横观各向同性非饱和黄土渗气特性与气体灾变驱动机制

郭楠; 农宇; 乔雄; 黄忠豪; 杨校辉

doi:10.3969/j.issn.0258-2724.20250360

横观各向同性非饱和黄土渗气特性与气体灾变驱动机制

doi: 10.3969/j.issn.0258-2724.20250360

郭楠^{1, 2,},
农宇^{1, 2},
乔雄^{1, 2, ,},
黄忠豪^{1, 2},
杨校辉^{1, 2}

1.
兰州理工大学土木与水利工程学院，甘肃兰州 730050
2.
兰州理工大学西部土木工程防灾减灾教育部工程研究中心，甘肃兰州 730050

基金项目: 国家自然科学基金项目（52168051，42462028，52368049）；甘肃省杰出青年基金（25JRRA057）

详细信息

作者简介:
郭楠（1987—），女，副教授，博士，研究方向为非饱和土与特殊土及地基处理等，E-mail：355094754@qq.com

通讯作者:
乔雄（1980—），男，副教授，博士，研究方向为土力学及黄土隧道等，E-mail：qiaoxiong@lut.edu.cn

中图分类号: TU43
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- 文章访问数: 12
- HTML全文浏览量: 7
- PDF下载量: 4
- 被引次数: 0
出版历程
- 收稿日期: 2025-07-10
- 修回日期: 2025-10-13
- 网络出版日期: 2026-01-17

Gas Permeability Characteristics and Gas Catastrophe Driving Mechanism of Transversely Isotropic Unsaturated Loess

GUO Nan^{1, 2
,},
NONG Yu^{1, 2},
QIAO Xiong^{1, 2
, ,},
HUANG Zhonghao^{1, 2},
YANG Xiaohui^{1, 2}

1.
School of Civil and Hydraulic Engineering, Lanzhou University of Technology, Lanzhou 730050, China
2.
Lanzhou University of Technology Western Civil Engineering Disaster Prevention and Mitigation Engineering Research Center of the Ministry of Education, Lanzhou 730050, China

摘要

摘要:
气体迁移在非饱和黄土地基普遍存在，相关规律及灾变驱动机制研究对黄土高原城市建设、基础设施服役安全性评价与黄土灾变问题解读等方面具有重要意义. 为此，考虑黄土地基的横观各向同性，采用改进非饱和三轴仪，对不同湿度与应力水平的原状与不同干密度重塑土样进行渗气试验，总结气体在横观各向同性非饱和黄土中迁移特性与气体灾变驱动机制，并提出横观各向同性非饱和黄土渗气系数模型. 结果表明：随着密度、湿度和应力水平的增大，在横观各向同性非饱和黄土中的气体流速和渗气系数均呈现出明显的先下降后稳定趋势，其中，当干密度≤1.51 g/cm³、含水率≤12.5%，竖向应力≤100 kPa时，渗气系数下降变化小于30%，相反加速衰减，三者引起土体内部空气孔隙体积的压缩、孔隙连通性降低及气体流动通道曲折化，致使最终渗气性能降低；横观各向同性非饱和黄土中的气体迁移在密度、湿度和应力水平影响下整体表现为“抑制-加压-驱动”的灾变机制. 研究成果不仅能提高非饱和黄土中渗气计算的准确性，丰富气体泄露防控理论，还可为加压气体致黄土地基灾变防控提供参考.
- 横观各向同性 /
- 非饱和黄土 /
- 气体 /
- 渗气特性 /
- 灾变驱动机制
Abstract:
Gas migration is prevalent in unsaturated loess foundations. Research into gas migration laws and catastrophe driving mechanisms holds great significance for urban construction, the evaluation of infrastructure service safety, and the interpretation of the loess catastrophe issue in the Loess Plateau. Therefore, by considering the transverse isotropy of loess foundations, an improved triaxial apparatus for unsaturated loess was used to conduct gas permeability tests on undisturbed soil samples (with different humidity and stress levels) and remolded soil samples (with various dry densities). The gas migration characteristics and gas catastrophe driving mechanism within transversely isotropic unsaturated loess were summarized, and a corresponding gas permeability coefficient model was proposed. The results indicate that with increases in density, moisture content, and stress level, both gas flow rate and gas permeability coefficient in transversely isotropic unsaturated loess exhibit a distinct trend of initial decrease followed by stabilization. Specifically, when the dry density is less than or equal to 1.51 g/cm³; the moisture content is less than or equal to 12.5%, and the vertical stress is less than or equal to 100 kPa, the observed decrease in gas permeability coefficient is less than 30%. Conversely, beyond these thresholds, the decay accelerates. Fundamentally, these factors induce compressed internal air pore volume, reduced pore connectivity, and increased tortuosity of gas flow paths, ultimately diminishing the gas permeability performance. Under the influence of density, moisture content, and stress level, the gas migration within transversely isotropic unsaturated loess collectively demonstrates a “suppression, pressurization, and driving” catastrophe mechanism. The research findings can not only improve the accuracy of gas permeability calculation in unsaturated loess and enrich the theory of gas leakage prevention and control but also offer valuable reference for the prevention and control of loess foundation catastrophe induced by pressurized gas.
- transverse isotropy /
- unsaturated loess /
- gas /
- gas permeability characteristic /
- catastrophe driving mechanism

HTML全文

图 1 FLSY-30型应力-应变控制式非饱和土三轴仪改进的三轴渗气仪

Figure 1. FLSY-30 improved triaxial gas permeameter based on stress-strain controlled triaxial apparatus for unsaturated soil

下载: 全尺寸图片幻灯片

图 2 各竖向力下原状黄土气体流速、渗气系数与压力梯度关系曲线

Figure 2. Relationship curves of gas flow rate, gas permeability coefficient, and pressure gradient of undisturbed loess under various vertical stresses

下载: 全尺寸图片幻灯片

图 3 不同干密度下各竖向力下黄土气体流速、渗气系数与压力梯度关系曲线

Figure 3. Relationship curves of gas flow rate, gas permeability coefficient, and pressure gradient of loess with different dry densities under various vertical stresses

下载: 全尺寸图片幻灯片

图 4 渗气过程的轴向变形差值

Figure 4. Axial deformation differences in gas permeation process

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图 5 各竖向力下黄土相对渗水系数与吸力关系曲线

Figure 5. Relationship curves between relative water permeability coefficient and suction of loess under various vertical stresses

下载: 全尺寸图片幻灯片

图 6 各竖向力下黄土相对渗气系数与吸力关系曲线

Figure 6. Relationship curves between relative gas permeability coefficient and suction of loess under various vertical stresses

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图 7 试验值与预测值对比

Figure 7. Comparison of tested and predicted values

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表 1 土样的基本物理指标

Table 1. Basic physical indices of soil samples

相对密度d_s	液限 w_L/%	塑限 w_P/%	最大干密度 ρ_dmax/（g•cm⁻³）	最优含水率 W_opt/%	孔隙比 e	杨氏模量/MPa
2.73	31.1	17.3	1.91	12.5	0.901	18.56

下载: 导出CSV

表 2 试验方案

Table 2. Test schemes

土样类型	干密度 ρ_d/（g•cm⁻³）	含水率 w/%	竖向力 P/kPa
重塑土	1.51、1.68、1.78	5.0、9.0、12.5、15.6、18.6	0、100、200
原状土	1.35	5.0、9.0、12.5、15.6、18.6	0、100、200

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表 3 渗气过程的轴向变形差值与压力梯度皮尔逊相关性

Table 3. Pearson correlation between axial deformation difference and pressure gradient in gas permeation process

竖向力 P/kPa	ρ_d/（g•cm³）
竖向力 P/kPa	1.35	1.51	1.68	1.78
0	−0.974	−0.975	−0.978	0.082
100	0.278	0.014	−0.253	−0.964
200	0.280	0.255	−0.230	−0.527

下载: 导出CSV

表 4 原状黄土试样修正VG模型拟合参数

Table 4. Fitting parameters of modified VG model for undisturbed loess samples

拟合参数	P=0	P=50 kPa	P=100 kPa	P=200 kPa
a	0.17729	0.12253	1.80529	0.319417
b	–235.70399	2.42148	7.11546	48.50468
c	1.71156	1.67515	1.70002	2.40017
R²	0.99465	0.99458	0.99374	0.99223

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表 5 重塑黄土试样修正VG模型拟合参数

Table 5. Fitting parameters of modified VG model for remolded loess samples

P/kPa	a			b			c			R²
P/kPa	ρ_d= 1.51g/cm³	ρ_d= 1.68g/cm³	ρ_d= 1.78g/cm³	ρ_d= 1.51g/cm³	ρ_d= 1.68g/cm³	ρ_d= 1.78g/cm³	ρ_d= 1.51g/cm³	ρ_d= 1.68g/cm³	ρ_d= 1.78g/cm³	ρ_d= 1.51g/cm³	ρ_d= 1.68g/cm³	ρ_d= 1.78g/cm³
0	0.26384	0.17768	0.17286	4.07213	3.57715	3.53542	1.40076	1.51924	1.47793	0.9864	0.99663	0.97553
50	0.03294	1.37073 E-5	0.00104	–2.27604	–11.72174	–4.1264	1.41465	1.46782	1.556001	0.9958	0.99369	0.97656
100	3.59e–4	1.27e–5	6.56e–7	–11.3539	–12.04581	–14.72824	1.41428	1.44995	1.39614	0.99528	0.98355	0.96564
200	2.07e–5	1.65e–7	1.25e–7	–18.1599	3.0185	–6.32039	1.46017	1.74544	1.55157	0.99743	0.98777	0.99245

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