| The physical state of the soil includes two states:loose,soft and hard state.the consistency or soft and hard state is the main physical state characteristic of the clay.It is very important to clarify the physical state of the soil in engineering construction.For cohesive soil,the determination of the liquid-plastic index will determine the classification of the soil,and the engineering properties can be basically judged based on this.However,based on the current"Standard for Geotechnical testing Method"(GB/T50123-2019)recommendation method combined with the liquid-plastic limit determination test,there are problems such as test error,accuracy,and efficiency.Therefore,under the research fund of the Natural Science Foundation of Jiangxi Province(20192BAB206045),the limit moisture content of the soil sample was taken as the research object.Through the independent research and development of a vertical penetration and compaction auxiliary test device,an auxiliary method for the combined determination of liquid and plastic limits was proposed the Vertical stratified sampling method.The paper has systematically studied the limit water content of four soil samples of patterned laterite,alluvial soil,brown calcic soil and mucky soil.The main conclusions are as follows:(1)Independently developed auxiliary testing equipment for vertical infiltration and compaction,covering all samples of clay soil under the limit state,which can meet the requirements of the combined determination of liquid-plastic limit test for moisture content.(2)For the vertical distribution of water content in the vertical penetration sample test,the overall water content of the sample is distributed between 19%and 41%,and the maximum multiples of the water content are 1.36,1.69,1.44,and 1.50,respectively.The average moisture content of each soil sample was more than 10%,and the reduction multiples were 2.74,1.94,2.10,and 2.62,respectively.The vertically penetrated samples all show rich water content.This method increases the accuracy of the liquid-plastic limit combined test.(3)The maximum deviation of the dry density is less than 10%,and the deviation of the amplitude in the first two layers and the bottom two layers is as high as 6.4%,and the maximum deviation in the middle two layers is about 2%.The uniformity of the dry density is less than 5%,the moisture content is greater than 2%.In the vertical infiltration sampling of samples with a lower limit moisture content,the difference in dry density deviation is arranged from large to small,brown calcic soil>mucky soil>patterned laterite>alluvial soil.(4)The linear fitting correlation R~2of the relationship curves of reticulated patterned laterite,alluvial soil,brown calcic soil and mucky soil are 0.98180,0.99811,0.99716,0.98709,respectively.Theh_p-w linear fitting correlations of the relationship curves of the four soil samples are all greater than 0.98,verifying that the vertical penetration sample preparation test meets the test requirements.(5)The deviation of the plastic limit of the alluvial soil in Puyang area is 7.7%,and the remaining deviations are less than 4%.The measured liquid-plastic limits are within a reasonable range.The plasticity index measured by the vertical infiltration layered sampling method and the recommended method of the"Standard for Geotechnical testing Method"(GB/T50123-2019)belongs to the same type of soil in the classification of clay soil engineering.(6)Regarding the theoretically given shear strength corresponding to the liquid limit of 1.7k Pa,the difference between the shear strength of the samples under the liquid limit state is less than 9%,and the difference between the shear strength of the samples under the plastic limit state is less than 5%,which is in line with the former The data range is given to further verify the reliability of the test. |
PDF Full Text Request