The Old Testament and Rape : Commentary on Deuteronomy 22:28-29
As Brown-Driver-Briggs demonstrates, the word can be used in relation to sexual intercourse as well as for other things. The following examples help demonstrate that shakab does not necessarily imply a forced sexual act:
"And the LORD spoke to Moses, saying, ‘Speak to the children of Israel, and say to them: ‘If any man's wife goes astray and behaves unfaithfully toward him, and a man lies (shakab) with her carnally, and it is hidden from the eyes of her husband, and it is concealed that she has defiled herself, and there was no witness against her, nor was she caught—" Numbers 5:11-13 NKJV
Here, the word shakab refers to a voluntary sexual act between two consenting parties, in this case to a woman who voluntarily chooses to commit adultery. It is clear that the woman in question wasn't forced into having sex. Again:
"If a man lies with a woman so that there is a seminal emission, they shall both bathe in water and be unclean until evening." Leviticus 15:18