蒋秀姿, 文宝萍, 张咪咪, 张亚芳, 苏杰, 陈琳. 2018: 不同状态下黏性土剪切蠕变行为对比分析. 工程地质学报, 26(3): 639-646. DOI: 10.13544/j.cnki.jeg.2017-275
    引用本文: 蒋秀姿, 文宝萍, 张咪咪, 张亚芳, 苏杰, 陈琳. 2018: 不同状态下黏性土剪切蠕变行为对比分析. 工程地质学报, 26(3): 639-646. DOI: 10.13544/j.cnki.jeg.2017-275
    JIANG Xiuzi, WEN Baoping, ZHANG Mimi, ZHANG Yafang, SU Jie, CHEN Lin. 2018: COMPARATIVE ANALYSIS OF CREEP SHEAR BEHAVIOR OF COHESIVE SOIL UNDER DIFFERENT STATES. JOURNAL OF ENGINEERING GEOLOGY, 26(3): 639-646. DOI: 10.13544/j.cnki.jeg.2017-275
    Citation: JIANG Xiuzi, WEN Baoping, ZHANG Mimi, ZHANG Yafang, SU Jie, CHEN Lin. 2018: COMPARATIVE ANALYSIS OF CREEP SHEAR BEHAVIOR OF COHESIVE SOIL UNDER DIFFERENT STATES. JOURNAL OF ENGINEERING GEOLOGY, 26(3): 639-646. DOI: 10.13544/j.cnki.jeg.2017-275

    不同状态下黏性土剪切蠕变行为对比分析

    COMPARATIVE ANALYSIS OF CREEP SHEAR BEHAVIOR OF COHESIVE SOIL UNDER DIFFERENT STATES

    • 摘要: 低速滑坡的缓慢活动特征受其滑带岩土的蠕变行为控制。但是,新生型低速滑坡和复活型低速滑坡滑带岩土的蠕变行为显然分属于峰前状态和残余状态下的蠕变行为。两种状态下滑带岩土蠕变行为有何差异,国内外尚无明确认识。为此,本文以取自两个典型巨型低速滑坡——甘肃舟曲泄流坡滑坡和锁儿头滑坡滑带的含角砾黏性土为研究对象,分别采用直接剪切蠕变试验和直剪反复剪后的直剪蠕变试验方法,对比研究了峰前状态和残余状态下黏性土的剪切蠕变行为。研究发现,峰前状态和残余状态下,黏性土剪切蠕变均呈现阶段性,各阶段转换的临界剪应力均与正应力水平和角砾含量正相关。但是,峰前状态下黏性土蠕变具有明显的稳定蠕变阶段;残余状态下黏性土蠕变缺失这一阶段;前者加速蠕变临界剪应力大于后者、但小于峰值强度,后者加速蠕变临界剪应力略微大于残余强度。两种状态下,黏性土蠕变行为差异的根本原因在于土体内部的不同结构。

       

      Abstract: It is well recognized that the characteristic of slow-moving landslides is controlled by creep shear behavior of its slip zone's materials. However, it is obvious that creep behavior of the slip zone's materials of the new-born and reactivated slow-moving landslides belongs to creep shear behavior under pre-peak state and at residual state, respectively. Up to now, neither certain answer has been given nor insight has been disclosed yet by professionals about the differences when the slip zone's materials experience creep shear under different states. To investigate this issue, creep behavior of the slip zones' materials of two giant slow-moving landslides in Zhouqu county of Gansu province, called the Suoertou landslide and the Xieliupo landslide respectively, were studied experimentally. Slip zones of the two landslides are composed of cohesive soil with various amount of gravel. The soils were sheared under the pre-peak state and at residual state respectively with direct shear creep test and that following reversed direct shear. It was found that the soils experienced various stages of creep under both states, and that the critical shear stresses at each creep stage linearly increased with both normal and shear stresses, and gravel content as well. However, there was no second creep stage when the soil was re-sheared at the residual state, while the soil experienced a significant second creep stage under the pre-peak state. Moreover, it was observed that for the soil experienced creep shear under pre-peak state its critical shear stress at the tertiary creep was greater than that at the residual state. Significantly, under pre-peak state, the soils' critical shear stress at the tertiary creep was much less than its peak strength and greater than its residual strength, whereas at the residual state, its critical shear stress at the tertiary creep was very slightly greater than the residual strength. It was further discussed that for the cohesive soil mechanism behind the different creep behavior of the cohesive soil under different state should be largely attributed to its structures, specifically no structural defect under pre-peak state versus occurrence of well-defined structural defect at the residual state. These findings give an important implication that the slopes composed of cohesive soils may be more prone to occur the reactivated slow-moving landslides than the new-born slow-moving landslides.

       

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