| Using cement as a solidified agent for reinforcement is a very effective soft ground treatment method, which has been widely used in the engineering practice. Howerve, the reinforce effect is sometimes not so good because of the organic matter existed in the soft soil. Some research has already proved that when the organic content was high, the strength of the cemented soil was obviously low.Through increasing humic acid to the air-dried soil, soil samples with different organic content were prepared. The paper studies the elements' influences on the soil reinforcement such as the organic matter, the stadium, the cement quantity and the water content, by indoor model and mechanical tests. And the paper also conducted the analysis on cemented soil ingredient though the X-ray diffraction experiment. At last, the microscopic soil pore structure was investigated by the means of mercury intrusion method, and the impact machanism was futhur studied in microscopic level. Some evaluable conclusions are obtained as following:1) the cement quantity is most important among all the factors which influence the cemented soil strength. There is bigger solidification strength when the cement quantity is higher, the water content is lower and the stadium is longer;2) the cemented soil strength is negative related to the porosity of the solidified cemented soil. There is a smaller strength with a bigger porosity. And the strength is positive related to the total production of two kind of hydrates, which are hydrated calcium silicate and hydrated calcium aluminate. When the total production is bigger, the strength is higher, and Simultaneously the porosity is smaller;3) the cemented soil strength increases along with the organic content in the soil reduces. With the increment of the organic content, hydrate production are suppressed and part of the hydrate is hydrolyzed, resulting the lower totle hydrate production, the bigger soil porosity and smaller cemented soil strength.
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