Acta Geotechnica最新文献

{"title":"Classifying roundness and sphericity of sand particles using CNN regression models to alleviate data imbalance","authors":"Donghwi Kim,&nbsp;Heejung Youn","doi":"10.1007/s11440-024-02410-z","DOIUrl":"10.1007/s11440-024-02410-z","url":null,"abstract":"<div><p>Determining the shape parameters of sand particles helps to understand the geotechnical properties of sand. This study aims to determine the roundness and sphericity of Jumunjin sand utilizing artificial intelligence (AI). A dataset comprising 1000 sand particle images from Jumunjin sand was used for testing. The training set included approximately 28,000 images, created through a combination of synthetic data (5000 images) and additional data augmentation techniques to address data imbalance issues. Unlike traditional methods for determining roundness and sphericity, this research proposes a model that combines a regression model with a convolutional neural network (CNN), using ResNet and DenseNet as the backbone networks. The results, evaluated based on the coefficient of determination (<i>R</i>²) between the predicted values using the DenseNet169 model and the true values, yielded an <i>R</i>² of 0.695 for roundness and 0.979 for sphericity. When classifying based on the Krumbein and Sloss chart using the trained model, the DenseNet169 model demonstrated the highest accuracy (73.6%), precision (77.9%), and recall (77.2%). A comparison between AI predictions and human evaluations revealed considerable variation in human classification, depending on the observers, whereas the AI model consistently exhibited robust performance in determining both roundness and sphericity.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6569 - 6584"},"PeriodicalIF":5.6,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434824","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":"Influence of soil property variability on the lateral displacement of liquefiable ground reinforced by granular columns","authors":"Tengfei Mo,&nbsp;Qiang Wu,&nbsp;Dian-Qing Li,&nbsp;Wenqi Du","doi":"10.1007/s11440-024-02407-8","DOIUrl":"10.1007/s11440-024-02407-8","url":null,"abstract":"<div><p>In this paper, three-dimensional nonlinear dynamic finite-element analyses are conducted to examine the effect of soil property variability on the lateral displacement (<i>D</i>) of liquefiable ground reinforced by granular columns. A suite of 20 ground motions is selected from the NGA-West2 database as input. A soil-granular column ground system consisting of an intermediate liquefiable layer is modeled in <i>OpenSees</i>. Both the random variable (RV) and random filed (RF) methods are adopted to model the variability of soil property parameters. Dynamic analyses are then conducted to estimate the earthquake-induced deformation of the soil-granular column system. It is found that modeling the variability of soil parameters based on the RV method generally increases the geometric mean and standard deviation (σ_ln<i>D</i>) of <i>D</i> for the soil-granular column system. Enlarging the spatial correlation of soil parameters in the RF model brings in a slight increase of the mean <i>D</i> and comparable σ_ln<i>D</i> values, respectively. Hence, incorporating the spatially correlated soil property parameters may not be necessarily increase the variation of <i>D</i> for the soil-granular column system. Specifically, the statistical distribution of <i>D</i> is more sensitive to the vertical scale of fluctuation rather than the horizontal one. The results presented could aid in addressing the variability issue for performance-based design of granular column-reinforced liquefiable ground in engineering applications.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6585 - 6598"},"PeriodicalIF":5.6,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434782","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":"Physico-mechanical aspects of liquefaction risk reduction in sand using geotextile-encased granular columns","authors":"Balaji Lakkimsetti,&nbsp;Gali Madhavi Latha","doi":"10.1007/s11440-024-02402-z","DOIUrl":"10.1007/s11440-024-02402-z","url":null,"abstract":"<div><p>Liquefaction-induced flow failures, excessive settlements, lateral spreading, and loss of shear strength in granular soils can become massive hazards during earthquakes. Among the various mitigation techniques available, soil reinforcement using dense granular columns can be considered as a very effective technique, and its effectiveness gets further improved by encasing the columns in a geotextile to maintain the integrity of the columns during earthquakes. This paper presents findings from a first-of-its-kind study of simple shear tests on sand reinforced with geotextile-encased granular columns (EGC) to understand the fundamental mechanisms leading to its improved liquefaction resistance and shearing response. The effects of area replacement ratio and grouping action of columns on the overall response are established by performing a series of multi-stage constant volume simple shear tests on unreinforced and EGC-reinforced sands. The area replacement ratio was varied between 4 and 16% in different tests, and the tests with 16% area replacement ratio were conducted on sand with a single column and a group of columns. The particle sizes, encasement tensile strength, and column configurations are carefully chosen to avoid scaling and boundary effects on the test results. The performance of EGCs against liquefaction was evaluated considering all fundamental mechanisms, including the progression of pore pressures, nonlinear hysteretic behaviour, strain energy accumulation, and shear modulus degradation. The potential of EGCs for mitigating the liquefaction and improving the post-liquefaction shear strength of sand was found to improve with the increase in the area replacement ratio. For a specific area replacement ratio, the beneficial effects were more significant when the EGCs were spread into a group of symmetrically placed columns instead of a single column at the centre. The stress concentration on the EGCs due to modulus contrast and additional confinement offered by the EGCs to intervening soil have collectively benefited the shearing response of sand before, during, and after liquefaction.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6843 - 6864"},"PeriodicalIF":5.6,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434784","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":"Simulation of hydro-deformation coupling problem in unsaturated porous media using exponential SWCC and hybrid improved iteration method with multigrid and multistep preconditioner","authors":"Shuairun Zhu,&nbsp;Lulu Zhang,&nbsp;Lizhou Wu","doi":"10.1007/s11440-024-02414-9","DOIUrl":"10.1007/s11440-024-02414-9","url":null,"abstract":"<div><p>Numerical models based on seepage-deformation coupling governing equations are often used to simulate soil hydrodynamics and deformation in unsaturated porous media. Among them, Picard iteration method with pressure head as the main variable is widely used because of its simplicity and ability to deal with partial saturation conditions. It is well known that the method is prone to convergence failure under some unfavorable flow conditions and is also computationally time-consuming. In this study, the soil–water characteristic curve (SWCC) of unsaturated soil described by the exponential function is used to linearize the coupling equations to overcome the repeated assembly of nonlinear ordinary differential equations. The finite element method with six-node triangular element is used to discretely linearize the coupling governing equations. Further, the classical Gauss–Seidel iterative method (GS) can be used to solve the linear equations generated from the linearized coupling equations. However, the convergence rate of GS seriously restricts the ill-condition of the linear equations, especially when the condition number of linear equations is much larger than 1.0. Thus, we propose an improved Gauss–Seidel iterative methods MP(<i>m</i>)-GSCMGI by combining multistep preconditioning and cascadic multigrid. The applicability of the proposed methods in simulating variably saturated flow and deformation in unsaturated porous media is verified by numerical examples. The results show that the proposed improved methods have faster convergence rate and computational efficiency than the conventional Picard and GS. The hybrid improved method MP(<i>m</i>)-GSCMGI can achieve more robust convergence and economical simulation.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"7011 - 7029"},"PeriodicalIF":5.6,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434783","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":"DEM investigation into the small-strain stiffness of bio-cemented soils","authors":"Aoxi Zhang,&nbsp;Vanessa Magnanimo,&nbsp;Hongyang Cheng,&nbsp;Timo J. Heimovaara,&nbsp;Anne-Catherine Dieudonné","doi":"10.1007/s11440-024-02387-9","DOIUrl":"10.1007/s11440-024-02387-9","url":null,"abstract":"<div><p>Bio-mediated methods, such as microbially induced carbonate precipitation, are promising techniques for soil stabilisation. However, uncertainty about the spatial distribution of the minerals formed and the mechanical improvements impedes bio-mediated methods from being translated widely into practice. To bolster confidence in bio-treatment, non-destructive characterisation is desired. Seismic methods offer the possibility to monitor the effectiveness and mechanical efficiency of bio-treatment both in the laboratory and in the field. To aid the interpretation of shear wave velocity measurements, this study uses the discrete element method to examine the small-strain stiffness of bio-cemented sands. Bio-cemented specimens with different characteristics, including properties of the host sand (void ratio, uniformity of particle size distribution) and properties of the precipitated minerals (distribution pattern, content, Young’s modulus), are modelled and subjected to static probing. The mechanisms affecting the small-strain properties of cemented soils are investigated from microscopic observations. The results identify two mechanisms controlling the mechanical reinforcement associated with bio-cementation, namely the number of effective bonds and the ability of a single bond to improve stiffness. The results show that the dominant mechanism varies with the properties of the host sand. These results support the use of seismic measurements to assess the mechanical efficiency and effectiveness of bio-mediated treatment.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6809 - 6823"},"PeriodicalIF":5.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11440-024-02387-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263576","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":"Assessing the reuse of liquid nitrogen in artificial ground freezing through field experiments","authors":"Hyun-Jun Choi,&nbsp;Seokjae Lee,&nbsp;Hyobum Lee,&nbsp;Sangyeong Park,&nbsp;Hangseok Choi,&nbsp;Jongmuk Won","doi":"10.1007/s11440-024-02388-8","DOIUrl":"10.1007/s11440-024-02388-8","url":null,"abstract":"<div><p>Liquid nitrogen is the most common refrigerant adopted in the artificial ground freezing (AGF) method for the rapid freezing of soil. However, the relatively high price of liquid nitrogen demands the reuse of liquid nitrogen in AGF, which utilizes partially gasified liquid nitrogen after an initial injection. This study investigated the reusability of liquid nitrogen in AGF by performing a field experiment. Temperatures of the ground were monitored near the sub-freezing pipes installed 1 m away from the main freezing pipes, where liquid nitrogen was initially injected. A frozen wall having a thickness of 1 m was formed between two sub-freezing pipes after 5 days of injecting liquid nitrogen into the main freezing pipes. Furthermore, the lowest temperature of  − 12 °C measured in the sub-freezing pipe implied that the temperature of nitrogen after circulating through the main freezing pipe was sufficiently low to freeze the surrounding soil formation. The freezing rate, elapsed time for freezing, and freezing duration evaluated from the monitored temperature data also demonstrated the promising potential of reusing liquid nitrogen in AGF for saturated silty deposits.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6825 - 6842"},"PeriodicalIF":5.6,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263577","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":"Laboratory-scale thermo-activated piles under long continuous operation and different mobilised shaft resistance","authors":"Luis Villegas,&nbsp;Amin Rafiei,&nbsp;Guillermo A. Narsilio,&nbsp;Chanakya Arya,&nbsp;Raul Fuentes","doi":"10.1007/s11440-024-02397-7","DOIUrl":"10.1007/s11440-024-02397-7","url":null,"abstract":"<div><p>This paper examines the shaft resistance mobilisation ratio as a predictor of cumulative displacement of small-scale floating and end-bearing energy pile foundations subjected to vertical compressive loads embedded in dry sandy soils. A reduced friction model pile was subjected to different mechanical loads and two long-duration, cyclic heating/recovery temperature changes. The pile, soil and container temperatures, pile strains, and vertical displacements are monitored, analysed, and discussed. The results further validate numerical analyses that propose the shaft resistance mobilisation ratio as a variable to identify thresholds above which permanent cyclic thermo-induced deformations may occur. Overall, the experimentally observed responses indicate incremental deformations as the shaft resistance mobilisation ratio increased. The results also suggest that a mobilisation ratio of 66% could be a potential conservative lower-bound limit that could control the increment of thermal-induced vertical displacements in the long term under free pile head conditions. This suggests that a performance-based design would be a reasonable approach for energy piles, and monitoring programs should be set in the field before loading and thermo-activation.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6787 - 6808"},"PeriodicalIF":5.6,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11440-024-02397-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263573","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 hydromechanical model for unsaturated soils based on state boundary hypersurface","authors":"Dongjie Hua,&nbsp;Guohua Zhang,&nbsp;Ruyan Liu,&nbsp;Qinghui Jiang","doi":"10.1007/s11440-024-02390-0","DOIUrl":"10.1007/s11440-024-02390-0","url":null,"abstract":"<div><p>This paper presents an elastoplastic model to estimate the hydromechanical behavior of unsaturated soils based on state boundary hypersurface. Through mechanical hypersurface, the influence of saturation on yield stress can be expressed in a full form rather than an incremental form. Two hydraulic hypersurfaces and one mechanical hypersurface are proposed to establish the model. Two hydraulic hypersurfaces, composed of degree of saturation, void ratio and matrix suction, define the plastic hydraulic boundary. The elastic hydraulic behavior of unsaturated soils can be represented by scanning lines between these two hydraulic hypersurfaces. The mechanical hypersurface, composed of degree of saturation, void ratio and effective stress, defines the plastic mechanical boundary. The elastic mechanical behavior of unsaturated soils can be represented by scanning lines below the mechanical hypersurfaces. A large number of laboratory tests are used to validated the proposed model, showing that it can reasonably capture important features of the hydromechanical behavior of unsaturated soils.</p></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"19 10","pages":"6599 - 6615"},"PeriodicalIF":5.6,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263578","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":"An experimental investigation on progressive failure mechanism of the earth-retaining structure with sloping backfill using image analysis","authors":"Shi-Yu Xu, Muhammad Irfan Khan, K. K. Pabodha M. Kannangara, Yiu Yin Lee","doi":"10.1007/s11440-024-02392-y","DOIUrl":"https://doi.org/10.1007/s11440-024-02392-y","url":null,"abstract":"<p>In this study, a reduced-scale retaining wall specimen was subjected to laboratory testing to examine the strain localization phenomena behind an earth-retaining structure under passive conditions. The specimen was backfilled with two distinct soil materials—sand and fine gravels—in a medium dense state, while also retaining sloping ground surfaces with varying inclinations. The soil particle movement within the backfill was monitored and tracked through successive images captured at a consistent rate using a camera, as the wall progressively approached the backfill. By employing the digital image correlation technique, von Mises strain contours within the backfill were subsequently deduced from the recorded soil particle displacement field. This method unveiled the distribution and progression of strain concentration bands. Moreover, the laboratory tests documented the horizontal force–displacement curve of the wall, the earth pressure distribution across depth, and the wall’s uplift. These findings were verified against various analytical models and finite element simulations, illustrating good alignment. The von Mises strain maps disclosed the presence of a distinct boundary within the backfill, beyond which soil particles remained immobile during the pushover test. This boundary manifested during the early phases of the test when stress levels were relatively low. For specimens with positive slopes, this boundary evolved into the ultimate failure surface, characterized by a geometry resembling a log-spiral curve. Conversely, for specimens with negative slopes, the failure surface may not adhere to this log-spiral boundary; instead, it might follow a more direct route, resembling the straight line predicted by Rankine theory.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"72 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214247","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":"Eco-efficient recycling of engineering muck for manufacturing low-carbon geopolymers assessed through LCA: exploring the impact of synthesis conditions on performance","authors":"Bingxiang Yuan, Jingkang Liang, Xianlun Huang, Qingyu Huang, Baifa Zhang, Guanghua Yang, Yonghong Wang, Junhong Yuan, Hongyu Wang, Peng Yuan","doi":"10.1007/s11440-024-02395-9","DOIUrl":"https://doi.org/10.1007/s11440-024-02395-9","url":null,"abstract":"<p>With the push toward global low-carbon and sustainable development goals, an urgent need exists to find building materials that can replace cement. Engineering muck (EM) produced by foundation pit engineering in subtropical areas is rich in clay minerals, which are suitable for the preparation of low-carbon geotechnical materials. In this study, the effects of SiO₂/Na₂O and the liquid–solid ratio on the performance of alkali-activated EM-based geopolymers were investigated. In addition, a life cycle assessment (LCA) was performed to evaluate the environmental impacts of EM-based geopolymers. The findings showed that the geopolymer with a SiO₂/Na₂O ratio of 1.5 achieved the highest 7-day compressive strength of 42 MPa, which was 47.46% and 56.49% greater than that of the geopolymer with SiO₂/Na₂O ratios of 0.9 and 1.8, respectively because of its densest structure and fewest cracks. Moreover, increasing the liquid–solid ratio from 0.75 to 0.90 slightly increased the 28-day compressive strength from 47 to 52 MPa because of the refined pore structure. However, this modification also increased carbonate formation and mass loss at elevated temperatures. Compared with those of concrete, the CO₂ and SO₂ emissions of EM-based geopolymers were reduced by 4–26% and 8–19%, respectively, owing to the considerable environmental impact of cement. The overall performance of the geopolymers was assessed via multiple influence indicator methods, and the optimal synthesis conditions for the geopolymers were a SiO₂/Na₂O ratio of 1.5 and a liquid–solid ratio of 0.75. This study suggests that using alkaline activation technology to transform EM into geopolymers has potential as a substitute for concrete, providing a new type of green material for geotechnical engineering.</p>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"71 1","pages":""},"PeriodicalIF":5.7,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142214248","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}