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松散土石体广泛存在于自然界及实际工程中。以强风化板岩松散碎石料为研究对象,在对松散土石体制样方法成功尝试后,采用大型叠环式剪切试验机对不同相对密度(D_r)及不同干湿状态的松散土石体开展系统力学试验,得到以下主要结论:松散土石体颗粒组构间约束效应及机械咬合弱,其应力–应变曲线无显著峰值,大变形过程主要呈现为颗粒间的滑动摩擦与翻转;对于试验中所选取的3种D_r(0.30,0.35和0.40),干燥状态下松散土石体内摩擦角由D_r=0.30时的13.18°小幅升至D_r=0.40时的13.97°,黏聚力则由6.95 kPa略降至4.90 kPa,湿润和浸水状态下亦呈现此规律,表明相同干湿状态时该松散度区间内土石体强度基本保持稳定;干燥状态松散土石体剪应力峰值显著高于湿润及浸水状态,表现出显著的水敏感性;以D_r=0.40为例,经与常规三轴试验成果对比,凸显了采用叠环式剪切试验研究松散土石体工程特性的优势与适用性。研究初步揭示了松散状态土石体强度及变形特性,其显著的水敏感性可定量解释松散堆积体、松散滑坡等受水的影响而发生大变形或失稳的机制。
Loose earth widely exists in nature and the actual project. Taking the strong weathered slate loose gravel as the research object, after the loose earth and stone sample preparation method was successfully tried, a large-scale circular ring shearing tester was used to test loose soil with different relative density (D_r) and different dry and wet conditions The results of the system mechanics test are as follows: The restraint effect and the mechanical bite between the loose earth and rock particles are not obvious, the stress-strain curve has no significant peak, the large deformation process mainly appears as the sliding friction and the flip between the particles; Three kinds of D_r (0.30,0.35 and 0.40) were selected. The internal friction angle of loose soil increased slightly from 13.18 ° at D_r = 0.30 to 13.97 ° at D_r = 0.40, while the cohesion decreased slightly from 6.95 kPa to 4.90 kPa, wetting and water immersion state also showed this law, indicating that the same wet and dry state within the loosening interval of soil mass intensity remained stable; dry state looser shear stress peak was significantly higher than the wet and flooding state, showing significant . Taking D_r = 0.40 as an example, compared with the results of conventional triaxial tests, it highlights the advantages and applicability of using cyclic shear tests to study the engineering characteristics of loose earth and stone. The study initially revealed the strength and deformation characteristics of loose earth and rock mass, and its significant water sensitivity can quantitatively explain the mechanism of large deformation or instability due to the influence of water such as loose deposits and loose landslides.