Soils and Foundations最新文献_第2页

Microstructural characterisation of foam-induced porosity in lightweight cemented soils using X-ray micro-tomography 用x射线微层析成像技术表征轻质胶结土泡沫孔隙的微观结构

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-11-06 DOI: 10.1016/j.sandf.2025.101706

F. Ferriero , L. Perrotta , L. Pappalardo , G. Buono , E. Vitale , G. Russo

Lightweight Cemented Soils (LWCS), produced by mixing natural soil, water, cement and air foam, are characterised by high workability, good mechanical properties and reduced unit weight. Their microstructure is complex and consists of large foam-induced voids embedded within a cemented porous matrix. The matrix has been recently studied, whereas there is a lack of knowledge about the distribution, size and stability of foam-induced voids during the chemo-physical evolution of the system. In this study, a novel microstructural investigation has been developed by performing X-ray microtomography on LWCS samples lightened with 40 % of foam at increasing curing time. The use of this technique allows quantitative analysis on the evolution of the foam-induced voids, not achievable by other conventional experimental techniques (e.g., Mercury Intrusion Porosimetry). Image analysis of X-ray microtomography scans shows that the foam-induced porosity remains stable (i.e., without collapse or coalescence) over curing time, whereas shrinkage fractures due to cement hydration lead to a slight increase of the porosity. Moreover, the frequency of largest voids decreases slightly due to precipitation of new compounds. The hydraulic conductivity of LWCS is estimated for the first time through a Pore Network Model, based on the real microstructure of the material, obtained from X-ray microtomography scans. The computed hydraulic conductivity is compared with the permeability of the matrix (i.e. cemented sample without foam) derived from Mercury Intrusion Porosimetry test and with the hydraulic conductivity estimated from experimental tests. The numerical result shows a good agreement with the experimental data (the values are of the same order of magnitude i.e., 10⁻¹⁰ m/s), highlighting that, for the considered foam content, hydraulic conductivity of LWCS is primarily controlled by the permeability of the matrix, as air voids and shrinkage fractures are isolated and accessible only through the matrix.

轻质胶结土（LWCS）是由天然土壤、水、水泥和空气泡沫混合而成，具有可加工性高、力学性能好、单位重量轻等特点。它们的微观结构复杂，由嵌入在胶结多孔基质中的大泡沫诱导空隙组成。近年来，人们对基质进行了研究，但在体系的化学物理演化过程中，人们对泡沫诱导空洞的分布、大小和稳定性缺乏了解。在这项研究中，通过对添加40%泡沫的LWCS样品在增加固化时间下进行x射线显微断层扫描，开发了一种新的微观结构研究。使用该技术可以定量分析泡沫诱导空洞的演变，这是其他传统实验技术（例如汞侵入孔隙法）无法实现的。x射线微断层扫描图像分析显示，在固化过程中，泡沫诱导的孔隙度保持稳定（即没有坍塌或聚结），而水泥水化导致的收缩裂缝会导致孔隙度略有增加。此外，由于新化合物的析出，最大空洞的频率略有降低。通过基于x射线显微断层扫描获得的材料真实微观结构的孔隙网络模型，首次估算了LWCS的水力导电性。将计算得到的水力导率与压汞孔隙法测试得到的基质（即无泡沫胶结试样）的渗透率以及实验测试估计的水力导率进行比较。数值结果与实验数据吻合较好（数值均为10 ~ 10m /s），说明在考虑泡沫含量的情况下，LWCS的导流率主要受基质渗透率的控制，孔隙和收缩裂缝是隔离的，只能通过基质进入。

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引用次数: 0

Field investigation of steel screw micropiles under axial loads in cohesionless and cohesive soils 无黏性和粘性土中轴向荷载作用下钢螺纹微桩的现场研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-10-30 DOI: 10.1016/j.sandf.2025.101705

João Batista de Oliveira Libório Dourado , Lijun Deng

Steel screw micropiles are a new pile type for light load applications or building remediation, offering several advantages over conventional concrete piles. Unique feature of screw micropile shafts requires distinctive design approaches; despite the growing use, there is limited field measured data on their axial failure or torque-based design. This study aims to evaluate the ultimate capacity of screw micropiles, analyze the axial failure mode, develop empirical correlations between installation torque and ultimate capacity, and refine a torque estimation method based on Cone Penetration Tests (CPT). Full-scale axial compression tests in both cohesionless and cohesive soils were performed on five screw micropile types with diameters ranging from 76 mm to 114 mm and lengths from 1.6 m to 3.0 m. Each test was repeated three times, totalling 30 tests. In-situ and laboratory investigations were conducted to characterize the soils. Results showed that in cohesionless soil, installation torque increased linearly with depth; while in cohesive soil, torque tended to stabilize after the threaded segment was fully embedded. The evidence suggests the impact of soil strength and disturbance on installation torque. A reliable linear relationship was observed between installation torque and ultimate capacities, with torque factors (defined as the ratio of pile ultimate capacity to max installation torque) ranging from 21.5 to 27.8 m⁻¹. Back-analysis suggested that the axial failure is governed by local bearing beneath each thread. The CPT-based torque estimation method in previous studies for piles in cohesive soil was revised to include the effect of smooth segment, and the revised method suggested consistent comparison with the measured torque.

钢螺旋微桩是一种用于轻载应用或建筑修复的新型桩型，与传统的混凝土桩相比具有许多优点。螺旋微桩桩身的独特特点要求其设计方法与众不同；尽管使用越来越多，但关于轴向失效或基于扭矩的设计的现场测量数据有限。本研究旨在评估螺旋微桩的极限承载力，分析轴向破坏模式，建立安装扭矩与极限承载力的经验相关性，并完善基于锥贯入试验（CPT）的扭矩估计方法。采用直径为76 mm ~ 114 mm、长度为1.6 m ~ 3.0 m的5种螺纹微桩进行了无黏性和粘性土的全尺寸轴压试验。每个试验重复3次，共30次。进行了现场和实验室调查，以表征土壤。结果表明：在无黏性土中，安装扭矩随深度线性增加；而在粘性土中，螺纹段完全嵌入后，扭矩趋于稳定。有证据表明，土的强度和扰动对安装扭矩的影响。安装扭矩与极限承载力之间存在可靠的线性关系，扭矩因子（定义为桩的极限承载力与最大安装扭矩的比值）在21.5 ~ 27.8 m−1之间。反分析表明轴向破坏是由每根螺纹下的局部轴承控制的。对以往研究中基于cpt的粘性土中桩的扭矩估计方法进行了修正，加入了光滑段的影响，修正后的方法与实测扭矩比较一致。

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引用次数: 0

Interface clogging between soil and attenuation layer of embankment based on LBM-DEM coupled numerical method 基于LBM-DEM耦合数值方法的路堤土与衰减层界面堵塞

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2025-10-17 DOI: 10.1016/j.sandf.2025.101697

Xudong Zhang, Atsushi Takai, Tomohiro Kato, Takeshi Katsumi

The reuse of excavated soil is a popular topic all around the world. To decrease the contaminants in excavated soil influencing the ground, an attenuation layer is generally used to absorb these contaminants and isolate the excavated soil and ground. The drainage clogging problem that is sometimes generated has attracted much attention in embankment engineering. The attenuation layer drainage effect is not only related to the loading capacity of the ground, but also to the soil properties. Thus, it is significant to clarify the mechanism of drainage clogging. As the micro monitoring of clogging is still difficult to achieve, a numerical simulation method is used in the present study to elaborate this mechanism. Based on the coupled lattice Boltzmann method (LBM) and discrete element method (DEM), the drainage clogging phenomenon during the filtering process is simulated from a micro perspective. The results indicate that particles can form an arch structure and lead to clogging above the pore of the attenuation layer. The formation of such a clogging arch structure prevents the discharge of soil particles and greatly decreases the fluid velocity, approximately 2.7 and 9.3 times for the two types of soil used in this study, namely, Soil A and Soil B, respectively. It is noted that the fluid velocity, rather than impermeability, remains a basic value. The velocity distribution around the pore of the attenuation layer has a certain shape depending on the velocity of the LBM cells. The size of this distribution regularly changes with the distance to the attenuation layer pore. In addition, knowledge of the soil skeleton is necessary for analyzing the arch-forming process in polydisperse particle systems. The larger particles (0.043–0.085 cm) are closely related to the formation of the soil skeleton, whereas the finer particles are related to the filling and stabilization of the soil skeleton. The clog stabilization of the soil particles in these two samples is mainly controlled by the average normal forces (1.87 × 10⁻⁶ N and 1.20 × 10⁻⁶ N, respectively) according to the variation in forces during the clogging process. Based on the analysis, an explanation of the clogging process is proposed in this study from a microscopic perspective, providing a better description of the soil skeleton clogging theory under embankment drainage.

挖掘土的再利用是一个世界性的热门话题。为了减少开挖土中污染物对地面的影响，一般采用衰减层来吸收这些污染物，将开挖土与地面隔离。堤防工程中经常出现的排水堵塞问题已引起人们的广泛关注。衰减层的排水效果不仅与地基的承载能力有关，还与土体性质有关。因此，阐明排水堵塞机理具有重要意义。由于堵塞的微观监测仍然难以实现，本研究采用数值模拟的方法来阐述这一机制。基于耦合晶格玻尔兹曼法（LBM）和离散元法（DEM），从微观角度模拟了滤波过程中的排水堵塞现象。结果表明：颗粒可形成拱形结构，导致衰减层孔隙上方堵塞；这种堵塞拱结构的形成阻止了土壤颗粒的排出，大大降低了流体流速，对于本研究中使用的两种土壤，即a土和B土，流速分别约为2.7倍和9.3倍。值得注意的是，流体速度，而不是不渗透性，仍然是一个基本值。衰减层孔隙周围的速度分布随LBM细胞的速度而具有一定的形状。该分布的大小随到衰减层孔隙的距离有规律地变化。此外，了解土壤骨架对于分析多分散颗粒体系的拱形过程是必要的。大颗粒（0.043 ~ 0.085 cm）与土骨架的形成密切相关，而细颗粒则与土骨架的填充和稳定有关。根据堵塞过程中作用力的变化，两种样品的土粒的堵塞稳定主要受平均法向力（分别为1.87 × 10−6 N和1.20 × 10−6 N）的控制。在此基础上，本研究从微观角度对堵塞过程进行了解释，更好地描述了路堤排水条件下的土骨架堵塞理论。

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引用次数: 0

Normal and seismic performance of backfill sand enhanced with biomass waste-derived materials under road pavement 路面下生物质废弃物源材料增强充填砂的正常及抗震性能

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.2025.101655

Yinglong Liu , Maliki Otieboame Djandjieme , Kimitoshi Hayano , Hiromoto Yamauchi , Cong Li

Sandy soils used in backfilling to support daily traffic and pavement loads are prone to liquefaction during earthquakes, causing extensive damage to underground infrastructures, disrupting daily life, and requiring costly repairs. Although stabilizers, such as cement-based treatments, have been widely used to address liquefaction, concerns regarding their environmental effects, particularly carbon emissions during cement production, necessitate the investigation into more sustainable materials. Compared with traditional cement-based materials, paper sludge ash-based stabilizer (PSAS) processing emits significantly lower amounts of carbon dioxide. Furthermore, PSA is produced as a by-product of paperboard and roll paper manufacturing, and wood is a renewable resource, while cement is made from limestone, a nonrenewable natural resource. In this study, PSAS-treated backfill sand was synthesized to assess its strength, liquefaction resistance, and durability. The PSAS-treated sand maintained a compressive strength of approximately 500 kPa at an addition ratio of 5.0 %, ensuring moderate strength for excavations near manholes and pipes. Consolidated drained triaxial compression tests showed that the cohesion (c_d) increased significantly with extended curing periods, increased density, and higher additive contents. Conversely, the angle of shear resistance (ϕ_d) remained largely unchanged with variations in density and curing periods, but increased as the additive content was increased. In addition, the treated sand demonstrated non-liquefaction behavior with increased deformation resistance over time. During dry–wet curing cycles, the compressive strength of the PSAS-treated sand initially increased, but then decreased as the number of cycles increased. However, the cone resistance of treated sand remained significantly higher than that of untreated sand, indicating high durability under restrained conditions. Thus, PSAS-treated sand was seen to meet the desired mechanical and structural requirements, while adhering to environmental sustainability goals, demonstrating significant potential as a backfill material in areas with seismic activity.

用于支持日常交通和路面负荷的回填砂土在地震期间容易液化，对地下基础设施造成广泛破坏，扰乱日常生活，并需要昂贵的维修。虽然稳定剂（如水泥基处理）已广泛用于解决液化问题，但考虑到它们对环境的影响，特别是水泥生产过程中的碳排放，有必要研究更可持续的材料。与传统的水泥基材料相比，纸污泥灰基稳定剂（PSAS）处理的二氧化碳排放量显著降低。此外，PSA是纸板和卷筒纸生产的副产品，木材是可再生资源，而水泥是由不可再生的自然资源石灰石制成的。在这项研究中，合成了psas处理的回填砂，以评估其强度，抗液化性和耐久性。在添加比为5.0%的情况下，经psas处理的砂保持了约500 kPa的抗压强度，确保了沙井和管道附近的开挖强度适中。固结排水三轴压缩试验表明，随着养护时间的延长、密度的增加和添加剂含量的增加，粘聚力（cd）显著增加。相反，抗剪角（ϕd）随着密度和养护时间的变化基本保持不变，但随着添加剂含量的增加而增加。此外，处理后的砂土表现出不液化的行为，随着时间的推移，抗变形能力增加。在干湿循环过程中，psas处理砂的抗压强度随循环次数的增加先增加后降低。然而，处理砂的锥体阻力仍显著高于未处理砂，表明在约束条件下具有较高的耐久性。因此，经psas处理的沙子既能满足预期的机械和结构要求，又符合环境可持续性目标，在地震活动地区作为回填材料具有巨大潜力。

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引用次数: 0

Dewatering of bentonite slurries by the combined use of polymeric ferric sulfate (PFS) and optimized flocculation-preloading-electroosmosis (FPE) 聚合硫酸铁（PFS）与优化絮凝-预载-电渗透（FPE）联合脱水膨润土浆料

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.2025.101701

Zhijia Xue , Qiquan Deng , Xin Hou , Xiao Lu , Ziwei Zhang , Chuanxin Du , Zhifeng Tian

To improve the dewatering of bentonite slurries, a combined approach using polymeric ferric sulfate (PFS) and preloading was introduced into a pretreatment program for electroosmotic dewatering. The mechanisms underlying the promotion of electroosmotic dewatering by PFS and the optimization of the flocculation-preloading-electroosmosis process were investigated. The flocculation effect of the slurry was positively correlated with PFS. A 2 % PFS solution increased flocculation settlement by 164.3 %, mainly by promoting the conversion of weakly bound water into free water and increasing the effective stress of the bentonite slurry. The bridging action of PFS flocculation promoted the formation of clear water flow channels, thus enhancing electroosmotic dewatering. Additionally, PFS reduced the proportion of electroosmotic dewatering in the FPE dewatering process, leading to lower power consumption. Preloading promoted dewatering and minimized the variations in flocculation settlement resulting from different PFS dosages during the flocculation dewatering stage. During electroosmosis, the pressure loading induced the closure of cracks formed due to negative pore water pressure, thereby increasing both the current and drainage volume. Furthermore, an optimized treatment scheme combining flocculation, preloading, and electroosmosis (3.10 h of flocculation and 18.33 h of preloading) produced optimized dewatering results. This study presents a potentially effective solution for mitigating the environmental impact of bentonite slurries.

为改善膨润土浆料的脱水性能，将聚合硫酸铁（PFS）与预压相结合的方法引入电渗透脱水预处理方案。研究了PFS促进电渗透脱水的机理及絮凝-预载-电渗透工艺的优化。浆料的絮凝效果与PFS呈正相关。2%的PFS溶液使絮凝沉降提高了164.3%，主要是通过促进弱结合水向自由水的转化和增加膨润土浆体的有效应力来实现的。PFS絮凝的桥接作用促进了清澈水流通道的形成，从而增强了电渗透脱水。此外，PFS降低了FPE脱水过程中电渗透脱水的比例，从而降低了功耗。预压促进了絮凝脱水，减小了不同PFS投加量对絮凝沉降的影响。在电渗透过程中，压力加载导致负孔隙水压力形成的裂缝闭合，从而增加了电流和排水体积。采用絮凝、预压、电渗相结合的最佳处理方案（絮凝时间3.10 h，预压时间18.33 h）获得最佳脱水效果。本研究提出了一种潜在的有效解决方案，以减轻膨润土浆料对环境的影响。

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引用次数: 0

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