Experimental Study On Thixotropy Of Silt

With the continuous development of the social level, all over the worldbuilding constantly go beyond the original building mode. In constructionengineering, thixotropy of soil may lead to reduced soil strength, andengineering disasters such as instability landslides, subsidence after work will becaused. To reduce these engineering geological hazard, more and more peopledevote to the study of soil thixotropy. In the past, people paid more attention tothe mechanism of thixotropy and trend of thixotropic strength recovery of soil.While the research on the factors of thixotropic strength recovery of soil isrelatively ignored.Based on the study of many scholars at China and abroad about thethixotropy, around the research on features of thixotropic strength recovery of siltsoil, the change of sample’s strengths is reflected by unconfined compressiontests. The laboratory vibrating model tests are carried out to simulate soildisturbance of undisturbed soil. The results are used to analyze the relationshipbetween disturbance degree of silt and strength recovery degree. Combinedpreparation method of compacted soil samples in Soil test specification, thecompacted soil sample were preparated with different dry density, compactionmoisture content, silt and clay content. The results are used to analyze the relationship between different factors of silt and strength recovery degree. Theconclusion is as follows:(1)Soil sample disturbance degree is controlled by the different vibratingtime. The samples of different disturbance degree is used to the unconfinedcompressive strength test. According to the drawing of the unconfinedcompressive strength test stress-deformation curve of different disturbancedegree is concluded: The greater disturbance degree of soil, the lower unconfinedcompression strength. Stewing the same time on samples of different degree ofdisturbance. Drawing the unconfined compressive strength teststress-deformation curve of disturbance models after stewing. Comparing thestress-deformation curve between before and after the same stewing time. Weconclude that the strength of soil with different disturbance degree all recoveredafter a certain period of stewing time.(2)Silt samples’ thixotropic absolute strength recovery degree and relativestrength recovery degree is discussed in different situations. Mapping curve ofrelationship of two strength recovery degree with disturbance degree. On basis ofthe curve, we conclude that the absolute strength recovery degree of soil anddisturbance degree have positive correlation, while the relative strength recoverydegree and disturbance degree have negative correlation.(3)According to many scholars’ achievement, formulas of the disturbancedegree ratio and the thixotropic strength ratio are established. The former can beused to judge soil’s influencing degree of disturbance, and the latter can be used to judge soil’s influencing degree of thixotropy. Absolute recovery degree andrelative recovery degree of the disturbed silt’s thixotropic strength can beestimated by using these two formulas.(4)To control a certain compacting work, the homemade manual compactiontool is used to prepare compacted silt in different compacting water content, drydensity and silt and clay content, then make these samples vacuum saturation.The unconfined compression strength tests is used to analysis the unconfinedcompressive strength test stress-deformation curve under different factors. It isconcluded that, the strength of compacted silt is effected by the compacting watercontent. The strength is bigger in the dry side and lower in the wet side. And thestrength of compacted silt is greater with the increasing dry density and thedecreasing silt and clay content.(5) Saturation compaction sample after stewing is used to the unconfinedcompression strength tests. The influencing degree of thixotropy is reflected bythixotropic strength ratio. Putting the experiment strength date into the formulasof thixotropic strength ratio and drawing the thixotropic strength ratio-factorscurve. According to the curve, it is concluded that, the thixotropy of compactedsilt have a positive correlation with the dry density and the silt clay content. Thethixotropy and compacting water content have a negative correlation in the dryside and have a positive correlation in the wet side.