Low And Medium Compressibility Of Silty Clay Compression Featueses And Structural Yield Stress Research

Soil consolidation test is to study the outside load stress (including gravity) under the action of compression feature, which stress conditions is a one-dimensional axial pressure. Test the index can be used to judge the compressibility of soil and foundation settlement calculation. The paper is based on the low and medium compressibility of clay as the rese-arch object, with WG (GDG) electro sanlian floating ring type high pressure consolidation apparatus for consolidation apparatus, demarcating and dealing with influence factor in the process of the test,The main achievements are as follows:1) With90%degree of compaction of low and medium compressibility reshape silty clay samples as test object, carrying out no load one dimensional expansion rate experiment, which free expansion is eight mm, proving that low compressibility of silty clay has a slight swelling. For its dilatability designed two-direction layered sample specimen maker, as resh-ape soil sample device. With two-direction layered sample specimen method prepared resh-ape soil sample,which method make its compactness more even, the vertical friction resistan-ce smaller.2) Low and medium compressibility of silty clay has the characteristics of small defor-mation and high strength, in order to be able to obtain more accurate test data, the compress-ion test preparatory work is particularly important. Therefore, the influence factors is demar-cated and dealed with in the process of compression test. Consolidation pressure instrument calibration value is smaller than the factory value about5%. When the temperature reduce one degree, dial indicator reading decrease0.4check.Instrument itself deformation is0.2mm under3200kpa pressure; Floating ring consolidation container can effectively offset circular knife friction and reduce the lateral restriction.3) Undisturbed soil and remolded soil samples make a series of compression test indoor, which measure the compression of soil parameters. Based on the results of compression test, compression feature is analyzed about the low and medium compressibility of silty clay, ma-inly including compression curve, the deformation and time curve, void ratio, compressibili-ty, consolidation coefficient, etc. The test results show that the void ratio, compression coeff-icient, along with the increase of the pressure coefficient of consolidation and a negative cor-relation, soil deformation and compression modulus increased as the pressure were positive-ly correlated.4) Clay has structure in most cases, traditional preconsolidation pressure stress should be called structured yield stress, which includes pre-consolidation pressure stress and stru-ctural strength, the low and medium compressibility of silty clay of structured yield stress is comfirmed based on C and f method, which the advantages and disadvantages were analyzed, discussing structured yield stress factor influence, there are mainly two aspects of internal cause and external cause, the low and medium compressibility of remodded silty clay of the early compact-tion pressure is determined,which based on the principle itself strength of method, soil compaction degree are90%,95%and90%respectively, the unsaturated the early compaction pressure is respectively800kpa,1200kpa,800kpa; the saturated the early compaction pressure is respectively550kpa,950kpa,1350kpa.