Experimental Study on Permeability of Soil–Phyllite Mixture in Northwest Sichuan
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摘要:
川西北地区千枚岩土石混合体分布广泛,在降雨条件下开挖边坡极易大面积失稳,对该地区交通工程施工和运营安全构成了重要威胁. 土石混合体渗透特性显著影响开挖边坡稳定性,而扁平状千枚岩块的空间定向性是影响千枚岩土石混合体渗透性的关键因素. 本文基于千枚岩岩块的空间定向特征,采用自行研发的大型渗透仪开展不同含石量、岩块粒径等条件下的千枚岩土石混合体渗透特性试验,研究含石量、岩块粒径对此类混合体渗透性的影响. 结果表明:当含石量从0%增至35%时,土石混合体渗透系数降低49.28%,临界和破坏水力梯度分别升高159.38%和54.17%,难以发生管涌破坏现象;当岩块粒径从20~40 mm增至60~80 mm时,其渗透系数增大34.62%,临界和破坏水力梯度分别降低23.15%和10.3%,更易发生管涌破坏等现象;可为川西北地区千枚岩土石混合体的水力特性评价及开挖边坡稳定性分析提供参考.
Abstract:The soil–phyllite mixtures are widely distributed in the northwest of Sichuan, and excavation of slopes in these areas under rainfall conditions can cause large-scale instability, posing threats to the safety of transportation engineering construction and operation. The permeability characteristics of soil–rock mixtures significantly affect the stability of excavated slopes, and the spatial orientation of flat phyllite is the key factor affecting the permeability of soil–phyllite mixtures. Based on the spatial orientation characteristics of phyllite, a self-developed large-scale permeameter was used to examine permeability characteristics of soil–phyllite mixtures under different conditions, including various rock content and particle sizes, and the influence of these factors on the permeability of such mixtures was studied. The results show that when the rock content increases from 0% to 35%, the permeability coefficient of the mixture decreases by 49.28%, while the critical and failure hydraulic gradients increase by 159.38% and 54.17%, respectively, making piping failure less likely to occur. When the rock size increases from 20–40 mm to 60–80 mm, the permeability coefficient increases by 34.62%, and the critical and failure hydraulic gradients decrease by 23.15% and 10.3%, respectively, making piping failure more likely to occur. These findings provide references for evaluating the hydraulic characteristics of soil–phyllite mixtures and assessing the excavated slope stability in northwest Sichuan.
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Key words:
- soil–phyllite mixture /
- permeability /
- orientation /
- rock content /
- rock particle size
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