The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loo...The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loop anchorage prestressing loss(PL) values of inner lining(IL)in Yellow River-crossing tunnel under two anchorage systems,including twice- tension anchorage system and HM(Chinese transliteration is huanmao)anchorage system,are introduced. The software ANSYS is selected to realize the three-dimensional(3D) finite element modeling to accomplish simulation and calculation works under the two anchorage systems,respectively. Stress processes of IL under the two working conditions,of which one is completed cable tensioning(CCT) and the other is water in the tunnel with the designed water pressure(DWP),are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete(WC). Meanwhile,the anchorage system has the advantages of improving security and stability of tunnel structure,reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable,and is worthy of promotion and application.展开更多
The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shand...The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shandong Jiaodong water diversion project, in which the concrete failed only 3-6 months after conslruction was completed. With electron microscopy scanning, energy dispersive analysis, XKD （X-ray diffraction） analysis and Raman spectrum analysis of the mineral composition of the failure concrete and precipitates, chemical and physical reactions that occurred in the concrete under engineering environment were investigated. The analysis indicated that the rapid corrosion and dissolution reaction of the concrete in weak sulfate environment is due to sulfate and carbonate corrosion with the catalytic magnesium salt at low temperature. Also, corrosion damage facilitates the sulfate ions and carbonate ions into the concrete, and the expansion of ettringite and TSA （thaumasite sulfate attack） reaction also accelerates the corrosion damage of the concrete.展开更多
基金National Natural Science Foundation of China(No.51079107)Fundamental Research Funds for the Central Universities(No.5082022)
文摘The load compensation equipment for anchor cable named low retraction prestressed anchorage system with twice-tension(referred to as twice-tension anchorage system) is proposed in the paper. Calculation results of loop anchorage prestressing loss(PL) values of inner lining(IL)in Yellow River-crossing tunnel under two anchorage systems,including twice- tension anchorage system and HM(Chinese transliteration is huanmao)anchorage system,are introduced. The software ANSYS is selected to realize the three-dimensional(3D) finite element modeling to accomplish simulation and calculation works under the two anchorage systems,respectively. Stress processes of IL under the two working conditions,of which one is completed cable tensioning(CCT) and the other is water in the tunnel with the designed water pressure(DWP),are contrasted and analyzed. Impacts of prestressing forces of anchor cables on structural safety under the two anchorage systems are contrasted. The calculation results show that the twice-tension anchorage system can reduce PL effectively and then increase prestresses of wall concrete(WC). Meanwhile,the anchorage system has the advantages of improving security and stability of tunnel structure,reducing project costs and saving steel consumption. The research work is available to related design and construction of anchor cable,and is worthy of promotion and application.
文摘The erosion failure mechanism of concrete is studied systematically based on field investigation and laboratory experiments of concrete samples from more than 30 km concrete lining and 10 hydraulic structures of Shandong Jiaodong water diversion project, in which the concrete failed only 3-6 months after conslruction was completed. With electron microscopy scanning, energy dispersive analysis, XKD （X-ray diffraction） analysis and Raman spectrum analysis of the mineral composition of the failure concrete and precipitates, chemical and physical reactions that occurred in the concrete under engineering environment were investigated. The analysis indicated that the rapid corrosion and dissolution reaction of the concrete in weak sulfate environment is due to sulfate and carbonate corrosion with the catalytic magnesium salt at low temperature. Also, corrosion damage facilitates the sulfate ions and carbonate ions into the concrete, and the expansion of ettringite and TSA （thaumasite sulfate attack） reaction also accelerates the corrosion damage of the concrete.
