When the force can not contact drill string with one side of the borehole wall, the stiffness of drill string can influence the contact force.

当外力不足以使钻柱紧贴于井壁的一侧时，钻柱的刚度对钻柱与井壁之间的接触力有影响。

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Elements of stonework excavation: Use down-hole drill assisted with hammer drill drilling. Control blasting loosely and side slope molding smoothing wall blasting.

石方开挖施工要点：采用潜孔钻机配以凿岩机钻眼，松动控制爆破和边坡成型光面爆破。

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Elements of stonework excavation: Use down-hole drill assisted with hammer drill drilling. Control blasting loosely and side slope molding smoothing wall blasting.

石方开挖施工要点：采用潜孔钻机配以凿岩机钻眼，松动控制爆破和边坡成型光面爆破。

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