研究表明，基本顶断裂线位于不同位置时，巷道围岩应力、煤柱应力及应变差异较大。

The results show that there are great differences in the stress of roadway surrounding rock, and the stress and strain in coal pillar while the fracture line of main roof locates in different places.

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图上有各种形式的线条，诸如：边框线、实线、虚线、剖面线、中心线、引出线、尺寸线、断裂线、假想线。

There are various types of lines on the drawing such as: border lines, visible lines, invisible lines, break lines, phantom lines.

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图上有各种形式的线条，诸如：边框线、实线、虚线、剖面线、中央线、引出线、尺寸线、断裂线、假想线。

There are various types of lines on the drawing such as: border lines visible lines invisible lines break lines phantom lines.

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