## 3 Research Methodology  
### LDA-DEMATEL-ISM Method  
In this paper, we will use the Latent Dirichlet Allocation (LDA) model, which was proposed by [PERSON] in 2003 as an unsupervised machine learning text-mining method that is able to mine the potential topics of a document from the original document [42] and differs from traditional topic mining methods; the LDA model is good at dealing with large-scale unstructured documents and provides good results [43]. In addition, all the parameters of the LDA model are unknown, it does not make manual settings in advance and it can mine potential topics from raw data documents. Therefore, applying the LDA model to the content analysis of documents can largely preserve the internal relationship of the documents and reveal the evolution path of research content by constructing the potential relationship between topics; therefore, it is more effective in extracting potential topics from the scientific and technological literature.  
The Decision Analysis Method in Laboratory (DEMATEL) method is a method based on graph theory and matrix tools to analyse the causal relationship between the factors proposed by the researchers [PERSON] and [PERSON] at Bastille National Key Laboratory, USA [44]. The DEMATEL method analyses the causal relationship between factors by constructing a comprehensive influence matrix describing the correlation between the elements within the complex system and uses the degree of influence, degree of being influenced, centre degree, cause degree and other related indicators to determine the cause and effect factors and the degree of influence of each factor on the complex system and to identify the key elements of the complex system pair [45].  
Interpretive Structural Modelling (ISM) is a systematic method proposed by Professor [PERSON] to analyse and construct the association patterns of elements within a complex system [46; 47]. The ISM method is based on the construction of a reachability matrix that describes the influence relationships between the elements within a complex system and then transforms and analyses the reachability matrix to construct a model that reveals the hierarchical relationships between the elements within the system and reveals the hierarchical relationships between the elements [48]. ISM uses graph theory to analyse the hierarchical relationship between the factors in the system and transforms the numerical relationship between the elements in the system into a hierarchical structure diagram that can be analysed intuitively and can effectively analyse the multivariate influence relationship between the factors.  
The LDA model, the DEMATEL method and ISM are used in combination. For the idea of integrating these processes into the LDA-DEMATEL-ISM method, first, the LDA model was used to mine the original text for potential topics to obtain the uncertainty indicator system of the next-generation digital technology application in China's construction industry. Then, the impact relationship between the indicators was assessed through an expert scoring method. The comprehensive influence matrix between each element was then constructed via the DEMATEL method. Taking into account the effects of the factors themselves, the combined impact matrix is calculated and then an appropriate correction factor is introduced to further convert it into an achievable matrix. The hierarchical structure of each element of the system can be divided using Boolean logic operations.