Research On Determination Method And Treatment Technology For Voids Beneath Cement Concrete Pavement

In recent years, with the development of highway construction, the construction mileages of cement concrete pavement are improved. Among the completed cement concrete pavements in China, parts of the road have been appeared various diseases in service cycle, and some diseases seriously affected the normal function of use, especially board crack early, faulting of slab ends caused by voids. The voids exist objectively in cement pavement structure. Because of the complexity of its status, it made difficult to treatment the voids. So voids are become a big difficult problem that has long bedeviled the road maintenance department. Rely on Yantai-Weihai test Road, based on collecting and analyzing relevant dates of the voids at home and abroad, this treatise analyzes detection technology, determination methods and treatment methods for the voids.The research in this paper consists of some aspects as follows: (1) systematical research and comparative analysis on domestic and overseas determination methods, the advantages and disadvantages of various determination methods are pointed out, the places to learn are obtained. The paper focuses on analyzing of three criteria using Deflectometer Benkelman Beam (BB) and seven determination methods using drop hammer Deflectometer (FWD). (2) The voids beneath cement concrete pavement are analyzed by ANSYS finite element software. It obtains the influence level on deflection value with void depth, cavity size, mass load capacity, and the relationship between deflection value and each factor. (3) The paper studies on the deflection detection methods, points out the recommended deflection detection method. Based on in-depth analysis of the current determination methods for voids in the relevant technical standard, according to the calculation results of finite element analysis and Westergaard formula and on-site deflection testing dates, it proposes the determination method that using slab edge - slab center deflection discrepancy and slab corner - slab center deflection discrepancy determine the voids, the criteria are given, and the criteria are verified by actual test data. (4) Based on analyzing of mixing proportion of materials in China, the paper designs the mixing proportion of cement type and organic type mud jacking materials with the shrinkage-compensating principle. Aiming at different levels of voids beneath cement concrete pavement, it puts forwards self-compensation mud jacking materials and recommends the right mix, and gives the evaluation criterion for the effect of mud jacking based on the grouting saturation and deflection. The effect of mud jacking technology is verified by test road.