| The soil in the Yingkou area of Liaoning Province is a silty soil or silty clayey soil with saline soil characteristics.According to the specification,it cannot be used as roadbed filler directly,so reinforcement materials are used to improve the soft chloride saline soil in this area.In this paper,slag powder,sisal fiber,and tailing sand were selected to treat this chlorosaline soft soil filler by comparing the treatment effect of different reinforcement agents.The effect of slag powder,sisal fiber and tailings sand on the change of soil strength was obtained through the(single-factor)(two-factor)unconfined compressive strength test of chlorosaline soft soil,and then the optimal mixing ratio of soil sample reinforcement was obtained through the three-factor three-level orthogonal test.Then the performance indexes before and after treatment were compared by triaxial test,bearing ratio test(CBR)and unconfined compressive test under freeze-thaw cycle and triaxial test.The main studies are as follows:(1)The basic performance parameters of saline soil were experimentally analyzed,and the total soluble salt ions in the soil sample was 3.776%,which can be named as medium-chloride saline soil according to the specification and cannot be used as roadbed filler directly.(2)Comparing the lifting effect of tailings sand on plain soil and slag powder reinforced soil,the lifting effect of tailings sand on reinforced soil is obviously greater than that of plain soil,which shows that tailings sand has the property of "strong when it meets strong",and under different soil conditions with the same amount of tailings sand,the higher the strength of soil,the more obvious the lifting effect of tailings sand.(3)The optimal combination of 15% slag powder,0.5% fiber and 20% tailings sand was obtained from the three-factor,three-level orthogonal test.The unconfined compressive strength of the modified chloride saline soft soil under the optimal combination reached 2.74 MPa,which was 470.8% higher than that of the plain soil,and the unconfined compressive strength improvement effect of the three optimal blending ratios was significantly higher than the sum of the improvement effect of the single external dopant,which indicated that the three blends had a certain positive promotion effect on each other.(4)The triaxial tests on the modified chlorosaline soft soil with plain soil and slag powder-fiber-tailing sand showed that the cohesive force of the modified soil increased by95.5% and the friction angle increased by 69.1% compared with that of the plain soil,which indicated that the shear strength of the modified chlorosaline soft soil improved significantly.After 3,6 and 9 freeze-thaw cycles,the decay rate of cohesive force and the decay rate of unconfined compressive strength of plain soil were larger than that of modified chlorosaline soft soil,and the decay rate of internal friction angle did not change much.It shows that the shear strength and unconfined strength of slag powder-fiber-tailing sand modified chlorosaline soft soil are significantly better than those of plain soil in terms of resistance to freeze-thaw cycles.(5)CBR tests were conducted on the plain soil and the modified chlorosaline soft soil,and the swelling of the modified chlorosaline soft soil was 3.78%,which was 91.8% less than that of the plain soil,showing that the limiting effect of slag powder-fiber-tailing sand on the swelling of the soil was very significant.The CBR value of the plain soil is 1.31,which does not meet the filling requirements of the highway.The CBR value of the modified chloride saline soft soil with the optimal mix ratio is 15.64,which is 1194% higher than that of the plain soil and meets all the filling requirements of the highway in the specification. |
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