The Whole Weathered Granite Improved Soil Engineering Properties And Its High-speed Railway Construction

At present, it is in the constraction period of high-speed railway in China. To ensure the train safety, comfortability, smooth operation, there are strict requirements for the embankment deformation of high-speed railway. Wuhan-Guangzhou passenger rail line passes through a wide range of weathered granite, and lack of A,B group fillings, It is uneconomic and unreasonable for transporting qualified filler completely. To ensure that the project can be efficient safe and economic and reach the required standard of filling, It is necessary to improve weathered granite completely. Based on comprehensive analysis of research of weathered granite at home and abroad, engineering properties of weathered granite and its improvement were studied through theoretical analysis,laboratory test and numerical simulation methods. Main contents and conclusions are as fellows:(1) Through a large number of expermimental studies, it is shown that physical and mechanical properties of weathered granite are poor: smaller internal friction angle, better absorption capacity, bigger natural moisture content, smaller force, loosely, higher liquid and plastic limits, higher content of fine particles, higher silt content, lower strength index of weathered granite, lower carrying capacity, lower CBR value, smaller modulus,deformation resistance and long-term water stability are poor.(2) Through experiments of improved soil with different additive, including analysis of particle, liquid limit and plastic limit, characteristics of compression, characteristics of compaction, stability with water, properties of strength, it is shown that:plasticity index was decreased; curve of particle anslysis was to the left and coarsening effect of particle was obvious; curve of compaction became gently which made the control of water content in easier construction; compressibility and permeability were decreased; permeability decreased; stability with water was increased; strength was increased. For DK2097+560, improved soil with 6% lime was able to meet the requirement; but not suitable mixing lime for DK2116+200, improved soil mixing with 6% cement was able to meet the requirement of high-speed railway.(3) Unconfined compression strength was predicted with BP model of MATLAB software,and influencing factors of unconfined compression strength was analyzed. There was an optimal incorporation for improved soil mixing with lime. Unconfined compression strength increased with increase of degree of compaction, and decreased after soaking. The strength will grow with age.(4) Formed element simulation model of embankment from ANSYS. When improved soil was used as a filling, dynamic characteristics were studied at different speed,different wheelload and different thickness of surface-based bed. Dyamic response reduced with increase of the depth. Maximum appeared under the rail or the center line of the right line. Dynamic response did not increase with increase of speed. There was a linear function between dynamic response and wheelload. Response increased with wheelload. Dynamic respose reduced with thickness of surface-based bed increased.