冻土石混合体、冰石混合物和冻土在压、拉作用下的破坏特征对比  

Comparison on the compressive and tensile failure properties of frozen soil-rock mixture,ice-rock mixture and frozen soil

作　　者：胡峰[1,2,3] 李志清 孙凯[1,2,3] 胡瑞林 HU Feng;LI Zhiqing;SUN Kai;HU Ruilin(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Science,University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China)

机构地区：[1]中国科学院地质与地球物理研究所页岩气与地质工程重点实验室,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]中国科学院地球科学研究院,北京100029

出　　处：《岩石力学与工程学报》2021年第S01期2923-2934,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0904);国家自然科学基金面上项目(41672316);中国科学院青年创新促进会资助项目(2017092)。

摘　　要：在寒区工程建设中了解冻混杂岩土材料,如冻土石混合体的力学性质是保证工程建设安全的前提条件。采用单轴压缩和巴西劈裂试验探讨纯冰、冰石混合物、冻土和冻土石混合体在不同冻结温度(-10℃,-20℃,-30℃)下的变形以及强度性质,同时借助显微成像技术观察试样内部的冰石、土石、冰土界面形态和受力开裂特征。试验得到以下结论:(1)在单轴压应力或劈裂拉应力作用下纯冰和冻土的破裂面相对平直;而冰石混合物和冻土石混合体的破裂面相对弯曲。(2)受块石形状的影响(外凸和内凹、锯齿边界),冰石混合物中可见对应的沿准确的冰石界面开裂和在界面附近冰体一侧开裂的2种裂缝类型;冻土石混合体中裂缝主要在冻土中和土石界面间发育。(3)试样的抗压和抗拉强度随冻结温度的降低呈现线性增加的趋势。随温度的降低冻土和冻土石混合体的压、拉强度增长速率要大于纯冰和冰石混合物的强度增长速率;各试样的压、拉强度比约为5。(4)在冻结温度为-10℃时,各试样的抗压、抗拉强度大小依次为冰石混合物>冻土石混合体>冻土>纯冰;然而在冻结温度为-30℃时,抗压强度大小依次为冻土>冻土石混合体>冰石混合物>纯冰,抗拉强度大小依次为:冻土石混合体>冻土>冰石混合物>纯冰。(5)冻土石混合体内部土石界面间除胶结冰的冻黏作用之外,还存在胶结冰的嵌入和互锁强化作用。在高含水量的冻土内部,土颗粒易溶于水中,在冰土界面土层一侧形成冰土混合交融层,该层强度大于纯冰强度,有效提高了冻土的强度。Understanding the mechanical properties of mixed frozen geotechnical materials,such as frozen soilrock mixture,is fundamental to guarantee construction safety in cold regions.A series of uniaxial compression and Brazilian tensile tests were conducted to acquire the strength and deformation characteristics of artificial ice,icerock mixture,frozen soil,and frozen soil-rock mixture(FSRM).The mesostructured and crack patterns of ice-rock,soil-rock and soil-ice interfaces were also analyzed using a microscopic imaging technique.The result shows that:(1)Ice and frozen soil present comparative flat fracture surfaces while frozen soil-rock mixture and ice-rock mixture mainly present tortuous cracks.(2)Influenced by the shape of rock blocks(convex or concave/serrated boundary),there are two types of cracks in the ice-rock mixture:cracks along the accurate ice-rock interface or cracks inside the ice near the interface;cracks in FRSM mainly develop between the frozen soil and the soil-rock interface.(3)The compressive and tensile strengths have an increasing linear trend with decreasing freezing temperature.The strength increasing rate of FSRM and frozen soil is more sensitive than that of pure ice and ice-rock mixture.The ratio of compressive and tensile strength is about 5.(4)Under a temperature of-10℃,the compressive and tensile strength of samples are present in decreasing order as follows:ice_rock mixture>frozen soil>FSRM>ice.However,under a temperature of-30℃,frozen soil has the maximum compressive strength,followed by FSRM,ice-rock mixture,and ice,and the tensile strength is decreasing in the following order:FSRM>frozen soil>ice-rock mixture>ice.(5)In frozen soil-rock interface,ice could fill small pores or fractures of blocks,namely,having the interface interlocked.With a higher soil water content,soil particles from frozen soil could dissolve in water and form an ice_soil mixed layer on one side of the soil layer at the ice-soil interface after freezing.Hence the strength of this layer is higher than that of pu

关 键 词：土力学 强度 破坏形态 冻土石混合体 冻结温度 土石界面 

分 类 号：TU43[建筑科学—岩土工程]