伊犁那巴公路滑坡区黄土的强度特性

张艳¹，朱林楦^2*，谢宏丽²，田叶青²，任玉波²，隋忠曈²

1.西咸新区沣西新城开发建设集团有限公司，陕西 西安  712000；2.长安大学公路学院，陕西 西安  710064

摘要：为探究伊犁黄土的强度特性，选取新疆伊犁那巴公路沿线黄土滑坡区的重塑黄土作为试验对象，通过三轴剪切试验、环形剪切试验以及径向压裂试验对比分析不同含水率对土体抗剪强度、残余强度、抗拉强度的影响，并结合扫描电镜试验，观察土样经环形剪切破坏后的微观形貌。研究结果表明：1）相同含水率下，土样抗剪强度随围压增大而显著增大；相同围压条件下，土样抗剪强度随含水率增大而显著减小；围压不大于200 kPa时，土样应力-应变曲线在达到峰值强度后，抗剪强度随轴向应变的增大而衰减，最终趋于残余强度；围压大于200 kPa时，土样应力-应变曲线无明显峰值点，抗剪强度随轴向应变的增大而渐进式增大，含水率增至20%后，应力-应变曲线由应变硬化型变为应变软化型；含水率由14%增至17%时，土样抗剪强度降幅最大。2）当法向应力为100~400 kPa时，峰值强度和残余强度随法向应力的增大而增大，同一含水率下各曲线形态相似；不同含水率下，剪切强度随剪切位移的增大先快速增至峰值强度后缓慢减小；含水率不大于17%时，曲线呈应变软化特征，含水率不小于20%时，曲线仅包含应变硬化与残余强度两个阶段，无应变软化现象。3）土样的残余强度与法向应力线性正相关，抗拉强度随含水率的增大而减小，原状土样与重塑土样的抗拉强度在含水率不小于17%时趋于一致，并缓慢减小；土样的抗拉强度与残余黏聚力相近，表明黏聚力是抗拉强度的主要来源。

关键词：边坡工程；伊犁黄土；抗剪强度；残余强度；抗拉强度

Strength characteristics of loess in the landslide area of Ili Naba Highway

ZHANG Yan¹, ZHU Linxuan^2*, XIE Hongli², TIAN Yeqing², REN Yubo², SUI Zhongtong²

1.Xixian New Area Fengxi New City Development and Construction Group Co., Ltd., Xi′an 712000, China;

2.School of Highway, Chang′an University, Xi′an 710064, China

Abstract: To explore the strength characteristics of the loess in Ili, remolded loess from the landslide area along the Naba Highway in Ili, Xinjiang is selected as the test object. Through triaxial shear tests, ring shear tests, and radial fracturing tests, the impact of different moisture capacity on the shear strength, residual strength, and tensile strength of the soil is analyzed. Combined with scanning electron microscope tests, the microscopic morphology of the soil samples after ring shear failure is observed. The research results indicate that: 1) Under the same moisture capacity, the shear strength of the soil samples significantly increases with the increase of confining pressure; under the same confining pressure, the shear strength of the soil samples significantly decreases with the increase of moisture capacity; when the confining pressure is not greater than 200 kPa, the stress-strain curve of the soil samples shows that after reaching peak strength, the shear strength decreases with the increase of axial strain, eventually approaching the residual strength; when the confining pressure is greater than 200 kPa, the stress-strain curve of the soil samples has no obvious peak point, and the shear strength gradually increases with the increase of axial strain. After the moisture capacity reaches 20%, the stress-strain curve changes from strain hardening to strain softening; when the moisture capacity increases from 14% to 17%, the reduction of the shear strength of the soil samples is the greatest. 2) When the normal stress changes from 100 kPa to 400 kPa, both peak strength and residual strength increase with the increase of normal stress, and the curves are similar under the same moisture capacity conditions; under different moisture capacity, the shear strength increases rapidly to the peak strength and then slowly decreases with the increase of shear displacement; when the moisture capacity is not greater than 17%, the curves exhibit strain softening characteristics, while the moisture capacity is not less than 20%, the curves only include two stages: strain hardening and residual strength, without strain softening phenomena. 3) The residual strength of the soil samples is linearly positively correlated with normal stress, and the tensile strength decreases with the increase of moisture capacity. The tensile strength of undisturbed soil samples and remolded sample tends to be consistent when the moisture capacity is not less than 17%, and slowly decreases; the tensile strength of the soil samples is close to the residual cohesion, indicating that cohesion is the main source of tensile strength.

Keywords: slope engineering; Ili loess; shear strength; residual strength; tensile strength