Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engin...Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engineering. Quiet boundary is adopted on the lateral face while free field boundary is employed at the bottom. Byrne model on dynamic pore water pressure generation is accepted and natural seismic wave EI Centro whose peak acceleration is adjusted to 0.2 g in proportion is used for input. A double-layer foundation with sandy soil in the upper portion while clay soil in the lower part is chosen as the calculation model, which is 30 m in length and 20 m in width. The groundwater level is on the ground surface. Excess pore water pressure rate is considered as a liquefaction index in the three-dimensional non-linear earthquake response computation. The anti-liquefaction effectiveness and its influencing factors, such as confinement element area are studied. For the natural double-layer foundation, it is liquefied when the excess pore water pressure rate reaches 1.0 under the seismic load. Under the same earthquake load, the peak excess pore water pressure reduces to 0.56 after adopting reinforcement of the continuous soil-cement wall, which is 46% lower than before. It indicates that continuous soil-cement wall confinement method can attain the purpose of anti-liquefaction. Accordingly, it can be a sort of engineering measure to carry on the anti-liquefaction foundation treatment.展开更多
In this work, the potentials of Bambusa vulgaris grown in southeast Nigeria for the manufacture of wood-cement composite panels were studied. Representative culms of Bambusa vulgaris were collected from a 4-year-old s...In this work, the potentials of Bambusa vulgaris grown in southeast Nigeria for the manufacture of wood-cement composite panels were studied. Representative culms of Bambusa vulgaris were collected from a 4-year-old stand at lower Anambra river basin, southeast, Nigeria. Fiber morphological properties and proximate chemical analysis were determined in accordance with the provisions of the Technical Association of the Pulp and Paper Industries (TAPPI, 1998). Fiber slenderness ratio was 160.95:1, component solubility of 3.09, 5.60, and 19.8 percent for cold water soak for 24 hrs;hot water soak at 80°C for 1 hr, and 1% NaOH soak for 24 hrs respectively. Composite panels were made at 1200 kg/m3 and 800 kg/m3 density levels with flakes of different soak treatments (untreated/control;cold water soak for 24 hrs;water at 80°C soak for 1 hr and 1% NaOH soak for 24 hrs) at variable cement/B. vulgaris mix ratios (1:1, 1.5:1, 2:1, 2.5:1 and 3:1 wt/wt) with 3% CaCl2 as accelerator applied to the wood furnish before cement mixing. Prepared furnish was subjected to initial pre-pressing of 0.5 N/mm2 and final consolidation of 1.4 N/mm2 retained for 24 hrs. Panels were sampled and tested after 28 days for Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) in bending and for water absorption (WA) and thickness swelling (TS) due to a 24-hr water soak. Test was in accordance with provisions of American Standard for Testing of Materials (ASTM-1998). Properties ranged from a low of 25.00 to 75.45 N/mm2 for MOR;4128 to 15,065 N/mm2 for MOE;15.01 to 36.11 percent for WA and 3.04 to 12.72 percent for TA. Effect of production mix on properties was determined using factorial analysis. Except for composite density whose effect was not significant at 0.05% level, all production mix was found significant at 0.01% level at the second order level of interactions. All panels met minimum property requirements of American National Standard Institute 208-2-1994 and 208-1-1993, British Standard (BS 5669, 1979) and Malaysian Standard (MS 934, 1984).展开更多
基金Project(50639010, 90815020) supported by the National Natural Science Foundation of ChinaProject(JKCX-200602) supported by South-to-North Water Diversion in Jiangsu Province, China
文摘Continuous soil-cement wall confinement method to resist liquefaction is a new kind of process. However, whether it also has a good effect on anti-liquefaction or not needs to be urgently answered for earthquake engineering. Quiet boundary is adopted on the lateral face while free field boundary is employed at the bottom. Byrne model on dynamic pore water pressure generation is accepted and natural seismic wave EI Centro whose peak acceleration is adjusted to 0.2 g in proportion is used for input. A double-layer foundation with sandy soil in the upper portion while clay soil in the lower part is chosen as the calculation model, which is 30 m in length and 20 m in width. The groundwater level is on the ground surface. Excess pore water pressure rate is considered as a liquefaction index in the three-dimensional non-linear earthquake response computation. The anti-liquefaction effectiveness and its influencing factors, such as confinement element area are studied. For the natural double-layer foundation, it is liquefied when the excess pore water pressure rate reaches 1.0 under the seismic load. Under the same earthquake load, the peak excess pore water pressure reduces to 0.56 after adopting reinforcement of the continuous soil-cement wall, which is 46% lower than before. It indicates that continuous soil-cement wall confinement method can attain the purpose of anti-liquefaction. Accordingly, it can be a sort of engineering measure to carry on the anti-liquefaction foundation treatment.
文摘In this work, the potentials of Bambusa vulgaris grown in southeast Nigeria for the manufacture of wood-cement composite panels were studied. Representative culms of Bambusa vulgaris were collected from a 4-year-old stand at lower Anambra river basin, southeast, Nigeria. Fiber morphological properties and proximate chemical analysis were determined in accordance with the provisions of the Technical Association of the Pulp and Paper Industries (TAPPI, 1998). Fiber slenderness ratio was 160.95:1, component solubility of 3.09, 5.60, and 19.8 percent for cold water soak for 24 hrs;hot water soak at 80°C for 1 hr, and 1% NaOH soak for 24 hrs respectively. Composite panels were made at 1200 kg/m3 and 800 kg/m3 density levels with flakes of different soak treatments (untreated/control;cold water soak for 24 hrs;water at 80°C soak for 1 hr and 1% NaOH soak for 24 hrs) at variable cement/B. vulgaris mix ratios (1:1, 1.5:1, 2:1, 2.5:1 and 3:1 wt/wt) with 3% CaCl2 as accelerator applied to the wood furnish before cement mixing. Prepared furnish was subjected to initial pre-pressing of 0.5 N/mm2 and final consolidation of 1.4 N/mm2 retained for 24 hrs. Panels were sampled and tested after 28 days for Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) in bending and for water absorption (WA) and thickness swelling (TS) due to a 24-hr water soak. Test was in accordance with provisions of American Standard for Testing of Materials (ASTM-1998). Properties ranged from a low of 25.00 to 75.45 N/mm2 for MOR;4128 to 15,065 N/mm2 for MOE;15.01 to 36.11 percent for WA and 3.04 to 12.72 percent for TA. Effect of production mix on properties was determined using factorial analysis. Except for composite density whose effect was not significant at 0.05% level, all production mix was found significant at 0.01% level at the second order level of interactions. All panels met minimum property requirements of American National Standard Institute 208-2-1994 and 208-1-1993, British Standard (BS 5669, 1979) and Malaysian Standard (MS 934, 1984).
