超微粒水泥滲透灌漿砂柱試體改良成效之研究

Abstract

本研究目的是要探討超微粒水泥漿體與砂柱灌漿後與灌漿前的差異性。為了達到此目的，藉由自行開發的三軸柔型滲透試驗儀、滲透性量測儀與三軸試驗繪圖軟體，於不同級配分佈之中、細砂(即渥太華砂編號250與403) 、不同水灰比，在灌漿後養護齡期28天的情況下進行試驗。試驗內容包括滲透性、力學性質與孔隙率試驗，此外本研究亦探討灌漿前之砂柱試體相對密度分佈，來確認砂柱試體的均勻性，俾可瞭解灌漿後改良之成效。 試驗結果顯示灌漿後有顯著的改善。滲透性試驗方面，與灌漿前比較，滲透係數(k)均改善至少一個冪次以上。以不同水灰比來說，細砂部分於水灰比4、5時有較顯著的改善，k值介於10-3至10-4(cm/s)間，而水灰比2、3時k值則介於10-4至10-5(cm/s)間，但影響有限；中砂部分則反之，在水灰比1至3時有越來越好的趨勢，k值介於10-3漸漸降低至10-５(cm/s)左右，而在水灰比4、5時k值介於10-2(cm/s)至10-3(cm/s)，其值比水灰比1至3時高出許多。 力學性質之有效凝聚值(c')方面，細砂隨著水灰比降低呈現均勻成長的趨勢，c'值介於0(kg/cm2)至5.45(kg/cm2)間，中砂則是水灰比低於2時較有明顯增加，c'值介於0(kg/cm2)至9.29(kg/cm2)間；有效應力摩擦角(Φ')方面，與灌漿前試驗比較來說，細砂部分改善至少2°以上，Φ'值介於32°至36°間，中砂則是至少1°以上，Φ'值介於33°至38°間。孔隙率方面，與灌漿前比較來說，細砂部分改善約小於16%至35%，中砂則是約9%至46%。 距灌注點不同距離的灌漿改良成效來看，在滲透性與力學性質試驗中細砂部分為第二節改良成效較佳，中砂為第一節，孔隙率試驗中則皆為第一節較佳。前兩個試驗與灌漿前砂柱試體相對密度分佈結果並無相對關係，後者則有。

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.