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Chen B.-C.,Fuzhou University | Lin S.-S.,Fuzhou University | Lin S.-S.,Fujian Communications Planning and Design Institute
Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering | Year: 2014

By the application of the calculation methods of masonry columns and plain concrete columns in Codes for Design of Highway Masonry Bridges and Culverts (JTG D61-2005) and the calculation methods of reinforced concrete columns in Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG D62-2004), the load-carrying capacities of 3 reinforced concrete arch bridges with the spans of 70, 160, 420 m were calculated respectively. The change rules of the bearing capacities of reinforced concrete columns were studied considering slenderness ratio, eccentricity, reinforcement ratio, and etc. The parameter ranges of the equivalent beam-column of concrete arches and the ultimate bearing capacities of masonry columns, plain concrete columns and reinforced concrete columns were analyzed. Analysis result shows that the bearing capacities calculated by JTG D61-2005 are greater than those calculated by JTG D62-2004 when reinforced concrete arches with low reinforcement ratio are treated as equivalent beam-column. For reinforced concrete columns with low reinforcement ratios and high slenderness ratios and eccentricities, the bearing capacities calculated by the formulas of reinforced concrete columns are smaller than those calculated by the formulas of masonry columns or plain concrete columns. Thus it can be seen that there are unreasonable factors in the calculation methods of eccentrically loaded concrete columns in two codes, which should be improved. 3 tabs, 7 figs, 25 refs. Source

Chen B.,Fuzhou University | Lin S.,Fuzhou University | Lin S.,Fujian Communications Planning and Design Institute
Jianzhu Jiegou Xuebao/Journal of Building Structures | Year: 2014

In calculation of the bearing capacity of the eccentrically loaded reinforced concrete columns, in order to consider the second order effect of bending moment in the section, the effect of bending moment enlargement coefficient is used, which includes two factors, i.e. the curvature influence coefficient of eccentricity ζ1 and the curvature influence coefficient of slenderness ratio ζ2. Some differences exist in the calculation methods of these two curvature influence coefficients among the current China design codes such as the GB 50010-2010 'Code for design of concrete structure' and JTG D62-2004 'Code for design of highway reinforced concrete and prestressed concrete bridges and culverts'. Through the bearing capacity tests of 14 reinforced concrete columns, the column bearing capacities obtained from test results were compared with those calculated by code methods. The results show that the calculated bearing capacity of the specimens by the GB 50010-2010 are lower than the test ones due to the ζ2 is deleted in the code, while the calculation method of ζ1 in JTG D62-2004 is not rational since the calculated bearing capacities are larger than the test ones and tend to be unsafe for structures especially when the eccentricity is small. Based on the experimental research, parametric analyses by the finite element method were carried out, and the calculation formulas for ζ1 and ζ2 were proposed. The accuracy of the proposed calculation method was verified by the collected test results of the references. Source

Zeng Q.-Y.,Fujian Communications Planning and Design Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

Through applying horizontal loads on pile top in model test, the displacement distributions of soils on the upper-surface and around piles are analyzed by the non-target digital photography deformation measure system. The surface horizontal displacement of sand around dual-piles is observed. The effect of space between piles on the interaction of piles is studied combining the relationship between displacement of pile top and horizontal load. Particle flow code in two dimensions (PFC 2D) is introduced to simulate the displacement of sand at some given depth. The particle flowing behavior of sand around active pile and the effect of space between piles on the pile-soil interaction are revealed. The results show that the displacement field of sand around piles seems two fusiform bodies; the deformation region of sand in front of pile extends with the increasing of compactness of sand; the effect of interaction between piles is obvious with small pile space. Source

Zhang G.-H.,CAS Wuhan Institute of Rock and Soil Mechanics | Chen L.-B.,Fujian Provincial Expressway Construction Headquarters | Qian S.-X.,Xiamen Road and Bridge Construction Group Co. | Cai G.-Y.,Xiamen Road and Bridge Construction Group Co. | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

The research on the stability of surrounding rock is carried out during the construction, as per twin-side heading method, of large section and small clear-distance tunnels under complex geological condition; through the on-site supervision measure of internal displacements of surrounding rock, vault settlement, pressure of surrounding rock and stress of bolt in combination with the engineering practice of Damaoshan tunnels. When the pilot tunnels start excavating, the variation trend, characteristics and displacement field of displacement inside surrounding rock should be clarified, as well as the mutual influence of neighboring pilot tunnels in construction, mutual adjusting mechanism between surrounding rock and retaining structure and the reason of smaller distortion measured by vault settlement than the actual distortion of surrounding rock, the stress state of retaining structure, stress of bolt, variation relation of surrounding rock displacement. The supervision results indicate the feasibility of existing construction technology and retaining parameter adopted for fault zone of V-grade surrounding rock section of large section and small clear distance tunnels because of controllable surrounding rock distortion, strong retaining structure, safe storage and stable surrounding rock. The method, analysis and conclusion of research will be valuable experience and for reference in design, construction, supervision and further theoretical research on tunnel engineering under similar condition. Source

Chen X.-X.,Fujian Electric Power Survey and Design Institute | Xia C.-C.,Tongji University | Miao Y.-B.,Fujian Communications Planning and Design Institute
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2011

The key block's time-space effect is existed because of the location or the size and the time of the key block when the tunnel was excavated in fractional steps construction. The definition of time-space effect of the key block is described, and then based on the Jinjishan tunnel which is extra-large eight spans multi-arch tunnel in the second stage of the Fuzhou Changle international airport highway project, the definition and the application of the time-space effect is explained in detail. The basic application principle of the time-space effect of key block is put forward. The analysis shows that the stability of the upper blocks in the tunnel could be improved by reservating the core part rock in the two side-wall pilot tunnel, the key block volume could be controlled by limiting the free face area, the mechanic properties of the joints could be weaken caused by creeping because of supported in time, and the temporary support could be reduced by the application of the guiding fundamental principles of key block, so that the safety and the economic efficiency are raised in the tunnel construction procedure. Source

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