Papers by Author: Jun Xiang Wang

Abstract: The self-developed finite element method has many advantages and good prospects to solve problems of underground engineering. The program is used to the simulation of the true tunnel, while it is embedded into self-developed algorithm. The results indicate that self-developed finite element method has many advantages and good prospects to solve geotechnical problems, and it can be used for quantitative analysis of underground engineering.

Abstract: The finite element method combines with differential evolution algorithm to develop the displacement back analysis program. For the field excavation of Dalian subway tunnel, the ground subsidence, crown settlement and convergence displacement are monitoring measurement, then data fitting and regression analysis; Using the independent development program and monitoring data to back analysis so that we can address rock mechanics parameters are not accurate "bottleneck"; According to the inversion parameters, the forward analysis of the finite element numerical simulation, to form a comprehensive monitoring and information feedback system based on the field monitoring - displacement back analysis - being analyzed - field monitoring. The results show that the mechanical parameters of displacement back analysis program are very close to the project survey, while the monitoring and information feedback system has an important theoretical and practical value for safety of surrounding rock and stability of construction process.

Abstract: Differential evolution algorithm is a new global optimization algorithm. DE does not require an initial value, and it has rapid convergence, strong adaptability to a nonlinear function, the features of parallelcalculation, especially in adoption to the complex problem of multivariable optimization. The constitutive integration algorithm affecting the incremental calculation step, and convergence and accuracy of the results is a key of finite element analysis. It is usually divided into an explicit and implicit integration. Return mapping algorithm is an implicit integration to avoid solving the equivalent plastic strain directly so that we achieve a fast and accurate solution for the constitutive equations. Making use of DE and return mapping algorithm to program, the elasticplastic finite element simulation and parameter inversion, the inversion and simulation results are verificated, the results show that it is closed to the actual situation, indicating usefulness and correctness of the program.

Abstract: Identifying ground stress based on rock core discing can save a lot of surveying cost, so studying “rock core disicing” has great meaning. Aiming at the limitation of conventional methods, the particle swarm optimization (PSO) arithmetic is introduced to be combined with numerical simulation, so as to identify the ground stress based on rock core disicing observation. The objective function of optimization is constructed by combing Mohr-Coulomb criterion and tension criterion. Adopts dynamically adjusting momentum term method and steric compression method so as to improve the PSO in convergence velocity and globally searching property. The proposed method is mentioned and used to identify the ground stress of Bakken formation in USA. The arithmetic has good convergence speed and the identified results are coincident with the former reported results.

Abstract: In this paper differential evolution algorithm (DE) which is a new global optimization algorithm is introduced into the displacement back analysis, and the self-developed back analysis program based on DE is used in metro station engineering. The results show that the superiority of DE and the practicability of intelligent displacement back analysis program, more importantly, it is being applied to engineering practice to provide reference and advanced prediction for the construction process.

Abstract: Aiming at the characters of high ground stress and high pore water stress, which resulting in water invasion risk in excavation of subsea rock, FLAC is adopted to simulate the strain localization phenomena of surrounding rock with different pore water pressure and confining pressure. In calculation, the strain soft constitutive relation and “first loading then unloading” pattern are used. Simulation result states that, the bigger the confining pressure is the more destruct the surrounding rock is, and the water invasion risk is more serious. In high confining pressure condition, shortly after excavation, the destroy zone is thin ring, subsequently, the arc shoulder and arc bottom occurs shallow hole, the destroy zone increasing, which presents zonal disintegration. Pore pressure has obvious influence at plastic strain of rock, the high pore water pressure results in surrounding rock destroy zone enlarging, which changing the seepage field of rock, and probably lead to seepage instability.

Abstract: Aiming at the complexity of high arc dam, and the limitation of conventional methods static and rigid body hypotheses of conventional slope stability analysis, which bring great difference with true engineering state. The paper proposed a concept of “abutment safety degree” considering the affection of dam body, and developed the model including dynamic contact element reflecting local rock crack and quasi continuous medium reflecting large deform. Based on above model, combing with 3D element strength reduction method and strain control criterion, the resist safety degree calculation method for dam shoulder high slope of high arc dam system has been constructed, which can fit the complex geo-mechanical engineering. Finally, the method is used in the dam shoulder slope analysis of Xiaowan arc dam system with height of 300m, the result is satisfied, the calculated safety degree is decreasing 20% to the result of conventional method. The method provides a powerful way to the safety evaluation of complex engineering.