不同含水量粉土与土钉界面的剪切特性

doi:10.11988/ckyyb.20230715

摘要/Abstract

摘要：

通过控制含水量的粉土与土-钉界面拉拔剪切室内试验,研究不同土体含水量及上覆压力时,钉-土界面的剪切应力与剪切位移关系、界面剪切强度及表观摩擦系数的变化规律。试验结果表明:钉-土界面剪切应力随上覆压力的增加而显著增加,峰值剪切应力对应的拉拔位移也逐渐增大,且剪切应力达到峰值后出现软化现象;钉-土界面的剪切应力与土体含水量呈负相关;峰值、残余剪切应力均随着上覆压力的增大近似呈线性增加,随着土体含水量的增大而显著下降;峰值应力与残余剪切应力的差值随着土体含水量的增加而减小,随着上覆压力的增加而增大。研究成果可为土钉拉拔承载性能研究提供参考。

关键词: 粉土, 含水量, 土钉, 界面拉拔, 剪切特性

Abstract:

To study the relationship between shear stress and shear displacement at the nail-soil interface, as well as the variation of interfacial shear strength and apparent friction coefficient with changes in soil water content and stress state, a pull-out shear test was conducted on the interface between silt and nail under controlled water content in this paper. The results of the soil-nail interface shear test were compared with those of the soil-structure shear test. Additionally, a calculation analysis of the shear stress at the nail-soil interface was conducted. The results show that the shear stress at the nail-soil interface increases significantly with the increase in overburden pressure, and the pull-out displacement corresponding to the peak shear stress also increases gradually. Meanwhile, a softening phenomenon occurs after the shear stress reaches its peak. The shear stress at the soil interface is negatively correlated with the soil’s water content. The shear stress in the low water content silt test is almost double that of the saturated silt test, and the pull-out displacement corresponding to the peak shear stress also increases by about twofold. The peak and residual shear stresses increase approximately linearly with increasing overburden pressure, and decrease significantly with increasing soil water content (w). The difference between them decreases with increasing w, and increases with increasing overburden pressure. The research results can provide a reference for studying the pull-out bearing capacity of nails.

Key words: silt, water content, soil-nail, interface pull-out, shear characteristics

中图分类号:

TU441.7

李永辉, 杨家旺, 王天东, 高健利. 不同含水量粉土与土钉界面的剪切特性[J]. 长江科学院院报, 2024, 41(11): 151-157.

LI Yong-hui, YANG Jia-wang, WANG Tian-dong, GAO Jian-li. Shear Characteristics of Interface between Silt and Soil Nail with Different Water Content[J]. Journal of Yangtze River Scientific Research Institute, 2024, 41(11): 151-157.

图/表 15

图1 钉-土界面剪切试验平台

Fig.1 Shear test platform of the soil- nail interface

图2 钉-土界面拉拔剪切箱

Fig.2 Drawing shear test box of the soil-nail interface

图3 模型箱与土钉连接组件

Fig.3 Connection components of model box and soil-nail

表1 试验土样的基本物理性质指标

Table 1 Basic physical properties of tested soil

含水量/%	相对密度	孔隙比	液限/%	塑限/%	塑性指数
13.24	2.71	0.688	21.6	15.2	6.4

表2 试验土样颗粒分析

Table 2 Particle analysis of tested soil

粒径/mm	(1,0.1]	(0.1,0.075]	(0.075,0.05]	(0.05,0.001)
质量分数/%	17.9	11.8	56.8	13.5

图4 试验土样的颗粒级配曲线

Fig.4 Particle gradation curve of the test soil sample

图5 试验用土钉构件

Fig.5 Tested soil nails

图6 不同含水量时钉-土界面剪切应力与拉拔位移曲线

Fig.6 Curves of shear stress and pull-out displacement of nail-soil interface with different overburden pressures (OP)

图7 不同上覆压力时钉-土界面剪切应力与拉拔位移曲线

Fig.7 Curves of shear stress and pull-out displacement of nail-soil interface with different overburden pressure

图8 钉-土界面峰值剪切应力对应的拉拔位移随OP、w的变化曲线

Fig.8 Variation curve of the pull-out displacement corresponding to the peak shear stress of the nail-soil interface with the change of OP and w

图9 钉-土界面峰值、残余剪切应力随OP、w的变化曲线

Fig.9 Variation curve of peak value and residual shear stress of nail-soil interface with the change of OP and w

图10 峰值、残余剪切应力差值的变化曲线

Fig.10 Variation curve of the difference of peak value and residual shear stress

图11 钉-土界面表观摩擦系数AFC随OP、w的变化曲线

Fig.11 Variation curve of apparent friction coefficient AFC of nail-soil interface with the change of OP and w

表3 钉-土界面峰值剪切强度计算参数取值

Table 3 Calculation parameters of peak shear stress of nail-soil interface

c'_a/ kPa	δ'/ (°)	φ'/ (°)	D₅₀/ mm	δ_m	α/ kPa^-1	n	h₁ / kPa	h₂/kPa
12.4	11.7	28	0.065	0.463	0.01	1.87	101.3	0.35

图12 粉土与土钉界面剪切强度计算值与试验结果对比

Fig.12 Comparison between the calculated shear strength of silt and soil nail interface and the experimental results

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