| This paper mainly explores the effect of roots after length of time degradation,which due to climate or human factors,on the strength of red clay in Hainan,in order to provide some new ideas and references for the management and protection of vegetation slope;Select a Common Bermuda grass lives in warm climate as test object,and make it grow in the natural environment of Hainan,and then through the artificial method to remove Bermuda above ground part to make the root into the natural degradation state;Select the degradation time was 0 months,3 months and 6 months of root tensile tests were performed at the same time screening site of red clay mixed with different length,different content and different degradation time of Bermuda grass root remodeling with root soil samples produced three triaxial test;similarly,select the different degradation time of undisturbed compound soil making samples for triaxial tests;the paper tests some results and conclusions are as follows:1.To improve the method of making three axis cylindrical specimens which can guarantee the natural state between root and soil,that is to say,it is convenient and fast,and greatly reduces the possible errors when making three axis specimens of the original composite soil.2.①The Bermuda in natural environment are less than 0.5mm in diameter of roots,and can be expanded to 0.9mm growth indoor cultivation;② through the degradation of Bermuda grass root 0 month normal growth under the condition of the tensile test,the test of Bermuda tension value of 2.55N;the tensile strength is in the range of 25.51 MPa～110.51 MPa;range of elastic modulus is 456.17MPa～4593.45MPa;the average tensile strength just 47.73MPa;the average elastic modulus is 1518.79MPa the degradation;③the root diameter of Bermuda reduced after 3 months decayed,tensile strength decreased,the average can only bear force is 0.83N;④the Bermuda grass root degradation of 6 months has been completely decomposed no longer have the mechanical properties,but has great damage to the soil;3.Through the three axis experiment on the reinforcement effect of Bermuda remolded soil and undisturbed soil have been studied and compared(selected intermediate confining pressure as the research object),①the degradation time at 0 month,1.011 to 1.890 is the effect of reinforcement coefficient with different length and content of the artificial environment of selected Bermuda grass roots the red clay produced,strength increased 1.1%～89%;②the natural growth of whole plant roots on the red clay reinforcement effect is 1.02～1.84,the strength is increased by 2%～84%;③ the root degradation at 3 months,the scope of the reinforcement effect of soil with root remodeling for the reinforcement effect with root remodeling the soil is 0.2～0.676,which showed that the root but makes its strength decreased from 32.4%to 80%unequal amplitude;④the degradation of the root after 3 months to reduce shear strength of the soil is about 80%.⑤The reinforcement effect of the root to the original soil for 6 months is 0.061～0.147,which basically reduces the strength of about 90%,and causes great damage to the soil.4.The stress deviator of original compound soil and the remodeled compound soil had decreased significantly with longer root degradation time in the same conditions.Such as 100kPa,1cm,cell pressure,the stress deviator of remodeling compound soil have 1 per 1000 content with root from 447.68kPa(0 months)reduced to 252.54kPa(3 months);When it contains 1 plant of original compound soil by 211.O1kPa(0 months)reduced to 24.815kPa(3 months),16.122kPa(6 months);the strength reduce of undisturbed and remolded soils are very obvious. |
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