Study On The Characters Of Deformation And Post-processing Technology Of Highway Widening Project

In recent years, with the rapid growth of economic construction in our country,especially since the accession to the WTO and the development of the logistics industry, city-to-city cooperation between more closely and traffic flow of highway increasing, the considerable portion of highway has been unable to meet the demand of traffic growth and the requirements of the social development, there is an urgent need to expand the capacity of the road. Because the construction of a new highway near the old highway would cause the large-scale of investment and the use of more land, and easily lead to uneven distribution network, the old road widening programme were adopted by the most of China's highway expansion projects at the present stageHighway expansion will inevitably involve the integration and link of old and new highway, and mutual influence of old and new embankments and other issues, After years of operating the existing embankment, the settlement has been completed, in its wider expansion on the slope, reclamation of the earth and the operation of the vehicle load is bound to cause additional settlement of the existing roadbed, and the relatively large difference settlement between in the new and old roadbed, then not only will cause deformation of roadbed, while there is a serious road-Kira, have been sinking fast, and other diseases, the immeasurable negative consequences will bring to the normal operation of highway; At the same time, the construction time of widening expansion projects of highway is normally tight, and the construction site is narrow, while also maintaining the normal transport, there are higher demands compared to the construction of a new highway. So it appears to be particularly important that to choose the economic, fast and reliable treatment measures in widening the existing highway to ensure the security operations of the existing highway and the reduceing of the differential settlement between the old and new hughway pavement after widening. Based on the above background of the project, the main contents of the study are listed as follows:1. The post-processing technology of small non-sand concrete pile is a new processing technology of thick filling area, through the detailed analysis of the construction technology and the pressure grouting and the post-processing mechanism of small non-sand concrete pile technology, we can see the post-processing technology have preloading, rapid drainage, exhaust consolidation, curing, the vertical displacement, and so on a comprehensive mechanism; Composite foundation with small non-sand concrete pile because of its unique construction process, its bearing capacity related in addition to the engineering and geological conditions, but also to filling materials, grouting and pressure grouting, grouting process and the replacement rate, so the parametersβ₁ (pile capacity to play a factor of small non-sand concretepile) andβ₁ (enhancing factor of bearing capacity of inter-pile soil) were introduced inthe bearing capacity formula of composite foundation with small non-sand concrete pile; Through the analysis of the vertical deformation coordination of the pile-soil, and the soil stress and deformation between the piles of composite foundation with small non-sand concrete pile, the optimal design based on the deformation control was solved2. First filling height is a key technical parameters in the post-processing technology of thick filling area, it direct related the economic and social effects of post-processing technology, so different methods of analysis were used for different geological conditions, when the weak saturated with shallow soil, bearing capacity is low, the calculation methods of first filling height based on the twin shear unified strength theory is discussed, which can give full play to the natural foundation of the original capacity, to achieve the purpose of reducing costs; When bearing capacity is high, the methods of analysis based on the stability of embankment can easily determined the first filling height, which eliminated the adverse effects due to filling its own stability before post-processing.3. Based on the particularity of widening filling load of thick filling area, analysis of the initial effective stress and ultra-pore water pressure of soil under various forms of loads were carried out; results of pore water pressure and degree of consolidation of soil were obtained in various stages based on the detail analysis of consolidation process for the first filling and construction of hole in the post-processing technology.4. Based on the expansion elastic theory of cylindrical cavity and the twin shear unified strength theory, analysis of stress state of soil around the pile and grouting pressure of small non-sand concrete pile is given, grouting pressure is obtained in the elastic limit state and elastic-plastic state of soil around the pile considered the intermediate principal stress, and the relationship is obtained between the grouting pressure and the plastic radius; When the soil around the pile is in different stress state, the correlativity of crack and densification of grouting is analyzed, and the relationship between the grouting pressure p and the plastic radius r_p is discussed withthe right coefficient b of the intermediate principal stress and initial press p₀ underdifferent value, which has provided theoretical basis for optimazation of grouting construction technology of small non-sand concrete pile.5. Based on the engineering background of the widening bilateral symmetry of highway, a detailed comparative analysis of the influence of The characters of deformation of the original foundation and the old embankment with the construction of the widening filling load on numerical simulation is carried out considering both cases that widening embankment is not used for processing and use of pre-processing and post-processing.6. In the applications of the post-processing technology in the road widening project, through the level and vertical deformation monitoring results of the old sloping shoulders and widening road shoulders slope position, we can see the post-processing technology not only can enhance the combination between the old and new embankment, but also can coordinate deformation between the old and new roadbed, significantly reduce the settlement after construction.