Research On Strength And Stability Of Abandoned Silt Improved By Cement And Fiber

In the current,the main treatment of silty soft soil is physical dehydration consolidation and chemical solidification,which are mainly used in the treatment of soft foundation.They are both in situ solidification of soft silt.However,there are a large amount of silt was discarded in the engineering construction,such as underground engineering and highway engineering,and the research on chemical solidifying and application about it is relatively small,abandoned silt not only can cause environmental pollution will cause the waste of resources,so the research on abandoned silt have a great significance.In this study,the abandoned silt of nansha was the research object,the method of improving silty soil with fiber reinforcement and cement solidification was adopted.Firstly,the maximum dry density and optimal moisture content of silt under different fiber and cement contents were obtained through compaction test,the silt mixture treated with cement and fiber was compacted to different degrees to make samples,and then UCS test,water stability test,wetting-drying test were carried outl,and the influence of cement,polypropylene fiber and dry density on the strength of solidified soil was obtained.The main test results are as follows:(1)In the early stage of curing,the strength of the silt improved by compaction under the optimal moisture content does not change much with the increase of cement content of 5%,10% and 15%.;With the increase of curing age,the UCS of solidified soil increases with the cement content,while its peak strain decreases.(2)Incorporating fiber can improve the characteristics of brittle failure of cement solidified soil,With the increase of the polypropylene fiber content by 0.1%,0.2%,0.4%and 0.6%,the UCS increases first and then decreases,and the optimal fiber content is0.4%,and when the cement content is 10%,it is more conducive to play the strengthening role of fiber on soil strength.(3)The strength of solidified soil increases with the increase of soil compaction,and the degree of compaction also has an effect on the enhancement efficiency of fiber,which is the highest when the degree of compaction is 90%.(4)The water stability coefficient of solidified soil increases with the increase of cement content.At 90% compaction degree,when the cement content exceeds 10%,the water stability coefficient does not increase significantly.Adding fiber can also improve the water stability of solidified soil.With the increase of fiber content,the value of water stability coefficient first increases and reaches the peak when the fiber content is 0.4%,which is the best to improve the water stability performance of cement solidified silt,and then decreases with the increase of fiber content.(5)With the increase of the number of dry and wet cycles,the mass loss of the solidified soil in a single cycle gradually decreases,while the UCS increases first and then decreases.The relative mass loss rate of solidified soil increased with the dosage of fiber.When the fiber content was more than 0.4%,the relative mass loss rate of solidified soil increased greatly.At the same cycle number,with the increase of fiber content,the strength of solidified soil first increases and reaches its maximum value when fiber content is 0.4%,and then decreases with the increase of fiber content.