全风化千枚岩、红黏土及其改良土裂隙演化规律

Fissure Evolution Laws of Completely Weathered Phyllite,Red Clay and Its Improved Soil

为了充分利用全风化千枚岩与红黏土作为路基填料,设计了红黏土与全风化千枚岩干质量比分别为0∶5、1∶4、2∶3、3∶2、4∶1、5∶0,石灰掺量分别为0、3%、5%和8%的组合改良方案,开展了环刀试样干湿循环试验;为了定量描述裂隙的发育状况,开发了裂隙率计算软件,提出基于AutoCAD裂隙总长度计算方法。试验结果表明:裂隙发育规律有继承性、自愈合性,膨胀裂隙与干缩裂隙并存特性;石灰掺量为0时,高红黏土掺和比(80%、100%)下混合改良土裂隙率随着干湿循环次数的增长而增长,且干湿循环次数大于5时还有增长趋势;中低红黏土掺和比(掺和比不大于60%)时,第2次干湿循环后裂隙率达到最大,然后下降或趋于稳定;石灰改良剂对裂隙发展有很强的抑制作用,当石灰掺量为3%或5%,且红黏土掺和比为40%或60%时,可以完全抑制裂隙的发育,其他红黏土掺和比下相对于纯红黏土裂隙率也有大幅降低;考虑石灰掺量、红黏土掺和比对裂隙率降低幅度的贡献,认为石灰掺量为3%、红黏土掺和比为40%或60%是裂隙控制的优化方案,不仅合理、经济,而且裂隙率为0。

In order to make full use of completely weathered phyllite and red clay as subgrade filler, multiple combined improvement schemes were designed, in which the dry mass ratio of red clay to completely weathered phyllite is 0∶5, 1∶4, 2∶3, 3∶2, 4∶1 and 5∶0, and the lime content is 0, 3%, 5% and 8%, respectively, and the drying-wetting cycle tests were carried out. In order to quantitatively describe the development of fissures, a calculation software of fissure rate and a calculation method of total fissure length based on AutoCAD were proposed. The quantitative analysis results show that the development of fissures is characterized by inheritance, self-healing, and the expansion fissures and shrinkage fissures coexist. When the lime content is 0, the fissure rate of mixed soil with high red clay blending ratio(80% and 100%) increases with the number of drying-wetting cycles, and still has an increasing trend when the drying-wetting cycles are greater than 5. When the blending ratio of red clay is medium or low(no more than 60%), the fissure rate decreases or tends to be stable after the second drying-wetting cycle. Lime modifier has a strong inhibitory effect on fissure development. The fissure development can be completely inhibited when the lime content is 3% or 5%and the red clay blending ratio is 40% or 60%, and the fissure rate also greatly reduces under other red clay blending ratios. Considering the contribution of lime content and red clay to the reduction of fissure rate, 3% lime content and 40% or 60% red clay blending ratio is the optimal scheme of fissure control, which is reasonable and economical, and the fissure rate is 0.