The Application And Establishment Method Of Filling Standards Of Wide Grading And Large Grain Diameter Coarse Grained Soil

Coarse Grained soil has been widely applied to engineering constructions because of its wide distribution; rich storage; better compaction; strong permeability; large filling density; high shearing strength; small settlement; high bearing capacity and other engineering characteristics. With the development of designing level, and with the adoption of large horsepower installation machinery and increasingly significant economic efficiency, tall earth-rock dam mainly built by the local material is superior in the tall dam construction both at home and abroad. However, filling standard of coarse grained soil in all tall earth-rock dam is generally decided by roller compaction experiment on site without any proof of relative density up to now, and this tends to bring much blindness to the design, construction of the dam, and to the deformation in the course of utilization, stability analysis, and forecast work. This is firstly because the equipment in the common experiment sections is usually in a small scale and it is difficult to measure its maximum density such as 400-1000mm wide grading sandy gravel; secondly because the insufficient study in theory cannot meet the needs of the engineering practice.Although roller compaction experiments can draw several filling standards curve of grading soil, it is few to the ever changing grading constitution, and this filling standards can hardly reflect the changeable scope of all the grading changes, and as a result, it will certainly bring blindness to both the quality evaluation and the safety proof, moreover, it may cause the project some hidden troubles of safety that are hardly remedied.Based on the borrow exploration, prototype experiment, grading range measure of the filling materials, and natural dry density in the previous period of the project, this research has adopted different methods to reduce grading scale in order to satisfy the current norms ("Civil engineering test regulations"SL237-1999) demands of the largest grain diameter(< 100mm) limited by the "relative density experiment, and simultaneously measured and analyzed different grading and their minimum and maximum density correlation; furthermore, found out its law, enlarged its largest grain diameter, and inferred the calculation formats of both the maximum and the minimum densities related to the grading large grain diameter decided on purpose(> 100mm). Finally, the research has made comparative proof by making full use of more than 300 groups real measure data on site.This method can provide scientific data, standards, and solid ground to the design, roller compaction experiment and the quality control, quality check, quality evaluation of the projects which adopt wide grading large grain diameter coarse grained soil as filling material.If situation permitting, it may be examined and proved with the help of the practice to make this achievement more accurate, and easier to operate. Establishing properly and exactly the standards of filling in advance means earlier stability analysis, deformation analysis, and settlement analysis of dam in the beginning period of a project, and thus makes the design more reliable, shortens greatly design period, anddecrease the design costs. As for the construction units, this can make the roller compaction experiment a clear aim, decrease greatly the experiment times and experiment investment. The quality control standards of the filling can clearly avoid the wastes of the machinery, energy, labor power, material resources, and working period caused by the blindness, make sure the quality control, easy and quick to operate, and can ensure the quality and period of the project.