Research On The Safety Risk Assessment And Control Of Masonry Buildings Adjacent To Deep Excavation

With the progress promoting and deepening of reform and opening-up,the pace of urbanization in China is accelerating, and the construction of underground projects is heating up continuously. Deep foundation pit is a common form of temporary structure. During the progress of deep excavation, nearby masonry structure buildings are more easily affected by surface subsidence and horizontal displacement caused by the release of soil than other structures. As a traditional architecture form in China,masonry structure buildings have been widely used. Therefore, it is significant to study the nearby masonry buildings’ safety condition of each state to assess the safety risk grades accurately before construction and conduct real-time control, so that safety risk can be investigated and security accidents can be prevented for timely stop-loss and security of people and their property. In this paper, theory and practical methods have been combined to carry out in-depth research on the subject.Firstly, on the basis of extensive reading of domestic and foreign articles, some deficiencies of existing research have been pointed out. To make up for these, the safety risk management procedure specially for masonry buildings adjacent to deep excavation has been put forward, which was combined with risk management basic principles, damage mechanism and influence factors of masonry.The focus of this paper is safety risk assessment ahead of construction.To evaluate risk safety grades reasonably, a practical model has been proposed based on integrated risk index matrix method. Firstly according to the effect mechanism of buildings affected by deep excavation construction and the damage mechanism of masonry structure buildings, 4 evaluating indexes from deep excavation and another 4 indexes from masonry structure were selected separately. They constituted the evaluating index system with other 3 correct indexes. Then AHP and the improved grey relation degree method were used to decide the selected indexes’ weights. A distinguishing evaluation standard and a chosen scoring method were then put forward and correction factors were considered to determine the safety risk grades formore accurate results. Next, risk response suggestions have been made aimed at high risk grade buildings. Finally, the operability and reliability of this model were verified by actual engineering examples.Next, safety risk control and forewarning of adjacent masonry buildings were studied during excavation and a real-time control model to monitor nearby masonry buildings safety condition has been established by the process control implementation steps. Besides, a three level risk forewarning system has been proposed in accordance with the current national norms.Finally, post-construction assessment procedures were discussed based on masonry structure’s characteristics. Then, for some buildings that are damaged obviously or need to be repaired and reinforced, some referenced measures and suggestions have been given.