Requirements documentation is a collection of partial specifications produced by different stakeholders. Obtaining a global specification is a fundamental step of a requirement analysis process. Merging requirement specifications is indeed a way to reveal inconsistencies between them. We propose in this paper a model-driven mechanism for that purpose. It takes as inputs a set of texts or models which conform to input requirement languages and produces a global requirements model. This mechanism is integrated in a platform called R2A which stands for ?requirements to analysis?. The R2A core element is its core requirement metamodel which has been defined for capturing the global requirements model. We illustrate our approach with requirement specifications expressed in a constrained natural language. This platform and its mechanism have been completely implemented with MDE (Model Driven Engineering) technologies. As such, it is a good example of how MDE technologies can contribute to requirements engineering as a technical solution.