No abstract

Response surface methods are often used to solve reliability analysis problems of complex engineering structure. But the solved reliability index of these methods is mostly geometric reliability. Some errors exist in geometric reliability index compared with the reliability in practical engineering which need to be improved. The importance sampling method in V-space was lead into this paper to transform the basic random variable space to V-space by Rosenblatt transformation and linear orthogonal transformation basing on the designed checking points and its nearby response surface, the complex structure reliability value was solved out by using Monte Carlo importance sampling method. The comparative analysis of several numerical examples’ results have showed that the method put forward in this paper is of high precision and suitable for the reliability solution of complex structures with strong nonlinear performance function.

On the basis of visualization of 3D stratum, deep excavation simulation is accomplished by combining with numerical analytical method, Excavation effect on surrounding environment is analyzed. By using experimental or semi-experimental models, the settlement values and their distribution features, which are caused by excavation, are discussed, by using 3D FEM, the horizontal displacement of excavated foundation ditch is calculated, and the OpenGL technology and triangle split arithmetic are chosen to implement the construction and splitting of 3D strata, the excavating process and its influence on the surrounding environment are ultimately realized. By comparing with engineering cases, the validity of analysis model and implement method are shown to be correct, feasible, and efficient.

By introducing generalized random space conception to deal with the relativity of shear strength variables of rock or soil, the calculation formulas of foundation bearing capacity reliability analysis in generalized random space were deduced and the program was worked out. The reliability of one project’s foundation bearing capacity was analyzed. The results proved that the relativity of random variables affects the reliability analysis result and must be considered.

Based on the property that micro-cells strength is consistent with lognormal distribution function, this paper presented a new statistical damage softening constitutive model simulating the full process of strain softening for rock. Through discussing the characteristics of random distributions for rock micro-cells strength, lognormal distribution assumption is tested by Kolmogorov-Smirnov test in statistics, and the reasonable method of geometry boundary condition is selected to determine model parameters that can be easily applied to the situations under different complex conditions. Gabbro experiment comparative analyses show that the new damage softening constitutive model is rational and convenient in engineering.

Four models of the tunnel bedding structure were analyzed under the impact loads of the train by simulating the infrastructure under the track. In this study, we examined the relationship between the vertical dynamic coefficient and the train velocity, and also analyzed the damage sustained by the bedding structure under the static and dynamic loads. It is suggested that the damage in the concrete bedding is detected in the longitudinal direction, immediately below the two rails, and that this damage is likely to occur not from attaining an elastic limit under static loads but more likely from damage accumulation in fatigue due to repeated loadings. It is not advisable to improve the tunnel bedding structure by simply increasing the thickness of the concrete bedding board; however, the bending resistance of the tunnel bedding structure can be enhanced by adopting compact reinforced concrete structure.

The stability control of the overlapped tunnels system has been one of the hot issues and difficulties in tunnel and underground engineering field. According to the whole process analysis for instability evolution of the overlapped tunnels, its nonlinear dynamics characteristics are studied by the nonlinear dynamics method, including material and energy metabolism, fluctuation, thermodynamics irreversible process, correlation dimension and entropy. On this basis, combining with stability control measures such as grouting, bolt and gunite and so on, the dynamics mechanism and energy dissipation mechanism for stability control of the overlapped tunnels system are studied by synergetics and dissipative structure theory. The nonlinear dynamics evolution law of the control process is also revealed. This research is not only able to provide theoretical support for establishing optimal control model and risk control principle based the nonlinear dynamics, but also of great significance for the stability control technology of the overlapped tunnels.

In order to insure the safe and reliable road-tunnel composite structure, it is important to consider the influence of different foundation treatment ways on the differential settlement of the composite structure. Based on the nonlinear FEM, connecting with the western corridor connecting project from Shenzhen to Hong Kong in China, a numerical model has been established to estimate the settlement of the road- tunnel composite structure under three different foundation treatment ways, such as pressure grouting, PHC piles (prestressed high-strength concrete piles) and foundation in natural state. This study shows that the influence of the different foundation treatment ways on the transverse and longitudinal differential settlement of the composite structure of road-tunnel is strong. The results from this study provide a useful guideline for settlement control of other similar projects composed of tunnel and road structure.