| This paper mainly analyzes of important characteristics of expansile earth distributed along Hefei-Nanjing express railway section, Xi'an-Nanjing railway, featured with conjunct railway both for passenger and freight transports at the speed 200km/h. Expanding rate and granule compounding and other testing index has been confirmed on accordance with the typical earth picking-up and testing in the indoor lab along the railway. The reasonable lime mix rate of the lime improved expansile earthworks has been confirmed by the ways of various lime and earthwork mixture rate upon different earthwork sample. Through comparatively research and testing of engineering method of mix in-situ and road mix construction, controlling method for lime content and granule radius during the process of improved lime expansle mixture engineering by ways of different construction technology, and the researching of reasonable lime content rate, loose paving depth and compaction times within filling material also has been included. At the same time, the economic analysis for various construction technologies upon various lime improved expansile mixture. Finally, some important conclusions and feasible project suggestions has been requested accordingly.1. after the lime improvement treatment of 5%-8% to the filling materials of weak and neutral expansile earth on testing section construction, the following capacities, such as granule elements, physical characteristics and expansing/shrinkage, dynam intensity and cement concrete stabilization will be obviously improved and reinforced.2.to adopt the relevent mechanism collocation, subgrade construction quality done by three kinds of expansile earthworks working procedures illustrated in the following paper can absolutely be satisfied the design requirement. In terms of suitable granule diameter, defined and equal lime mixing dosage controling and quallity control, the method of central-mix is better than road-mix method, while, more difficult to control the construction intensity, comparasively to road-mix. Still, both central-mix and road-mix is relativelydifficult to control the lime content and equality as well as manual lime spraying and spreading.3. moisture content will inevitably influence to the three kinds of working procedures illustrated in the following paper. During the method of central-mix proceeds; the crushed effect and producing capacity will be absolutedly better and larger when moisture content is near to the best impacting one in the expansile granule; moisture contend should be determined by construction environment and condition for both central mix method and road-mix method; general speaking; the perfect moisture content should be controlled within the range of Wopt+2%—+4% for the best impact moisture content.4.the granule diameter of milling expansile earth will be occupied certain proportion when adopting central-mix method; if it doesn't meet the demand; the works of improvement and adjustment should be done.on conditon of proper moisture content both for central-mix and road-mix; the occupution proportion of /^15mm will be less than 20% after 3 times blending/ mixing and crushing for the method of road-mix and fix point road-mix on the borrow -pits.5. it is easier to control the accurate lime content and equanltiy for for method of central-mix than road-mix and fix point road-mix on the borrow-pits.6.when improved earthworks constructing; the best loose pavement depth is 35cm; and the best road-mix depth should be 30cm; and after rolling and compacting for 4 and 5 times; the compaction coefficient and subgrade coefficient will be absolutedly satistied the design requirement.7. central-mix method can be done on condition of close production; and easy to control fly dirt and reduce the environment pollution; and semi-close production can be done for fix point road-mix; and the pollution will be distrubited by points; and harmfulness is less than road-mix method.
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