| Geotechnical model test play an important role in research in the field of geotechnical engineering, it can reveal all kinds of mechanical behavior and mechanism of soil,which is an effective way to verify the theory of deformation and strength and improve the soil, anditalso providebasisfor geotechnical design. Sample preparation is the important part of geotechnical model test.Sand poureris the most commonly used method for preparing sand foundation model.But the main factor in the effects of sand pourer is not clear.Centrifugal model test and prototype have the same stress state, not only can reduce the size of the model, and greatly reduces test time, and also set up a variety of heterogeneous model, simulate complex engineering situation, problems so it is very applicable for geotechnical centrifugal model test which can not be ignored the gravity.In order to know the relative density main effect of sand foundation model prepared by sand pourer, designed and machined a set of point and line type sand shakeout device, discussed the relative densitychanging law follow with the drop height, size of sand production pore, total flow of sand production head and the average speed, analyzed spatial uniformity distribution of the relative density. By conducting centrifugal model test of sandslope stability, Studied the slope gradient, soil moisture content influence on slope stability, and the development regularity and failure mode of the Sand slope, discussed the moisture control principles in the Preparation of unsaturated sand slope during the centrifuge model. Statistics and analysis the parallel experimental results of other units laboratory, explore the sources of the experiment errorand the size of the error.itprovide a certain reference value for centrifugal model test.Preliminary get the following conclusions and recommendations:1)With the increasing of drop height, and theenhance of sand particles potential, the relative density Dr is increasing also, but growth rateslow down gradually, whenthe drop height between 70 and 100centimeterthe relative density Dr is basically stabilized.2) Stable relative density was negative linear correlation with size of sand production pore, the regression equation was Dr=99.7-4d,andmake Φ= 5mm sand funnel-point for the experimental verification.3)Through the selection of Φ=4mm funnel-point sand mouth and b= 3.23mm line point sand mouth are the target relative density of 55% and 75% of the validation tests carried out, the actual relative density and relative density of the target maximum error is-2.74%, the minimum error is 0.29%.It indicated that the sand pourer is reliable for preparing sand foundation model.4)Geotechnical centrifugal model test show that with the slope gradient increasing, Slope stability is reduced fast. When the slope gradient increases from 65°to 75°, slope instability critical acceleration fell by 45g to 23 g, reduced about 49%, indicating that the slope gradient slope stability is one of the core factors. Contrast parallel test results of the other laboratories, it has dropped to critical acceleration mean by 55.6g to 25.6g, reduced about 52.2%, whinch has a high degree of consistency.5) Statistics and analysis the parallel experimental results of other laboratory,moisture content influence on slope stabilitycan not be obtained by this experiment, during the tests, the slope body moisture transferred significantly, so in the preparation of sand models, the soil moisture content should be controlled,that is not greater than the water in the soil and water characteristic curve membrane absorption area and strong adsorption zone boundaries of moisture content..6)Statistics and analysis the parallel experimental results of other laboratory, the experiment error is mainly random error and without obvious systematic error. If the experimental means as exact value, the absolute error bounds of the parallel experimental is 10g,the relative error is about 20%. The results show geotechnical centrifuge can perform a high accuracy. |
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