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Reliability-based settlement analysis of embankments over soft soils reinforced with T-shaped deep cementmixing piles

Chana PHUTTHANANON; Pornkasem JONGPRADIST; Daniel DIAS; Xiangfeng GUO; Pitthaya JAMSAWANG; Julien BAROTH

《结构与土木工程前沿(英文)》 2022年 第16卷 第5期   页码 638-656 doi: 10.1007/s11709-022-0825-1

摘要: This paper presents a reliability-based settlement analysis of T-shaped deep cement mixing (TDM) pile-supported embankments over soft soils. The uncertainties of the mechanical properties of the in-situ soil, pile, and embankment, and the effect of the pile shape are considered simultaneously. The analyses are performed using Monte Carlo Simulations in combination with an adaptive Kriging (using adaptive sampling algorithm). Individual and system failure probabilities, in terms of the differential and maximum settlements (serviceability limit state (SLS) requirements), are considered. The reliability results for the embankments supported by TDM piles, with various shapes, are compared and discussed together with the results for conventional deep cement mixing pile-supported embankments with equivalent pile volumes. The influences of the inherent variabilities in the material properties (mean and coefficient of variation values) on the reliability of the piled embankments, are also investigated. This study shows that large TDM piles, particularly those with a shape factor of greater than 3, can enhance the reliability of the embankment in terms of SLS requirements, and even avoid unacceptable reliability levels caused by variability in the material properties.

关键词: T-shaped deep cement mixing piles     piled embankments     settlement     reliability analysis     soil uncertainties    

Bending performance of composite bridge deck with T-shaped ribs

Qingtian SU, Changyuan DAI, Xu JIANG

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 990-997 doi: 10.1007/s11709-019-0532-8

摘要: This paper proposes a new type of steel-concrete composite deck, which is composed of orthotropic steel deck (OSD) with T-shaped ribs, concrete plate and studs connecting OSD and concrete plate. The OSD can act as framework for concrete plate and contribute to load bearing capacity at the same time, which could save construction time. Compared with conventional OSD system, this new type of composite bridge deck can also improve fatigue performance. Considering that this type of composite deck is not yet applied in practical engineering and its mechanical performance is not revealed in previous literatures, two full-scale specimens were designed and manufactured in this research. The mechanical performance, particularly, bending capacity in positive and negative region was carefully tested and analyzed. The load-deflection curve, load-slip relation, strain distribution in concrete and steel were obtained. The test results showed that the plastic performance of this kind of composite bridge deck was satisfying and the bending capacity was high.

关键词: bending performance     composite bridge deck     T-shaped steel ribs    

T形截面柱框架节点试验及非线性有限元分析

陈昌宏,黄莺,马乐为,吴敏哲,单建

《中国工程科学》 2007年 第9卷 第11期   页码 92-95

摘要:

对6个T形截面柱框架节点试件进行了试验,分别以梁截面高度、柱轴压比和节点区水平箍筋体积配箍率为变量参数,研究了节点区裂缝的形成与开展、节点的破坏机理;提出在低周期反复荷载作用下T形柱框架节点的裂缝呈反“K” 型,而不是类似于常规矩形节点的“X”型交叉裂缝,其受力机理偏于较陡的斜压杆受力模型;运用大型通用有限元软件ANSYS的二次开发语言APDL对T形截面柱节点进行非线性有限元分析,结果表明离散型非线性有限元模型计算结果与试验结果有很好的吻合。

关键词: T形节点     裂缝     破坏机理     ANSYS     非线性有限元    

A method for predicting consolidation settlements of floating column improved clayey subsoil

Jinchun CHAI, Supasit PONGSIVASATHIT,

《结构与土木工程前沿(英文)》 2010年 第4卷 第2期   页码 241-251 doi: 10.1007/s11709-010-0024-3

摘要: A method of predicting the consolidation settlement-time curve of floating soil-cement column on improved soft clayey subsoil has been proposed. The degree of the consolidation (()) of the system is calculated by the double soil-layer consolidation theory, and the methods for evaluating the equivalent hydraulic conductivity () and the coefficient of volume compressibility () of the part of the column improved layer have been proposed. The effectiveness of the method was verified by comparing predictions with the results of finite element analysis (FEA) using a unit cell model. The consolidation settlement (()) can be calculated by the method of treating a part of the column improved layer as an unimproved layer and using the corresponding average () value. By comparing the predicted results with the measurements of laboratory model tests and three case histories in Fukuoka, Japan, the effectiveness of the proposed methods has been verified. It is suggested that the method can be used for designing the soft clayey subsoil improvement using floating soil-cement columns.

关键词: cement depth mixing     ground improvement     consolidation     settlement    

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

《结构与土木工程前沿(英文)》 2022年 第16卷 第8期   页码 1017-1028 doi: 10.1007/s11709-022-0871-8

摘要: The effect of size on the biaxial flexural strength (BFS) of Portland cement mortar was investigated by using the recently proposed triangular plate method (TPM). An experimental program was conceived to study the size effect by keeping a constant water-cement ratio of 0.485, cement-sand ratio of 1:2.75, and using unreinforced triangular mortar plates of five different thicknesses and seven different side lengths. The BFS of the produced specimens was tested, and variations of BFS depending on specimen thickness and side length were determined. The results indicated that increases in triangular plate specimen side length and specimen thickness led to a decrease in the BFS of Portland cement mortar. The effect of specimen length increase on BFS was more significant than on the effect of the specimen thickness. The variations in specimens’ thickness indicated a deterministic Type I size effect, while the variations in specimens’ length showed an energetic-statistical Type I size effect.

关键词: testing     apparatus & methods     plain concrete     tensile properties     biaxial flexural strength     triangular plate method    

Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

《结构与土木工程前沿(英文)》 2013年 第7卷 第3期   页码 296-303 doi: 10.1007/s11709-013-0217-7

摘要: This paper investigates the performance of T-stub connected semi-rigid joint of rectangular tubular columns and H-shaped steel beams. The finite element analysis software ABAQUS is used to analyze the nonlinear performance of the joint under monotonic loading. Meanwhile, the dimensions of T-stub, column and beam are considered as analytic parameters to discuss the performance of the joint. The analysis shows that the thickness and the length of T-stub webs, the height of beam section, bolt diameter, shear connector and the preloaded force affect the performance of the joint largely, and the thickness of the steel tube, the thickness and length of T-stub flange, bolt spacing have relatively little influences on the performance of the joint. The research results indicate that this joint is semi-rigid joint.

关键词: rectangular tubular columns     T-stub     semi-rigid     nonlinear finite element analysis     moment-rotation curves    

深层搅拌桩墙围护结构裂缝成因探讨

高文华,王祥秋,陈秋南,张志敏

《中国工程科学》 2005年 第7卷 第12期   页码 88-91

摘要:

针对基坑支护中深层搅拌桩墙围护结构出现的开裂,采用Mindlin厚板理论对其受力与变形性状进行弹塑性分析,建立了墙体的厚板力学模型和三维有限元分析模型,并编制了有限元分析程序;基于墙体受到纵向弯矩、横向弯矩和扭矩的综合作用,提出采用等效弯矩法评价墙体的综合抗弯性能;利用所编制的程序,获得了某基坑深层搅拌桩墙围护结构墙体水平位移和等效弯矩的空间分布规律;计算结果表明,墙体东侧环球广场横向支撑附加力的作用是使墙体形成破裂面的主要原因。

关键词: 裂缝     深层搅拌桩墙     厚板     等效弯矩     三维有限元    

A methodology of implementing target mixing ratio for asphalt mixture

Yucheng HUANG, Lun JI, Rui WEN, Ming ZHANG

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 308-314 doi: 10.1007/s11709-017-0405-y

摘要: In order to implement the objective mix design of hot mix asphalt adequately during the construction process, the significance of objective mixing ratio was elaborated, and the variability of materials and its control method were analyzed. An engineering example is used to illustrate the debugging process of asphalt mixture batching & mixing plant and the dynamic quality management methods. The results show that the set of methods can not only implement the objective mixing ratio of hot mix asphalt adequately, but also control production during the construction process effectively.

关键词: asphalt mixture     target mixing ratio     mix design implementation     batching & mixing plant debugging    

深部矿产资源开采与利用中的挑战

蔡美峰,Brown Edwin T.

《工程(英文)》 2017年 第3卷 第4期   页码 432-433 doi: 10.1016/J.ENG.2017.04.027

Characterization of micro-mixing in a novel impinging streams reactor

Hui HU, Zhiming CHEN, Zhen JIAO

《化学科学与工程前沿(英文)》 2009年 第3卷 第1期   页码 58-64 doi: 10.1007/s11705-009-0106-8

摘要: This paper presents an experimental investigation of a novel impinging stream reactor (ISR) with the aim of high mixing intensity. The integral mixing quality in the reactor was measured with the iodide-iodate reaction and showed excellent mixing performance. The impact of the operating parameters, such as fluxes, circulation and inter-nozzle distances, was investigated in terms of segregation index. The results showed that the increase of flux, the decrease of inter-nozzle distance and a suitable circulation can improve the micro-mixing efficiency. Based on turbulence theory, it was estimated that the characteristic micro-mixing time was 0.002—0.02 s, which was much shorter than that in the stirred tank reactor. The micro-mixing time was related to the segregation index, which was in good agreement with those in the literature.

关键词: micro-mixing     impinging streams reactor     turbulent mixing     mass transfer    

Probabilistic analysis of secant piles with random geometric imperfections

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 682-695 doi: 10.1007/s11709-021-0703-2

摘要: The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed, resulting in water leakage or even ground collapse. To establish a more realistic simulation and provide guidelines for designing a safe and cost-effective secant-pile wall, a three-dimensional model of a secant pile, considering the geometric imperfections of the diameter and direction of the borehole, is introduced. An ultrasonic cross-hole test was performed during the construction of secant piles in a launching shaft in Beijing, China. Based on the test results, the statistical characteristics of the pile diameters and orientation parameters were obtained. By taking the pile diameter D, inclination angle β, and azimuth angle α as random variables, Monte Carlo simulations were performed to discuss the influence of different design parameters on the probability density functions of the overlap of secant piles. The obtained results show that the randomness of the inclination angle and pile diameter can be well described by a normal distribution, whereas the azimuth angle is more consistent with a uniform distribution. The integrity of the secant-pile wall can be overestimated without considering the uncertainty of geometric imperfections. The failure of the secant-pile wall increases substantially with increasing spatial variability in drilling inclination and diameter. A design flowchart for pile spacing under the target safety level is proposed to help engineers design a safe and economical pile wall.

关键词: secant piles     ultrasonic cross-hole testing     probabilistic analysis     reliability-based design     random imperfections    

苏通大桥索塔深水群桩基础冲刷防护工程的设计与施工

何平,管义军,张雄文,张群,周建华

《中国工程科学》 2009年 第11卷 第3期   页码 44-50

摘要:

从苏通大桥深水群桩基础结构方案出发,分析了冲刷及防护对大桥安全性的影响,进而从防护工程理念、结构设计与施工、防护效果监测等方面阐述了苏通大桥基础冲刷难题的解决方法。

关键词: 苏通大桥     深水群桩     冲刷防护     设计与施工    

Chemical probe systems for assessing liquid–liquid mixing efficiencies of reactors

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1323-1335 doi: 10.1007/s11705-022-2275-7

摘要: Liquid–liquid mixing, including homogeneous and heterogeneous mixing, widely exists in the chemical industry. How to quantitatively characterize the mixing performance is important for reactor assessment and development. As a convenient and direct method for mixing characterization, the chemical probe method uses some special test reactions to characterize the mixing results. Here, the working principle and selection requirements of this method are introduced, and some common chemical probe systems for homogeneous and heterogeneous mixing processes are reviewed. The characteristics and applications of these systems are illustrated. Finally, the development of the new system is proposed.

关键词: mixing     chemical probe     liquid–liquid     heterogeneous    

Extending blending proportions of ordinary Portland cement and calcium sulfoaluminate cement blends:

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1249-1260 doi: 10.1007/s11709-021-0770-4

摘要: This study extended blending proportion range of ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement blends, and investigated effects of proportions on setting time, workability, and strength development of OPC-CSA blend-based mixtures. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were conducted to help understand the performance of OPC-CSA blend-based mixtures. The setting time of the OPC-CSA blends was extended, and the workability was improved with increase of OPC content. Although the early-age strength decreased with increase of OPC content, the strength development was still very fast when the OPC content was lower than 60% due to the rapid formation and accumulation of ettringite. At 2 h, the OPC-CSA blend-based mortars with OPC contents of 0%, 20%, 40%, and 60% achieved the unconfined compressive strength (UCS) of 17.5, 13.9, 9.6, and 5.0 MPa, respectively. The OPC content had a negligible influence on long-term strength. At 90 d, the average UCS of the OPC-CSA blend-based mortars was 39.2 ± 1.7 MPa.

关键词: calcium sulfoaluminate cement     cement blends     hydration reaction     setting     workability     compressive strength    

ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cementmortar; influence of cement fineness and water/cement ratio

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 191-201 doi: 10.1007/s11709-021-0792-y

摘要: A new insight into the interfacial transition zone (ITZ) in cement mortar specimens (CMSs) that is influenced by cement fineness is reported. The importance of cement fineness in ITZ characterizations such as morphology and thickness is elucidated by backscattered electron images and by consequences to the compressive (Fc) and flexural strength (Ff), and porosity at various water/cement ratios. The findings indicate that by increasing the cement fineness the calcium silicate hydrate formation in the ITZ is favored and that this can refine the pore structures and create a denser and more homogeneous microstructure. By increasing cement fineness by about 25% of, the ITZ thickness of CMSs was reduced by about 30% and Fc was increased by 7%–52% and Ff by 19%–40%. These findings illustrate that the influence of ITZ features on the mechanical strength of CMSs is mostly related to the cement fineness and ITZ microstructure.

关键词: cement fineness     interfacial transition zone     compressive and flexural strength    

标题 作者 时间 类型 操作

Reliability-based settlement analysis of embankments over soft soils reinforced with T-shaped deep cementmixing piles

Chana PHUTTHANANON; Pornkasem JONGPRADIST; Daniel DIAS; Xiangfeng GUO; Pitthaya JAMSAWANG; Julien BAROTH

期刊论文

Bending performance of composite bridge deck with T-shaped ribs

Qingtian SU, Changyuan DAI, Xu JIANG

期刊论文

T形截面柱框架节点试验及非线性有限元分析

陈昌宏,黄莺,马乐为,吴敏哲,单建

期刊论文

A method for predicting consolidation settlements of floating column improved clayey subsoil

Jinchun CHAI, Supasit PONGSIVASATHIT,

期刊论文

Effect of size on biaxial flexural strength for cement-based materials by using a triangular plate method

Hakan T TURKER

期刊论文

Performance study on T-stub connected semi-rigid joint between rectangular tubular columns and H-shaped

Guochang LI, Hongping YU, Chen FANG

期刊论文

深层搅拌桩墙围护结构裂缝成因探讨

高文华,王祥秋,陈秋南,张志敏

期刊论文

A methodology of implementing target mixing ratio for asphalt mixture

Yucheng HUANG, Lun JI, Rui WEN, Ming ZHANG

期刊论文

深部矿产资源开采与利用中的挑战

蔡美峰,Brown Edwin T.

期刊论文

Characterization of micro-mixing in a novel impinging streams reactor

Hui HU, Zhiming CHEN, Zhen JIAO

期刊论文

Probabilistic analysis of secant piles with random geometric imperfections

期刊论文

苏通大桥索塔深水群桩基础冲刷防护工程的设计与施工

何平,管义军,张雄文,张群,周建华

期刊论文

Chemical probe systems for assessing liquid–liquid mixing efficiencies of reactors

期刊论文

Extending blending proportions of ordinary Portland cement and calcium sulfoaluminate cement blends:

期刊论文

ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cementmortar; influence of cement fineness and water/cement ratio

期刊论文