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Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

《结构与土木工程前沿（英文）》 2020年第14卷第3期页码 646-663 doi: 10.1007/s11709-020-0584-9

摘要： There are two major challenges faced by modern society: energy security, and lowering carbon dioxide gas emissions. Thermo-active diaphragm walls have a large potential to remedy one of these problems, since they are a renewable energy technology that uses underground infrastructure as a heat exchange medium. However, extensive research is required to determine the effects of cyclic heating and cooling on their geotechnical and structural performance. In this paper, a series of detailed finite element analyses are carried out to capture the fully coupled thermo-hydro-mechanical response of the ground and diaphragm wall. It is demonstrated that the thermal operation of the diaphragm wall causes changes in soil temperature, thermal expansion/shrinkage of pore water, and total stress applied on the diaphragm wall. These, in turn, cause displacements of the diaphragm wall and variations of the bending moments. However, these effects on the performance of diaphragm wall are not significant. The thermally induced bending strain is mainly governed by the temperature differential and uneven thermal expansion/shrinkage across the wall.

关键词： thermo-active diaphragm wall finite element analysis thermo-hydro-mechanical coupling ground source heat pump

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Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

《结构与土木工程前沿（英文）》 2009年第3卷第1期页码 93-100 doi: 10.1007/s11709-009-0015-4

摘要： Rectangular-closed-diaphragm-wall foundation is a new type of bridge foundation. Diaphragm wall-soil-cap interaction was studied using a model test. It was observed that the distribution of soil resistance under the cap is not homogeneous. The soil resistance in the corner under the cap is larger than that in the border; and that in the center is the smallest. The distribution of soil resistance under the cap will be more uniform, if the sectional area of soil core is enlarged within a certain range. Due to the existence of cap, there is a “weakening effect” in inner shaft resistance of the upper wall segments, and there is “enhancement effect” in the lower wall segments and in toe resistance. The load shearing percentage of soil resistance under the cap is 10%-20%. It is unreasonable to ignore the effects of the cap and the soil resistance under the cap in bearing capacity calculations.

关键词： diaphragm wall bridge foundation low cap interaction

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The behavior of a rectangular closed diaphragm wall when used as a bridge foundation

Qiangong CHENG, Jiujiang WU, Zhang SONG, Hua WEN

《结构与土木工程前沿（英文）》 2012年第6卷第4期页码 398-420 doi: 10.1007/s11709-012-0175-5

摘要： The rectangular closed diaphragm (RCD) wall is a new type of bridge foundation. Compared to barrette foundation, measuring the performance of RCD walls is relatively complicated because of their incorporation of a soil core. Using the FLAC3D software, this paper investigates the deformation properties, soil resistance and skin friction of a laterally loaded RCD wall as well as the settlement, axial force and load-sharing ratio of a vertically loaded RCD wall. Special attention is given to the analysis of factors that influence the performance of the soil core. It was found that under lateral loading, the RCD wall behaves as an end-bearing friction wall during the entire loading process. The relative displacement between the wall body and the soil core primarily occurs below the rotation point, and the horizontal displacement of the soil core is greater than that of the wall body. Under vertical loading, the degree of inner skin friction around the bottom of the soil core and the proportion of the loading supported by the soil core increase with increased cross-section size. The wall depth is directly proportional to the loading supported by the outer skin friction and the tip resistance of the wall body and is inversely proportional to the loading borne by the soil core.

关键词： diaphragm wall soil core bridge foundation FLAC3D bearing behavior

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Soil arching effect of Lattice-Shaped Diaphragm Wall as bridge foundation

Jiujiang WU, Lingjuan WANG, Qiangong CHENG

《结构与土木工程前沿（英文）》 2017年第11卷第4期页码 446-454 doi: 10.1007/s11709-017-0397-7

摘要： As a new type of bridge foundation, Lattice-Shaped Diaphragm Wall (hereinafter for LSDW) is highly concerned in relevant construction area but its research is far from achievement. Based on PFC , the soil arching effect of LSDWs is studied thoroughly in this paper and the special attention is given to its influencing factors. It turns out to be that a differential wall-soil settlement can be found at the lower location of soil core of an LSDW which is one of the trigger factors of soil arching; meanwhile, the differential settlement degree can reflect the exertion degree of soil arching; the shape of soil arching is basically a hemisphere which can be explained by the theory proposed by Hewlett and Randolph; normally, the chamber number is a negative factor for the development of soil arching; the soil arching effect is significantly influenced by the distance of two adjacent wall elements and the foundation depth, and a relatively large or small value of these factors is disadvantageous to the exertion of soil arching; in addition, the soil arching effect increase with the growth of stiffness and friction coefficient of particles and the friction coefficient of particles has insignificant influence on the development of soil arching effect compared with particle stiffness.

关键词： LSDW soil arching PFC^2D shape of soil arching influencing factors

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Parametric sensitivity analysis of cellular diaphragm wall

Xi CHEN, Wei XU

《结构与土木工程前沿（英文）》 2012年第6卷第4期页码 358-364 doi: 10.1007/s11709-012-0177-3

摘要： The deformation law of the cellular diaphragm wall in deep foundation pits was studied through numerical simulation. Based on the example of the dock wall in engineering, the full three-dimensional finite element model was used to simulate the excavation of the foundation pit. Interaction between the cellular diaphragm wall and the soil was also taken into account in the calculation. The results indicated that the maximum lateral displacement, which is the evaluation index of sensitivity analysis, appeared on the top of the interior longitudinal wall with an excavation depth of 10 m. The centrifuge model test was carried out to study the deformation regulation for a cellular diaphragm wall. The most sensitive factor was found by adjusting the length of the partition wall, the spacing of the partition wall and the thickness of the wall. In the end, a suggestion was proposed to optimize the cellular diaphragm by adjusting the length of the partition wall.

关键词： cellular diaphragm wall sensitivity analysis optimization centrifuge model test

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Multi-scale investigation of active failure for various modes of wall movement

《结构与土木工程前沿（英文）》 2021年第15卷第4期页码 961-979 doi: 10.1007/s11709-021-0738-4

摘要： Retained backfill response to wall movement depends on factors that range from boundary conditions to the geometrical characteristic of individual particles. Hence, mechanical understanding of the problem warrants multi-scale analyses that investigate reciprocal relationships between macro and micro effects. Accordingly, this study attempts a multi-scale examination of failure evolution in cohesionless backfills. Therefore, the transition of retained backfills from at-rest condition to the active state is modeled using the discrete element method (DEM). DEM allows conducting virtual experiments, with which the variation of particle and boundary properties is straightforward. Hence, various modes of wall movement (translation and rotation) toward the active state are modeled using two different backfills with distinct particle shapes (spherical and nonspherical) under varying surcharge. For each model, cumulative rotations of single particles are tracked, and the results are used to analyze the evolution of shear bands and their geometric characteristics. Moreover, dependencies of lateral pressure coefficients and coordination numbers, as respective macro and micro behavior indicators, on particle shape, boundary conditions, and surcharge levels are investigated. Additionally, contact force networks are visually determined, and their influences on pressure distribution and deformation mechanisms are discussed with reference to the associated modes of wall movement and particle shapes.

关键词： discrete-element modelling granular materials retaining walls particle shape arching

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南京长江第四大桥南锚碇地下连续墙支护结构设计

董萌,贾立峰,李丹

《中国工程科学》 2013年第15卷第8期页码 26-30

摘要：

南京长江第四大桥南锚碇基础为支护开挖深埋扩大基础，采用井筒式地下连续墙支护体系，平面形状为“∞”形，长82 m，宽59 m，由两个外径59 m的非完整圆和一道隔墙组成，壁厚为1.5 m。隔墙为前后两个非完整圆的支撑结构，抬高隔墙底标高，使得基础底板为一整体结构；填心混凝土施工完成后凿除部分墙体，既解决了开挖状态下的支护问题，又使基础顶板有效连为整体。采用“∞”形比圆形或矩形结构形式布置平面面积小，截面惯性矩大，且半径较小，墙体环向应力小，安全性及可实施性高，有效降低了工程投入，提高了结构的安全性。

关键词：锚碇地下连续墙 “∞”形南京长江第四大桥

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Isogeometric analysis of coupled thermo-elastodynamic problems under cyclic thermal shock

Asghar AMANI DASHLEJEH

《结构与土木工程前沿（英文）》 2019年第13卷第2期页码 397-405 doi: 10.1007/s11709-018-0473-7

摘要： The isogeometric analysis (IGA) method was extended for the solution of the coupled thermo-elastodynamic equations. The dimensionless formulation was accepted in discretization of the uncoupled and coupled thermoelasticity equations and the Generalized Newmark method was used in the time integration procedure. First, the performance of the proposed method was verified against a two-dimensional benchmark example subjected to constant thermal shock with available exact analytical solutions. Then a two-dimensional half-space benchmark example under thermal shock was solved. Finally, cyclic thermal shock (CTS) loading was applied on the half-space problem. The results dedicated that IGA can be used as a suitable approach in the analysis of the general thermomechanical problems.

关键词： isogeometric analysis coupled thermo-elastodynamic dynamic analysis generalized newmark cyclic thermal shock

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Power performance of circular piezoelectric diaphragm generators

TANG Kehong, KAN Junwu, YANG Zhigang, CHENG Guangming, PENG Taijiang

《机械工程前沿（英文）》 2008年第3卷第4期页码 434-440 doi: 10.1007/s11465-008-0069-3

摘要： Energy generation performance of a piezoelectric generator depends mainly on several elements such as the structural style, boundary conditions, geometry parameters, materials, vibration-source frequency, and external load. To obtain the optimal energy-harvesting device, the Raleigh method is used to establish the analysis model of circular piezoelectric composite diaphragms. Simply supported and clamped boundary conditions were considered. The relationships between the output power and the structural parameters of piezoelectric composite diaphragms, and the external load resistance and frequency were shown. Given the correlative material parameters and boundary conditions, the output power, using structural parameters, external load, or vibrating frequency as variables, can be calculated. Simulation results show that there are optimal structural parameters and load for a composite diaphragm to achieve the maximum output power. A piezoelectric diaphragm generator with given dimensions tends to achieve higher output power under clamped boundary conditions than that under simply supported boundary conditions.

关键词： clamped boundary energy-harvesting composite diaphragm piezoelectric composite maximum

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Free vibration analysis of functionally graded porous curved nanobeams on elastic foundation in hygro–thermo–magnetic

《结构与土木工程前沿（英文）》 2023年第17卷第4期页码 584-605 doi: 10.1007/s11709-023-0916-7

摘要： Herein, a two-node beam element enriched based on the Lagrange and Hermite interpolation function is proposed to solve the governing equation of a functionally graded porous (FGP) curved nanobeam on an elastic foundation in a hygro–thermo–magnetic environment. The material properties of curved nanobeams change continuously along the thickness via a power-law distribution, and the porosity distributions are described by an uneven porosity distribution. The effects of magnetic fields, temperature, and moisture on the curved nanobeam are assumed to result in axial loads and not affect the mechanical properties of the material. The equilibrium equations of the curved nanobeam are derived using Hamilton’s principle based on various beam theories, including the classical theory, first-order shear deformation theory, and higher-order shear deformation theory, and the nonlocal elasticity theory. The accuracy of the proposed method is verified by comparing the results obtained with those of previous reliable studies. Additionally, the effects of different parameters on the free vibration behavior of the FGP curved nanobeams are investigated comprehensively.

关键词： functionally graded porous material curved nanobeam hygro–thermo–magnetic enriched finite element method

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behavior of stiffened joints between concrete-filled steel tubular column and steel beam with narrow outer diaphragm

Chunyan QUAN,Wei WANG,Jian ZHOU,Rong WANG

《结构与土木工程前沿（英文）》 2016年第10卷第3期页码 333-344 doi: 10.1007/s11709-016-0357-7

摘要： This paper presented an investigation on a stiffened joint in practical engineering which was between concrete-filled steel tubular column and steel beam with narrow outer diaphragm and partial joint penetration welds. Through the low-frequency cyclic loading test, the cyclic behavior and failure mode of the specimen were investigated. The results of the test indicated the failure mode and bearing capacity of the specimen which were influenced by the axial compression ratio of the concrete-filled tubular column. On the contrary, the inner diaphragm and inner stiffeners had limited impacts on the hysteretic behavior of the joint. There was no hysteresis damage fracture on the narrow outer diaphragm connected to the concrete-filled steel tubular column with partial joint penetration welds. Due to the excellent ductility and energy dissipating capacity, the proposed joint could be applied to the seismic design of high-rise buildings in highly intensive seismic region, but axial compression ratio should be controlled to avoid unfavorable failure modes.

关键词： narrow outer diaphragm concrete-filled tubular column joint inner and outer stiffening cyclic behavior

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南京长江第四大桥工程建设及关键技术

武焕陵

《中国工程科学》 2013年第15卷第8期页码 4-11

摘要：

南京长江第四大桥是世界上首座主跨1 418 m的三跨连续弹性支承体系钢箱加劲梁悬索桥，首次采用了弹性支承体系以及缆索的分布传力锚固系统，克服了复杂地质条件下超大“∞”形地下连续墙（以下简称地连墙）及超大规模沉井深基础的设计施工技术难题，提出了主缆缆索混编技术及富氩气体保护焊技术，采用了复合浇筑式沥青钢桥面铺装技术，运用综合技术手段严格控制大体积混凝土施工质量。本文从建设管理及关键技术创新方面进行了综述。

关键词：建设管理关键技术创新复杂地质条件超大“∞”形地连墙超大规模沉井

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Simulation and experimental improvement on a small-scale Stirling thermo-acoustic engine

Mao CHEN,Yonglin JU

《能源前沿（英文）》 2016年第10卷第1期页码 37-45 doi: 10.1007/s11708-015-0390-6

摘要： Compared with the traditional engines, the thermo-acoustic engines are relatively new and can act as the linear compressors for refrigerators. Many institutes have shown great interest in this kind of machine for its absence of moving mechanical part. In this paper, the influence of the dimensions of the main parts of the small-scale Stirling thermo-acoustic engine was numerically simulated using a computer code called DeltaEC. The resonator and the resonator cavity were found to be the most convenient and effective in improving the performance of the engine. Based on the numerical simulation, a small-scale Stirling thermo-acoustic engine were constructed and experimentally investigated. Currently, with a resonator length of only 1 m, the working frequency of the engine was decreased to 90 Hz and the onset temperature difference was decreased to 198.2 K.

关键词： thermo-acoustic Stirling engine small-scale simulation experiment

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一种作为主动控制宽带吸波器的热可调超材料 Article

邢校菖, 曹阳, 田小永, 吴玲玲

《工程（英文）》 2023年第20卷第1期页码 143-152 doi: 10.1016/j.eng.2022.04.028

摘要：

近年来，超材料因其操纵电磁波的强大能力而受到越来越多的关注。然而，大多数先前报道的超材料无法动态调控超宽波段电磁波。在本文中，我们提出了一种使用具有不同相变温度的石蜡基复合材料（PDCs）来实现热可调谐宽带吸波的超材料结构体（T-TBM）。通过在不同相变温度下控制PD-Cs 的固液态，实现了从低频到高频的T-TBM反射损耗峰值的动态调控。T-TBM可以改变吸收峰值带宽（反射损耗值小于−30 dB），并且通过调整T-TBM 的温度依然满足宽带吸波（反射损耗值小于−10 dB）。实验结果表明，T-TBM中PD-Cs的相变恒温效应为在不同热条件下主动控制电磁波吸收响应提供了时间窗口。该器件在电磁吸收、智能超材料、多功能结构器件等领域具有广阔的应用前景。

关键词：超材料主动控制热可调宽带吸波

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Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

《结构与土木工程前沿（英文）》 2015年第9卷第4期页码 441-447 doi: 10.1007/s11709-015-0319-5

摘要： This is the first manuscript presenting an extended meshfree method for thermo- elastic fracture which does not exploit a crack tip enrichment. The crack is modeled by partition of unity enrichment of the displacement and temperature field. Only a step function is employed that facilitates the implementation. To ensure that crack tip is at the correct position, a Lagrange multiplier field ahead of the crack tip is introduced along a line. The Lagrange multiplier nodal parameters are discretised with the available meshfree functions. Two benchmark examples illustrate the efficiency of the method.

关键词： meshfree method thermo-elasticity

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标题作者时间类型操作

Finite element modeling of thermo-active diaphragm walls

Yi RUI, Mei YIN

期刊论文

Diaphragm wall-soil-cap interaction in rectangular-closed- diaphragm-wall bridge foundations

Hua WEN, Qiangong CHENG, Fanchao MENG, Xiaodong CHEN

期刊论文

The behavior of a rectangular closed diaphragm wall when used as a bridge foundation

Qiangong CHENG, Jiujiang WU, Zhang SONG, Hua WEN

期刊论文