Soils and Foundations最新文献_第2页

Numerical and experimental study on the seismic performance of caisson foundations 沉箱基础抗震性能的数值与试验研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-10-10 DOI: 10.1016/j.sandf.2025.101702

Sohail Ahmad , Tianbo Peng , Muhammad Salman Khan

Caisson foundations are widely used in long-span bridges for their superior load-bearing capacity and stability, yet their seismic behavior remains inadequately understood. Current seismic design approaches often neglect soil-caisson dynamic interaction (SCDI), leading to inconsistencies between theoretical models and actual responses. This study investigates the seismic response of caisson foundations through large-scale shaking table tests and finite element simulations in Abaqus, validated using experimental results from the Taizhou Yangtze River Highway Bridge. The findings indicate that the presence of caisson foundations has minimal impact on the fundamental frequency of the soil, while an increase in bridge tower mass reduces the system’s first-order frequency, altering its dynamic characteristics. Specifically, a 21 % reduction in the first-order frequency was observed when the tower mass increased from 230 kg to 370 kg. Additionally, acceleration responses at the tower top differed by less than 6 % when using the Clough hyperbolic contact model compared to experimental results, demonstrating strong agreement. The results also show that caisson foundations primarily undergo rigid body motion under seismic excitation, with negligible deformation. Furthermore, the Clough hyperbolic constitutive model accurately captures nonlinear contact behavior at the soil-caisson interface, providing better agreement with experimental observations under high-intensity seismic loading. This study highlights the importance of incorporating realistic SCDI effects in seismic design and suggests that enhanced numerical modeling techniques can improve the reliability of seismic performance predictions for long-span bridges with caisson foundations. These insights contribute to the development of more resilient seismic design strategies, reducing structural vulnerabilities in seismic-prone regions.

沉箱基础以其优越的承载能力和稳定性被广泛应用于大跨度桥梁中，但对其抗震性能的研究还不够充分。目前的抗震设计方法往往忽略了土-沉箱动力相互作用（SCDI），导致理论模型与实际反应不一致。通过大型振动台试验和Abaqus有限元模拟，研究沉箱基础的地震响应，并利用台州长江公路大桥的试验结果进行验证。结果表明，沉箱基础的存在对土体基频的影响最小，而桥塔质量的增加降低了体系的一阶频率，改变了其动力特性。具体来说，当塔的质量从230公斤增加到370公斤时，一阶频率降低了21%。此外，与实验结果相比，使用克拉夫双曲接触模型时，塔顶的加速度响应差异不到6%，表明了很强的一致性。结果还表明，沉箱基础在地震作用下以刚体运动为主，变形可以忽略不计。此外，Clough双曲本构模型准确地捕捉了土-沉箱界面的非线性接触行为，与高烈度地震荷载下的实验观测结果吻合较好。这项研究强调了在抗震设计中纳入真实SCDI效应的重要性，并表明增强的数值模拟技术可以提高大跨度沉箱基础桥梁抗震性能预测的可靠性。这些见解有助于开发更具弹性的抗震设计策略，减少地震易发地区的结构脆弱性。

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引用次数: 0

Shear wave velocity based prediction of CaCO3 content and UCS in MICP-treated soils with different particle sizes 基于剪切波速的不同粒径micp处理土壤CaCO3含量和UCS预测

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-10-03 DOI: 10.1016/j.sandf.2025.101700

Yuhang Zeng , Hui Xu , Yubin Zheng , Hao Zheng , Ping Chen

As an emerging soil reinforcement technology, microbial-induced carbonate precipitation (MICP) requires in-situ testing to assess its field performance. Shear wave velocity (V_s) is a viable in-situ method. However, a clear predictive model linking its variations with the CaCO₃ content (C_m) and unconfined compressive strength (UCS) of MICP-treated soil—considering particle size as a variable—remains to be established, constraining broader applications of this approach. This study conducts MICP treatment tests on mixtures of excavated soil (silty sand) and surplus sludge (elastic silt), using the mean particle size (d₅₀) as the indicator of particle size. In addition, by varying the sludge proportion (P_s), the impact of particle size on the V_s, C_m, and UCS is examined. During the MICP process, an increase in P_s reduces the increase rate of C_m and V_s. Moreover, V_s stabilizes about 10 h earlier than C_m at a given P_s. This is probably attributed to a shift in CaCO₃ precipitation modes from significant strength/stiffness enhancement for soil mixtures to minor contribution. After MICP treatment, V_s, C_m, and UCS decrease linearly with increasing P_s. Following this, V_s-based prediction models for C_m and UCS are respectively developed by considering the particle size. The prediction models are proven to accurately forecast C_m and UCS in MICP-treated soils with different d₅₀ values. This advancement enhances in-situ monitoring techniques that employ V_s to evaluate MICP cementation effectiveness.

微生物诱导碳酸盐沉淀（MICP）作为一种新兴的土壤加固技术，需要通过现场测试来评估其现场性能。横波速度（Vs）是一种可行的原位方法。然而，将其变化与CaCO3含量（Cm）和micp处理土壤的无侧限抗压强度（UCS）联系起来的明确预测模型（考虑粒径作为变量）仍有待建立，这限制了该方法的更广泛应用。本研究采用平均粒径（d50）作为粒径指标，对开挖土（粉砂）与剩余污泥（弹性粉砂）的混合物进行了MICP处理试验。此外，通过改变污泥比例（Ps），考察了粒径对Vs、Cm和UCS的影响。在MICP过程中，Ps的增加降低了Cm和Vs的增加速率，并且在给定Ps下，Vs比Cm早稳定约10 h。这可能是由于CaCO3降水模式从显著增强土壤混合物的强度/刚度转变为贡献较小。在MICP处理后，Vs、Cm和UCS随Ps的增加而线性降低。在此基础上，考虑粒径，分别建立了基于Vs的Cm和UCS预测模型。结果表明，该预测模型能较准确地预测不同d50值下micp处理土壤的Cm和UCS。这一进步增强了使用v来评估MICP固井效果的原位监测技术。

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引用次数: 0

Geostatistical-learning-based site-optimum 3D integration of borehole logs and geophysical data in urban area in South Korea 在韩国城市地区，基于地质统计学习的井眼测井和地球物理数据的最佳现场三维集成

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-29 DOI: 10.1016/j.sandf.2025.101684

Joung-Woo Han , Mingi Kim , Han-Saem Kim , Taek-Kyu Chung , Choong-Ki Chung

Success in civil engineering projects fundamentally depends on thoroughly understanding the site-specific subsurface characteristics. Site investigation, a critical process in the early stages of construction and design, serves as the foundation for ensuring the safety and efficiency of structural development and safeguards against potential disasters. However, owing to financial and time constraints, the number of site investigations is often limited, making spatial uncertainty one of the most significant challenges in geotechnical engineering. Geostatistics-based spatial interpolation techniques are widely used to overcome the limitations of spatial variability and information scarcity in geotechnical engineering. Reliable geospatial analysis is essential for identifying site-specific subsurface stratification information. In this study, site investigation data were collected at a subway construction site at which subsidence occurred during tunnel excavation. Borehole data were optimized using outlier removal to maximize reliability, and geophysical data were digitized to create a 3D integrated database with borehole data. Considering the subsurface characteristics, the optimal stratigraphic boundary elevations were determined using seismic wave velocities values, which clarified the optimized stratigraphic boundaries. Using kriging and simulation-based integrated analysis techniques, the subsurface stratigraphic information was predicted in 3D, and the cross-sectional and longitudinal geotechnical profiles confirmed that the layers with the least deviation effectively reflect the actual strata, which is consistent with the evaluation results, through a learning process that seeks the optimal method and parameters that produce the least prediction residuals. This approach highlights the importance of integrating advanced geostatistical-learning-based integration and geotechnical engineering practices to improve the accuracy and reliability of subsurface evaluations, thereby ensuring safer and more efficient construction.

土木工程项目的成功从根本上取决于对特定场地的地下特征的彻底了解。现场调查是施工和设计早期阶段的一个关键过程，是确保结构开发安全和效率以及防范潜在灾害的基础。然而，由于资金和时间的限制，现场调查的数量往往有限，使得空间不确定性成为岩土工程中最重大的挑战之一。基于地质统计学的空间插值技术被广泛应用于岩土工程中，以克服空间变异性和信息稀缺性的局限性。可靠的地理空间分析对于确定特定地点的地下分层信息至关重要。本研究以某地铁施工现场为研究对象，在隧道开挖过程中发生了沉降。井眼数据通过去除异常值来优化，以最大限度地提高可靠性，并将地球物理数据数字化，以创建井眼数据的三维集成数据库。结合地下特征，利用地震波速度值确定了最佳地层边界标高，明确了最佳地层边界。利用克里格和基于模拟的综合分析技术，对地下地层信息进行了三维预测，通过寻找预测残差最小的最优方法和参数的学习过程，通过剖面和纵向岩土剖面证实，偏移最小的层段有效反映了实际地层，与评价结果一致。这种方法强调了将先进的基于地质统计学习的集成与岩土工程实践相结合的重要性，以提高地下评估的准确性和可靠性，从而确保更安全、更高效的施工。

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引用次数: 0

Enhanced microstructural analysis of black cotton soil stabilized through rice husk ash integration 稻壳灰分固化黑棉土的微观结构分析

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-27 DOI: 10.1016/j.sandf.2025.101698

Ankur Abhishek , Anasua GuhaRay , Toshiro Hata

Black cotton soil (BCS) poses significant complexities in geotechnical applications due to its swelling and shrinkage behavior. It causes significant economic losses globally due to reconstruction and rehabilitation efforts. Reliable soil reinforcement techniques are, therefore, essential to mitigate the deleterious effects of expansive BCS and to ensure the long-term stability of the structures built upon them. The present study explores the application of rice husk ash (RHA) to BCS using nitrogen (N₂) gas adsorption techniques such as Brunauer–Emmett–Teller (BET), Langmuir, and adsorption isotherm analyses. These techniques are based on the principle that N₂ gas is adsorbed onto the reactive surface sites. The surface of BCS is considered reactive due to its high clay content and the presence of montmorillonite. With the addition of RHA, pozzolanic reactions progress, leading to the development of cementitious phases such as calcium silicate hydrate (C-S-H), which gradually fill these reactive surface sites, leading to a decrease in the material’s gas adsorption capacity. This reduction in N₂ gas adsorption provides a measurable indication of pozzolanic activity, allowing for a more detailed microstructural assessment of stabilized soil systems. A sharp reduction in N₂ gas adsorption was observed in BET, Langmuir, and adsorption isotherm analyses at 6 % RHA content, conducted on 28-day cured Unconfined compressive strength (UCS)-tested samples. BET results showed a reduction in adsorption from 0.0635 mg/g for untreated BCS to 0.0385 mg/g at 6 % RHA concentration. This 6 % RHA content also corresponds with peak mechanical performance observed in UCS, California bearing ratio (CBR), indirect tensile strength (ITS), and cone penetration test (CPT), highlighting a strong correlation between microstructural improvement and engineering behavior. The UCS of untreated BCS (183 kPa) increased to a maximum of 819 kPa after 7 days and 1370 kPa after 28 days of curing, confirming 6 % RHA as the optimum dosage.

黑棉土由于其膨胀和收缩特性，在岩土工程应用中具有很大的复杂性。由于重建和恢复工作，它在全球造成重大经济损失。因此，可靠的土壤加固技术对于减轻膨胀BCS的有害影响并确保在其上建造的结构的长期稳定性至关重要。本研究利用brunauer - emmet - teller （BET）、Langmuir等氮气吸附技术和吸附等温线分析，探讨了稻壳灰（RHA）在BCS中的应用。这些技术是基于N2气体被吸附到反应表面的原理。由于其高粘土含量和蒙脱土的存在，BCS的表面被认为是活性的。随着RHA的加入，火山灰反应的进行，导致水合硅酸钙（C-S-H）等胶凝相的发展，这些胶凝相逐渐填充这些反应表面位点，导致材料的气体吸附能力下降。N2气体吸附的减少为火山灰活性提供了可测量的指示，从而可以对稳定土壤系统进行更详细的微观结构评估。在固化28天的无侧限抗压强度（UCS）测试样品中，BET、Langmuir和6% RHA含量的吸附等温线分析显示，N2气体吸附急剧减少。BET结果表明，在6% RHA浓度下，未处理BCS的吸附量从0.0635 mg/g降至0.0385 mg/g。6%的RHA含量也与UCS、加州承载比（CBR）、间接抗拉强度（ITS）和锥体穿透测试（CPT）中观察到的峰值力学性能相对应，突出了微观结构改善与工程行为之间的强烈相关性。未处理BCS （183 kPa）的UCS在固化7天后达到最大值819 kPa，固化28天后达到最大值1370 kPa，确定6% RHA为最佳剂量。

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引用次数: 0

Dynamic analysis of wave propagation due to pile installation using numerical simulations 基于数值模拟的桩基波传播动力分析

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-27 DOI: 10.1016/j.sandf.2025.101699

Maliha Tasnim Tilat, Sascha Henke

This paper discusses the results of a preliminary study of numerical simulations investigating wave propagation during the installation of in-situ driven concrete piles (type Franki pile). Franki piles are cast-in-situ piles that are installed by driving a steel casing into the ground using heavy ramming of a cylindrical hammer. It is a dynamic pile installation process where the hammer directly transfers the dynamic forces to the soil within the installation tube causing high wave propagation through the soil. When installed in groups, the vibrations caused by the driving process of one pile may result in damages to the early-age concrete of adjacent piles. The dynamic response of a pile during driving is very complex, involving the interactions of hammer, pile, and soil during the impact. Such complex soil-structure interaction problems can be represented numerically by modeling the pile installation process using realistic parameters (ground conditions, ramming energy etc.). As a preliminary study, a single pile installation is simulated using the FEM software Abaqus. The simulation is based on a Coupled Eulerian-Lagrangian (CEL) approach where the soil is modeled using the hypoplastic constitutive model. The aim is to investigate parts of the installation process regarding the effect of discrete hammer drops. Within the CEL method, the pile hammer is modeled as a Lagrangian part, while the soil is treated as a Eulerian part. As a result of the simulations, a realistic amplitude pattern can be observed. This study serves as the basis for the subsequent phase, wherein a newly installed neighboring pile is introduced alongside the pre-existing pile. In this context, the influence of the adjacent pile on the wave propagation due to the neighboring pile is evaluated.

本文讨论了原位灌注桩（Franki型桩）安装过程中波浪传播数值模拟的初步研究结果。法兰基桩是一种现浇桩，它是通过使用圆柱锤将钢套管打入地面而安装的。这是一种动力桩安装过程，锤头直接将动力传递给安装管内的土体，使高波在土体中传播。成组安装时，单桩打入过程产生的振动可能会对相邻桩的早期混凝土造成破坏。桩在冲击过程中的动力响应非常复杂，涉及锤、桩和土在冲击过程中的相互作用。这种复杂的土-结构相互作用问题可以通过使用实际参数（地面条件、夯击能量等）对桩安装过程进行数值模拟来表示。作为初步研究，利用有限元软件Abaqus对单桩安装进行了模拟。模拟是基于耦合欧拉-拉格朗日（CEL）方法，其中土壤模型采用欠塑性本构模型。目的是调查安装过程中有关离散锤滴影响的部分。在CEL方法中，桩锤被建模为拉格朗日部分，土被处理为欧拉部分。模拟的结果，可以观察到一个真实的振幅模式。该研究可作为后续阶段的基础，后续阶段在原有桩的基础上引入新安装的相邻桩。在这种情况下，评估了相邻桩对相邻桩引起的波传播的影响。

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引用次数: 0

Investigation on the lateral performance of new piles in sand sites containing existing piles and shallow cement-treated backfill 既有桩与浅层水泥处理充填体的砂场地新桩横向性能研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-19 DOI: 10.1016/j.sandf.2025.101686

Hongjiang Li , Tianyuan Wu , Songyu Liu , Liyuan Tong , Shuji Tamura , Wenyuan Liu

Piles are extensively utilized as the foundation to support buildings, bridges, and other superstructures subjected to lateral loads. The lateral load-bearing performance of newly installed piles in sites with existing piles is inevitably influenced by the presence of existing piles due to the interactions between the new pile, soil, and existing piles. Conversely, the lateral capacity of new piles can be significantly enhanced by effectively regulating these interactions. This study quantified the effect of shallow cement improvement on laterally loaded new piles in sand sites containing existing piles and shallow cement-treated backfill for different variables. A numerical model of new pile-soil-existing pile interactions under lateral loads was initially validated against 40 g centrifuge tests in density sand. Subsequent analyses incorporating shallow cement-treated backfill explored the lateral bearing mechanism of new piles and the corresponding response of existing piles. The findings indicate that cement-treated backfill can substantially enhance the lateral capacity of new piles for ultimate limit state (ULS) design limit by two times, compared with the condition without cement-treated backfill. With the increase of the depth of the new pile embedded in the cap, the thickness and modulus of the cement-treated backfill, the lateral capacity of the new pile increases. However, the depth of the existing pile embedded in the backfill has a limited influence on new pile capacity. Finally, a practical method for assessing lateral new pile capacities in sand sites containing existing piles and shallow cement-treated backfill was developed, demonstrating considerable advantages in designing laterally loaded new piles considering shallow cement improvement.

桩被广泛用作支撑建筑物、桥梁和其他承受横向荷载的上层结构的基础。在已有桩的场地上，由于新桩与土、已有桩的相互作用，新桩的横向承载性能不可避免地会受到已有桩存在的影响。相反，通过有效调节这些相互作用，可以显著提高新桩的抗侧承载力。本研究量化了不同变量下浅层水泥改善对既有桩和浅层水泥处理回填体的砂场地横向加载新桩的影响。在密度砂土中进行了40g离心试验，初步验证了侧向荷载作用下新桩-土-既有桩相互作用的数值模型。随后的分析结合浅层水泥处理回填体探讨了新桩的横向承载机制和现有桩的相应响应。研究结果表明：与未加水泥处理的情况相比，水泥处理后的新桩在达到极限状态（ULS）设计极限时的抗侧承载力提高了2倍；随着新桩嵌入承台深度的增加、水泥处理充填体的厚度和模量的增加，新桩的侧承载力增大。然而，现有桩嵌入回填体的深度对新桩承载力的影响有限。最后，开发了一种实用的方法来评估含有现有桩和浅水泥处理回填体的砂场地的横向新桩承载力，在设计考虑浅水泥改善的横向加载新桩方面具有相当大的优势。

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引用次数: 0

Upcycling rice husk biowaste to improve cement-based peat soil stabilization 稻壳生物废弃物升级利用改善水泥基泥炭土稳定性

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-18 DOI: 10.1016/j.sandf.2025.101685

Zhiliang Wang , Jiangpeng Cai , Miao Li , Linfang Shen

Traditional stabilizers, such as kaolin and sodium bentonite, introduce complications when applied to cement-based peat soil stabilization. This study explores biowaste stabilizers – rice husk ash (RHA) as a pozzolan material and rice husk fiber (RHF) as reinforcing – as a sustainable and practical alternative. A three-stage experimental strategy was designed to identify the optimal stabilization method. Stage 1 determined the ideal RHA particle size and content without RHF. Stage 2 incorporated RHF to assess its best pretreatment method and optimal dosage; Stage 3 investigated the stabilization mechanisms. A series of physical and mechanical experiments confirmed that RHA and RHF improved cement-based peat soil stabilization. RHA played a primary role as a pozzolanic material, while RHF is secondary as reinforcement. Unconfined compressive strength (UCS) increased by 146.6 % with RHA alone and by 202.1 % with both RHA and RHF compared to cement only. This is achieved by using fine RHA particles and Ca(OH)₂-treated RHF. The content for both RHA and RHF is critical, especially noting that the optimal content of RHA varies as the cement content varies. Microscopic analysis confirmed that RHA enhanced pozzolanic reaction, producing more cementitious products (C-S-H) that filled pores and bonded soil particles. Additionally, a significant quantity of cementitious products formed on the coarse surface of pre-treated RHF, reinforcing soil-fiber bonding. Stabilizing 1 m³ of peat soil by upcycling biowaste reduces carbon emissions by 61.9 % and costs by 25.8 % compared to using cement only. This study demonstrates that upcycling biowaste provides an effective, sustainable, economical, and easy-to-implement solution for improving cement-based peat soil stabilization.

传统的稳定剂，如高岭土和钠基膨润土，在应用于水泥基泥炭土稳定时引入了复杂性。本研究探索了生物废物稳定剂——稻壳灰（RHA）作为火山灰材料和稻壳纤维（RHF）作为增强剂——作为一种可持续和实用的替代品。设计了一个三阶段的实验策略来确定最优的稳定方法。第1阶段确定了理想的RHA粒度和含量，没有RHF。第二阶段纳入RHF，评价其最佳预处理方法和最佳剂量；第三阶段研究了稳定机制。一系列物理力学实验证实，RHA和RHF改善了水泥基泥炭土的稳定性。RHA作为火山灰材料起主要作用，而RHF作为补强剂起次要作用。无侧限抗压强度（UCS）与水泥相比，单独使用RHA可提高146.6%，同时使用RHA和RHF可提高202.1%。这是通过使用精细的RHA颗粒和Ca(OH)2处理的RHF来实现的。RHA和RHF的含量都是至关重要的，特别是RHA的最佳含量随着水泥含量的变化而变化。微观分析证实，RHA增强了火山灰反应，产生了更多的胶凝产物（C-S-H），这些胶凝产物填充了孔隙并粘合了土壤颗粒。此外，预处理后的RHF粗糙表面上形成了大量胶凝产物，加强了土壤-纤维的结合。与仅使用水泥相比，通过升级利用生物垃圾稳定1立方米泥炭土可减少61.9%的碳排放和25.8%的成本。该研究表明，生物垃圾的升级利用为改善水泥基泥炭土的稳定性提供了一种有效、可持续、经济且易于实施的解决方案。

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引用次数: 0

Triaxial mechanical properties and microstructure of Tianjin clay stabilized with fly ash-based geopolymer 粉煤灰基地聚合物稳定天津粘土的三轴力学性能及微观结构

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-17 DOI: 10.1016/j.sandf.2025.101687

Rui Jia , Zhenxing Chu

The triaxial mechanical properties and microscopic mechanisms of fly ash-based geopolymer-stabilized Tianjin clays with different fly ash (FA) contents, alkaline activator (AA) contents, curing times and confining pressures were investigated via triaxial and scanning electron microscopy (SEM) tests. Based on the triaxial test results, compared with the unstabilized clay, the stabilized clay exhibited a steeper stress–strain curve, a greater peak strength and pronounced strain softening behavior. A significant increase in cohesion (from 4.18 kPa to 64.5 kPa) and a slight reduction in the internal friction angle (from 30.3° to 28.6°) occurred after geopolymer stabilization. The stiffness, peak strength and residual strength of stabilized clay generally increased with increasing FA content, AA content, curing time and confining pressure. An FA/clay ratio greater than 0.1 and an AA/FA ratio greater than 0.6 were needed to achieve high strength at ambient temperature. The stabilized clay exhibited a significant strength improvement after 28 d and had a relatively high long-term strength. SEM results revealed that the chemical reactions between FA and AA led to the formation of sodium aluminosilicate hydrate (N-A-S-H) gel, which strengthened the bonds, filled the voids and reduced the porosity of the clay. As a result, the overall stiffness and strength of the stabilized clay improved. SEM analysis revealed that with a higher FA/clay ratio, a higher AA/FA ratio or a longer curing time, the geopolymerization process was more pronounced, leading to increased formation of the N-A-S-H gel and resulting in a more densely stacked and stronger bonded structure.

通过三轴和扫描电镜（SEM）研究了不同粉煤灰（FA）含量、碱性活化剂（AA）含量、养护时间和围压条件下粉煤灰基地聚合物稳定天津粘土的三轴力学性能和微观机理。三轴试验结果表明，与非稳定化粘土相比，稳定化粘土的应力-应变曲线更陡，峰值强度更高，应变软化行为明显。地聚合物稳定后，黏聚力显著增加（从4.18 kPa增加到64.5 kPa），内摩擦角略有减少（从30.3°减少到28.6°）。稳定粘土的刚度、峰值强度和残余强度随FA含量、AA含量、养护时间和围压的增加而增大。在室温条件下，FA/clay的比值大于0.1，AA/FA的比值大于0.6才能获得较高的强度。稳定黏土在28 d后强度显著提高，长期强度较高。SEM结果表明，FA与AA的化学反应生成了水合硅酸铝钠凝胶，增强了黏结，填充了空隙，降低了粘土的孔隙率。结果表明，稳定粘土的整体刚度和强度均有提高。SEM分析表明，FA/clay比越高、AA/FA比越高或固化时间越长，地聚合过程越明显，导致N-A-S-H凝胶的形成增加，形成更密集的堆积和更强的键合结构。

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引用次数: 0

Slaking mechanisms of a mudstone and prediction of its number-size distribution considering shape evolution 考虑形态演化的泥岩溶蚀机理及数粒分布预测

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-01 DOI: 10.1016/j.sandf.2025.101682

Danxi Sun , Hailong Wang , Hideo Komine , Guojun Cai , Gaofeng Pan , Daichi Ito

The wide distribution of mudstone poses challenges to efficient construction and safe long-term maintenance of infrastructure, primarily due to its susceptibility to slaking. To explore the slaking mechanisms, cyclic wetting–drying slaking tests under both atmospheric and vacuum conditions were conducted on natural mudstone collected from Akita Prefecture, Japan. A multi-view approach was employed to capture the evolution of three-dimensional particle shape, enabling quantitative analysis of slaking mechanisms and the development of number-size and surface area-size distribution models that account for shape effects. The results indicate that the atmospheric slaking proceeds more rapidly than vacuum slaking tests, attributed to the elimination of the air-breakage phenomenon. Shape evolution analysis reveals that the shell-like medium-sized particles possess higher specific surface areas, resulting from the typical layered slaking phenomenon observed during slaking. These layered fragments are attributed to differential swelling, driven by non-uniform moisture distribution in the specimens. The contribution of this mechanism is validated and quantitatively assessed through a comparative analysis of particle shape compositions across different slaking conditions. Finally, particle shape evolution is integrated into predictive models for number-size and surface area-size distributions. The performance of these models is verified against experimental measurements.

泥岩的广泛分布给基础设施的高效建设和长期安全维护带来了挑战，主要是由于泥岩易滑脱。为探索泥岩的熟化机理，在常压和真空条件下对日本秋田县天然泥岩进行了干湿循环熟化试验。采用多视角方法捕捉三维颗粒形状的演变，实现了对松弛机制的定量分析，并建立了考虑形状效应的数量-尺寸和表面积-尺寸分布模型。结果表明，由于消除了空气破碎现象，常压熟化试验比真空熟化试验进行得更快。形状演化分析表明，壳状中等颗粒具有较高的比表面积，这是由于在熟化过程中观察到典型的分层熟化现象所致。这些层状碎片是由于试样中水分分布不均匀造成的差异膨胀。这一机制的贡献是验证和定量评估，通过比较分析颗粒形状组成在不同的软化条件。最后，将颗粒形状演变整合到数量-尺寸和表面积-尺寸分布的预测模型中。通过实验验证了这些模型的性能。

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引用次数: 0

Laboratory experiments on small-scale freezing sampling method for sand 砂土小尺度冻结取样方法的室内试验研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-09-01 DOI: 10.1016/j.sandf.2025.101657

Pei-Chen Hsieh , Takashi Kiyota , Toshihiko Katagiri , Masataka Shiga , Manabu Takemasa , Ryohei Kobayashi

The need to collect high-quality undisturbed samples to accurately determine in-situ liquefaction resistance of sandy soils in laboratory tests is widely recognized. Decades ago, the freezing sampling method was developed to minimize sample disturbance by pre-freezing the ground. However, due to the large scale and high cost of the work, this method is rarely used in common geotechnical surveys. To address this issue, a small-scale freezing sampling method has recently been developed. It reduces the sampling time and amount of required coolant, and can be applied to conventional borehole surveys. On the other hand, the quality of the samples collected by this new method has not been properly assessed. In this study, therefore, the appropriate conditions for inserting the freezing tube with the help of a cylindrical sand column were discussed, and the small-scale freezing sampling method was successfully implemented in a calibration chamber, whereby hollow cylindrical frozen samples with an outer diameter of 100 mm were collected within approximately 40 min and using only about 70 kg of liquid nitrogen. The focus of the quality assessments of the collected frozen samples was placed on the density and shear wave velocity measurements. The results showed that the changes in the small strain shear moduli were −0.5 % between the stages before and after the sampling, suggesting that the implementation of small-scale freezing sampling can be expected to improve the accuracy of in-situ liquefaction resistance estimates and, in turn, the accuracy of liquefaction assessments.

在实验室测试中，需要收集高质量的原状样品来准确地测定沙土的原位液化阻力，这一点已得到广泛认识。几十年前，冻结取样法是通过对地面进行预冻结来减少取样扰动而发展起来的。但由于工程规模大、成本高，在普通岩土工程勘察中很少采用该方法。为了解决这一问题，最近开发了一种小规模冷冻取样方法。它减少了采样时间和所需冷却剂的量，可以应用于常规的井眼测量。另一方面，用这种新方法采集的样品的质量还没有得到适当的评价。因此，本研究探讨了利用圆柱形砂柱插入冷冻管的适宜条件，并在校准室中成功实施了小规模冷冻取样方法，在大约40分钟内收集了外径为100 mm的空心圆柱形冷冻样品，仅使用了约70 kg的液氮。冰冻样品的质量评价重点放在密度和横波速度的测量上。结果表明，取样前后的小应变剪切模量变化幅度为- 0.5%，表明实施小规模冻结取样有望提高现场液化阻力估算的准确性，进而提高液化评估的准确性。

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引用次数: 0