Crackenn.克拉肯crackv.破裂；砸开；发出爆裂声；撞击；破解；变嘶哑；崩溃；制裁；<非正式>开玩笑n.裂缝；裂痕；爆裂声；猛击；尝试；俏皮话adj.训练有素的Crack depth of roller轧辊裂纹深度cracked combined roof破碎复合顶板crack on the concrete混凝土裂缝crack a criminal case破案cracking fractionator裂化设备的精馏塔crack's areal densitycrack growth exponent裂纹缓慢扩展指数crackability of stock燃料的裂化度crack characteristics裂缝特征crack in parapet wall女儿墙裂缝

1. To study the mechanism of crack extension by hyduaulic fracturing, the mass hyduaulic fracturing experiments are carried out in granodiorite at Fangshan District, Beijing, China.
   为研究水压致裂过程中裂缝的扩展机制，在北京市房山区花岗岩体中开展大流量水压致裂试验。