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1)  π pattern girder
π型梁
1.
Based on mining tests on the monomerprop and π pattern girder caving method with full shear height, analysis and studies on the ground behavior regularity of conventional caving method coal face on “Soft Seam With Soft surrounding” and extremely unstable seam have been porformed.
通过对单体支柱、π型梁放顶煤一次采全高技术的开采试验 ,研究了在“三软”极不稳定煤层条件下 ,普通放顶煤开采工作面的矿压显现规律 ,试验研究了合理的支护方式及支护参数。
2)  π type steel girder
π型钢梁
1.
In Mining old mine section,the stage pillars are recovered by using single hydraulic prop and π type steel girder support.
在旧区复采过程中,选用单体液压支柱与π型钢梁配套支护回收阶段煤柱,进行老旧、残区回采,极大地提高了矿井煤炭资源回收率,使已经废弃的资源得已再回收。
3)  type-π of metal cap
金属π型顶梁
4)  Π cross-section main girder
Π型截面主梁
1.
A model for a prestressed concrete cable-stayed bridge with a Π cross-section main girder was established in a scale of one to five for a concrete cable-stayed bridge over the Jinsha River in Yibin City.
针对宜宾中坝金沙江斜拉桥,按1∶5的几何尺寸制作了Π型截面主梁预应力混凝土斜拉桥模型,对其剪力滞效应进行了试验研究,并与有限元分析结果进行了比较,两者吻合。
5)  Concreteπgirder
混凝土Π型梁
6)  π type steel caving
π型钢梁放顶煤
1.
By comparation of the basic performance between the BDY sliding hudraulic support with paralleling top beams and π type steel caving technology,the understanding of BDY hudraulic supports with paralleling top beams was raised.
通过对BDY型并联顶梁滑移液压支架与π型钢梁放顶煤工艺基本性能的比较,提高了对BDY并联顶梁液压支架的认识,使该支架得到了更好的应用并发挥效能,实现了煤矿的安全生产。
补充资料:π, π-conjugation
分子式:
CAS号:

性质:单键和双键相互交替排列的共轭体系。最简单的为1,3-丁二烯,而苯分子则是一个具有高度对称结构的闭合共轭体系。除碳碳双键外,碳碳叁键、碳氧双键等,都可组成π,π-共轭。例如:CH2=CH—C≡CH;CH2=CH—CH=O。由π,π-共轭引起的使分子内能降低、键长发生平均化等电子效应,称为π,π-共轭效应。

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