Thornfield Hall represents the difficulty and joy in being that is an essential part to the novel. As its name implies, Jane experiences much in way of both in terms of finding "fields" of happiness and the "thorns" that go along with it. Jane experiences the joys and hurt intrinsic to love. She also recognizes the conditions in the world that prevent full understanding and the threshold of revelation that helps to overcome these elements. This dynamic is further enhanced with the physical destruction and spiritual restoration of Thornfield which takes place at the end of the narrative. It is at Thornfield where Jane is able to learn more of herself and the world, and as a result, the function of the setting is one where Jane's character is widely developed. Thornfield functions as the realm where many of the novel's themes are fully realized.
Different critical evaluations of the setting do exist. Some have taken to a Marxist analysis of Thornfield, reflective of how the strict power structure where someone like Jane would have no power or voice can be overcome. Thornfield and thus its burning to the ground is reflective of the force of change that Marx articulates within his theory. The "blackened ruin" in Thornfield's destruction and its restoration of a Thornfield represents the challenge and reversal of an oppressive class structure for Jane and Rochester. Another set of critical evaluations of Thornfield reflects its Gothic character, a world where something beyond individual comprehension exists. In these approaches, critical evaluations of the setting, discussions that help to add significance to Thornfield Hall, are displayed.
Any number of scholarly articles can be obtained from the Reference section of a college library or a city library in the Contemporary Literary Criticisms. There is an index in which you can look of Jane Eyre or settings in Jane Eyre.
Of course, these are also accessible on JSTOR or ERIC if you can go to a college library or have access to a virtual library card.