts at sidewalls, respectively. Reducing excavation rate helps to lower the SED peak and EDR peaks, thus mitigating the rockburst potential; transient unloading can cause a more sudden and significant initial energy release, obviously increasing the risk of instantaneous rockbursts. Pilot tunnel contributes to energy pre-concentration of rock mass ahead of excavation face, thereby decreasing energy peak upon secondary tunneling. The findings of this study provide theoretical basis for evaluation and control of rockburst and large deformation in deep tunnels.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 4","pages":"1549 - 1570"},"PeriodicalIF":5.6,"publicationDate":"2024-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lateral behavior of large-diameter monopiles in clay using transparent soil and centrifuge tests","authors":"Guangwei Cao,&nbsp;Siau Chen Chian,&nbsp;Xuanming Ding,&nbsp;Zhibo Chen,&nbsp;Peng Zhou","doi":"10.1007/s11440-024-02463-0","DOIUrl":"10.1007/s11440-024-02463-0","url":null,"abstract":"<div><p>The response characteristics of large-diameter monopiles under lateral loads greatly differ from those of traditional small-diameter piles. By means of transparent soil and centrifuge tests, as well as numerical analyses, the soil flow mechanism and lateral behavior of large-diameter monopiles in soft clay were investigated. The study result reveals that a rotational failure mechanism, different from wedge-full-flow mechanisms, exists in the large-diameter monopile–soil system. For stubby large-diameter monopiles, using the classic wedge-full-flow mechanisms can lead to an overestimation of lateral capability due to its absence in considering the rotational mechanism. In addition, the normalized <i>p–y</i> curves in the rotational soil flow zone are also observed to have larger initial stiffness and attain yield plateau earlier than those in wedge-full-flow zone. Differences in <i>N</i>_<i>p</i> values among different centrifuge tests are partly attributed to the different means of obtaining the clay’s undrained shear strength. When the undrained strength from consolidated undrained triaxial tests is taken, consistent values of <i>N</i>_<i>p</i> originating from different test results are observed. Finally, based on the results from centrifuge tests and well-calibrated numerical analyses, an empirical formulation of <i>N</i>_<i>p</i> for large-diameter monopiles in soft clay is proposed.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 4","pages":"1795 - 1812"},"PeriodicalIF":5.6,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143717003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}