Consolidation Properties of Composite Soil Treated by Quicklime Piles

• Main Authors: Chu, Jen-Hung, 朱振宏
• Other Authors: Huei-Wen Chang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/43899417884545002609

碩士 === 國立中央大學 === 土木工程學系 === 85 === The method of quicklime pile has been proved to be very effective instabilizing the soft soil ground with high water content.The bearing capacity of the soil ground can be raised , the settlementcan be reduced and the mechanical properties can be improved.Despiteof these facts,the theoretical study of this method is still not enough. In particular,there are few literatures about the variationsof pore water pressure of the composite soil and the lateral expansionpressure and displacement of the pile during the chemical and mechanical reactions of the quicklime pile.Besides, the residue settlement of the soil ground can*t be estimatedeffectively in analytic and designing process. So, this research describesexperimental results about expansion consolidation behavior of composite soil treated by quicklime piles, and provides a method to estimate the settlement of ground. We can apply the results for analysis and in situ construction. The soil we study in this research is the silty clay of the Taipei basin and the material used in the soil improvement is thequicklime powder.A series of laboratory tests are carried out. The remolded soil sample is firstly preconsolidated, and it is drilled to creat a cylindrical hole in the center. The quicklime powder is filled into the hole and the slaked reaction starts. Then the test data is collected and a series of analyses isdone according to different conditions of improvement. The experimental data shows that the improvement effects of the quicklime plie on the soil sample is obvious. These include the reduction of the resiude settlement and improve the consolidationproperties . Even if the soil sample is subjected to the stress increase and is drown with water, the total improvement effect of it is still satisfactory. This shows that the quicklime pile has a high stability in treating soft soil ground. The stability is gained from the slaked reaction, which makes the bonding forces between the soil grains increase.Moreover, the gel of calcium silicate created in the slaked reaction can help to solidify the soil and raise its stiffness, such that the affinity between the soil and the water as well as the sensitivity of the stress variationare reduced. In this way the engineering properties of the soilsample are improved. In addition, this research also includes a theoretical study, which considering the chemical reaction of the quicklime material, the phase reaction of the soil, and the improvement conditions A theoretical model for estimating the resuide settlement is proposedafter we have considered the water content reductions. The estimatingequation can be used in design and construction.