A Study of the Effectiveness of the Sand-Packed Column with Microfine Cement Permeation Grouting

• Main Authors: Wei-Cheng Chuang, 莊偉成
• Other Authors: Jen-Chen Fan
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/78719336979489201126

碩士 === 臺灣大學 === 生物環境系統工程學研究所 === 97 === 　　The main purpose of this study was to investigate the differences of ungrouted sand and groutes sand colums of microfine cement grout. To achieve this goal, a medium sand and a fine (namely, Ottawa sand Nos.250 and 403, respectively) were grouted with different water-to-cement ratios (w/c) and tested 28 days after grouting by using a triaxial cell, permeability test device and a graphic softwave, which were developed in this study. The experiments included permeability, mechanical properties and porosity. Aside from these, the uniformity of the grouted sand columns were identified by determining their, so that the effects of the grouted sand columns might be better understood. 　　The results show that the effects of grouted sand columns were apparent. Firstly, for both the medium and fine sand, after grouted, the coefficients of permeability (k) were at least one order less than ungrouted ones.While under different w/c ratios, the k values of the fine sand ranged from 10-3 to 10-4 cm/s for the sand columns with w/c ratios of 4 or 5; however, the the k values of ranged from 10-4 to 10-5 cm/s for the sand columns with w/c ratios of 2 or 3, yet the improvement was not very significant. As for the medium sand, while the w/c ratios were between 1 to 3, the k values ranged from 10-3to 10-5 cm/s; however, while the w/c ratios were between 4 or 5, the k values ranged from 10-2 to 10-3 cm/s, which were much higher than those with lower w/c ratios. 　　Secondly, the effective cohesion (c) of the grouted fine-sand columns increases inversely with the w/c ratios, and their value were in the range of 0 to 5.45(kg/cm2); on the other hand, the medium-sand columns increases significantly when the w/c ratios is less than 2, and their value were in the range between 0 to 9.29(kg/cm2). The effective stress friction angle of the grouted fine-sand columns is at least 2 degrees greater than that of ungrouted one, and their values were in the range between 32 to 36 dregree; on the other hand, the medium-sand columns is at least 1 degree greater than that of ungrouted one, and their values were in the range between 33 to 38 dregree. Last, the porosity of both grouted two sand columns is smaller than that of ungrouted ones. The former decreases 16 to 35% and the latter is 9 to 46%. 　　With respect to distances from the injected point, in the experiments about permeability and mechanical properties, the second (first) section of the grouted fine (medium) grain-size sand columns have better effect; however, in the experiment about porosity, the first sections of both grouted two grain-size sand columns have better effect. Besides, the former two experiments do not have relation with relative density of ungrouted sand column, but the latter has.