What is 入墓 (rù mù) in Chinese metaphysics?

A stem falling into the palace where its element is "entombed" (e.g. Yi at Wei, Bing at Xu) — power trapped, matters delayed.

Original (Chinese): 天干落入其墓地之宫(如乙入未宫、丙入戌宫),主力量被困、事情迟滞。