Stability Study Of Rock Foundation With Caverns

With the increase of urban underground and ground engineering, the conflict between ground building and underground engineering is more and more. It is more important to evaluate accurately the stability of rock foundation with caverns. It becomes a special outstanding and urgent problem to study stability of rock foundation with caverns in Chongqing mountain city. In the dissertation, systematic research of rock foundation with caverns is carried out by combining with Chongqing light rail rock cavern foundation. Main conclusions are summarized as follows:(1) Failure model and stability criterion of rock foundation with caverns is carefully researched in this dissertation. The author classifies the cavern foundation into three typical failure model as follows: 〨round building is failure but cavern is safe; ヽavern is failure but ground building is safe; 〣oth ground building and cavern are failure. For ground building's safety and cavern's safety, stability criterion of rock foundation with cavern is controlled by safety strength and deformation of ground and underground engineering.(2) According to influencing depth of foundation ground additional stress and influencing scope of deuterogenous stress of cave under foundation, the author classifies the cavern foundation into three types, that is, deep burying cavern foundation, shallow burying cavern foundation and cavern foundation without influence of cavern. Analytical solution of stress and displacement from shallow burying cavern foundation can be determined by using the theory of elastic mechanics. For deep burying cavern foundation, it is treated as a problem of infinite plate containing a hole, whose analytical solution can be obtained by using elasticity theory.(3) By using strength reduction FEM and load-increasing FEM, the author proposed that the foundation with an opened cavern is subjected to loading. As a result, load-increasing FEM is suitable for stability analysis of foundation with an opened cavern, but for foundation with an opening cavern, strength reduction FEM is feasible.(4) The ratio of between plastic zone area and cavern area, etc, is proposed to determine the safety factor of cavern foundation. The results from the realistic example show that the method is feasible.(5) By combining adaptive-network-based fuzzy inference (ANFIS), which provides an analytical approximation of the true FEM calculation, and uniformexperimental design, which select typical sample points, intelligent identification system to analyse the stability of cavern foundation is established. The results from the realistic example show that the present intelligent identification system is efficient.(6) Based on the analysis of two complex rock cavern foundation engineering examples in Chongqing city, this dissertation provides a synthesized analysis method, and recommend the research route for study stability of complex cavern foundation.Results obtained in the dissertation are basically consistent with the results by in-situ monitoring. It is showed that the method and theory in the dissertation are reasonable, and important for decision, design and construction of rock foundation with a cavern.