考虑降雨条件陕北Q<sub>2</sub>黄土斜坡稳定性的非线性劣化研究

周少伟; 边小卫; 李卫波; 马园园; 李菲

doi:10.19509/j.cnki.dzkq.tb20230432

考虑降雨条件陕北Q₂黄土斜坡稳定性的非线性劣化研究

doi: 10.19509/j.cnki.dzkq.tb20230432

陕西省地质调查院陕西省地质科技中心, 西安 710004

基金项目:

陕西省重点研发计划项目“地质作用对陕北生态脆弱区生态环境影响机理研究” 2021SF2-03

陕西省地质灾害防治体系建设项目 202320

详细信息

通讯作者:
周少伟，E-mail：418585618@qq.com

中图分类号: P642.22;P642.13
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出版历程
- 收稿日期: 2023-07-25
- 录用日期: 2024-01-02
- 修回日期: 2023-12-18

Nonlinear degradation of stability of Q₂ loess slopes in northern Shaanxi considering rainfall conditions

Shaanxi Geological Science and Technology Center, Shaanxi Institute of Geological Survey, Xi'an 710004, China

More Information

Corresponding author: ZHOU Shaowei, E-mail: 418585618@qq.com

摘要

摘要:
降雨致灾是陕北黄土斜坡最常见的灾害之一, 揭示降雨对黄土斜坡稳定性影响特征有利于预防滑坡灾害的发生。通过一系列室内试验研究了降雨条件下陕北Q₂黄土的力学特性变化特征, 并结合数值模拟分析了其对陕北黄土斜坡稳定性的影响。首先设计干湿循环试验(循环路径和次数)以模拟降雨条件(如强度、频次等); 其次通过三轴剪切试验获取陕北Q₂黄土的力学性质的变化规律; 最后以陕北地区某黄土斜坡为例, 利用有限元计算并分析不同降雨条件下斜坡安全系数和塑性区的变化特征。结果表明: (1)干湿循环作用后Q₂黄土的抗剪强度存在非线性劣化特征。当干湿循环次数超过一定范围后, 黄土物理力学性质参数劣化的边际效应减弱, 并趋于稳定。(2)降雨作用下黄土斜坡的稳定性呈现出随着降雨频次或降雨强度的增加而降低的趋势。(3)Q₂黄土斜坡的塑性区范围随着Q₂黄土力学性能的不断劣化而增大, 体现了降雨条件对黄土斜坡稳定性影响的非线性特征。研究结果为降雨型滑坡预防提供参考。
- 降雨条件 /
- Q₂黄土 /
- 干湿循环作用 /
- 抗剪强度 /
- 安全系数 /
- 黄土斜坡 /
- 非线性劣化 /
- 陕北地区
Abstract: Objective
Rainfall disasters are one of the most common disasters on loess slopes in northern Shaanxi, and revealing the effects of rainfall on loess slope stability is beneficial for preventing and controlling such disasters.
Methods
This research studied the mechanical properties of Q₂ loess in northern Shaanxi under rainfall conditions through a series of tests. Combined with numerical simulation technology, the influence of these changes on the stability of loess slopes in northern Shaanxi was analyzed.Firstly, the drying-wetting cycles test (cyclic path and the number of cycles) was designed to simulate rainfall conditions (such as intensity, frequency, etc.).Secondly, a triaxial shear test was performed to obtain the variation law of the mechanical properties of the Q₂ loess in northern Shaanxi.Finally, taking a loess slope in northern Shaanxi region as an example, finite element calculations were carried out, by which the change characteristics of the slope safety coefficients and plasticity zones under different rainfall conditions were analyzed.
Results
The results show that (1) the shear strength of Q₂ loess after the action of drying-wetting cycles has nonlinear deterioration characteristics. When the number of drying-wetting cycles exceeds a specific range, the marginal effect of the deterioration of the physical and mechanical property parameters of loess is weakened and tends to stabilize. (2) The stability of loess slopes decreases under the effect of rainfall, and it decreases with the increase of rainfall frequency or intensity. (3) The plastic zone of Q₂ loess slopes in northern Shaanxi increases with the continuous deterioration of the mechanical properties of the Q₂ loess, which reveals a nonlinear characteristic of the influence of rainfall on the stability of the loess slopes.
Conclusion
The research results can provide a reference for preventing rainfall-induced landslide.
- rainfall condition /
- Q₂ loess /
- drying-wetting cycles effect /
- shear strength /
- safety factor /
- loess slope /
- nonlinear degradation /
- northern Shaanxi
注释:

所有作者声明不存在利益冲突。

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图 1 陕西省志丹县DBXP088斜坡地理地貌概况(a)及潜在滑坡处取样点(b, c)

Figure 1. Geographical and geomorphological survey(a) and sampling points of potential landslides(b, c) of DBXP088 slope in Zhidan County, Shaanxi Province

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图 2 陕西省志丹县多年月平均降水量示意图(2000-2022年，志丹县气象局)

Figure 2. Schematic diagram of monthly average precipitation for many years in Zhidan County, Shaanxi Province

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图 3 GDS三轴试验系统主要组成

Figure 3. Main components of GDS triaxial test system

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图 4 不同干湿循环作用下Q₂黄土的应力-应变关系(n为干湿循环次数，路径信息见表 4，下同)

Figure 4. Stress-strain relationship of Q₂ loess under different drying-wetting cycles

下载: 全尺寸图片幻灯片

图 5 不同干湿循环作用下Q₂黄土参数的变化规律

Figure 5. Variation of shear strength of Q₂ loess under different drying-wetting cycles

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图 6 DBXP088斜坡有限元模型

Figure 6. Finite element model of DBXP088 slope

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图 7 不同干湿循环作用下斜坡安全系数变化

Figure 7. Change of slope safety factor under different drying-wetting cycles

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图 8 当折减系数F_v=1.57时不同干湿循环作用下斜坡滑动面云图

Figure 8. Nephogram of slope sliding surface under different drying-wetting cycles with a reduction factor F_v of 1.57

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表 1 DBXP088斜坡中Q₂黄土物理性质

Table 1. Physical propeities of Q₂ loess in DBXP088 slope

指标	含水率/%	天然密度/(g·cm^-3)	干密度/(g·cm^-3)	比重	孔隙比/%	饱和度/%	液限/%	塑限/%
值	10.30	1.88	1.36	2.71	0.69	74.7	29.37	16.55

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表 2 DBXP088斜坡中Q₂黄土粒径分布特征

Table 2. Distribution of Q₂ loess particles in DBXP088 slope

粒径种类	粗粒	细粒
粒径种类	粗粒	粉粒组	黏粒组
粒径/mm	≥0.075	0.075~0.005	≤0.005
质量分数/%	3.72	67.62	28.66

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表 3 DBXP088斜坡中黄土力学参数

Table 3. Main mechanical parameters in DBXP088 slope

地层	变形模量/MPa	泊松比	黏聚力/kPa	内摩擦角/(°)	抗剪强度/kPa
Q₂黄土	18.09	0.29	87.38	27.90	612.33

地层	天然密度/(g·cm^-3)	变形模量/MPa	泊松比	黏聚力/kPa	内摩擦角/(°)	地层厚度/m
Q₃黄土	1.58	5.62	0.31	31.73	23.60	5.00

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表 4 干湿循环作用路径试验设计方案

Table 4. Experimental design scheme of drying-wetting cycles action path

路径编号	下限质量含水率/%	上限质量含水率/%	质量含水率幅度(上限-下限)/%	停止后质量含水率/%
路径1	4.0	18.0	14.0	10.3
路径2	4.0	24.0	20.0
路径3	4.0	30.0	26.0

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表 5 Q₂黄土试样编号及不同干湿循环作用下主要物理力学参数

Table 5. Number of Q₂ loess samples and main physical and mechanical parameters under different drying-wetting cycles

试样标号	循环路径	循环次数/次	天然密度/(g·cm^-3)	泊松比	变形模量/MPa	黏聚力/kPa	内摩擦角/(°)
N-0	无干湿循环作用	0	1.88	0.29	18.09	87.38	27.9
N1-1	路径1	1	1.88	0.29	17.43	80.40	25.8
N1-2		3	1.88	0.29	16.52	74.36	23.7
N1-3		7	1.88	0.29	14.24	69.90	22.3
N1-4		10	1.88	0.29	10.17	58.66	21.7
N1-5		14	1.88	0.29	13.55	66.96	22.1
N1-6		18	1.88	0.29	10.21	70.11	22.2
N1-7		21	1.88	0.29	10.15	70.79	21.9
N2-1	路径2	1	1.88	0.29	16.69	75.72	23.7
N2-2		3	1.88	0.29	11.17	65.38	20.5
N2-3		7	1.88	0.29	10.32	51.48	19.9
N2-4		10	1.88	0.29	9.07	54.62	20.4
N2-5		14	1.88	0.29	8.23	61.81	21.1
N2-6		18	1.88	0.29	8.73	64.71	21.3
N2-7		21	1.88	0.29	8.66	60.60	21.3
N3-1	路径3	1	1.88	0.29	15.24	63.81	21.9
N3-2		3	1.88	0.29	9.82	31.73	19.8
N3-3		7	1.88	0.29	8.47	26.59	19.6
N3-4		10	1.88	0.29	6.84	38.24	20.2
N3-5		14	1.88	0.29	6.75	49.01	20.9
N3-6		18	1.88	0.29	7.43	55.09	21.2
N3-7		21	1.88	0.29	7.54	58.66	21.0

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