Study On The Effect Of Mechanical Property Test Of Cement Composite Stabilized Soil Mixed With Nanometer-SiO₂ And Numerical Analysis

As a typical representative of the road base in our country, the semi-rigid base course of cement stabilized soil is directly related to the service life of the road. Studying and improving the performance and mechanical index and solving the insufficient strength and extending service life have important significance. The nano-SiO2 used as outside the cement stabilized soil mixing agent, the paper research on cement stabilized soil uniaxial unconfined compressive strength test and systematically summarizes laws in different cement content and nano-SiO2 content and different curing age. Otherwise, the paper study on the splitting strength laws and the relationship between splitting strength and compressive strength. Finally, based on the Plaxis finite element software, the advantages of nano-SiO2 cement soil were compared and analyzed. The main research results can be concluded as follows:(1) First, under standard curing condition, according to 5%,7%,9% and 11% four kinds of cement content,0%,2%,4%,6% and 8% of five kinds of nano-SiO2 doped amount,7days,14 days and 28 days three curing age, the paper gains stress-strain curve of unconfined compressive strength and peak stress. The results show that adding nano-SiO2 can increase the strength of cement soil, but not the more the better, the best dosage of nano-SiO2 should be 3%～5%, addition of 4% nano-SiO2 can improve the cement 7d strength of about 20%～40%and 28d strength of about 10%～25%, nano-SiO2 can improve the early strength of cement stabilized soil better than the late. Regardless of whether the addition of nano-SiO2, the compressive strength of cement stabilized soil increases by the increase of cement content with highly linear relationship, the compressive strength of cement stabilized soil increases by the increase of curing age with linear relationship.(2) Under standard curing condition 7 days, according to 5%,7%,9% and 11% four kinds of cement content,0% and 4% of two kinds of nano-SiO2 doped amount, the paper gains the stress-strain curve of splitting strength and peak stress. The result show that the splitting strength of the nano-Si02 cement soil was increased by about 20% compared with that of the sheer nano-SiO2 cement soil. No matter whether the addition of nano-SiO2, splitting strength increases by the increase of cement content with highly linear relationship.(3) Through analysis and comparison, there is a close relationship between compressive strength and splitting strength. The ratio between splitting strength and compressive strength of cement soil is between 0.141-0.231. It is found that there is a highly linear relationship between the compressive strength and splitting strength, the splitting strength can be calculated by the fitting formula.(4) Based on the above experimental results and the Plaxis finite element software, last, the paper analyzes and compares the performance of the cement stabilized soil with nano-SiO2 and sheer cement stabilized soil used as the semi-rigid base of road.When the cement content is 7%, the cement stabilized soil of adding 4% nano-SiO2 can prolong the service life of 7.2 years, in comparison with no adding nano-SiO2.