通过对杭州市某隧道工程开挖产生的废弃粉质黏土添加不同改良剂后开展无侧限抗压强度(unconfined compression strength,UCS)试验,研究了不同矿渣掺量、矿渣-粉煤灰比例、聚丙烯纤维掺量条件下改良土样的抗压强度特性,并对抗压强度形成的机理进行了分析;同时,基于扫描电镜(scanning electron microscope,SEM)试验对表征土体孔隙特征的有关指标展开了定量分析.结果表明:在矿渣掺量为12％时UCS最大,为6 738.04 kPa,较素土强度提高80.69倍;粉煤灰的掺入可提高试样后期强度,在K8F2(矿渣/粉煤灰比例80％:20％)试样中最优;聚丙烯纤维的掺入能有效地改善材料的脆断性能,最优纤维掺量为0.4％.试样孔隙的定向频率在80°-100°区间内分布的概率最大,掺入粉煤灰后定向性较为均匀;孔隙率随着矿渣掺量的增加、地质聚合物中矿渣含量的增多均逐渐减小,在试样K12(矿渣掺量12％)和K8F2中出现最小值;而随着纤维掺量的增加,呈现先降低后升高的趋势,当纤维掺量为0.4％时其值最小,为6.204％;孔隙平均直径主要分布在0～1 μm,矿渣掺量增多则小孔隙增多,大孔隙减少;孔隙丰度主要分布在0.4-0.6,孔隙形状主要为椭圆.
Experimental Study on Unconfined Compressive Strength of Silty Clay Modified by Fiber-toughened Geological Polymers
The unconfined compressive strength(UCS)test was carried out on the waste silty clay from a tunnel excavation in Hangzhou City after adding different amendments.The compressive strength characteristics of the improved clay sample under different slag content,slag to fly ash ratio and polypropylene fiber content were studied.The formation mechanism of compressive strength was briefly analyzed.At the same time,based on scanning electron microscope(SEM)test,the pore characteristics of the reaction soil were quantitatively analyzed.The results show that the maximum UCS value is 6 738.04 kPa when the slag content is 12％,which is 80.69 times higher than that of plain soil.The addition of fly ash can improve the late strength of the sample,which is the best in K8F2(slag and fly ash ratio of 80％:20％)sample.The addition of polypropylene fiber can effectively improve the brittleness of the material,and the optimal fiber content is 0.4％.The orientation frequency of the pores of the sample is the largest distribution probability in the range of 80°～100°,and the orientation is more uniform after the addition of fly ash.With the increase of slag content and the increase of slag content in geopolymer,the porosity decreases gradually,and the minimum value appeares in K12(slag content 12％)and K8F2 samples.With the increase of fiber content,the value of fiber content decreases first and then increases,and the minimum value is 6.204％when the fiber content is 0.4％.The average pore diameter is mainly 0～1 μm,and the small pores increase and the large pores decrease with the increase of slag content.The pore abundance is mainly distributed in the range of 0.4～0.6,and the pore shape is mainly elliptical.
silty clayslagfly ashpolypropylene fiberunconfined compressive strengthquantitative analysis of microscopic pore
万方数据
维普
