Soils and Foundations最新文献

Numerical insight into twin tunnelling-induced soil-structure interaction in battered pile-supported systems under lateral loading 横向荷载作用下双隧道冲击桩支护体系土-结构相互作用的数值分析

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-30 DOI: 10.1016/j.sandf.2026.101747

Mukhtiar Ali Soomro, Sharafat Ali Darban

With rapid increasing urbanization, the construction of twin tunnels adjacent to existing foundations has become common in underground development projects. This study investigates the influence of twin parallel tunnelling on elevated battered pile group and battered piled raft subjected to lateral loading in soft clay. A series of three-dimensional coupled consolidation finite element analyses, incorporating an advanced hypoplastic clay model with small-strain stiffness are carried out. The model parameters are validated using centrifuge test data to ensure realistic simulation of tunnelling-induced ground deformations. Twin tunnels are positioned at varying depths relative to the battered piled foundation: neat the shaft, near the toe, and below the toe of the piles. Results reveal that the largest lateral displacements and differential settlements occur when tunnelling is near the pile toe. The second tunnel further increases movement toward the first tunnel due to degraded ground stiffness. Compared to elevated battered pile groups, battered piled rafts exhibit significantly reduced lateral displacements, deflections, and settlements because of additional resistance from raft-soil interaction. Twin tunnelling in each case also alters axial load distribution. Twin tunnelling near pile shaft caused reduction of 61% in shaft resistance whereas 20% of end-bearing decreased in twin tunnelling near pile toe. The maximum bending moments were induced near the pile head in battered elevated pile group but are smaller in piled rafts (up to 30% reduction) in each case.

随着城市化的快速发展，在地下开发项目中，在既有基础上修建双隧道已成为一种普遍现象。研究了双平行隧道开挖对软土中受侧向荷载作用的高架破桩群和破桩筏的影响。采用先进的小应变刚度欠塑性粘土模型，进行了一系列三维耦合固结有限元分析。利用离心试验数据对模型参数进行了验证，保证了隧道开挖引起的地面变形模拟的真实性。双隧道的位置相对于破损的桩基有不同的深度：在竖井附近，在桩趾附近，在桩趾以下。结果表明，在桩端附近开挖时，桩侧位移最大，沉降差最大。由于地面刚度降低，第二条隧道进一步增加了向第一条隧道的移动。与高架桩群相比，由于筏-土相互作用的额外阻力，受损桩筏表现出显著减少的侧向位移、挠度和沉降。两种情况下的双隧道开挖也会改变轴向荷载的分布。靠近桩身的双隧道施工使桩身阻力降低61%，靠近桩脚的双隧道施工使端承降低20%。在受冲击的高架桩群中，最大弯矩在桩顶附近产生，而在桩筏中，最大弯矩减小30%。

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引用次数: 0

Sustainable soil improvement using marine-derived biopolymers: strength and durability perspectives 利用海洋生物聚合物的可持续土壤改良：强度和耐久性的观点

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-24 DOI: 10.1016/j.sandf.2026.101730

Runshen Wang , Hadi Fatehi , Dominic E.L. Ong , Jimmy Yu , Ilhan Chang , Khosro Shabani

This study provides a comprehensive evaluation of marine biopolymers for sustainable soil stabilization. It offers critical insights for countries with abundant ocean resources to support the selection of suitable biopolymer for soil enhancement. The experimental program covers a wide range of mechanical and microstructural evaluations to support a broad understanding of biopolymer-treated soil behaviour. A range of marine biopolymers was tested with a specific focus on chitosan due to its distinct structure and bonding capability. The study focused on engineered kaolinite-sand mixtures, selected for their ability to represent complex and variable soil conditions commonly encountered in the field. Experimental variables such as biopolymer content, curing time, and soil composition were systematically controlled. Mechanical properties were assessed using UCS, and static and dynamic triaxial tests to determine shear strength and resilient modulus. Durability was assessed through five cycles of wetting and drying to replicate long-term environmental exposure. Results showed that biopolymer content and soil type significantly influenced strength development and water resistance. Chitosan achieved up to a tenfold increase in UCS, with substantial strength retention and low mass loss under cyclic conditions. Microstructural analysis using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) provided insights into the chemical bonding and physical interactions at the soil–biopolymer interface. A mechanical model was proposed to explain these interactions. Overall, the study demonstrates the potential of marine biopolymers as effective, ecofriendly alternatives to traditional chemical stabilizers, offering a sustainable solution for geotechnical engineering applications.

本研究对海洋生物聚合物在土壤可持续稳定中的应用进行了综合评价。它为拥有丰富海洋资源的国家提供了重要的见解，以支持选择合适的生物聚合物用于土壤增强。实验项目涵盖了广泛的机械和微观结构评估，以支持对生物聚合物处理土壤行为的广泛理解。由于壳聚糖具有独特的结构和结合能力，因此对一系列海洋生物聚合物进行了测试。该研究的重点是工程高岭石-砂混合物，选择它们是因为它们能够代表在现场经常遇到的复杂和可变的土壤条件。实验变量如生物聚合物含量、固化时间和土壤成分被系统地控制。力学性能评估使用UCS，静态和动态三轴试验，以确定剪切强度和弹性模量。耐久性评估通过五个循环的湿润和干燥，以复制长期的环境暴露。结果表明，生物聚合物含量和土壤类型对强度发育和耐水性有显著影响。在循环条件下，壳聚糖的UCS增加了10倍，具有显著的强度保持和低质量损失。利用扫描电子显微镜（SEM）和傅里叶变换红外光谱（FTIR）进行微观结构分析，可以深入了解土壤-生物聚合物界面的化学结合和物理相互作用。提出了一个力学模型来解释这些相互作用。总的来说，该研究证明了海洋生物聚合物作为传统化学稳定剂的有效、环保替代品的潜力，为岩土工程应用提供了可持续的解决方案。

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引用次数: 0

Polyacrylamide improves the strength of peat soil while reducing cement consumption: An experimental and machine learning investigation 聚丙烯酰胺提高泥炭土的强度，同时减少水泥消耗：一项实验和机器学习研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-23 DOI: 10.1016/j.sandf.2026.101745

Yangshou Yu , Zhiliang Wang , Miao Li , Lei Lang , Linfang Shen , Yang Yu

Peat soil presents poor geotechnical properties, posing significant risks to structural stability when used as a foundation material. This study investigates the potential of polyacrylamide (PAM) as an adhesive additive to enhance the strength of peat soil stabilized with cement and sand. Unconfined compressive strength (UCS) tests were conducted to evaluate PAM’s effectiveness, complemented by microscopic analyses to explore underlying improvement mechanisms. Results show that PAM significantly increases soil strength, with higher PAM content yielding greater gains. Specifically, adding 10 % PAM boosts the UCS of untreated peat soil by up to 2.5 times and improves the strength of peat soil treated with 30 % cement and 30 % sand by 174.1 kPa. PAM also reduces soil permeability without exhibiting ecotoxicity. Microscopic observations reveal that PAM forms cross-linked gel networks that bind soil particles into large aggregates. 10 % PAM decreases the specific surface area, pore volume, and average pore size by 32.6 %, 42.2 %, and 21.4 %, respectively. Importantly, PAM does not alter the chemical composition of the stabilized soil and remains stable over time. Finally, a gene expression programming (GEP) algorithm was used to develop a predictive mathematical model for UCS, achieving a coefficient of determination (R²) above 0.97. An analysis of cement consumption using this model indicates that incorporating 10 % PAM can reduce cement consumption by 26.1 % to achieve a target strength of 300 kPa, compared with using only cement and sand. These findings demonstrate that PAM is an effective and environmentally beneficial stabilizer for peat soil.

泥炭土具有较差的岩土力学特性，当用作地基材料时，对结构稳定性构成重大风险。本研究探讨了聚丙烯酰胺（PAM）作为粘接添加剂对水泥和砂土稳定泥炭土强度的增强潜力。通过无侧限抗压强度（UCS）测试来评估PAM的有效性，并辅以微观分析来探索潜在的改进机制。结果表明，PAM能显著提高土壤强度，PAM含量越高，收益越大。具体而言，添加10% PAM可使未处理泥炭土的单抗强度提高2.5倍，使30%水泥和30%沙子处理的泥炭土强度提高174.1 kPa。PAM还能降低土壤渗透性而不表现出生态毒性。微观观察表明，PAM形成交联凝胶网络，将土壤颗粒结合成大的聚集体。10%的PAM比表面积、孔体积和平均孔径分别降低32.6%、42.2%和21.4%。重要的是，PAM不会改变稳定土壤的化学成分，并随着时间的推移保持稳定。最后，利用基因表达编程（GEP）算法建立UCS预测数学模型，确定系数（R2）在0.97以上。使用该模型对水泥消耗量进行的分析表明，与仅使用水泥和砂相比，加入10%的PAM可以减少26.1%的水泥消耗量，以达到300 kPa的目标强度。这些结果表明，PAM是一种有效的环境友好型泥炭土稳定剂。

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引用次数: 0

Cross-model feature-importance analysis of soil properties for predicting optimum moisture content and maximum dry unit weight of fine-grained soils 预测细粒土最佳含水量和最大干重的土壤特性的交叉模型特征重要性分析

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-21 DOI: 10.1016/j.sandf.2025.101728

Harish Paneru, Netra Prakash Bhandary

This study evaluates the influence of routine soil index properties on the prediction of optimum moisture content (w_opt) and maximum dry unit weight (γ_dmax), which are the primary outcomes of the Proctor compaction test, using machine learning (ML) methods. A curated database of fine-grained soils (n = 465, drawn from 15 sources) included gravel content (GC), sand content (SC), fines content (FC), liquid limit (LL), plastic limit (PL), plasticity index (PI), specific gravity (Gs), w_opt, and γ_dmax. After correlation-based feature filtering, three models were developed: Generalized Additive Model (GAM), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). The training used nested cross-validation with Bayesian optimization, corresponding to an overall 80–20 train-test split. The model performance was evaluated using R², RMSE, MAE, MAPE, r, and the overfitting ratio calculated for the test set. For w_opt, the best GAM model achieved R² = 0.84 and RMSE = 2.16%, outperforming RF and XGBoost. For γ_dmax, the best GAM and XGBoost models reached R² = 0.79 and RMSE = 0.76 kN/m³, respectively. SHapley Additive exPlanations (SHAP), model-based importance scores, and single ablation analyses consistently identified LL and PL as the most influential predictors, and FC provided secondary contributions, while GC and Gs added little once LL and PL had been included. Moreover, paired-feature ablation confirmed the joint influence of LL and PL on the prediction. Overall, all three models predicted compaction parameters with good accuracy; however, GAM models achieved comparable or better predictive metric values than the ensembles (RF and XGBoost) while offering interpretability through plots linking soil indices with the predicted outcomes. This balance of accuracy and interpretability supports GAM as the preferred model for prediction modeling.

本研究利用机器学习（ML）方法，评估了常规土壤指标特性对Proctor压实试验主要结果——最佳含水量（wopt）和最大干重（γdmax）预测的影响。一个精心设计的细粒土壤数据库（n = 465，来自15个来源）包括砾石含量（GC）、砂含量（SC）、细粒含量（FC）、液体极限（LL）、塑性极限（PL）、塑性指数（PI）、比重（Gs）、wopt和γdmax。经过相关特征滤波，建立了广义加性模型（GAM）、随机森林模型（RF）和极端梯度增强模型（XGBoost）。训练使用嵌套交叉验证与贝叶斯优化，对应于整体80-20训练测试分割。使用R2、RMSE、MAE、MAPE、r和计算测试集的过拟合比率来评估模型的性能。对于wopt，最佳GAM模型的R2 = 0.84, RMSE = 2.16%，优于RF和XGBoost。对于γ - dmax， GAM模型和XGBoost模型分别达到R2 = 0.79和RMSE = 0.76 kN/m3。SHapley加性解释（SHAP）、基于模型的重要性评分和单一消融分析一致认为LL和PL是最具影响力的预测因子，FC提供了次要贡献，而GC和Gs在包括LL和PL后几乎没有添加。此外，配对特征消融证实了LL和PL对预测的共同影响。总体而言，三种模型对压实参数的预测精度均较高；然而，GAM模型获得了与集成（RF和XGBoost）相当或更好的预测度量值，同时通过将土壤指数与预测结果联系起来的图提供了可解释性。这种准确性和可解释性的平衡支持GAM作为预测建模的首选模型。

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引用次数: 0

Enhanced diesel removal from contaminated soil: A coupled approach of negative-pressure extraction and subzero-temperature-induced migration 提高柴油从污染土壤中去除：负压萃取和零下温度诱导迁移的耦合方法

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-20 DOI: 10.1016/j.sandf.2026.101742

Liyu Yi , Jielong Rao , Yong Wan , Yaoqiang Chen , Zhixiang Chen

To reduce the energy demand of conventional high-temperature thermal desorption and related technologies for remediating organic-contaminated soils, and to elucidate the evolution of liquid-phase contaminants in soils subjected to coupled temperature–pressure fields, this study develops a remediation process that couples negative-pressure extraction with subzero-temperature-induced migration of diesel in porous media. The method exploits the depression of liquid boiling points under reduced pressure and the acceleration of fluid transport driven by temperature gradients in porous media. Saturated diesel-contaminated soils with different initial dry densities (ρ_d) were treated under low-temperature negative-pressure conditions, and diesel removal tests were conducted. The results show that, for all ρ_d considered, the removal efficiency exhibits a characteristic three-stage temporal evolution. Under subzero temperature and negative pressure, the residual diesel mass fraction in the samples stabilizes at approximately 10–12%, approaching the residual liquid content of the soil and indicating that late-stage removal is controlled by high-boiling fractions and strong sorption. Post-test energy-dispersive X-ray spectroscopy further confirms that the carbon content in the soil decreases from about 35% to 13%, demonstrating a substantial reduction in organic contamination. Overall, the proposed approach achieves stepwise, high-efficiency removal of high-boiling organic pollutants at moderate to low energy input, and provides quantitative criteria for the scale-up design and energy optimization of subzero negative-pressure remediation processes.

为了减少传统高温热解吸及相关技术修复有机污染土壤的能源需求，并阐明温度-压力耦合场下土壤中液相污染物的演变，本研究开发了一种将负压萃取与柴油在多孔介质中的亚零度迁移耦合的修复工艺。该方法利用了多孔介质中温度梯度驱动的减压下液体沸点的降低和流体输运的加速。在低温负压条件下对不同初始干密度（ρd）的饱和柴油污染土壤进行处理，并进行脱柴油试验。结果表明，对于所有考虑的ρd，去除效率都表现出特征的三阶段时间演化。在零下温度和负压条件下，样品中残余柴油质量分数稳定在10-12%左右，接近土壤残液含量，表明后期去除受高沸点和强吸附控制。测试后的能量色散x射线光谱进一步证实，土壤中的碳含量从约35%下降到13%，表明有机污染大幅减少。总体而言，该方法在中低能量输入下实现了高沸点有机污染物的分步高效去除，为零下负压修复工艺的规模化设计和能量优化提供了定量标准。

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引用次数: 0

Research on creep mechanical properties and damage mechanisms of water-saturated coal-bearing sandstone under freeze-thaw cycles 冻融循环作用下含水煤砂岩蠕变力学特性及损伤机理研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-19 DOI: 10.1016/j.sandf.2026.101743

Peng Wu , Lianying Zhang , Shuai Guo , Yiwen Mao , Fuqiang Zhu

To reveal the long-term instability mechanism of rock slopes in open-pit coal mines in cold regions, this study takes water-saturated coal-bearing sandstone from the Antaibao Open-pit Coal Mine as the research object. Systematic uniaxial compression creep tests were conducted under different freezing temperatures (−5°C, −10°C, −15°C, −20°C) and freeze–thaw cycles (5, 10, 15, 20 times). Combined with longitudinal wave velocity measurements, porosity tests, and scanning electron microscopy (SEM) meso-analysis, the coupled damage evolution law under freeze–thaw-creep conditions was elucidated. The results show that: With decreasing freezing temperature and increasing freeze–thaw cycles, the reduction rate of longitudinal wave velocity and the increment of porosity significantly increase (e.g., wave velocity reduction rate reached 29.58% at −20°C/20 cycles). The number of freeze–thaw cycles exhibits higher sensitivity to damage than freezing temperature. The creep failure stress significantly attenuates (decreased by 21.8% at −20°C compared to −5°C, and by 53.0% after 20 cycles compared to 5 cycles). The ratio of long-term strength to peak strength remained stable at approximately 80%. Microscopically, a sequential damage mechanism is identified, initiating with ice-expansion cracking, progressing to thermal fatigue accumulation, followed by pore networking, and culminating in particle spalling. This process leads to a transition in the macroscopic failure mode from pure shear to a tensile-shear composite. This study provides a theoretical basis for stability assessment and prevention of coal mine slopes in cold regions.

为揭示寒区露天矿岩质边坡长期失稳机理，本研究以安泰堡露天矿含水饱和含煤砂岩为研究对象。系统进行了不同冻结温度（- 5°C、- 10°C、- 15°C、- 20°C）和冻融循环（5、10、15、20次）下的单轴压缩蠕变试验。结合纵波测速、孔隙率测试和扫描电镜细观分析，阐明了冻融蠕变条件下的耦合损伤演化规律。结果表明：随着冻结温度的降低和冻融循环次数的增加，纵波速度降低率和孔隙率增量显著增加（−20℃/20循环时，波速降低率达到29.58%）；冻融循环次数对损伤的敏感性高于冻结温度。蠕变破坏应力显著衰减（在- 20°C时比- 5°C降低21.8%，在20次循环后比5次循环降低53.0%）。长期强度与峰值强度的比值稳定在80%左右。微观上，确定了连续的损伤机制，从冰膨胀开裂开始，发展到热疲劳积累，然后是孔隙网络，最后是颗粒剥落。这一过程导致宏观破坏模式由纯剪切向拉剪复合破坏转变。该研究为寒区煤矿边坡稳定性评价及防治提供了理论依据。

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引用次数: 0

Study on the vertical bearing characteristics and influencing factors of threaded piles 螺纹桩竖向承载特性及影响因素研究

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-19 DOI: 10.1016/j.sandf.2026.101731

Lina Xu , Peng Zhang , Chenhui Qi , Lei Niu , Junjie Zheng

This study investigated the mechanism by which thread height affects the load-bearing performance of threaded piles, as this is a critical factor influencing their vertical bearing capacity. Laboratory half-pile model tests combined with Digital Image Correlation (DIC) were used for this investigation. Concurrently, numerical simulation analysis was used to systematically examine the influence of thread height, thread pitch, thread shape and thread thickness on the load-bearing capacity of threaded piles. The findings suggest that the threaded parameters primarily influences the bearing capacity of individual threaded piles by increasing the contact area between the pile and the soil and enhancing the mechanical interlocking effects, compared to straight piles. As thread height increases, the pile’s bearing capacity increases, though at a gradually diminishing rate. Concurrently, the pile body’s material utilisation rate reaches a peak, with optimal performance observed when the thread height is between 8 and 10 mm. When the pitch ratio (i.e. the ratio of thread pitch to main pile diameter) is 1.0, the threaded pile demonstrates superior bearing capacity. In terms of thread geometry, trapezoidal threads correspond to the highest ultimate bearing capacity. Furthermore, under identical settlement values for threaded piles, trapezoidal threads maximise material utilisation efficiency. Additionally, thread thickness has a relatively minor influence on pile bearing performance.

螺纹高度是影响螺纹桩竖向承载力的关键因素，研究了螺纹高度影响螺纹桩承载性能的机理。采用室内半桩模型试验与数字图像相关（DIC）相结合的方法进行研究。同时，采用数值模拟分析方法系统考察了螺纹高度、螺纹节距、螺纹形状和螺纹厚度对螺纹桩承载能力的影响。研究结果表明，与直桩相比，螺纹参数主要通过增加桩与土的接触面积和增强机械联锁效应来影响单螺纹桩的承载力。随着螺纹高度的增加，桩的承载力逐渐增大，但增大的幅度逐渐减小。同时，桩身的材料利用率达到峰值，当螺纹高度在8 ~ 10 mm之间时性能最佳。当螺纹节距比（即螺纹节距与主桩直径之比）为1.0时，螺纹桩具有较好的承载能力。在螺纹几何形状方面，梯形螺纹对应最高的极限承载能力。此外，在相同的沉降值下，梯形螺纹最大限度地提高了材料利用效率。此外，螺纹厚度对桩的承载性能影响较小。

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引用次数: 0

Macroscale and microscale triaxial compressive behaviors of loose saturated sand under excess pore water pressure generation 超孔隙水压力作用下松散饱和砂宏、微尺度三轴压缩特性

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-19 DOI: 10.1016/j.sandf.2025.101725

Ryunosuke Kido , Yuya Ohtani , Yosuke Higo

Investigating the triaxial compressive behavior of loose saturated sand under excess pore water pressure generation, based on both macroscale and microscale observations, contributes to a better understanding of the instability mechanisms associated with the non-localized failure mode. In this study, the original intention was to conduct undrained triaxial tests on dense and loose saturated sands. However, due to the unavoidable limitations associated with X-ray CT imaging, the tests were consequently conducted under a partially drained condition. Nevertheless, the use of X-ray CT imaging, combined with image analyses, revealed clear differences in both the macroscopic responses and microscale structural evolution between dense and loose saturated sands that exhibit localized and non-localized failure modes. The loose sand examined in the present study showed a gradual increase in deviator stress until the end of shearing. During this process, the local void ratio gently decreased and the number of particle contacts gently increased due to compression. The particle-contact orientation did not change significantly from the initial state to the end of shearing. Shear strain was found to be relatively uniformly distributed over a wide region in the loose sand specimens. It is likely that these deformation characteristics of loose sand correspond to positive second-order work, indicating the stable state of the material. This behavior was clearly different from that of the dense sand specimens, for which significant dilation, a decrease in the number of particle contacts, and a change in the particle-contact orientation that occurred, were associated with a localized failure mode characterized by negative second-order work.

基于宏观尺度和微观尺度的观察，研究饱和松散砂在超孔隙水压力下的三轴压缩行为，有助于更好地理解与非局部破坏模式相关的失稳机制。本研究的初衷是对致密和松散饱和砂进行不排水三轴试验。然而，由于x射线CT成像不可避免的局限性，因此测试是在部分排水的条件下进行的。然而，使用x射线CT成像结合图像分析，揭示了致密和松散饱和砂的宏观响应和微观结构演化的明显差异，表现为局部和非局部破坏模式。本研究检测的松散砂在剪切结束前，偏应力逐渐增大。在此过程中，由于压缩作用，局部孔隙率逐渐降低，颗粒接触次数逐渐增加。从初始状态到剪切结束，颗粒接触取向没有明显变化。剪切应变在较宽的区域内相对均匀地分布。松散砂土的这些变形特征很可能对应于正二阶功，表明材料处于稳定状态。这种行为明显不同于致密砂试件，在致密砂试件中，显著的膨胀、颗粒接触数量的减少和颗粒接触方向的改变与负二阶功特征的局部破坏模式有关。

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引用次数: 0

Failure area change estimation and tunnel face pressure characteristics of large soil-covering tunnel tests 大型覆土隧道试验破坏区变化估算及工作面压力特征

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-12 DOI: 10.1016/j.sandf.2025.101723

Ryo Kawanoue , Yota Togashi , Masahiko Osada , Jiro Kuwano

Estimating the tunnel face earth pressure is essential for determining the limit support pressure in shield tunneling and for urban mountain tunnels in Japan. To meet these demands, limit equilibrium methods for calculating tunnel face pressures remain extremely important methods of calculation in tunneling practice. In limit equilibrium calculations, the appropriate setting of the failure zone prism affects the accuracy. It is crucial to properly account for changes in the height of the failure zone prism due to the frictional resistance of the ground. In this study, an improved simple method is proposed for estimating the height of the failure zone prism. The method utilizes a versatile logistic equation to describe the relationship between the soil cover and the prism height. The proposed method is a model in which the height of the failure zone prism converges to a constant value in the logistic equation as the soil cover increases, indicating an increase in frictional resistance. To validate the proposed method, tunnel tests with large soil cover ratios up to

C / D = 10

in a 1 g field are conducted, and changes in the failure zone prism and the nature of the soil pressure are determined. As a result of the tunnel tests, the width of the failure zone can be approximately expressed by the width of the wedge derived under the condition of active earth pressure. The face pressure at the initial stage of tunnel pulling in the tunnel tests is proportional to the soil cover pressure when the soil cover is small. On the other hand, as the soil cover increases, it shows a value between the earth pressure at rest and the active earth pressure. This is thought to be due to the fact that the frictional resistance of the ground increases in proportion to the soil cover. Furthermore, the height of the failure zone prism, identified by a PIV (particle image velocimetry) analysis, can be adequately represented by the proposed method. An example of how the proposed equation can be incorporated into a simple limit equilibrium calculation is described, and it is shown that the results of this calculation can properly evaluate the experimental results.

隧道工作面土压力的估算是确定盾构隧道和日本城市山地隧道极限支护压力的基础。为了满足这些要求，极限平衡法计算巷道工作面压力仍然是隧道施工实践中极为重要的计算方法。在极限平衡计算中，失效区棱柱的合理设置会影响计算精度。这是至关重要的，以适当地考虑在破坏区棱镜的高度变化，由于地面的摩擦阻力。本文提出了一种改进的简单方法来估计失效区棱镜的高度。该方法利用一个通用逻辑方程来描述土壤覆盖与棱镜高度之间的关系。所提出的方法是一个模型，在logistic方程中，随着土壤覆盖面积的增加，破坏区棱柱的高度收敛于一个常数，表明摩擦阻力的增加。为了验证该方法的有效性，在1 g条件下进行了大覆盖比（C/D=10）的隧道试验，并对破坏区棱柱的变化和土压力的性质进行了分析。隧道试验结果表明，在主动土压力条件下，破坏区宽度可近似表示为楔形板宽度。隧道试验中隧道拉拔初始阶段的工作面压力与土覆盖压力成正比。另一方面，随着覆盖面积的增加，静止土压力与活动土压力之间存在一个值。这被认为是由于地面的摩擦阻力与土壤覆盖成比例地增加。此外，通过PIV（粒子图像测速）分析，该方法可以充分表示故障区棱镜的高度。文中给出了将所提方程与简单的极限平衡计算相结合的实例，结果表明，所提方程的计算结果能较好地评价实验结果。

{"title":"Failure area change estimation and tunnel face pressure characteristics of large soil-covering tunnel tests","authors":"Ryo Kawanoue , Yota Togashi , Masahiko Osada , Jiro Kuwano","doi":"10.1016/j.sandf.2025.101723","DOIUrl":"10.1016/j.sandf.2025.101723","url":null,"abstract":"<div><div>Estimating the tunnel face earth pressure is essential for determining the limit support pressure in shield tunneling and for urban mountain tunnels in Japan. To meet these demands, limit equilibrium methods for calculating tunnel face pressures remain extremely important methods of calculation in tunneling practice. In limit equilibrium calculations, the appropriate setting of the failure zone prism affects the accuracy. It is crucial to properly account for changes in the height of the failure zone prism due to the frictional resistance of the ground. In this study, an improved simple method is proposed for estimating the height of the failure zone prism. The method utilizes a versatile logistic equation to describe the relationship between the soil cover and the prism height. The proposed method is a model in which the height of the failure zone prism converges to a constant value in the logistic equation as the soil cover increases, indicating an increase in frictional resistance. To validate the proposed method, tunnel tests with large soil cover ratios up to <span><math><mrow><mi>C</mi><mo>/</mo><mi>D</mi><mo>=</mo><mn>10</mn></mrow></math></span> in a 1 g field are conducted, and changes in the failure zone prism and the nature of the soil pressure are determined. As a result of the tunnel tests, the width of the failure zone can be approximately expressed by the width of the wedge derived under the condition of active earth pressure. The face pressure at the initial stage of tunnel pulling in the tunnel tests is proportional to the soil cover pressure when the soil cover is small. On the other hand, as the soil cover increases, it shows a value between the earth pressure at rest and the active earth pressure. This is thought to be due to the fact that the frictional resistance of the ground increases in proportion to the soil cover. Furthermore, the height of the failure zone prism, identified by a PIV (particle image velocimetry) analysis, can be adequately represented by the proposed method. An example of how the proposed equation can be incorporated into a simple limit equilibrium calculation is described, and it is shown that the results of this calculation can properly evaluate the experimental results.</div></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"66 2","pages":"Article 101723"},"PeriodicalIF":3.3,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterizing the shearing strength of compacted Qiantang River silty clay from a state-dependent perspective 基于状态依赖的钱塘江粉质黏土抗剪强度表征

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations

Pub Date : 2026-01-09 DOI: 10.1016/j.sandf.2025.101727

Xiao Wei , Hongliang Liu , Lisha Zhang , Kaiyuan Han , Xin Liu , Zhongxuan Yang

Compacted clay is widely used in geotechnical projects involving road embankment, subgrades, backfillings, etc. The shearing strength of saturated compacted clay is an important parameter in the analysis of the stability of these structures, and it is affected by states of soil, fabric, stress history, etc., making the characterization of the shearing strength remain difficult. This study investigated the shearing behaviors and shearing strength of a saturated and compacted Qiantang River silty clay using undrained triaxial compression tests. The specimens were compacted to different void ratios and saturated, followed by consolidation to different effective confining pressures for triaxial compression. The shearing behaviors are found to be state-dependent, namely, dependent on the void ratio and effective confining pressure before shearing. Several characteristic states, such as the undrained instability state, quasi-steady state, phase transformations state, and critical state, have been identified for each specimen. The deviatoric stresses at these states were characterized in the framework of critical state soil mechanics. The state parameter can be used to characterize the state-dependent shearing strength, while a modified state pressure index was proposed and found to be a better state variable for characterizing the state-dependent shearing strength of the compacted clay.

压实粘土广泛应用于道路路堤、路基、回填等岩土工程中。饱和压实黏土的抗剪强度是分析这些结构稳定性的重要参数，它受土体状态、织物状态、应力历史等因素的影响，使得抗剪强度的表征仍然很困难。采用不排水三轴压缩试验研究了饱和压实的钱塘江粉质粘土的剪切特性和抗剪强度。将试件压实至不同空隙比并达到饱和状态，然后在不同有效围压下进行三轴压缩固结。结果表明，剪切行为与剪切前孔隙比和有效围压有关。几个特征状态，如不排水不稳定状态，准稳态，相变状态，和临界状态，已确定为每个样品。在临界状态土力学框架下，对这些状态下的偏应力进行了表征。状态参数可用于表征状态相关抗剪强度，修正状态压力指数是表征压实黏土状态相关抗剪强度的较好状态变量。

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引用次数: 0