在季节性冻土区，植被护坡作为一种结合植物与工程措施的生态防护技术，其理论在工程应用上仍存在脱节，尤其是冻融循环下根系对土体力学性能的影响机制边坡加固效果尚不明确。本文基于土力学、弹性力学、损伤力学以及临界状态理论等，采用室外调研和室内试验相结合的方式，将试验数据处理结果与理论分析相结合的技术路线，研究黄土高原地区某公路黄土边坡上植物根系对边坡土体力学特性的影响规律，同时对浅层边坡稳定性及加固机制进行研究。主要研究内容和结论如下：

（1）通过原位黄土取样和根系采集、室内试验获取了黄土的关键物理性质指标。基于此设计冻融循环梯度（0、1、5、10、15次）和含水率（10%、14%、18%），对含根黄土与黄土试样进行三轴压缩试验。试验结果显示，随冻融次数增加含根黄土弹性阶段缩短，峰值强度降低，主要原因是水冰相变引发土颗粒位移和胶结结构破坏；冻融循环对含根黄土强度的劣化效应呈现明显的阶段性特征：初期（0-5次循环）强度下降剧烈，后期（5-15次循环）强度下降趋缓，表明冻融循环的初期破坏主要源于水冰相变过程中对孔隙结构的剧烈扰动，而后期则以已有裂隙的渐进扩展为主；当含水率从18%降至10%时，含根黄土破坏模式由塑性累积转为脆性破坏；10%含水率试样破坏强度比18%含水率试样高出一倍以上，相同轴向应变所需偏应力增加20%-60%；围压提升时，含根黄土变形特征从应变软化转为硬化。

（2）对比含根黄土与黄土在不同条件下的差异性，高围压下根系的加入更能改变黄土的变形特征，含根黄土RW10在200kPa围压下应力-应变曲线转变为应变硬化型；由破坏模式可知，含根黄土的剪胀现象显著弱于普通黄土，且其剪切带的发育范围更为有限；同时随着冻融次数的增加，根系的加入使抗剪强度的增强效果越发明显，在15次冻融后100kPa、150kPa、200kPa三种围压下强度分别提升20%、50%、70%以上。

（3）根据三轴试验结果表明根系的加入能够让土体的粘聚力和内摩擦角得到明显的增强，且粘聚力的提升更为显著；两种类型黄土的粘聚力和内摩擦角均随冻融循环次数的累积呈现指数型衰减规律，且与含水率的也呈负相关性；当冻融循环次数持续增加时，强度参数的衰减速率呈现明显的递减趋势。

（4）基于土体破坏的临界状态理论，试验数据表明随冻融循环次数和含水率增加，含根黄土与黄土的临界状态应力比M均呈现递减趋势，但含根黄土的临界应力比M较普通黄土提升20.23%-64.28%，尤其在10%含水率与未冻融条件下，M增长率达64.28%；临界摩擦角较峰值摩擦角平均增加8°~12°，表明了冻融作用诱发更强烈的颗粒破碎，新生颗粒通过增加接触点密度显著强化摩擦效应。

（5）采用Midas/GTS软件用有限元强度折减法对黄土边坡稳定性进行模拟计算，研究结果显示：相较于无植被覆盖的裸土边坡，含有植物根系的黄土边坡在所有冻融次数下均表现出更高的稳定性。证实了根系在冻融循环过程中对边坡土体具有明显的力学增强作用。尽管随着冻融次数的增加，两类边坡的稳定性都呈现递减趋势，但含根系边坡稳定始终优于无根系边坡稳定性3%-6%，这充分说明植物根系能够显著抑制冻融循环导致的边坡力学性能的退化。

In seasonal frozen soil regions,vegetation slope protection,as an ecological protection technology integrating plants and engineering measures, still suffers from a disconnect between theory and engineering application. Particularly, the influence mechanism of root systems on the mechanical properties of soil under freeze-thaw cycles and their slope reinforcement effects remain unclear.This study employs soil mechanics, elasticity theory, damage mechanics, and critical state theory as theoretical foundations,adopting a methodology that combines field investigations with laboratory experiments.An integrated technical approach was developed to correlate experimental data processing with theoretical analysis.The research focuses on elucidating the influence patterns of plant roots on the mechanical properties of loess slopes along a highway in the Loess Plateau region.Concurrent investigations were conducted on shallow slope stability and reinforcement mechanisms.The principal research components and conclusions are summarized as follows:

(1)Key physical property indices of loess were obtained through in-situ sampling, root system collection, and laboratory testing.Based on this, freeze-thaw cycle gradients (0,1,5,10,15 cycles) and moisture contents (10%,14%,18%) were designed, and triaxial compression tests were conducted on root-reinforced loess and plain loess samples.Test results indicated that with increasing freeze-thaw cycles, the elastic phase of root-reinforced loess shortened, and peak strength decreased, primarily due to soil particle displacement and cementation structure damage caused by water-ice phase transition.The strength deterioration effect of freeze-thaw cycles on root-reinforced loess exhibited distinct stage-dependent characteristics: a sharp decline in the initial stage (0-5 cycles), followed by a gradual reduction in the later stage (5-15 cycles).This suggests that initial damage primarily resulted from intense pore structure disturbance during water-ice phase transition, whereas later-stage damage was dominated by progressive crack propagation.When moisture content decreased from 18% to 10%, the failure mode of root-reinforced loess shifted from plastic accumulation to brittle fracture;The failure strength of 10% moisture content samples was more than double that of 18% samples, with deviatoric stress required for the same axial strain increasing by 20%-60%;Under increasing confining pressure, the deformation behavior of root-reinforced loess transitioned from strain softening to hardening.

(2)Comparative analysis of root-reinforced loess versus plain loess under varying conditions revealed significant differences.The incorporation of root systems under high confining pressure demonstrates more pronounced modifications to the deformation characteristics of loess.The stress-strain curve of root-reinforced loess RW10 transitions to strain-hardening behavior at 200kPa confining pressure.Failure mode analysis indicates that the dilatancy effect in root-reinforced loess is markedly weaker compared to conventional loess.Furthermore, the development scope of shear bands is considerably more constrained.Notably, the shear strength enhancement effect induced by root systems becomes progressively more evident with increasing freeze-thaw cycles.After 15 freeze-thaw cycles, the strength improvements exceed 20%,50%,and 70% under the three respective confining pressure conditions(100kPa,200kPa,200kPa).

(3)The triaxial test results demonstrated that:The incorporation of root systems significantly enhances both the cohesion and internal friction angle of soil, with a more pronounced improvement observed in cohesion; The cohesion and internal friction angle of both loess types exhibit exponential decay patterns with accumulating freeze-thaw cycles.These parameters also demonstrate negative correlations with moisture content.As freeze-thaw cycles progress, the deterioration rate of strength parameters shows a distinct decelerating trend.

(4)According to the critical state theory of soil failure, experimental data revealed that:Both root-reinforced loess and plain loess exhibited decreasing trends in critical state stress ratio M with increasing freeze-thaw cycles and moisture content;However, the critical stress ratio M of root-reinforced loess was 20.23%-64.28% higher than that of plain loess,The enhancement reached 64.28% under 10% moisture content and unfrozen conditions;The critical friction angle showed an average increase of 8°-12° compared to the peak friction angle.This indicates that freeze-thaw action induces more intensive particle breakage,the newly generated particles significantly enhance frictional effects by increasing contact point density.

(5)Numerical simulation of loess slope stability was conducted using the finite element strength reduction method in Midas/GTS software. The results demonstrate that compared to bare slopes without vegetation cover, loess slopes with plant roots exhibit higher stability under all freeze-thaw cycles, confirming the significant mechanical reinforcement effect of root systems on slope soil during freeze-thaw processes. Although the stability of both slope types decreases with increasing freeze-thaw cycles, the rooted slopes consistently outperform the rootless ones by 3%-6%, indicating that plant roots can effectively mitigate the degradation of slope mechanical properties induced by freeze-thaw action.

[1]石学瑾, 张彪, 郭家龙,等. 黄土高原典型小流域土壤侵蚀时空演变[J]. 地理学报, 2024, 79 (07): 1787-1803.

[2]Cao Y ,Xiao B ,Ghanbarian B. Biocrusts enhance soil structural stability during freeze-thaw cycles and improve soil erosion resistance in cold-winter drylands [J]. Catena, 2024, 243 108206-108206.

[3]杨更社, 田俊峰, 叶万军. 冻融循环对阳曲隧道黄土细观损伤演化规律影响研究[J]. 西安科技大学学报, 2014, 34 (06): 635-640.

[4]肖涛,李萍,侯艺飞,等. 植被护坡研究综述[C]// 中国地质学会. 2019年全国工程地质学术年会论文集. 西北大学大陆动力学国家重点实验室地质学系;河海大学地球科学与工程学院;, 2019:7.

[5]周德培, 张俊云. 植被护坡工程技术[M]. 北京,人民交通出版社, 2003.

[6]Morgan P R ,Rickson R. Slope Stabilization and Erosion Control: A Bioengineering Approach[M]. Taylor and Francis: 2003-09-02.4

[7]Norris J E, Stokes A, Mickovski S B, et al. Slope stability and erosion control: Ecotechnological Solutions[M]. Springer, New York, 2008.

[8]Zhang C B, Chen L H, Jiang J, et al. Effects of gauge length and strain rate on the tensile strength of tree roots[J]. Trees-Struct Funct, 2012, 26(5): 1577-1584.

[9]周幼吾. 中国冻土[M]. 北京, 科学出版社, 2000．

[10]周泓,张泽,秦琦,等. 冻融循环作用下黄土基本物理性质变异性研究[J]. 冰川冻土, 2015, 37 (01): 162-168.

[11]俞茂宏. 土力学新论[M]. 浙江大学出版社: 202001. 527.

[12]Li Y ,Shi W ,Aydin A , et al. Loess genesis and worldwide distribution[J]. Earth-Science Reviews, 2020, 201 102947-102947.

[13]毕庆涛,范肖肖,董文萍. 采用环剪仪对重塑黄土抗剪强度特性的研究[J]. 水利与建筑工程学报, 2022, 20 (05): 96-101.

[14]邱明明,郑隆君,田宇轩,等. 延安新区原状黄土强度各向异性试验研究[J]. 工程勘察, 2023, 51 (09): 14-20.

[15]张建华,姚志华,冯世清,等. 基于现场和室内剪切试验的原状黄土强度特性研究[J]. 水利水电技术(中英文), 2021, 52 (06): 188-197.

[16]Yu B ,Dijkstra T ,Fan W , et al. Advanced multi-scale characterization of loess microstructure: Integrating μXCT and FIB-SEM for detailed fabric analysis and geotechnical implications[J]. Engineering Geology, 2024, 341 107727-107727.

[17]Bingyao H ,Qiangbing H ,Xiaosen K , et al. Experimental study on the disintegration characteristics of undisturbed loess under rainfall-induced leaching[J]. Catena, 2023, 233

[18]Leng Y ,Peng J ,Wang Q , et al. A fluidized landslide occurred in the Loess Plateau: A study on loess landslide in South Jingyang tableland[J]. Engineering Geology, 2018, 236 129-136.

[19]Zhiyu G ,Qiangbing H ,Yue L , et al. Model experimental study on the failure mechanisms of a loess-bedrock fill slope induced by rainfall[J]. Engineering Geology, 2023, 313

[20]Hua S C ,Jun X P ,Yu H W , et al. Centrifuge model test of an irrigation-induced loess landslide in the Heifangtai loess platform, Northwest China[J]. Journal of Mountain Science, 2018, 15 (1): 130-143.

[21]马鹏辉,彭建兵,朱兴华,等. 黄土浅层降雨入渗规律研究[J]. 水土保持通报, 2017, 37 (04): 248-253.

[22]Cong W ,Jing L ,Qinhuo L , et al. Eastern‐Pacific and Central‐Pacific Types of ENSO Elicit Diverse Responses of Vegetation in the West Pacific Region [J]. Geophysical Research Letters, 2022, 49 (3):

[23]沙贝宁,杨余辉,黄佛君,等. 中国西北地区逆温时空变化[J]. 干旱区研究,2025,42(03):397-408.

[24]Pan Z ,Yang G ,Ye W , et al.Effect of Freeze–Thaw Cycles and Initial Water Content on the Pore Structure and Mechanical Properties of Loess in Northern Shaanxi[J].Sustainability,2023,15(14):

[25]杨更社,高宇璠,田俊峰,等. 冻融循环对黄土电阻率及水分迁移影响的试验研究[J]. 科学技术与工程, 2016, 16 (35): 267-272.

[26]吕倩俐,张艳阳,张天栋,等. 不同冻融循环次数及含水率条件下伊犁地区黄土力学强度损伤特性[J]. 工程地质学报, 2023, 31 (04): 1269-1281.

[27]刘富强. 冻融循环作用下高含水率黄土动力变形特性研究[D]. 兰州大学, 2021.

[28]Ogata N, Kataoka T, Komiya A. Effect of freezing-thawing on the mechanical properties of soil[C]//Kinosita S, Fukuda M. Proceedings of the 4th internationgal symposium on ground freezing sapporo, Japan. Rotterdam: A A Balkema, 1985: 201-207.

[29]Wang D Y, Ma W, Niu Y H, et al. Effcet of cyclic freezing and thawing on mechanical properties of Qinghai-Tibet clay[J]. Clod regions science and Technology Engineering Geology, 2007, (13): 34-43.

[30]许健,郑翔,张辉. 黄土地区边坡冻融剥落病害机理及稳定性分析[J]. 西安建筑科技大学学报(自然科学版),2018,50(04):477-484.

[31]叶万军,杨更社,彭建兵,等. 冻融循环导致洛川黄土边坡剥落病害产生机制的试验研究[J]. 岩石力学与工程学报, 2012, 31 (01): 199-205.

[32]Qin B,Li X,Yang W, et al. Study on thermal‐hydro‐mechanical coupling and stability evolution of loess slope during freeze–thaw process[J]. Earth Surface Processes and Landforms, 2024, 49 (6): 2010-2026.

[33]王掌权,许健,郑翔,等. 反复冻融条件下黄土边坡稳定性分析[J]. 中国地质灾害与防治学报, 2017, 28(2): 15-21.

[34]Norris J E, Stokes A, Mickovski S B, et al. Slope stability and erosion control: Eco technological Solutions[M]. Springer, New York, 2008.

[35]Endo T, Tsureta T. The effect of tree roots upon the shearing strength of soil[J]. Annual report of the Hokkaido Branch. Tokyo forest experiment station, 1969, 16(18): 168-179.

[36]余芹芹,乔娜,卢海静,等. 植物根系对土体加筋效应研究[J]. 岩石力学与工程学报, 2012, 31(S1): 3216-3223.

[37]Gray D H, Ohashi H. Mechanics of fiber reinforcements in sand[J]. Journal of Geotechnical Engineering, 1983, 109(3): 335-353.

[38]谢贤健,苟千陶. 植被恢复边坡土壤抗蚀性及其影响因子耦合协调分析[J]. 人民黄河, 2024, 46 (05): 123-127.

[39]Gray D H, Ohashi H. Mechanics of fiber reinforcements in sand[J]. Journal of Geotechnical Engineering, 1983, 109(3): 335-353.

[40]胡其志,周勇,马强,陶高梁. 根系与格栅复合加筋土的力学特性试验研究[J]. 长江科学院院报, 2022, 39 (10): 109-115.

[41]Reubens B ,Poesen J ,Danjon F , et al. The role of fine and coarse roots in shallow slope stability and soil erosion control with a focus on root system architecture: a review.[J]. Trees. Structure and Function, 2007, 21 (4): 385-402.

[42]Miranda M I, Mahler C F. Study of the Shear Strength of A Tropical Soil with Grass Roots[J]. Soils and Rocks, 2017, 40(1):31-37.

[43]Hamidifar H, Keshavarzi A, Truong P. Enhancement of River Bank Shear Strength Parameters Using Vetiver Grass Root System[J]. Arabian Journal of Geosciences, 2018, 11(20).

[44]Lian B, Peng J, Zhan H, et al. Mechanical Response of Root-reinforced Loess with Various Water Contents[J]. Soil and Tillage Research, 2019, 193:85-94.

[45]Feng B, Zong Q, Cai H, et al. Calculation of Increased Soil Shear Strength from Desert Plant Roots[J]. Arabian Journal of Geosciences, 2019, 12(16):525-535.

[46]Hengchaovanich D. VGT: A bioengineering and phytoremediation option for the new Millennium[J]. IVC2 Plenary Papers, 2002(1): 1-5.

[47]程洪,颜传盛,李建庆,等. 草本植物根系网的固土机制模式与力学试验研究[J]. 水土保持 研究. 2016(01): 62-65.

[48]肖宏彬,田青青,李珍玉,等. 林草混交根-土复合体的抗剪强度特性[J]. 中南林业科技大学 学报, 2014, 34(2): 1-5.

[49]嵇晓雷. 植物根系分布对边坡护坡效应的数值模拟[J]. 中国科技论文, 2020, 15(06): 652 656.

[50]Endo T, Tsureta T. The effect of tree roots upon the shearing strength of soil[J]. Annual report of the Hokkaido Branch. Tokyo forest experiment station, 1969, 16(18): 168-179.

[51]Manbeian T. The influence of soil moisture section, cyclic wetting and drying, and plant roots on the shear strength of a cohesive Soil[R]. Berkeley: University of California, 1973.

[52]程磊,姚磊华,张生旭,等. 根系形态对土体强度影响的试验研究[J]. 自然灾害学报, 2018, 27(01): 40-49.

[53]Bordoni M, Cislaghi A, Vercesi A, et al. Effects of Plant Roots on Soil Shear Strength and Shallow Landslide Proneness in An Area of Northern Italian Apennines[J]. Bulletin of Engineering Geology and the Environment, 2020, 79(7):3361-3381.

[54]Liu Y, Hu X, Yu D, et al. Influence of the Roots of Mixed-planting Species on the Shear Strength of Saline Loess Soil[J]. Journal of Mountain Science, 2021, 18(3):806-818.

[55]李广信. 高等土力学[M]. 北京, 清华大学出版社, 2016.

[56]王建军. 奚守仲某高路堑岩石边坡失稳机制及加固措施研究[J]. 公路. 2011(06): 24-28.

[57]秦世旺. 基于ABAQUS的不同排水条件下红黏土边坡稳定性分析研究[D]. 桂林理工大学, 2021.

[58]Blijenberg H M. Application of physical modelling of debris flow triggering to field conditions: Limitations posed by boundary conditions[J]. Engineering Geology, 2007, 91(1): 25-33.

[59]王掌权,许健,郑翔,等. 反复冻融条件下黄土边坡稳定性分析[J]. 中国地质灾害与防治学 报, 2017, 28(2): 15-21.

[60]嵇晓雷. 植物根系分布对边坡护坡效应的数值模拟[J]. 中国科技论文, 2020, 15(06): 652 656.

[61]李国荣,胡夏嵩,毛小青,等. 青藏髙原东北部黄土区灌木植物根系护坡效应的数值模拟[J].岩石力学与工程学报, 2010, 29(9): 1877-1884.

[62]Lin D G, Huang B S, Lin S H. 3-D numerical investigations into the shear strength of the soil root system of Makino bamboo and its effect on slope stability[J]. Ecological Engineering, 2010, 36(8): 992-1006.

[63]肖本林,罗寿龙,陈军,等. 根系生态护坡的有限元分析[J]. 岩土力学, 2011, 32(6): 1881 1885.

[64]宋维峰,陈丽华,刘秀萍. 林木根系与土体相互作用的有限元数值模拟中几个关键问题的探讨[J]. 水土保持研究, 2009, 16(4): 6-13.

[65]GB/T 50123-2019, 土工试验方法标准[S].

[66]马巍,徐学祖,张立新. 冻融循环对石灰粉土剪切强度特性的影响[J]. 岩土工程学报, 1999, (02): 23-25.

[67]包卫星,吴倩,吴谦,等. 冻融循环作用下伊犁盐渍化黄土力学特性[J]. 岩石力学与工程学报, 2024, 43 (07): 1775-1787.

[68]Fang Z ,Shengjun S ,Songhe W . Effect of freeze-thaw cycles on the strength behaviour of recompacted loess in true triaxial tests [J]. Cold Regions Science and Technology, 2021, 181 103172-.

[69]高海娟,柴凤久,刘泽东,尤海洋,杨伟光,黄新育,徐艳霞. 苜蓿的价值与利用[A]. 饲料博览，2014（3）：22-25

[70]姚怡宁,宗桦,周璐,等. 川西大渡河干热河谷优势灌草植物的根系特征及其固土能力研究[J/OL]. 生态学报, 2025, (06): 1-13[2025-03-31].

[71]边小斐. 黄土高原沟壑区生态护坡模型试验与护坡机理研究[D]. 长安大学, 2024.

[72]Muhemaier R ,Wei M ,Liangfu X , et al. Study on The Influence of Freezing and Thawing Cycle and Dry and Wet Alternation on Mechanical Properties and Engineering Application of Loess Slope [J]. European Journal of Computational Mechanics, 2024, 33 (4): 389-410.

[73]JTG 3430-2020, 公路土工试验规程[S].

[74]廖孟柯. 冻土本构的硫酸盐渍化影响及蠕变特性研究[D]. 兰州：中国科学院研究生院, 2016.

[75]刘松玉. 土力学（第四版）[M]. 中国建筑工业出版社：201612. 316.

[76]Zhang T ,Li S ,Lan H , et al. Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions [J]. Journal of Rock Mechanics and Geotechnical Engineering, 2025, 17 (2): 1163-1181.

[77]郑颖人,孔亮. 岩土塑性力学[M]. 北京：中国建筑工业出版社, 2014.

[78]赵成刚, 刘艳. 临界状态土力学[M]. 北京：北京交通大学出版社. 2021．

[79]刘明朋. 泡沫轻质土力学特性及弹塑性本构模型研究[D]. 山东大学, 2022.

[80]孙昊, 钱建固, 时振昊. 粉黏混合土的临界状态统一本构模型研究[J]. 地基处理, 2022, 4(S1): 72-77.

[81]李杭州, 张志龙, 廖红建,等. 结构性土的三维修正剑桥模型研究[J]. 岩土工程学报, 2022, 44(S1): 12-16.

[82]Ali Rahman Z, Toll D, Gallipoli D. Critical state behavior of weakly bonded soil indraind state[J]. Gemechanics and Geoengineering, 2018, 13(4): 233-245.

[83]Suebsuk J, Horpibulsuk S, Liu MD. A critical state model for overconsolidated structured clay[J]. Computers and Geotechnics, 2011, 38(5): 648-658.

[84]苏步云. 泡沫混凝土力学性能及其弹塑性损伤本构研究[D]. 太原理工大学, 2017.

[85]Liu J ,Zhu Z ,He J , et al. Experimental study on shear strength and creep properties of loess modified by microbially induced calcium carbonate precipitation (MICP) under freeze-thaw cycles [J]. Case Studies in Construction Materials, 2025, 22 e04119-e04119.

[86]赵向阳. 冻融作用下根-土复合体的力学特性及其护坡效应研究[D]. 内蒙古大学, 2023.

[87]王金奎. 基于灌草根系行为的根土复合体力学特性研究[D]. 西安理工大学, 2024.

[88]Jian-peng D ,Hui L . Freezing and thawing erosion test and particle flow simulation of caragana root-soil complex[C]// Qinghai University (China), 2022:

[89]赵志豪,丁洋,孙浩然,等. 植物对江岸边坡固坡效应及稳定性数值分析 [J]. 中国水运, 2025, (05): 89-91. DOI:10.13646/j.cnki.42-1395/u.2025.05.028.

[90]Kelifa S ,Democracy D . Three-dimensional strength reduction and two-dimensional limit equilibrium methods of slope stability analysis [J]. Heliyon, 2023, 9 (7): e17966-e17966.