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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    

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    

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    

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    

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    

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    

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    

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    

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)    

Retraction note to: 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)》 2016年 第10卷 第3期   页码 440-440 doi: 10.1007/s11705-016-1573-3

Geotechnical forensic investigation of a slope failure on silty clay soil—A case study

Mohammad Abubakar NAVEED, Zulfiqar ALI, Abdul QADIR, Umar Naveed LATIF, Saad HAMID, Umar SARWAR

《结构与土木工程前沿(英文)》 2020年 第14卷 第2期   页码 501-517 doi: 10.1007/s11709-020-0610-y

摘要: Qila Bala Hisar is one of the noteworthy places of Peshawar, Khyber Pakhtunkhwa. The fort was constructed on a filled ground during the 18th century and it was renovated several times by the occupants ever since. Recently, due to an earthquake of magnitude 7.3, the upper part of the south-western wall of the fort collapsed. The collapse of the wall was attributed to the failure of the retained slope. This research was undertaken to characterize the slope material, study causal factors of failure and evaluate remedial strategy. The investigation involved conventional field and laboratory testing and geophysical investigation using electrical resistivity technique to evaluate the nature of stratum. Also, X-ray Diffraction and Scanning Electron Microscopy was used to study the slope material at a molecular level to evaluate the existence of swelling potential. The analysis has shown that excessive seepage of water caused by the poor maintenance of runoff and sewage drains is the causal factor triggered by the seismic event. A remedial strategy involving soil nails, micro piles and improvement of the surface drainage is recommended.

关键词: forensic geotechnical investigation     slope failure     slope analysis     finite element method     numerical analysis     seismic loading     Qila Bala Hisar    

Nonlinear elastic model for 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2期   页码 187-194 doi: 10.1007/s11709-009-0033-2

摘要: In this paper, a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface (CCCI) based on the principle of transition mechanism failure (TMF). A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms; i.e., sliding failure and deformation failure. The clay soil used in the test was collected from the “Shuang Jang Kou” earth rockfill dam project. It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized. Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator. The mathematical relations were then incorporated into the interface model. The performance of the model is verified with the experimental results. The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.

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

Predicting resilient modulus of recycled concrete and clay masonry blends for pavement applications using

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    

Removal of elemental mercury by KI-impregnated clay

Boxiong SHEN,Jianhong CHEN,Ji CAI

《环境科学与工程前沿(英文)》 2016年 第10卷 第2期   页码 236-243 doi: 10.1007/s11783-014-0765-7

摘要: This study described the use of clay impregnated by KI in gas phase elemental mercury (Hg ) removal in flue gas. The effects of KI loading, temperature, O , SO and H O on Hg removal were investigated using a fixed bed reactor. The Hg removal efficiency of KI-clay with 3% KI loading could maintain at a high level (approximately 80 %) after 3 h. The KI-clay demonstrated to be a potential adsorbent for Hg removal when compared with activated carbon based adsorbent. O was found to be an important factor in improving the Hg removal. O was demonstrated to assist the transfer of KI to I on the surface of KI-clay, which could react with Hg directly. NO and SO could slightly improve Hg removal, while H O inhibited it greatly. The results indicated that after adsorption, most of the mercury escaped from the surface again. Some of the mercury may have been oxidized as it left the surface. The results demonstrated that the chemical reaction primarily occurred between KI and mercury on the surface of the KI-clay.

关键词: clay     elemental mercury     removal efficiency     potassium iodide     mechanism    

Evaluation of the stability of terraced slopes in clayey gravel soil using a novel numerical technique

《结构与土木工程前沿(英文)》 2023年 第17卷 第5期   页码 796-811 doi: 10.1007/s11709-023-0922-9

摘要: Conventional geotechnical software limits the use of the strength reduction method (SRM) based on the Mohr–Coulomb failure criterion to analyze the slope safety factor (SF). The use of this constitutive model is impractical for predicting the behavior of all soil types. In the present study, an innovative numerical technique based on SRM was developed to determine SF using the finite element method and considering the extended Cam–clay constitutive model for clayey gravel soil as opposed to the Mohr–Coulomb model. In this regard, a novel user subroutine code was employed in ABAQUS to reduce the stabilizing forces to determine the failure surfaces and resist and drive shear stresses on a slope. After validating the proposed technique, it was employed to investigate the performance of terraced slopes in the context of a case study. The impacts of geometric parameters and different water table elevations on the SF were examined. The results indicated that an increase in the upper and lower slope heights led to a decrease in SF, and a slight increase in the horizontal offset led to an increase in the SF. Moreover, when the water table elevation was lower than the toe of the terraced slope, the SF increased because of the increase in the uplift force as a resistant component.

关键词: terraced slope     safety factor     finite element method     ABAQUS     extended Cam–clay    

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

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

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

CHEN Yunmin, CHEN Yingping, HUANG Bo

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

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

Retraction note to: Synthesis, characterization and assessment thermal properties of clay based nanopigments

Mohammad Banimahd Kievani,Milad Edraki

期刊论文

Geotechnical forensic investigation of a slope failure on silty clay soil—A case study

Mohammad Abubakar NAVEED, Zulfiqar ALI, Abdul QADIR, Umar Naveed LATIF, Saad HAMID, Umar SARWAR

期刊论文

Nonlinear elastic model for compacted clay concrete interface

R. R. SHAKIR, Jungao ZHU

期刊论文

Predicting resilient modulus of recycled concrete and clay masonry blends for pavement applications using

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

期刊论文

Removal of elemental mercury by KI-impregnated clay

Boxiong SHEN,Jianhong CHEN,Ji CAI

期刊论文

Evaluation of the stability of terraced slopes in clayey gravel soil using a novel numerical technique

期刊论文