Experimental Study On Fully Weathered Soft Rock And Improved Soil Filler Of Menghua Railway

There are so much weathered or easily weathered soft rock widely distribute at Yueyang to Jian, a section of a coal transport channel, Meng Hua railway. It can significantly save engineering investment of subgrade if the weathered or easily weathered soft rock is used to fill sub-grade. Otherwise,there are short of systematic study on using mixed filler of soft rock C,D to fill the sub-grade of heavy haul railways, and lack of mature experience for reference at home and aboard. Therefore, physical, chemical analysis and mechanical index test conducted on rock filling materials and cement, lime improved. As well as complete and systematical studies on the basic physical and mechanical properties of cement, lime improved solution. The main work and conclusions are as follows:(1)X-ray diffraction and X-ray fluorescence spectrumof weathered soft rock of Meng Hua railway are analyzed. The mineral composition in packing contains quartz, white mica with rich iron, feldspar, kaolinite and chlorite. The highest content is quartz, the second is white mica, clay mineral kalifeldspath and chlorite content are relatively few. There are 24 kinds of chemical components in packing, most with SiO2, Al2O3, K2O and Fe.(2)Weathered soft rock of MengHua railway and its basic physical properties of cement, lime improved solution are experimental studied. The data shows, the full weathered soft rock is high liquid limit silty clay, belonging to the D group filler, which can be available for heavy haul railway roadbed after improved; the compaction test of different blend ratio of cement and lime stabilized soil indicated that the maximum dry density of the cement improved soil increased 0.01-0.02g/cm3 compared to plain soil, while the maximum dry density of lime improved soil decreased 0.01～0.02g/cm3, the optimum moisture content of both lime improved soil and cement improved soil are increased, there are not obvious influence of the incorporation of ratio on maximum dry density and optimum water content.(3)Having unconfined compressive strength test on cement soil and lime soil with different mixing ratio, different compaction degree and different curing age. The Data shows that the strength of cement improved soil is 3-4 times of plain soil, and the strength of lime stabilized soil is 2-3 times of plain soil, the effect of cement improved soil is better than lime improvement; The changes The change of incorporation in the amount significantly influence the strength, The mixed quantity of cement soil increased 1%, the strength increased about 20%, the content of lime soil increased 1%, strength increased about 30%; The increase of cement soil strength with early rapidly and later slowly characteristics. According to the results of test, selected 3.5% of cement mixing ratio for the improved solution.(4)The basic mechanical properties test of the full weathered soft rock filler and the improved scheme of the cement are finished. The test shows that the permeability coefficient of 90%～95% compaction degree of the whole weathered soft rock filler in the range of 1×10-5cm/s～3×10-5cm/s, the cement content changes in the range of 3.0%-4.0%, there is a little change of the variation of permeability coefficient of cement soil; the effect on cement improved and weathered soft rock is obvious, the shear strength of cement soil improvement is about 2 times compared to the plain soil, the maximum dry density of the CBR values increased from 6.3% of the plain soil to 58.9%(7d),83.3%(28d), the compression coefficient of cement soil is 1/3 of the plain soil, compression modulus is 3-6 times of the soil; the influence of the age of improved soil strength is significantly, and with the curing time increasing, both soil cohesion and internal friction angle increase.