| 摘要: |
| 【目的】研究含水率与干密度对砂质黄土强度的影响，揭示土体力学强度与结构强度对沙漠-黄土高原过渡区砂质黄土边坡滑塌的影响。【方法】通过直接剪切试验，分析了砂质黄土含水率（7%，11%，15%和19%）、干密度（1.60，1.65，1.70和1.75 g/cm3）、砂粒质量分数（30%，35%，40%和45%）对抗剪强度及其参数的影响。在此基础上，通过砂质黄土构度试验，分析其结构强度特性规律并建立其与抗剪强度之间的关系，对比分析含水率、土性（砂质黄土、粉质黄土、黏质黄土）对构度的影响。【结果】砂质黄土的抗剪强度、黏聚力、内摩擦角随着含水率的增大而逐渐减小，含水率由7%增加到19%时，其黏聚力由5.5 kPa降低至2.0 kPa，内摩擦角由33.22°降低至26.98°。砂质黄土的抗剪强度、黏聚力、内摩擦角随着干密度的增大而逐渐增大，干密度由1.60 g/cm3增加到1.75 g/cm3时，其黏聚力由5.5 kPa增加至60.5 kPa，内摩擦角由25.64°增加至26.15°。砂质黄土的抗剪强度、内摩擦角随着砂粒质量分数的增大而逐渐增大，黏聚力随着砂粒质量分数的增大而逐渐减小，砂粒质量分数由30%增加到45%时，其黏聚力由3.82 kPa降低至1.48 kPa，内摩擦角由22.56°增加至25.42°。砂质黄土、粉质黄土、黏质黄土的构度均随着含水率的增加而逐渐降低，含水率由7%增加到19%时砂质黄土构度下降了38.83%，粉质黄土构度下降了84.57%，黏质黄土构度下降了34.89%。随着砂质黄土构度的增加，其抗剪强度也随之增加，亦即结构性越强其抗剪强度越大。【结论】含水率与干密度对砂质黄土剪切强度及结构强度影响较大，应重视因含水率增加或干密度降低使得土体剪切强度及结构强度降低，进而引发黄土滑塌的灾害。 |
| 关键词: 砂质黄土 抗剪强度 构度 边坡滑塌 沙漠-黄土高原过渡区 |
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| 基金项目:国家自然科学基金面上项目“汾渭盆地典型地裂缝动力场地效应对比研究”（41772275）；中央高校基本科研业务费专项“边坡地震力计算及稳定性评价方法研究”（300102268203） |
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| Experimental study on strength of sandy loess in the transition zone of desert and the Loess Plateau |
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MU Huandong,DENG Yahong,ZHANG Wendong,et al
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| Abstract: |
| 【Objective】The effects of water content and dry density on strength of sandy loess were studied to reveal the influence of soil mechanical strength and structural strength on sandy loess slope collapse in the transition zone of desert and the Loess Plateau.【Method】Through the direct shear test,the influence of sandy loess water content (7%,11%,15% and 19%),dry density (1.60,1.65,1.70 and 1.75 g/cm3),and sand mass fraction (30%,35%,40% and 45%) on shear strength and its parameters was analyzed.Through the structure index test of sandy loess,the regularity of its structural strength characteristics and its relationship with shear strength were analyzed,and the influence of water content and soil property (sandy loess,silty loess and viscous loess) on the structure was analyzed.【Result】With the increase of water content,shear strength,cohesion and friction angle of sandy loess decreased gradually.When the water content was increased from 7% to 19%,cohesion reduced from 5.5 kPa to 2.0 kPa and friction angle reduced from 33.22 ° to 26.98 °.With the increase of dry density,shear strength,cohesion and friction angle of sandy loess increased gradually.When dry density increased from 1.60 g/cm3 to 1.75 g/cm3,cohesion increased from 5.5 kPa to 60.5 kPa and friction angle increased from 25.64 ° to 26.15 °.With the increase of sand mass fraction,shear strength and friction angle increased gradually,while cohesion decreased gradually.When the sand mass fraction increased from 30% to 45%,cohesion reduced from 3.82 kPa to 1.48 kPa and friction angle increased from 22.56 ° to 25.42 °.With the increase of water content,the structure index of sandy loess,silty loess,and clay loess gradually decreased.When water content increased from 7% to 19%,the sandy loess structure index decreased by 38.83%,the silty loess structure index decreased by 84.57%,and the clay loess structure index decreased by 34.89%.With the increase of structure index of sandy loess,its shear strength increased.【Conclusion】Moisture content and dry density had great influence on shear strength and structural strength of sandy loess.More attention should be paid to the reduction of soil shear strength and structural strength caused by water content increase or dry density decrease. |
| Key words: sandy loess shear strength structure index slope slump transition zone of desert and the Loess Plateal |
