Research On Mechanical Properties Of Municipal Solid Waste Incineration Bottom Ashes Mixed Soil

Bottom ashes（BA）as a product of municipal solid waste incineration（MSWI）,is sand-like soil,can be used as filling material in subgrade.It argues about the municipal solid waste incineration（MSWI）bottom ashes（BA）mixed soil,which is the mixture of MSWI BA and clay,as if it is the subgrade filling material.Having surveyed in a large scale,the geotechnical test was conducted then,finally,its mechanical characteristics was concluded as follows:According to the particles analysis test and the geotechnical particle classification,MSWI BA is sand soil,belong to the coarse grained soil,is poorly-graded soil.Mix up the MSWI bottom ashes and clay to mixed soil in weight of1:0,5:1,4:1,3:1,2:1,1:1,0:1,then do the heavy compaction test for these seven kinds of mixed soil.It produced the maximum dry density and the optimum moisture content.As a result,the test also indicate that with the increasing of clay content,the compaction effect of mixed soil increases firstly and then decreases,the maximum compaction effect will be produced by clay content as from 25%to 33.3%.And the effect of moisture on the move of soil particles and the proportion of coarse and fine particles on the result of test was presented.Having the particle proportion test of the optimal ratio of mixture of MSWI BA mixed soil（MSWI BA to clay 1-0,4:1,3:1,2:1）been made,it concluded that proportion of MSWI BA mixed soil is low as well as the more lightweight soil.On the basis of the physical test,by the compactness of 96%and 94%respectively and by the ratio of MSWI bottom ashes to clay were 2:1、3:1、4:1、1:0 respectively,test on the large direct shear test.The shear strength and internal friction angle and the cohesion was concluded.The shear strength of MSWI bottom ashes mixed soil increased with the content of MSWI BA or compactness.Analysis of the mechanism of dilatancy of soil under the different conditions,and the effect of dilatancy of soil on the stress-strain curve.And conduct the contribution of embedded bite of soil particles against shear strength.Conduct the large compression test to the MSWI BA mixed soil on the same condition of large direct shear test,the result shows that:under the maximum load of 3200 kPa,the MSWI BA mixed soil produce smaller deformation,at lower density、higher moisture content and higher persents of MSWI the compression deformation is smaller.Using grey relational analysis on these three factors and compression deformation,obtain the degree of these factors to the strength of the effect of compression deformation.Compared to the initial degree of compaction,the influence of test load on the change of void ratio is very small.The a_1～2and C_C is far lower than the limit of low compressibility soil and the E_S is much higher than the limit of low compressibility soil.The consolidated undrained triaxial compression tests and consolidated drained triaxial compression tests in two densities respectively for the purpose of its strength and deformation characteristics was presented.The strength and deformation characterstics of BA are similar to sand soil,which has been concluded by the stress-strain curve.The law of the deviatoric stress,volumetric change and pore water pressure changing with axial strain and the corresponding relationship was analyzed.The effect of dilatancy and particles crushing on the stress-strain curvewas presented.when the confining pressure is lower and the densities is higher,the strain soften is more obvious.The Duncan-Chang model parameters of MAWI BA in two densities were concluded from the consolidation undrained test data.The geotechnical test shows that:the MSWI BA mixed soil is of good compaction property,relatively lightweight,and higher shear strength,small compression deformation,which is an excellent mechanical properties of subgrade filling material.