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DX桩 11

承载力 9

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A study on bearing characteristic and failure mechanism of thin-walled structure of a prefabricated subway

Lianjin TAO; Cheng SHI; Peng DING; Sicheng LI; Shang WU; Yan BAO

《结构与土木工程前沿（英文）》 2022年第16卷第3期页码 359-377 doi: 10.1007/s11709-022-0816-2

摘要： In order to study the bearing performance of a new type of prefabricated subway station structure (PSSS), firstly, a three-dimensional finite element model of the PSSS was established to study the nonlinear mechanics and deformation performance. Secondly, the bearing mechanism of a PSSS was investigated in detail. Finally, the development law of damages to a thin-walled prefabricated component and the failure evolution mechanism of a PSSS were discussed. The results showed that this new type of the PSSS had good bearing capacity. The top arch structure was a three-hinged arch bearing system, and the enclosure structure and the substructure were respectively used as the horizontal and vertical support systems of the three-hinged arch structure to ensure the integrity and stability of the overall structure. Moreover, the tongue-and-groove joints could effectively transmit the internal force between the components and keep the components deformed in harmony. The rigidity degradation of the PSSS caused by the accumulation of damages to the spandrel, hance, arch foot, and enclosure structure was the main reason of its loss of bearing capacity. The existing thin-walled components design had significant advantages in weight reduction, concrete temperature control, components hoisting, transportation and assembly construction, which achieved a good balance between safety, usability and economy.

关键词： prefabricated subway station thin-walled components finite element analysis bearing characteristic failure mechanism

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液体静压支承静态性能新表达式探索

孟心斋,杨建玺,孟昭焱

《中国工程科学》 2002年第4卷第5期页码 63-66

摘要：

文章分析了液体静压支承传统的静态性能表达式存在的严重缺陷及其产生原因，提出了新的静态性能表达式。这种新的静态性能表达式精确地表达了外加载荷与轴承间隙之间的非线性关系，真实地反映了支承的静态性能。新的静态性能通用表达式可表达各种传统节流器与新型可变节流器节流时支承的主要静态性能，很有应用价值。新的静态性能表达式只有一个变量即外加载荷与油垫推力比，故可在支承节流与尺寸参数未确定之前知道支承的主要静态性能，它有利于事先选择与确定支承在应用时的主要性能，为正确应用液体静压支承提供了可靠的技术基础。

关键词：液体静压支承传统节流器新型可变节流器静态性能

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薄膜润滑径向轴承特性分析

曲庆文,柴山,姚福生

《中国工程科学》 2003年第5卷第6期页码 44-48

摘要：

薄膜润滑轴承的特性远不同于常规轴承，在考虑间隙对润滑剂产生的影响后，润滑剂的特性将发生较大的变化。由于这种变化，薄膜润滑的特性才被广泛地研究和重视。文章应用等效粘度修正模型对径向滑动轴承进行了性能分析,对无限宽轴承可得出压力计算的解析表达式,从而可精确地计算轴承的性能。

关键词：薄膜润滑等效粘度径向轴承

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液体静压支承动态性能新表达式探索与实验验证

孟心斋,杨建玺,孟昭焱

《中国工程科学》 2003年第5卷第3期页码 62-66

摘要：

液体静压支承具有很多优良性能：高运动精度，低摩擦功耗，小轴心偏移，大承载能力，强抗振性能与长使用寿命等，但这些优良的静态性能必须在上佳的动态性能保证下才能充分显示出来，因此，液体静压支承静态性能保证机床运动与加工精度，而动态性能则保证设备的安全与工作条件。文章根据力平衡与流量连续条件建立支承系统传递函数，导出支承系统动态性能新表达式即稳定性判别、抗瞬态干扰能力、固有频率与在稳态周期干扰力作用下产生的动刚度与最大振幅。通过试验台实验证实，液体静压支承动态性能新表达式计算结果可靠而且物理概念清晰，公式简单，故可用于实际。

关键词：动态性能传递函数动刚度谐振频率液体静压支承

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DX旋挖挤扩灌注桩单桩抗拔承载性状的数值分析

陈立宏,张清林,袁希雨

《中国工程科学》 2012年第14卷第1期页码 31-36

摘要：

总结了DX桩的抗拔研究现状，采用FLAC3D对具有两个承力盘的DX单桩和相同直径与长度的普通直孔桩做了抗拔的数值计算分析，对DX单桩抗拔的性状进行了研究。模型参数依据土工试验获取并采用现场大比尺试验结果进行校验。通过模拟分级加载，得到了DX桩和直孔桩的抗拔承载力曲线，同时得到了沿桩身的轴力分布，依据这些计算结果展开分析，可以发现DX单桩的抗拔承载力比相同直径的普通直孔桩高出一倍以上，其上下承力盘的发挥作用是由上而下，但当荷载增大到一定程度时，下盘将发挥更大的作用。

关键词： DX桩抗拔数值分析

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DX桩群桩承载性状的数值分析

张清林,陈立宏

《中国工程科学》 2012年第14卷第1期页码 51-59

摘要：

通过数值计算对不同桩间距的DX桩群桩进行了分析研究。结果表明：DX桩的群桩效应随着桩间距的减小而逐渐明显，间距为6倍桩径的群桩极限承载力是间距为3倍桩径的群桩极限承载力的1.32倍；群桩间距由3倍桩径增大为6倍桩径时，群桩效应系数由0.59增大为0.78；群桩间土体沉降的最大值发生在两扩盘中间位置处，且随着桩间距的增大而减小。

关键词： DX桩群桩沉降数值分析

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Analysis of the dynamic hysteresis characteristic of finger seal

LEI Yanni, CHEN Guoding

《机械工程前沿（英文）》 2007年第2卷第1期页码 32-36 doi: 10.1007/s11465-007-0005-y

摘要： The research about hysteresis characteristic of finger seal (FS), which was carried out based on the model with static loads, could not reflect the dynamics behavior of FS system when the rotor runs at high speed. To solve this problem, the relations between the dynamics parameters, structure parameters as well as working parameters in the system were given out through the analysis of finite element analysis result. A mass spring damper dynamics model of FS system was proposed and the hysteresis characteristic of the FS system was analyzed. This work shows that the dynamics characteristic analysis of the FS is necessary and the dynamics model proposed in this paper is valid. This dynamics model is the basis for the optimization design of FS system.

关键词： FS necessary hysteresis characteristic optimization spring

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Iterative HOEO fusion strategy: a promising tool for enhancing bearing fault feature

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0725-z

摘要： As parameter independent yet simple techniques, the energy operator (EO) and its variants have received considerable attention in the field of bearing fault feature detection. However, the performances of these improved EO techniques are subjected to the limited number of EOs, and they cannot reflect the non-linearity of the machinery dynamic systems and affect the noise reduction. As a result, the fault-related transients strengthened by these improved EO techniques are still subject to contamination of strong noises. To address these issues, this paper presents a novel EO fusion strategy for enhancing the bearing fault feature nonlinearly and effectively. Specifically, the proposed strategy is conducted through the following three steps. First, a multi-dimensional information matrix (MDIM) is constructed by performing the higher order energy operator (HOEO) on the analysis signal iteratively. MDIM is regarded as the fusion source of the proposed strategy with the properties of improving the signal-to-interference ratio and suppressing the noise in the low-frequency region. Second, an enhanced manifold learning algorithm is performed on the normalized MDIM to extract the intrinsic manifolds correlated with the fault-related impulses. Third, the intrinsic manifolds are weighted to recover the fault-related transients. Simulation studies and experimental verifications confirm that the proposed strategy is more effective for enhancing the bearing fault feature than the existing methods, including HOEOs, the weighting HOEO fusion, the fast Kurtogram, and the empirical mode decomposition.

关键词： higher order energy operator fault diagnosis manifold learning rolling element bearing information fusion

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Flow characteristic and wastewater treatment performance of a pilot-scale airlift oxidation ditch

Hongtao PANG, Hanchang SHI, Huiming SHI,

《环境科学与工程前沿（英文）》 2009年第3卷第4期页码 470-476 doi: 10.1007/s11783-009-0143-z

摘要： A pilot-scale airlift oxidation ditch using bubble diffuser and baffle as aerator was operated in a wastewater treatment plant (WWTP) to investigate its flow characteristic and wastewater treatment performance. Compared with the conventional oxidation ditch process, effective depth and oxygen utilization efficiency of this new process was improved by underwater aeration. Furthermore, it had a reversed velocity distribution, which decreased from the bottom to the top on vertical section. Velocity measurement showed that a velocity over 0.2m/s at the bottom was sufficient to prevent sludge settlement during long term operation. Application of these concepts would save land area and energy consumption by about 25%―50% and 55%, respectively. In this new system, organic biodegradation and nitrification could be well achieved. Denitrification could occur steadily in the straight part by adjusting the airflow rate. An average TN removal rate of 63% was achieved with dissolved oxygen (DO) concentrations between 0.6mg/L and 1.5mg/L. The main pollutants in the effluent could meet the strictest discharge standard (COD<50mg/L, NH―N<5mg/L, and TN<15mg/L) in China now.

关键词： airlift oxidation ditch flow characteristic wastewater treatment

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New analysis model for rotor-bearing systems based on plate theory

Zhinan ZHANG, Mingdong ZHOU, Weimin DING, Huifang MA

《机械工程前沿（英文）》 2019年第14卷第4期页码 461-473 doi: 10.1007/s11465-019-0525-2

摘要： The purpose of this work is to develop a new analysis model for angular-contact, ball-bearing systems on the basis of plate theory instead of commonly known approaches that utilize spring elements. Axial and radial stiffness on an annular plate are developed based on plate, Timoshenko beam, and plasticity theories. The model is developed using theoretical and inductive methods and validated through a numerical simulation with the finite element method. The new analysis model is suitable for static and modal analyses of rotor-bearing systems. Numerical examples are presented to reveal the effectiveness and applicability of the proposed approach.

关键词： rotor-bearing system rolling element bearing plate theory finite element analysis

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Weak characteristic information extraction from early fault of wind turbine generator gearbox

Xiaoli XU, Xiuli LIU

《机械工程前沿（英文）》 2017年第12卷第3期页码 357-366 doi: 10.1007/s11465-017-0423-4

摘要：

Given the weak early degradation characteristic information during early fault evolution in gearbox of wind turbine generator, traditional singular value decomposition (SVD)-based denoising may result in loss of useful information. A weak characteristic information extraction based on µ-SVD and local mean decomposition (LMD) is developed to address this problem. The basic principle of the method is as follows: Determine the denoising order based on cumulative contribution rate, perform signal reconstruction, extract and subject the noisy part of signal to LMD and µ-SVD denoising, and obtain denoised signal through superposition. Experimental results show that this method can significantly weaken signal noise, effectively extract the weak characteristic information of early fault, and facilitate the early fault warning and dynamic predictive maintenance.

关键词： wind turbine generator gearbox µ-singular value decomposition local mean decomposition weak characteristic information extraction early fault warning

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API-based assessment on urban air environment bearing capability in China

Jinnan WANG,Jing ZHANG,Hongqiang JIANG,Yaling LU

《环境科学与工程前沿（英文）》 2015年第9卷第6期页码 1049-1055 doi: 10.1007/s11783-014-0662-0

摘要： Given the complexity and time-consuming of the conventional environmental capacity based assessment on air environment carrying capacity; a new method for assessing urban air environment carrying capacity based on air pollution index (API) is presented. By using this new method, the air environmental bearing capability of 333 cities at the prefecture level and above is assessed. The results show that of the 333 cities 9.6% is of high bearing capability, 34.5% relatively high bearing capability, 52.6% medium bearing capability, 2.7% low capability, and 0.6% is of weak bearing capability; in terms of regional distribution, the western region is of relatively high air environment bearing capability, followed by north-eastern and eastern regions, and the ambient air quality in the middle region is quite poor; among the 12 urban agglomerations in key regions, Pearl River delta, west side of Taiwan Strait and Chengdu-Chongqing agglomerations are of relatively high carrying capacity while other agglomerations are of medium bearing capability. The assessment results imply that the existing air quality standard (GB3095-1996) is quite unsound.

关键词： air pollution index (API) air environment bearing capability key city assessment method

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The convexity about ultimate bearing hypersurfaces of structures

Chengxi GUO,Tingting GUO

《结构与土木工程前沿（英文）》 2016年第10卷第4期页码 456-461 doi: 10.1007/s11709-016-0334-1

摘要： The relationship between the convexity on the ultimate bearing surface of a structure and the second-order effects of loads is discussed. All of generalized non-overload forces acted on a structure forms a convex set when ignoring the second-order effects (coupling effects between the generalized forces). It is true also when the Hessian matrix composed of the second-order partial derivatives on the hypersurface about the ultimate bearing of the structure is negative definite. The outward convexity is kept when the surface is expressed by certain dimensionless parameters. A series of properties based on the convexity are pointed out. Some applications in the analysis of bearing capacity of structures were illustrated with examples. The study shows that an evaluation about the bearing capacity state of a complex structure can be made on the basis of several points on the surface of the ultimate bearing of the structure.

关键词： service limit load ultimate bearing surface convexity generalized force generalized displacement frame structure

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Foundations bearing capacity subjected to seepage by the kinematic approach of the limit analysis

Mehdi VEISKARAMI, Ghasem HABIBAGAHI

《结构与土木工程前沿（英文）》 2013年第7卷第4期页码 446-455 doi: 10.1007/s11709-013-0227-5

摘要： An estimate of the ultimate load on foundations on soil layers subject to groundwater flow has been presented. The kinematic approach of the limit analysis was employed to find the upper-bound limit of the bearing capacity. Both smooth and rough base strip foundations were considered associated with different collapse patterns. Presence of the groundwater flow leads to a non-symmetric collapse pattern, i.e., a weak side and a strong side in two-sided collapse patterns, depending on the direction of the flow. It was found that the bearing capacity has a decreasing trend with increase in the groundwater flow gradient and hence, a reduction factor has been introduced to the third term in the bearing capacity equation as a function of the flow gradient.

关键词： foundation bearing capacity limit analysis numerical computation plasticity seepage

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Undrained seismic bearing capacity of strip footing adjacent to a heterogeneous excavation

《结构与土木工程前沿（英文）》 2023年第17卷第4期页码 566-583 doi: 10.1007/s11709-023-0905-x

摘要： The analysis of the bearing capacity of strip footings sited near an excavation is critical in geotechnics. In this study, the effects of the geometrical features of the excavation and the soil strength properties on the seismic bearing capacity of a strip footing resting on an excavation were evaluated using the lower and upper bounds of the finite element limit analysis method. The effects of the setback distance ratio (L/B), excavation height ratio (H/B), soil strength heterogeneity (kB/c_u), and horizontal earthquake coefficient (k_h) were analyzed. Design charts and tables were produced to clarify the relationship between the undrained seismic bearing capacity and the selected parameters.

关键词： excavation finite element limit analysis heterogeneous soil strip footing undrained bearing capacity