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Experimental study on pile-end post-grouting piles for super-large bridge pile foundations

Weiming GONG, Guoliang DAI, Haowen ZHANG

《结构与土木工程前沿(英文)》 2009年 第3卷 第2期   页码 228-233 doi: 10.1007/s11709-009-0019-0

摘要: The application of pile-end post-grouting piles for super-large bridge pile foundations in some important projects was introduced in this paper. There are totally 21 test piles. The maximum pile diameter varies from 2.5 m to 3 m, and the maximum length is 125 m; the bearing capacity of the post-grouting piles is over ten thousands tons. Based on the test results, the bearing capacity, displacement, and bearing characteristic before and after grouting were analyzed. The results show that the bearing capacity of the piles are increased in different degrees after grouting although the technical parameters, including the patterns of grouting pipes, pressure, dosages of cement, duration of grouting lasting time, are different. However, the obtained values are very discrete. In addition, the calculation formula for the post-grouting piles under specified grouting condition was deduced based on the statistics analysis results of 57 test piles. The research results have been applied in the design of bridge foundation.

关键词: self-balanced testing technique     pile-end post-grouting     bearing capacity     grouting technology    

声学综合无损检测技术

陈积懋

《中国工程科学》 2000年 第2卷 第4期   页码 64-69

摘要:

论述了检测复合材料和胶接结构不连续(缺陷)的新型多模综合无损检测技术。该技术以声与超声检测技术为基础,包含五种不同检测模式,用以检测复合材料与胶接结构的失粘、脱粘、分层、疏松、夹芯压皱及其他缺陷。它适用于复合材料与构件的制造、维修和使用现场。它的适用对象范围广泛,几乎覆盖了现有常用的复合材料和胶接结构。它的检测可靠性高,重复精度好。文章还讨论了组成多膜声学综合胶接检测仪的五种不同检测模式的原理,并从我们和国内外同行的大量实践经验出发,说明了综合无损检测技术的巨大发展前景。

关键词: 声学综合检测     综合无损检测     复合材料无损检测     机械阻抗分析     振动分析     共振检测    

Novel sensing techniques for full-scale testing of civil structures

Kaoshan DAI, Zhenhua HUANG

《结构与土木工程前沿(英文)》 2012年 第6卷 第3期   页码 240-256 doi: 10.1007/s11709-012-0172-8

摘要: Performing full-scale structural testing is an important methodology for researchers and engineers in the civil engineering industry. Full scale testing helps the researchers understand civil infrastructures’ loading scenarios, behaviors, and health conditions. It helps the engineers verify, polish, and simplify the structural design and analysis theories. To conduct a full-scale structural testing, sensors are used for data acquisitions. To help structural researchers and engineers get familiar with sensing technologies and select the most effective sensors, this study reviewed and categorized new sensing techniques for full-scale structural testing applications. The researchers of this study categorized sensors used for civil-infrastructure testing into traditional contact sensors and remote sensors based upon their application methodologies, and into cabled sensors and wireless sensors based upon their data communication strategies. The detailed descriptions of wireless sensors and remote sensing techniques and their on-site full-scale applications are presented.

关键词: sensing technique     full-scale testing     wireless sensor     remote sensing     LiDAR     laser vibrometer    

New experimental technique to determine coal self-ignition duration

ZHANG Xinhai, XI Guang, ZHANG Xinhai

《能源前沿(英文)》 2008年 第2卷 第4期   页码 479-483 doi: 10.1007/s11708-008-0058-6

摘要: An artificial neural network (ANN) model was adopted to simulate the relationship between self-ignition duration and sulfur content, ash content, oxygen consumption rate, carbon monoxide as well as carbon dioxide generation rate of coal at different temperatures of self heating process. The data from spontaneous combustion experiments were used for ANN training to obtain the connection strength between nerve cells. An oil-bath programmed temperature experiment device was designed and the experimental condition and the size of the test tube were determined for testing the oxygen consumption and the gases generation rate of coal during self-heating process. The sulfur content, the ash content and the data from the oil-bath experiment were taken as ANN inputs to calculate the experiment self-ignition duration of coal. Compared with spontaneous combustion experiment, less than 1% of coal sample and 10% of time are required with an error of less than 3 days to test self-ignition duration of coal.

自供能主动式振动控制——从概念到模拟测试 Article

李锦阳, 朱松晔

《工程(英文)》 2022年 第11卷 第4期   页码 126-137 doi: 10.1016/j.eng.2021.03.022

摘要:

主动式振动控制技术通常拥有优异的控制性能,但其在大型结构应用中常常伴随着巨大的能耗,使得我们在实际工程应用中较难看到它的身影。针对这一问题,本文创新性地提出了一种全新的解决方案:自供能的主动式振动控制系统;并针对性地对其拓扑设计、工作原理、能量流动等方面进行了介绍。通过对振动过程中能量流动的详细分析,我们进一步确认了系统的自供能可行性。此外,我们于实验室内搭建了一套所提出的自供能主动式控制系统,并成功将其应用到一个小型主动隔振台上。通过对解析、数值和实验结果的一系列探究,这个新型系统的有效性与可行性得到了充分的印证。预期这套新型装置可以非常容易地推广到其他多种工程领域中来实现所期望的主动控制效果。

关键词: 自供能主动式振动控制     能量采集     天钩控制     能量平衡     智能控制    

Heavy vehicle dynamics with balanced suspension based on enveloping tire model

Yongjie LU, Shaopu YANG, Shaohua LI

《机械工程前沿(英文)》 2010年 第5卷 第4期   页码 476-482 doi: 10.1007/s11465-010-0120-z

摘要: The tire-road contact mechanics is the key problem in vehicle ride comfort and road-friendliness research. A flexible roller contact (FRC) tire model with the enveloping property is introduced to reflect the contact history between the tire and the road. Based on D’Alembert principle, an integral balanced suspension (IBS) model is established, considering mass and moment of? inertia of? the stabilizer rod. ?The sprung mass accelera- tion and tire dynamic force for balanced suspension and the traditional quarter-vehicle model are compared respectively for frequency and time domain responses. It is concluded that the quarter-vehicle model can be used to evaluate the ride comfort of vehicles; however, it has some limitations in evaluating the vehicle road-friendliness. Then, the dynamics performances for IBS model are analyzed with the single point contact (SPC) model and FRC model, respectively. These works are expected to propose a new idea for the vehicle-road interaction research.

关键词: heavy vehicle     integral balanced suspension     enveloping properties     ride comfort     road-friendliness    

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 146-149 doi: 10.1007/s11465-013-0260-z

摘要:

To predict more precisely the frequency of force-balanced micro accelerometer with different bias voltages, the effects of bias voltages on error sensitivity of frequency is studied. The resonance frequency of accelerometer under closed loop control is derived according to its operation principle, and its error sensitivity is derived and analyzed under over etching structure according to the characteristics of Deep Reaction Ion Etching (DRIE). Based on the theoretical results, micro accelerometer is fabricated and tested to study the influences of AC bias voltage and DC bias voltage on sensitivity, respectively. Experimental results indicate that the relative errors between test data and theory data are less than 7%, and the fluctuating value of error sensitivity under the range of voltage adjustment is less than 0.01 μm . It is concluded that the error sensitivity with designed parameters of structure, circuit and process error can be used to predict the frequency of accelerometer with no need to consider the influence of bias voltage.

关键词: Micro-Electro-Mechanical Systems (MEMS)     micro accelerometer     force-balanced micro accelerometer     frequency     error sensitivity    

Review of challenges and strategies for balanced urban–rural environmental protection in China

Beidou XI,Xiaoguang LI,Jixi GAO,Ying ZHAO,Hongliang LIU,Xunfeng XIA,Tianxue YANG,Lieyu ZHANG,Xuan JIA

《环境科学与工程前沿(英文)》 2015年 第9卷 第3期   页码 371-384 doi: 10.1007/s11783-014-0744-z

摘要: With the rise of environmentalism in China, great efforts have been devoted to environmental protection over the past several decades. Compared with urban environmental protection, rural environmental protection has not been attached enough importance in China due to the dual-track structure of socio-economic development. As a result, rural China is shouldering disproportionally heavy environmental burdens partly because of the differences and biases between urban and rural environmental protection seen in environmental policies, environmental rights and interests, environmental protection investment, and the environmental protection awareness of people. To eliminate the gap between rural and urban environmental protection, and achieve the goal of “balanced urban–rural environmental protection” (BUREP), government should consider mapping out proper policies and strategies. In this paper we put forward an innovative strategy of BUREP against the background of China’s urban-rural environmental protection. First, we review the current status of rural environmental protection status and its challenges compared with urban environmental protection in China. Secondly, we analyzed the main driving factors and reasons deeply, and then we put forward the BUREP strategy base on the unequal status between urban and rural environment. Finally, we proposed the framework of BUREP. This study may serve as a scientific reference regarding decision-making in coordinating urban and rural environmental protection and in constructing the new countryside of China.

关键词: urban environment     rural environment     balanced urban–rural environmental protection     framework of balanced urban–rural environmental protection (BUREP)    

Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

《机械工程前沿(英文)》 2019年 第14卷 第3期   页码 273-281 doi: 10.1007/s11465-018-0495-9

摘要: Terahertz (THz) waves, whose frequencies range between microwave and infrared, are part of the electromagnetic spectrum. A gap exists in THz literature because investigating THz waves is difficult due to the weak characteristics of the waves and the lack of suitable THz sources and detectors. Recently, THz nondestructive testing (NDT) technology has become an interesting topic. This review outlines several typical THz devices and systems and engineering applications of THz NDT techniques in composite materials, thermal barrier coatings, car paint films, marine protective coatings, and pharmaceutical tablet coatings. THz imaging has higher resolution but lower penetration than ultrasound imaging. This review presents the significance and advantages provided by the emerging THz NDT technique.

关键词: terahertz pulsed imaging (TPI)     nondestructive testing (NDT)     composite material     thermal barrier coating    

基于平衡记分卡的连锁经营企业绩效评价研究

曹杰,曹国,何建敏

《中国工程科学》 2008年 第10卷 第4期   页码 90-96

摘要:

以平衡记分卡(BSC)为基础,从BSC的财务、客户、内部经营过程以及学习与成长等方面,设计了连锁经营企业的绩效考核指标体系与模糊综合评判模型,克服了传统评价体系的不足,有利于从成长的角度全面评价连锁企业绩效。

关键词: 平衡记分卡     连锁经营     绩效评价     模糊综合评价    

Degree of bending of concrete-filled rectangular hollow section K-joints under balanced-axial loadings

Rui ZHAO; Yongjian LIU; Lei JIANG; Yisheng FU; Yadong ZHAO; Xindong ZHAO

《结构与土木工程前沿(英文)》 2022年 第16卷 第4期   页码 461-477 doi: 10.1007/s11709-022-0818-0

摘要: It has been found that the fatigue life of tubular joints is not only determined by the hot spot stress, but also by the stress distribution through the tube thickness represented as the degree of bending (DoB). Consequently, the DoB value should be determined to improve the accuracy of fatigue assessment for both stress-life curve and fracture mechanics methods. Currently, no DoB parametric formula is available for concrete-filled rectangular hollow section (CFRHS) K-joints, despite their wide use in bridge engineering. Therefore, a robust finite element (FE) analysis was carried out to calculate the DoB of CFRHS K-joints under balanced-axial loading. The FE model was developed and verified against a test result to ensure accuracy. A comprehensive parametric study including 190 models, was conducted to establish the relationships between the DoBs and four specific variables. Based on the numerical results, design equations to predict DoBs for CFRHS K-joints were proposed through multiple regression analysis. A reduction of 37.17% was discovered in the DoB, resulting in a decrease of 66.85% in the fatigue life. Inclusively, the CFRHS K-joints with same hot spot stresses, may have completely different fatigue lives due to the different DoBs.

关键词: fatigue assessment     K-joint     design equations     degree of bending     fracture mechanics    

Permeability testing of drilling core sample from pavement

WANG Suda, TANG Zhengguang, NING Xiaojun, WU Peiguan, XING Pingyi

《结构与土木工程前沿(英文)》 2008年 第2卷 第4期   页码 391-394 doi: 10.1007/s11709-008-0045-3

摘要: The permeability coefficient of pavement material is a very important parameter in designing the drainage of pavement structures and is also used to evaluate the quality of road construction. New equipment is used to measure the permeability coefficient of the pavement drilling core sample and relevant testing methods are introduced. Testing drilling core samples from a certain highway of Yunnan province has been proven to be feasible. The test results are also analyzed.

关键词: province     material     feasible     permeability coefficient     equipment    

类差分平衡函数的性质及其应用

张文英,李世取

《中国工程科学》 2004年 第6卷 第3期   页码 45-52

摘要:

定义了布尔函数的类差分和类差分平衡函数,研究了类差分平衡函数的密码学性质以及构造方法。作为类差分平衡函数的应用,给出了〓上逻辑函数是完全非线性函数的充要条件,并在首先分析得到所有四元类差分平衡函数的基础上,编程搜索出〓上所有的完全非线性函数。

关键词: Bent函数     完全非线性函数     2-基展开     类差分     类自相关函数     类差分平衡函数    

Shaking table testing of hard layered soil-pile-structure interaction system

LI Peizhen, REN Hongmei, LU Xilin, SONG Heping, CHEN Yueqing

《结构与土木工程前沿(英文)》 2007年 第1卷 第3期   页码 346-352 doi: 10.1007/s11709-007-0046-7

摘要: Shaking table tests on a dynamic interaction system of hard layered soil, pile foundation and frame structure were carried out. The earthquake damage of the superstructure and foundation was reproduced. Based on these tests, several key issues about the seismic response of the dynamic soil-structure interaction (SSI) system were studied. The natural frequency of the system was less than that of the structure on rigid foundation if the SSI is not taken into account, while its damping ratio was larger than that of the structure. The mode shape of the system was different from that of the structure on the fixed base in that there were rocking and swinging at the foundation. Magnification or reduction of vibration transferred by soil was related to soil characteristic, excitation magnitude, and so on. Generally, sand magnifies vibration, while viscous powder soil dampens vibration. The components of the acceleration response at the top of the superstructure were based on the relative magnitude of the rocking stiffness, the swing stiffness of the foundation and the stiffness of the super-structure. The multi-direction excitations have little effect on the key issues of the horizontal SSI.

关键词: super-structure     Generally     Magnification     frequency     different    

Experimental monitoring of the strengthening construction of a segmental box girder bridge and field testing

Ali Fadhil NASER, Zonglin WANG

《结构与土木工程前沿(英文)》 2012年 第6卷 第3期   页码 308-320 doi: 10.1007/s11709-012-0140-3

摘要: Prestressed concrete segmental box girder bridges are composed of short concrete segments that are either precast or cast in situ and then joined together by longitudinally post-tensioning internal, external, or mixed tendons. The objectives of this study are to monitor the construction process of the external prestressing tendons to strengthen the bridge structure and perform a field load test to measure the strain and the deflection of the anchorage devices of the external prestressing tendons to determine the state of these devices after tension forces are applied. The monitoring process of the external prestressing tendons construction includes inspecting the cracks in the diaphragm anchorage and the deviation block devices before the tension forces are applied to the external tendons; measuring the deformation of the steel deviation cross beam during the tension process; measuring the deformation of the box girder after different levels of tension forces are applied; measuring the elongation of the external tendons in each level of the tension; and measuring the natural frequency of the external tendons after the tension process is complete. The results of the monitoring process show that the measured values of the deformation, the elongation, and the natural frequency meet the requirements. Therefore, there is no damage during the construction and the tensioning of the external prestressing tendons. A field load test is performed to the anchorage beam, the steel deviation block devices, and the steel deviation cross beam. The field load test results of the anchorage devices show that the values of the strains, the stresses, and the deflection are less than the respective allowable limit values in the requirements. Therefore, the anchorage devices have sufficient strength, and the working state is good after the tension forces are applied to the external prestressing tendons.

关键词: prestressed concrete     box girder     monitoring     external tendons     strain     deflection    

标题 作者 时间 类型 操作

Experimental study on pile-end post-grouting piles for super-large bridge pile foundations

Weiming GONG, Guoliang DAI, Haowen ZHANG

期刊论文

声学综合无损检测技术

陈积懋

期刊论文

Novel sensing techniques for full-scale testing of civil structures

Kaoshan DAI, Zhenhua HUANG

期刊论文

New experimental technique to determine coal self-ignition duration

ZHANG Xinhai, XI Guang, ZHANG Xinhai

期刊论文

自供能主动式振动控制——从概念到模拟测试

李锦阳, 朱松晔

期刊论文

Heavy vehicle dynamics with balanced suspension based on enveloping tire model

Yongjie LU, Shaopu YANG, Shaohua LI

期刊论文

Dependence of error sensitivity of frequency on bias voltage in force-balanced micro accelerometer

Lili CHEN, Wu ZHOU

期刊论文

Review of challenges and strategies for balanced urban–rural environmental protection in China

Beidou XI,Xiaoguang LI,Jixi GAO,Ying ZHAO,Hongliang LIU,Xunfeng XIA,Tianxue YANG,Lieyu ZHANG,Xuan JIA

期刊论文

Progress in terahertz nondestructive testing: A review

Shuncong ZHONG

期刊论文

基于平衡记分卡的连锁经营企业绩效评价研究

曹杰,曹国,何建敏

期刊论文

Degree of bending of concrete-filled rectangular hollow section K-joints under balanced-axial loadings

Rui ZHAO; Yongjian LIU; Lei JIANG; Yisheng FU; Yadong ZHAO; Xindong ZHAO

期刊论文

Permeability testing of drilling core sample from pavement

WANG Suda, TANG Zhengguang, NING Xiaojun, WU Peiguan, XING Pingyi

期刊论文

类差分平衡函数的性质及其应用

张文英,李世取

期刊论文

Shaking table testing of hard layered soil-pile-structure interaction system

LI Peizhen, REN Hongmei, LU Xilin, SONG Heping, CHEN Yueqing

期刊论文

Experimental monitoring of the strengthening construction of a segmental box girder bridge and field testing

Ali Fadhil NASER, Zonglin WANG

期刊论文