Study on the Change Characteristics of Shear Resistance and Strength Prediction of Root Soil Composite
The shear properties of root soil complex are affected by root content and compactness.In or-der to explore the extent of their impact on the shear properties of root soil complex,the triaxial compression tests of root soil complex with different root content(0%,0.15%,0.3%,0.45%,0.6%)and different compactness(85%,90%,95%)are carried out with the ryegrass root soil com-posite body weight plastic sample as the research object,The variation rule of ultimate principal stress difference and shear strength index corresponding to 15%strain is analyzed,and the shear strength calculation formula is established.The results show that:①under the same confining pressure,the ultimate principal stress difference of root soil composite increases by 6～79.9kPa,6.8%～65.5%,compared with that of plain soil.②At the same compactness,with the increase of root content,the ultimate principal stress difference of the root soil composite increases first and then decreases.When the compactness is 85%,90%and 95%,the ultimate principal stress differ-ence is the largest when the root content is 0.3%,0.3%and 0.45%,which is the optimal root content.③Based on the test results,a formula for calculating the shear strength of root soil com-posite considering root content,compactness and confining pressure is established,and the fitting accuracy(R2)of the formula is 0.943.The formula was verified with undisturbed soil root soil composite sample,and it was found that the prediction accuracy(R2)of the formula was 0.96.The results provide a theoretical basis for ryegrass root system soil fixation.
Root soil complexRoot contentDegree of compactionConfining pressure
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