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全长粘结式锚杆加固节理边坡的动静态位移响应 被引量:18
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作者 林杭 曹平 +1 位作者 李江腾 何忠明 《岩土力学》 EI CAS CSCD 北大核心 2009年第6期1787-1792,共6页
锚杆通常被作为表面粗糙的轴力杆单元进行分析,但在节理边坡加固中,由于节理面的错动,同时考虑锚杆的轴向和横向作用显得更加合理。通过理论分析,建立锚杆三弹簧单元的力学特征模型和变形特征模型,对其受力和变形进行全面分析;运用拉格... 锚杆通常被作为表面粗糙的轴力杆单元进行分析,但在节理边坡加固中,由于节理面的错动,同时考虑锚杆的轴向和横向作用显得更加合理。通过理论分析,建立锚杆三弹簧单元的力学特征模型和变形特征模型,对其受力和变形进行全面分析;运用拉格朗日元数值方法(FLAC3D),建立以理想弹塑性本构Mohr-Coulomb准则为基础的节理边坡模型,应用三弹簧锚杆单元,对其锚固前后的动静态位移响应进行模拟。结果表明:节理面锚固处理后,岩体的刚度得到提高;边坡各部位的位移减小,节理两侧位移的突变值变小;锚杆对节理的上下盘岩体起到有效的拉结作用,抑制了两盘之间的较大变形位移,有利于边坡稳定。 展开更多
关键词 锚杆 节理边坡 力学特征 变形特征 横向作用 动静态位移 FLAC3D
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Elevated metabolic rate during passive stretching is not a sufficient aerobic warm-up
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作者 Arnold G.Nelson Joke Kokkonen 《Journal of Sport and Health Science》 SCIE 2013年第2期109-114,共6页
Purpose: The purpose of this study was to determine the extent that a static stretching program could increase heart rate (HR) and oxygen consumption (VO2), and if the increases were sufficient to serve as a warm... Purpose: The purpose of this study was to determine the extent that a static stretching program could increase heart rate (HR) and oxygen consumption (VO2), and if the increases were sufficient to serve as a warm-up for aerobic activity. Methods: The HR and VO2 of 15 male and 16 female college students were measured after either 12 min of passive static stretching (SS), or 12 rain pseudo-stretching (PS), which consisted of moving through the stretching positions without placing the muscles on stretch. Four different lower body stretches were used with each stretch held for 30 s before the participant moved to a different position, with the circuit being repeated four times. VO2 was determined by averaging breath-by-breath measures over the total 12 min. HR was obtained every 30 s and the 24 values were averaged. Warm-up benefit was determined from the 02 deficit accrued during 7-min cycling at 60% VOzmax. Results: HR (beats/rain, mean 4. SD) for SS (84 ± 11) was a significant (p 〈 0.05) 9% greater than PS (78 ± 12). Similarly, VO2 (mL/min, mean 4. SD) for SS (0.53 ± 0.13) was a significant 44% greater than PS (0.38 ± 0.11). The O2 deficit (L, mean 4, SD) for SS (0.64 ± 1.54) was not different from PS (0.72 ± 1.61). Conclusion: These data indicate that passive static stretching increases both HR and VO2, indicating that metabolic activity can be increased without muscle activation. The magnitude of the increases, however, is not sufficient to elicit a warm-up effect. 展开更多
关键词 Acute stretching Heart rate Metabolic activity Oxygen consumption O2 deficit Passive stretching
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