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Bearing and uplift capacities of under-reamed piles in soft clay underlaid by stiff clay using lower-bound

Mantu MAJUMDER, Debarghya CHAKRABORTY

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 537-551 doi: 10.1007/s11709-021-0708-x

摘要： Ensuring a safe foundation design in soft clay is always a challenging task to engineers. In the present study, the effectiveness of under-reamed piles in soft clay underlaid by stiff clay is numerically studied using the lower-bound finite element limit analysis (LB FELA). The bearing and uplift capacities of under-reamed piles are estimated through non-dimensional factors and , respectively. These factors increased remarkably and marginally compared to and of the piles without bulbs when the bulb is placed in stiff and soft clay, respectively. For a given ratio of undrained cohesion of stiff to soft clay ( / ), the factors and moderately increased with the increase in the length-to-shaft-diameter ratio ( / ) and adhesion factors in soft clay ( ) and stiff clay ( ). The variation of radial stress along the pile–soil interface, distribution of axial force in the under-reamed piles, and state of plastic shear failure in the soil are also studied under axial compression and tension. The results of this study are expected to be useful for the estimation of the bearing and uplift capacities of under-reamed piles in uniform clay and soft clay underlaid by stiff clay.

关键词： bearing capacity     uplift capacity     under-reamed pile     clay     limit analysis    

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Experimental investigation of the influence on static and cyclic deformation of structural soft clay

CHEN Yunmin, CHEN Yingping, HUANG Bo

《结构与土木工程前沿（英文）》 2007年 第1卷 第4期   页码 422-429 doi: 10.1007/s11709-007-0057-4

摘要： This paper presents the experimental results performed to study the static and cyclic deformation behavior of undisturbed and remolded soft clays sampling from Xiaoshan. The consolidation tests indicated that the vertical strains of

关键词： consolidation     deformation     experimental     undisturbed    

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Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

《结构与土木工程前沿（英文）》 2014年 第8卷 第2期   页码 194-200 doi: 10.1007/s11709-014-0251-0

摘要： The paper presents a numerical study on the undrained lateral response of a single, free-head, reinforced concrete pile in soft clays. Soil conditions simulating normally consolidated clays are examined—undrained shear strength increasing with depth—and the pile-soil interaction under static lateral loading is analyzed. The nonlinear ? curves proposed in literature for soft clays are imported into a beam-on-nonlinear-Winkler-foundation simulation in order to predict the pile head lateral load—displacement curve and the distribution of the horizontal displacement and bending moment along the pile. The striking differences among these methods require further investigation via 3D finite element analyses. The determination of the ultimate soil resistance from the results of the finite element analyses aims at providing the estimation of a range of values for the ultimate soil resistance coefficient with depth and the comparison of the derived values to the corresponding ones proposed by existing methodologies.

关键词： laterally loaded     pile     soft clay     p?y curves     finite element method (FEM)    

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Predicting resilient modulus of recycled concrete and clay masonry blends for pavement applications usingsoft computing techniques

Mosbeh R. KALOOP, Alaa R. GABR, Sherif M. EL-BADAWY, Ali ARISHA, Sayed SHWALLY, Jong WAN HU

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1379-1392 doi: 10.1007/s11709-019-0562-2

摘要： To date, very few researchers employed the Least Square Support Vector Machine (LSSVM) in predicting the resilient modulus ( ) of Unbound Granular Materials (UGMs). This paper focused on the development of a LSSVM model to predict the of recycled materials for pavement applications and comparison with other different models such as Regression, and Artificial Neural Network (ANN). Blends of Recycled Concrete Aggregate (RCA) with Recycled Clay Masonry (RCM) with proportions of 100/0, 90/10, 80/20, 70/30, 55/45, 40/60, 20/80, and 0/100 by the total aggregate mass were evaluated for use as UGMs. RCA/RCM materials were collected from dumps on the sides of roads around Mansoura city, Egypt. The investigated blends were evaluated experimentally by routine and advanced tests and the values were determined by Repeated Load Triaxial Test (RLTT). Regression, ANN, and LSSVM models were utilized and compared in predicting the of the investigated blends optimizing the best design model. Results showed that the ’s of the investigated RCA/RCM blends were generally increased with the decrease in RCM proportion. Statistical analyses were utilized for evaluating the performance of the developed models and the inputs sensitivity parameters. Eventually, the results approved that the LSSVM model can be used as a novel tool to estimate the of the investigated RCA/RCM blends.

关键词： Least Square Support Vector Machine     Artificial Neural Network     resilient modulus     Recycled Concrete Aggregate     Recycled Clay Masonry    

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Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 26-43 doi: 10.1007/s11709-017-0439-1

摘要： Empirical data on deep urban excavations can provide designers a significant reference basis for assessing potential deformations of the deep excavations and their impact on adjacent structures. The construction of the Shanghai Center involved excavations in excess of 33-m-deep using the top-down method at a site underlain by thick deposits of marine soft clay. A retaining system was achieved by 50-m-deep diaphragm walls with six levels of struts. During construction, a comprehensive instrumentation program lasting 14 months was conducted to monitor the behaviors of this deep circular excavation. The following main items related to ground surface movements and deformations were collected: (1) walls and circumferential soils lateral movements; (2) peripheral soil deflection in layers and ground settlements; and (3) pit basal heave. The results from the field instrumentation showed that deflections of the site were strictly controlled and had no large movements that might lead to damage to the stability of the foundation pit. The field performance of another 21cylindrical excavations in top-down method were collected to compare with this case through statistical analysis. In addition, numerical analyses were conducted to compare with the observed data. The extensively monitored data are characterized and analyzed in this paper.

关键词： deep excavation     foundation pit     soft clay     top-down method     field observation     ground surface movements     ground deformations    

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Model testing of tripod caisson foundations in silty clay subjected to eccentric lateral loads

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 467-476 doi: 10.1007/s11709-023-0933-6

摘要： In this study, model tests were conducted to investigate the bearing capacities of tripod caisson foundations subjected to eccentric lateral loads in silty clay. Lateral load–rotation curves of five eccentric-shaped tripod suction foundations were plotted to analyze the bearing capacities at different loading angles. It was observed that the loading angle significantly influenced the bearing capacity of the foundations, particularly for eccentric tripod caisson foundations. Compared with eccentric tripod caisson foundations, the traditional tripod foundation has a relatively high ultimate lateral capacity at the omnidirectional loading angle. By analyzing the displacement of the caissons, a formula for the rotational center of the tripod caisson foundation subjected to an eccentric lateral load was derived. The depth of the rotation center was 0.68–0.92 times the height of the caisson when the bearing capacity reached the limit. Under the undrained condition, suction was generated under the lid of the “up-lift” caisson, which helps resist lateral forces from the wind and waves.

关键词： tripod caisson foundation     silty clay     eccentric lateral capacity     model tests    

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Behavior of compacted clay-concrete interface

R. R .SHAKIR, Jungao ZHU

《结构与土木工程前沿（英文）》 2009年 第3卷 第1期   页码 85-92 doi: 10.1007/s11709-009-0013-6

摘要： Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared. Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface roughness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

关键词： soil structure interaction     simple shear test     interface     friction     compacted clay     interface modeling    

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Analysis of cement-treated clay behavior by micromechanical approach

Dong-Mei ZHANG, Zhen-Yu YIN, Pierre-Yves HICHER, Hong-Wei HUANG

《结构与土木工程前沿（英文）》 2013年 第7卷 第2期   页码 137-153 doi: 10.1007/s11709-013-0204-z

摘要： Experimental results show the significant influence of cement content on the mechanical properties of cement-treated clays. Cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debonding during mechanical loading are introduced in two ways: an additional cohesion in the shear sliding and a higher yield stress in normal compression. The model is used to simulate isotropic compression and undrained triaxial tests under various confining stresses on cement-treated Ariake clay and Singapore clay with various cement contents. The applicability of the present model is evaluated through comparisons between numerical and experimental results. The evolution of local stresses and local strains in inter-cluster planes are discussed in order to explain the induced anisotropy due to debonding at contact level under the applied loads. The numerical simulations demonstrate that the proposed micromechanical approach is well adapted for taking into account the main physical properties of cement-treated clay, including damage and induced anisotropy under mechanical loading.

关键词： microstructure     cementation     clay     micromechanics     anisotropy     debonding    

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Synthesis, characterization and assessment thermal properties of clay based nanopigments

Mohammad Banimahd KIEVANI, Milad EDRAKI

《化学科学与工程前沿（英文）》 2015年 第9卷 第1期   页码 40-45 doi: 10.1007/s11705-015-1505-7

摘要： Nano-clay based pigments (NCP) are new type of pigments composed of organic dyes and layered silicate-clay nano-particles, and have already been used in polymeric coatings to improve mechanical thermal and stability properties. In this paper, the basic blue 41(BB41) was intercalated into Na - montmorillonite in an aqueous medium. The dye-intercalated montmorillonite was centrifuged, dried, and milled to prepare the nanopigment particles. X-ray diffraction showed an increase in the basal spacing, thus confirming intercalation of the BB41 molecules within the nanostructures of the interlayer spaces. Fourier transform infrared spectroscopy was used for identifying the functional groups and chemical bounding of Na -montmorillonite, BB41 and montmorillonite-BB41. The morphology of NCP was also studied by transmission electron microscopy. Finally, thermo-gravimetric analysis and differential thermograms suggested the thermal stability of the intercalated dye was improved.

关键词： nanopigment     layered silicate     cationic dye     thermal properties    

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Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 1016-1024 doi: 10.1007/s11709-021-0751-7

摘要： This study investigated the use of recycled tire-derived aggregate (TDA) mixed with kaolin as a method of increasing the ultimate bearing capacity ( UBC) of a strip footing. Thirteen 1g physical modeling tests were prepared in a rigid box of 0.6 m × 0.9 m in plan and 0.6 m in height. During sample preparation, 0%, 20%, 40%, or 60% (by weight) of powdery, shredded, small-sized granular (G 1–4 mm) or large-sized granular (G 5–8 mm) TDA was mixed with the kaolin. A strip footing was then placed on the stabilized kaolin and was caused to fail under stress-controlled conditions to determine the UBC. A rigorous 3D finite element analysis was developed in Optum G-3 to determine the UBC values based on the experimental test results. The experimental results showed that, except for the 20% powdery TDA, the TDA showed an increase in the UBC of the strip footing. When kaolin mixed with 20% G (5–8 mm), the UBC showed a threefold increase over that for the unreinforced case. The test with 20% G (1–4 mm) recorded the highest subgrade modulus. It was observed that the UBC calculated using finite element modeling overestimated the experimental UBC by an average of 9%.

关键词： kaolin     physical modeling tests     stabilization     numerical modeling    

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Optimized porous clay heterostructure for removal of acetaldehyde and toluene from indoor air

Pu ZHAO,Lizhong ZHU

《环境科学与工程前沿（英文）》 2016年 第10卷 第2期   页码 219-228 doi: 10.1007/s11783-014-0760-z

摘要： Adsorption is the most widely used technology for the removal of indoor volatile organic compounds (VOCs). However, existing adsorbent-based technologies are inadequate to meet the regulatory requirement, due to their limited adsorption capacity and efficiency, especially under high relative humidity (RH) conditions. In this study, a series of new porous clay heterostructure (PCH) adsorbents with various ratios of micropores to mesopores were synthesized, characterized and tested for the adsorption of acetaldehyde and toluene. Two of them, PCH25 and PCH50, exhibited markedly improved adsorption capability, especially for hydrophilic acetaldehyde. The improved adsorption was attributed to their large micropore areas and high micropore-to-mesopore volume ratios. The amount of acetaldehyde adsorbed onto PCH25 at equilibrium reached 62.7 mg·g , eight times as much as the amount adsorbed onto conventional activated carbon (AC). Even at a high RH of 80%, PCH25 removed seven and four times more of the acetaldehyde than AC and the unmodified raw PCHs did, respectively. This new PCH optimized for their high adsorption and resistance to humidity has promising applications as a cost-effective adsorbent for indoor air purification.

关键词： porous clay heterostructure     volatile organic compounds     adsorption     adsorbent     indoor air    

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Development of soft kernel durum wheat

Craig F. MORRIS

《农业科学与工程前沿（英文）》 2019年 第6卷 第3期   页码 273-278 doi: 10.15302/J-FASE-2019259

摘要：

Kernel texture (grain hardness) is a fundamental and determining factor related to wheat ( spp.) milling, baking and flour utilization. There are three kernel texture classes in wheat: soft and hard hexaploid ( ), and very hard durum ( subsp. ). The genetic basis for these three classes lies with the Puroindoline genes. Phenotypically, the easiest means of quantifying kernel texture is with the Single Kernel Characterization System (SKCS), although other means are valid and can provide fundamental material properties. Typical SKCS values for soft wheat would be around 25 and for durum wheat≥80. Soft kernel durum wheat was created via homeologous recombination using the mutation, which facilitated the transfer of ca. 28 Mbp of 5DS that replaced ca. 21 Mbp of 5BS. The 5DS translocation contained a complete and intact locus and both puroindoline genes. Expression of the puroindoline genes in durum grain resulted in kernel texture and flour milling characteristics nearly identical to that of soft wheat, with high yields of break and straight-grade flours, which had small particle size and low starch damage. Dough water absorption was markedly reduced compared to durum flour and semolina. Dough was essentially unchanged and reflected the inherent gluten properties of the durum background. Pasta quality was essentially equal-to-or-better than pasta made from semolina. Agronomically, soft durum germplasm showed good potential with moderate grain yield and resistance to a number of fungal pathogens and insects. Future breeding efforts will no doubt further improve the quality and competitiveness of soft durum cultivars.

关键词： soft durum wheat     grain hardness     puroindolines     milling     baking     pasta     noodles    

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Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

《结构与土木工程前沿（英文）》 2015年 第9卷 第3期   页码 323-340 doi: 10.1007/s11709-015-0301-2

摘要： This paper presents a combined experimental and numerical study on the damage and performance of a soft-hard-soft (SHS) multi-layer cement based composite subjected to blast loading which can be used for protective structures and infrastructures to resist extreme loadings, and the composite consists of three layers of construction materials including asphalt concrete (AC) on the top, high strength concrete (HSC) in the middle, and engineered cementitious composites (ECC) at the bottom. To better characterize the material properties under dynamic loading, interface properties of the composite were investigated through direct shear test and also used to validate the interface model. Strain rate effects of the asphalt concrete were also studied and both compressive and tensile dynamic increase factor (DIF) curves were improved based on split Hopkinson pressure bar (SHPB) test. A full-scale field blast test investigated the blast behavior of the composite materials. The numerical model was established by taking into account the strain rate effect of all concrete materials. Furthermore, the interface properties were also considered into the model. The numerical simulation using nonlinear finite element software LS-DYNA agrees closely with the experimental data. Both the numerical and field blast test indicated that the SHS composite exhibited high resistance against blast loading.

关键词： high strength concrete (SHS)     engineered cementitious composite     interface     blast test     strain rate effect    

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Adsorption of fluoride on clay minerals and their mechanisms using X-ray photoelectron spectroscopy

Junyi DU, Daishe WU, Huayun XIAO, Ping LI

《环境科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 212-226 doi: 10.1007/s11783-010-0255-5

摘要： This research investigates the adsorption mechanisms of fluoride (F) on four clay minerals (kaolinite, montmorillonite, chlorite, and illite) under different F concentrations and reaction times by probing their fluoride superficial layer binding energies and element compositions using X-ray photoelectron spectroscopy (XPS). At high F concentrations ( = 5–1000 mg·L ), the amount of F adsorbed ( ), amount of hydroxide released by clay minerals, solution F concentration, and the pH increase with increasing . The increases are remarkable at >50 mg·L . The increases significantly by continuously modifying the pH level. At <5–100 mg·L , clay minerals adsorb H to protonate aluminum-bound surface-active hydroxyl sites in the superficial layers and induce F binding. As the increases, F , along with other cations, is adsorbed to form a quasi-cryolite structure. At >100 mg·L , new minerals precipitate and the product depends on the critical Al concentration. At [Al ]>10 mol·L , cryolite forms, while at [Al ]<10 mol·L , AlF is formed. At low (0.3–1.5 mg·L ), proton transfer occurs, and the F adsorption capabilities of the clay minerals increase with time.

关键词： clay mineral     fluoride (F)     adsorption mechanism     X-ray photoelectron spectroscopy (XPS)    

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Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0678-2

摘要： Owing to their inherent great flexibility, good compliance, excellent adaptability, and safe interactivity, soft robots have shown great application potential. The advantages of light weight, high efficiency, non-polluting characteristic, and environmental adaptability provide pneumatic soft robots an important position in the field of soft robots. In this paper, a soft robot with 10 soft modules, comprising three uniformly distributed endoskeleton pneumatic artificial muscles, was developed. The robot can achieve flexible motion in 3D space. A novel kinematic modeling method for variable-curvature soft robots based on the minimum energy method was investigated, which can accurately and efficiently analyze forward and inverse kinematics. Experiments show that the robot can be controlled to move to the desired position based on the proposed model. The prototype and modeling method can provide a new perspective for soft robot design, modeling, and control.

关键词： pneumatic artificial muscles     soft robot     modeling approach     principle of virtual work     external load    

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标题 作者 时间 类型 操作

Bearing and uplift capacities of under-reamed piles in soft clay underlaid by stiff clay using lower-bound

Mantu MAJUMDER, Debarghya CHAKRABORTY

期刊论文

Experimental investigation of the influence on static and cyclic deformation of structural soft clay

CHEN Yunmin, CHEN Yingping, HUANG Bo

期刊论文

Numerical investigation of the ultimate lateral resistance of piles in soft clay

Konstantinos P. TZIVAKOS,Michael J. KAVVADAS

期刊论文

Predicting resilient modulus of recycled concrete and clay masonry blends for pavement applications usingsoft computing techniques

Mosbeh R. KALOOP, Alaa R. GABR, Sherif M. EL-BADAWY, Ali ARISHA, Sayed SHWALLY, Jong WAN HU

期刊论文

Shanghai center project excavation induced ground surface movements and deformations

Guolin XU, Jiwen ZHANG, Huang LIU, Changqin REN

期刊论文

Model testing of tripod caisson foundations in silty clay subjected to eccentric lateral loads

期刊论文

Behavior of compacted clay-concrete interface

R. R .SHAKIR, Jungao ZHU

期刊论文

Analysis of cement-treated clay behavior by micromechanical approach

Dong-Mei ZHANG, Zhen-Yu YIN, Pierre-Yves HICHER, Hong-Wei HUANG

期刊论文

Synthesis, characterization and assessment thermal properties of clay based nanopigments

Mohammad Banimahd KIEVANI, Milad EDRAKI

期刊论文

Ultimate bearing capacity of strip footing resting on clay soil mixed with tire-derived aggregates

期刊论文

Optimized porous clay heterostructure for removal of acetaldehyde and toluene from indoor air

Pu ZHAO,Lizhong ZHU

期刊论文

Development of soft kernel durum wheat

Craig F. MORRIS

期刊论文

Performance of soft-hard-soft (SHS) cement based composite subjected to blast loading with consideration

Jun WU,Xuemei LIU

期刊论文

Adsorption of fluoride on clay minerals and their mechanisms using X-ray photoelectron spectroscopy

Junyi DU, Daishe WU, Huayun XIAO, Ping LI

期刊论文

Design and modeling of a novel soft parallel robot driven by endoskeleton pneumatic artificial muscles

期刊论文