土工基础

土工基础 ›› 2023, Vol. 37 ›› Issue (3): 506-511.

• 测试技术 • 上一篇    下一篇

裂隙扩展对膨胀土抗剪强度影响的试验研究

黄鹏1，程永辉1，熊勇1，冯党2，曹先振2   

  1. （1.长江科学院岩土力学与工程重点实验室，武汉 430010;2.南水北调中线干线工程建设管理局渠首分局，河南南阳 473000）
  • 收稿日期:2022-01-10 修回日期:2022-01-27 出版日期:2023-06-30 发布日期:2023-07-06
  • 通讯作者: 熊勇（1987-），男，工程师，博士，研究方向为岩土工程加固处理。
  • 作者简介:黄鹏（1997-），男，硕士研究生，研究方向为岩土工程。
  • 基金资助:
    国家自然科学基金青年科学基金项目（51709016）；中央级公益性科研院所基本科研业务费（CKSF2019199/YT）

Experimental Study on the Effect of Crack Propagation on the Shear Strength of Expansive Soils

HUANG Peng1, CHENG Yonghui1, XIONG Yong1, FENG Dang2， CAO Xianzhen2   

  1. (1.Key Laboratory of Geotechnical Mechanics and Engineering of Ministry of Water Resources, Yangtze River Scientific Research Institute, Wuhan 430010；2.Headwork branch of construction administration bureau of middle route of South to North Water Diversion Project, Nanyang 473000)
  • Received:2022-01-10 Revised:2022-01-27 Online:2023-06-30 Published:2023-07-06

摘要： 深层裂隙扩展直接影响深挖方膨胀土渠道边坡长期服役性能。为了研究不同裂隙扩展程度对膨胀土强度的影响，采用薄膜模拟手段，制备了含不同比例裂隙面的膨胀土剪切试样，开展了不同上覆荷载作用下的直接剪切试验，测试了不同裂隙扩展程度试样的峰值剪切强度。分析表明，试验条件下，峰值剪应力均随着裂隙扩展依次呈快速衰减、缓慢衰减和快速衰减的非线性三阶段衰减规律，通过归一化处理，得到了两种上覆荷载作用下的峰值剪切强度衰减量比曲线，分析可得上覆荷载对膨胀土块的峰值强度衰减量比的影响不大，变化幅度在10%以内；对衰减曲线进行多段式拟合，确定了非线性衰减三阶段的裂隙面积占比阈值分别为30%和70%；当裂隙扩展处于快速衰减（一阶段）与缓慢衰减（二阶段）之间阈值时，峰值强度衰减量比为(42.9%~47.8%)，处于缓慢衰减（二阶段）与快速衰减（三阶段）之间阈值时，峰值强度衰减量比为(50.3%~55.1%)。研究成果为膨胀土地区深挖方渠道边坡的设计计算与运营维护提供理论支撑。 

关键词: 膨胀土, 裂隙扩展, 峰值抗剪强度, 衰减量比

Abstract: The propagation of deep cracks directly affects the long-term service performance of expansive soil channel slope with the deep excavation. To study the influence of different degree of crack expansion on the strength of expansive soil, the membrane simulation method was used to prepare the expansive soil shear samples with different proportion of crack plane, and the direct shear tests under different overlying load were carried out to test the peak shear strength of the samples with different degree of crack expansion. Analysis shows that under the test conditions, the peak shear strength exhibits a nonlinear three-stage attenuation law of rapid attenuation, slow attenuation, and rapid attenuation with the crack expansion. Through the normalized processing, the attenuation ratio curve of the peak shear strength under the two overlying loads is obtained. It is analyzed that the overlying load has little effect on the attenuation ratio of the peak strength of the expansive clod, and the variation range is within 10%. The threshold of crack area proportion in three stages of nonlinear attenuation can be determined by multi-stage fitting of attenuation curve. When the crack propagation is at the threshold between rapid attenuation (stage I) and slow attenuation (stage II), the attenuation ratio of peak strength is (42.9%~47.8%), and when the crack propagation is at the threshold between slow attenuation (stage II) and fast attenuation (stage III), the attenuation ratio of peak strength is (50.3%~55.1%).The research results provide theoretical support for the design, calculation, operation and maintenance of deep excavation channel slope in expansive soil area.


Key words: Expansive Soils, Crack Propagation, Peak Shear Strength, Attenuation Ratio

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