Studies On Grouting Theories And It's Applications In Highway Engineering

Grouting has been widely used in the field of highway engineering, such as reinforcement, water shutoff, slope treatment, roadbed disease treatment and treatment in special section, etc. However, current available theory cannot be used to solve the grouting pressure design calculations, grouting control and grouting quality test. In addition, in the course of the roadbed construction, the current available methods cannot be used to solve the issues of compaction in certain section, where the conventional rolling techniques cannot be applied on compaction, and of rapid repair of roadbed. This thesis aims to improve and develop the grouting design calculations and engineering application problems. Innovative research results can be summarized as the following four areas:(1) The current available design of splitting grouting pressure is estimated on the basis of experience and field trials, which does not adapt the development of engineering application. Based on stress-strain relationship with respect to plane strain state of soil and the theory of large deformation, this thesis provided the design calculation theory of the soil splitting grouting pressure under the condition of plane strain; moreover, the design formulas were obtained as well. Compared with the experimental, the calculation results show a good agreement with the actual situation and it is successfully applied in experimental design of flexible pipe reinforced grouting and some engineering treatments. Thus, the economic and social benefits are evident.(2) Based on hydraulic fracturing theory and nonlinear Hoek-Brown strength criterion, the issues of design and calculation about fracturing grouting pressure of broken rock were analyzed, meanwhile, theoretical formula for design and calculation were established. The comparison between field results and the theoretical results shows that the theoretical results are identical with the engineering practice.(3) In order to theoretically analyze the grouting reinforcement of pavement slab void in terms of arrangement of holes and then obtain the design of grouting pressure, we assumed that the flow in the soil slurry cracks obeys Darcy's law and width of crack formed by fracturing grouting are uniform. Then, we obtain the arrangement of holes of grouting and grouting pressure design methods for 2 holes,3 holes,4 holes and 5 holes under the condition of the pavement slab void grouting. The theoretical results are closed to the measured values which prove the validation of these conclusions. Furthermore, we pointed out that the current specification of 5-hole grouting program has some limitations, and suggested that it is more reasonable to adopt 3-hole and 2-hole layout schemes to conduct grouting reinforcement of the pavement slab void. The theory provides a theoretical foundation for the general engineering applications. (4) On the basis of circular hole expansion theory and combined with grouting experiments results and mechanism analysis with respect to grouting, this thesis systematically presented a new construction technology (i.e., technology of flexible pipe stiffened grouting) and its design and construction procedures. The achievement has been successfully applied in some engineering practices, for instance, the filling soil treatment of abutment back of Yuanling Bridge of Changji Expressway in Hunan Province and roadbed subsidence rapid treatment of Duyun highway in Guizhou Province. The engineering applications show that the application of this kind of new technology on the treatments with respect to bridge abutment, roadbed subsidence emergency repairs, which issues cannot be dealt with by conventional rolling techniques, is very effective. The achievement has been obtained identification as an international leading-level research.