| Remarkable achievements have been made in the infrastructure of western China in the wake of rapid development of national economy for the past few years.And reconstructed and newly-built airports can be regarded as a typical representative of achievements in infrastructure.Sand-mudstone filler refers to the coarse aggregates mixed sand with mudstone after the sandstone and mudstone stratums with interbeded structure has been excavated and blasted by machinery.As a kind of architectural filler,it has been widely used in engineering such as airports fill,hydraulic dam and subgrade of highway and railway.The high-filled sand-mudstone fillers at Chongqing Airport will be taken as the research object and five sets of grading samples has been designed in this paper.By relevant experimental means including compaction test,uniaxial compression test,triaxial compression test,and discrete element simulation triaxial test,the coarse-grained content was studied to present the influence that it exerts on the mechanical properties of high-filled sand-mudstone fillers at airport like the characteristics of stress-strain,shear strength and compression as well as fracture.By comparing the two engineering classifications of soils in the Standard Practice for Classification of Soils for Engineering Purposes?Unified Soil Classification System??ASTM:D2487?and Technical Code for High Filling Engineering of Airport?MH/T5035-2017?which are laid down by US and China respectively,this paper states the classification method for fillers of high-filled engineering at civil airport.On this basis,the engineering classifications of sand-mudstone fillers at Chongqing Airport were proposed and applied to the filling engineering of New Chengdu Airport in order to illustrate the reasonable classifications of the sand-mudstone fillers.As a result,the classifications can provide mechanical parameter values for similarly high-filled engineering of sand-mudstone fillers and be used for reference.Tasks had been done by the author and related conclusions drawn in this paper are as follows:?1?Using the coarse-grained soil compaction mould designed by the research group to carry out compaction tests on the various grading samples.It turned out that the maximum dry density of the samples has negative correlation with their coarse-grained content.?2?There is a positive correlation among the strength failure value,cohesion,internal friction angle,compressive modulus and the coarse-grained content of fillers.?3?When the coarse-grained content P5 increases to 60%,the relation between fine-grained soil and coarse-grained soil changes.And when coarse granule begins to serve as a skeleton,the fine-grained soil only plays a filling role.?4?The larger the coarse-grained content of the samples,the greater the fragmentation of the granules.Likewise,the stress-strain curve of the sample presents a growing phenomenon of softening.?5?Comparing the two engineering classification of fillers defined by US standard ASTM:D2487 and technical code for high filling engineering of airport MH/T 5035-2017,the author finds that the latter pays more attention to the practical application of engineering.?6?The mechanical parameters acquired by numerical simulation with inverse method and the parameter values obtained by looking up tables after synthesizing related indexes are very close to each other,especially their values of the internal friction angle only differ by 5.43%.It shows that the classification of sand-mudstone fillers is reasonable,and it provides reference value for similar engineering. |
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