内排水 meaning in English

internal drainage

By doing single fracture drainage experiments , this paper has successfully presented the logarithm function relationship between ratio of drainage discharge through upward and plumb drainage hole and the ratio of their equivalent diameters . the drainage effect will be the best when the included angle between drainage hole and fracture surface is 21 ~ 36
4 、通过单裂隙排水试验，建立了倾斜孔和垂直孔的排水量之比与其交界线的等效直径比之间的自然对数关系式，排水孔排水量基本随其与裂隙面的交角减小而增大；对单组裂隙排水的初步分析表明，排水孔与裂隙面的夹角在21 ~ 36范围内排水效果最佳。