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<p>Excessive soil permeability during Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) operations in sandy strata can induce screw conveyor spewing. Although bentonite slurry is widely used to mitigate such risks by reducing permeability, the selection of slurry parameters for sandy soils with different particle sizes is still mainly based on experience. This study researched the permeability characteristics of sandy soils conditioned with bentonite slurry. Three sandy soil samples with different effective particle sizes (<i>d</i><sub>10</sub>) were selected for the experiment. The experiment was conducted by adjusting the bentonite slurry concentration (<i>Sc</i>), slurry injection ratio (<i>SIR</i>) and air pressure (<i>P</i>). The <i>k</i> was calculated as the main performance indicator. Regression analysis and least squares methods were employed to establish a <i>k</i> prediction model considering <i>P</i>, <i>d</i><sub>10</sub>, <i>SIR</i>, and <i>Sc</i>. The validity of the prediction model was verified using data from the literature and Extreme Gradient Boosting algorithm, respectively. Research found that the <i>k</i> decreases with increasing <i>Sc</i> and <i>SIR</i>, respectively. The reason is that an increase in <i>Sc</i> enhances local flow resistance and Reynolds number, thereby obstructing pore fluid flow, while an increase in <i>SIR</i> promotes the filling of fine particles in the pores. As <i>d</i><sub>10</sub> increases, the pore size of sandy soil increases, leading to a higher <i>k</i>. Based on the empirical threshold, the study provides reasonable <i>Sc</i> and <i>SIR</i> ranges for sandy soils with different <i>d</i><sub>10</sub> values. Under pressure, the regularity of the influence of various factors on the <i>k</i> is consistent with that without <i>P</i>.</p>

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Conditioning and prediction methods for the permeability of the slurry mixed sandy soil

  • 期刊论文

  • 发表日期：

    2026年1月22日

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  • Xiong Zhou,
  • Xiaoyang Liu,
  • Yuyou Yang,
  • Jiangbo Yang,
  • Yajian Wang

摘要

Excessive soil permeability during Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) operations in sandy strata can induce screw conveyor spewing. Although bentonite slurry is widely used to mitigate such risks by reducing permeability, the selection of slurry parameters for sandy soils with different particle sizes is still mainly based on experience. This study researched the permeability characteristics of sandy soils conditioned with bentonite slurry. Three sandy soil samples with different effective particle sizes (d10) were selected for the experiment. The experiment was conducted by adjusting the bentonite slurry concentration (Sc), slurry injection ratio (SIR) and air pressure (P). The k was calculated as the main performance indicator. Regression analysis and least squares methods were employed to establish a k prediction model considering P, d10, SIR, and Sc. The validity of the prediction model was verified using data from the literature and Extreme Gradient Boosting algorithm, respectively. Research found that the k decreases with increasing Sc and SIR, respectively. The reason is that an increase in Sc enhances local flow resistance and Reynolds number, thereby obstructing pore fluid flow, while an increase in SIR promotes the filling of fine particles in the pores. As d10 increases, the pore size of sandy soil increases, leading to a higher k. Based on the empirical threshold, the study provides reasonable Sc and SIR ranges for sandy soils with different d10 values. Under pressure, the regularity of the influence of various factors on the k is consistent with that without P.