In modern Trinitarian apologetics, it is very common to hear the claim that in 1 Corinthians 8:6, the Apostle Paul takes the famous confession of faith given in Deuteronomy 6:4, called the Shema, and augments it to include Jesus Christ, thereby identifying Him as the one God, Yahweh.
The passages in question are:
Deuteronomy 6:4 (NRSVUE)
4 "Hear, O Israel: The LORD is our God, the LORD alone.
1 Corinthians 8:6
6 But to us there is but one God, the Father, of whom are all things, and we in him; and one Lord Jesus Christ, by whom are all things, and we by him.
Notice above that in the Shema, the words "Lord" (Yahweh) and "God" refer to the same subject. There is only one subject in the sentence - Yahweh.
In distinction, the passage in 1 Corinthians has two subjects - the "one God", who is "the Father", and the "one Lord", who is "Jesus Christ". If the Shema were in view in this passage, it would only be in the first part of the verse. The first part of the verse, which says, "to us there is but one God, the Father", exhausts the content of the Shema. So, one could say that the Apostle Paul "expands" the Shema in the sense that he mentions the additional position of "one Lord". But, it can be shown from the New Testament that the position of "Lord" is one to which the Father has exalted Jesus (Acts 2:36, 5:31, Ephesians 1:20-22, Philippians 2:9-11, etc.), and Jesus remains below God while occupying that position (1 Corinthians 11:3). It is a distinct position created by God, under God. Therefore, it may be valid to say the Apostle Paul "expands" the Shema, but definitely not via the application of the title "Yahweh" to Jesus. The New Testament position of "Lord" is not "Yahweh".
However, while the possibility that the Apostle Paul had the Shema in mind cannot be ruled out, he does not actually quote the Shema here. He definitely had what the Shema teaches in mind - that there is one God, the Father - but this is a general teaching of the Bible, taught in many places, and so whether he was intending to reference the Shema specifically cannot be stated dogmatically.
There are other passages in which the Apostle Paul appeals to the general teaching of Scripture that the "one God" is the Father alone, and they do not require one to assert that he was expanding the Shema there, either:
Notice above that the passages do not share enough words (in English or Greek), or a style to the extent that it would really warrant any of them being designated a "quotation" of the Shema, although they all reference the central truth taught in the Shema. Also, notice above that all three of these passages teach that the position and identity of Jesus is distinct from the "one God", who is the Father.
Therefore, it is an over-reading to assert that in the passage in 1 Corinthians chapter 8, the Apostle Paul was somehow bringing Jesus into the Shema in a way that would identify Him as the Shema's "Lord" (Yahweh). There is one subject in the Shema, and it is Yahweh, who is the Father (Isaiah 63:16, 64:8). Nothing in the passages in question would lead one to think that the author is teaching that Jesus is the Lord Yahweh spoken of in the Shema.