The Stability Of Roadbeds And Remediation

Due to widely dispersed, frequently occurring and having enormous harm, the water damage is one of most principal natural calamities on highway subgrade during each rainy season. Based on the site investigation and literature review results, the stability of subgrade due to underground water table rising are analyzed in detail by using the kinematical approach of limit analysis theory and finite difference method in this dissertation. The effect of a class of reinforcement measures to improve the stability of water damage subgrade is studied by use of the strength reduction finite difference method based on engineering practice, and commonly used engineering repair technology to deal with the reinforcement of water damage subgrade are given. The main content is as follows:(1) The characteristics, generation and production mechanism, repairing technology and practical experience of water damage subgrade are analyzed in detail according to the site investigation results. And the types of collapse and subsidence, the basic rules of water damage and the formation conditions are summarized and analyzed by combining the documents consultation method.(2) Profited from the predecessor research results and based on the linear failure criterion and associated flow rule, the critical height of slope and the stability factor are studied by means of the kinematical approach of limit analysis theory. And the planar knematically admissible failure mechanism is constructed elaborately for the calculation schemes. The objective functions of the critical height of slope and the stability factor are obtained by equating the work rate of external force to internal dissipation along the velocity discontinuities, finally the objective functions were transformed as a upper-bound mathematic optimization model for the critical height of slope and the stability factor as low as possible. Based on the mathematic software MATLAB, the result of upper bound method for planar failure mechanism has been obtained via the sequential quadratic programming (SQP). (3) Discussed the basic principle and method of strength reduction technology and the realization in FLAC programming. Some simple examples are calculated by using the large-scale finite difference FLAC programming, and the comparison and analysis with the calculation result by using the upper-bound theorem of limit analysis method and finite difference method are made.(4) Based on engineering practice, the stability of subgrade due to underground water table rising are analyzed in detail by using the strength reduction finite difference method. At the same time, the effect of a class of reinforcement measures to improve the stability of water damage subgrade is studied as well.(5) Based on the site investigation, stability theoretical analysis and numerical calculation results, introductions are made on the consolidation design and construction applications of commonly used engineering repair technology of water damage subgrade under different construction conditions. These are of instructive significance for design and construction of water damage subgrade.