Research On The Growth Mechanism And Engineering Properties Of The Ancient Li Xia-he Lagoon Facies Soft Soil

In order to get the conclusion of the growth mechanism of the ancient Li-Xia-He lagoon facies soft soil, series of studies on the mechanism of the ancient Li-Xia-He lagoon were performed after detailed investigation of areal geology of JiangSu, based on the previous achievement on lagoon both in and out of country. Then, the engineering properties of the ancient Li-Xia-He lagoon facies soft soil were analyzed from point of view of geology. After that, aimed to get the trait of high water content, high organic matter content, high compressibility, a series of indoor tests were carried out and systematical research on the mechanism of fly-ash-cement mixed pile reinforcement method on the ancient Li-Xia-He lagoon facies soft soil were carried through, based on analysis of the test data. Further more, the evaluation method of the effect of cement mixing ground treatment method was carried through, and it's illustration on some mechanics result from soft soil growth mechanism and chemical mechanism were brought out. Finally, a settlement forecast model on grey theory aimed at the settlement rule of the lagoon facies soft soil was set up. The main content of this paper is:1. The conclusion that the ancient Li-Xia-He lagoon is transgression and regression integrated barrier-lagoon sedimentary system was reached, based on the previous achievement on lagoon and through detailed investigation of areal geology of JiangSu. And the ancient Li-Xia-He lagoon soft soil developed under such sedimentary environment and influenced by the alluvium of the old HuangHe River, therefore there formed the typical lagoon facies soft soil with high water content, high organic matter content, high compressibility and inferior engineering properties.2. In order to open out the strength increasing mechanism of cement-soil, research on the operation mechanism of fly-ash-cement-soil system was performed based on summary up of the previous achievements on cement and fly ash hydration reaction.3. In order to open out the development rule of strength, water content and electrical resistance ratio of cement-soil and the chemical mechanism of it, and the action mechanism of fly ash, organic matter and sodium chloride on cement-soil a series of indoor test were carried out. The result shows that the strength of cement-soil lows down with the increase of organic matter content, but if we add some sodium chloride to soil then the result is the opposite. Still more, increase of the drink water ratio, unconfined compressive strength and electrical resistance ratio value of cement-soil is the constant crystal and recrystal effect of the cement hydrolysate.4. In order to study the evaluation method of cement mixing ground treatment, the dependability of estimation index was cleared out through mathematical method, based on the analysis of site test data. Then, the quality of single column was appraised, furthermore to appraise the unitary reinforcement effect with probability and statistics theory method. The result shows that the choiceness ratio of fly-ash-cement-soil pile is higher than cement-soil pile, if ground treatment time longer than 80 days, the unitary reinforcement effect of the 2 kinds of column is consistent.5. In order to find a settlement forecast method on lagoon facies soft soil, some modification on grey theory was made, aimed at the sedimentary trait of the ancient Li-Xia-He lagoon facies soft soil. As a result, a modificatory settlement forecast model on grey theory was set up.