近源堆沉积土石体细观结构与抗剪强度指标关联分析
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摘要
细观结构是认知土石体力学行为本质的关键科学问题。本文通过引入物理学和数学等方法,借助颗粒物质力学理论,从几何排列与接触力的空间分布来定量刻画水平固结与山前坡地堆积两种典型环境下土石体的细观结构特征,并建立其与抗剪强度指标的关联。研究表明,(1)两种环境的土石体在细观结构上存在较大差异。在几何排列上,水平固结环境下的土石体具有长程无序和短程有序的特点,坡地堆沉积环境下的土石体表现出了无序的无定形结构;在接触力与单位接触向量的空间分布上,两者较为相似,绝大多数接触力以小于均值接触力的形式存在,其概率密度曲线P(f)呈幂函数衰减;90%以上接触方位角集中在40°～160°和220°～340°范围内。(2)基于径向分布函数、接触力概率密度和单位接触向量分别定义细观结构的特征量K_a,K_s和K_o,发现三个特征量的增大对内摩擦角呈线性促进作用,对黏聚力呈非线性削弱作用。
The mesostructure is the key scientific problem in the mechanical characteristics of the soil-rock mixture.In this paper,by introducing physics,mathematics and other methods,with the help of granular matter mechanics theory,the mesostructure characteristics of soil-rock mixture are quantitatively described from the geometric arrangement and the spatial distribution of contact force under two typical environments,and establish its association with shear strength parameters is established.The results show that(1) There are significant differences on the mesostructure of the soil-rock mixture under the two environments.In the geometric arrangement,the soil-rock mixture under horizontal consolidation environment has long-range disorderly,but short-range orderly characteristics.The soil soil-rock mixture under the slope deposition environment shows a disorderly amorphous structure.The two are similar on the spatial distribution of contact force and unit contact vector.The majority of contact forces are less than the mean contact force,the probability density curve P(f) is a decreasing the power function.More than 90% contact azimuth is concentrated in the range of 40°～160° and 220°～340°.(2) Based on the radial distribution function,the contact force probability density and the unit contact vector,the characteristic quantities K_a,K_s and K_o have been defined.The influence of K_a,K_s and K_o on the internal friction angle shows a positive linear correlation,and the cohesion shows a decreasing trend of parabola with the increase of K_a,K_s and K_o.
The mesostructure is the key scientific problem in the mechanical characteristics of the soil-rock mixture.In this paper,by introducing physics,mathematics and other methods,with the help of granular matter mechanics theory,the mesostructure characteristics of soil-rock mixture are quantitatively described from the geometric arrangement and the spatial distribution of contact force under two typical environments,and establish its association with shear strength parameters is established.The results show that(1) There are significant differences on the mesostructure of the soil-rock mixture under the two environments.In the geometric arrangement,the soil-rock mixture under horizontal consolidation environment has long-range disorderly,but short-range orderly characteristics.The soil soil-rock mixture under the slope deposition environment shows a disorderly amorphous structure.The two are similar on the spatial distribution of contact force and unit contact vector.The majority of contact forces are less than the mean contact force,the probability density curve P(f) is a decreasing the power function.More than 90% contact azimuth is concentrated in the range of 40°～160° and 220°～340°.(2) Based on the radial distribution function,the contact force probability density and the unit contact vector,the characteristic quantities K_a,K_s and K_o have been defined.The influence of K_a,K_s and K_o on the internal friction angle shows a positive linear correlation,and the cohesion shows a decreasing trend of parabola with the increase of K_a,K_s and K_o.
引文
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[15] 孙其诚,金峰,王光谦,等.二维颗粒体系单轴压缩形成的力链结构[J].物理学报,2010,59(1):30-37.(SUN Qi-cheng,JIN Feng,WANG Guang-qian,et al.Force chains in a uniaxially compressed static granular matter in 2D[J].Acta Physica Sinica,2010,59(1):30-37.(in Chinese))
[2] 樊海柱.西域砾岩结构特性及力学特性的试验研究[D].北京交通大学,2016.(FAN Hai-zhu.Test Research on Structure Characteristics and Mechanical Charactieristics of Xiyu Conglomerate[D].Beijing Jiaotong University,2016.(in Chinese))
[3] 涂新斌,王思敬,岳中琦.风化岩石的破碎分形及其工程地质意义[J].岩石力学与工程学报,2005,24(4):587-595.(TU Xin-bin,WANG Si-jing,YUE Zhong-qi.Fractal fragmentation of weathered rock and its application in engineering geology[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(4):587-595.(in Chinese))
[4] 徐文杰,胡瑞林,岳中琦,等.土石混合体细观结构及力学特性数值模拟研究[J].岩石力学与工程学报,2007,26(2):300-311.(XU Wen-jie,HU Rui-lin,YUE Zhong-qi,et al.Mesostructural character and numerical simulation of mechanical properties of soil-rock mixtures[J].Chinese Journal of Rock Mecha-nics and Engineering,2007,26(2):300-311.(in Chinese))
[5] 赵春发,张徐,翟婉明.高速铁路碎石道砟振动的离散元模拟[J].计算力学学报,2015,32(5):674-680.(ZHAO Chun-fa,ZHANG Xu,ZHAI Wan-ming.A discrete element simulation of high-speed railway ballast vibration[J].Chinese Journal of Computational Mechanics,2015,32(5):674-680.(in Chinese))
[6] 油新华.土石混合体的随机结构模型及其应用研究[D].北方交通大学,2001.(YOU Xin-hua.Stochastic Structural Model of the Soil-Rock Aggregate and Its Application[D].Northern Jiaotong University,2001.(in Chinese))
[7] 董云,柴贺军.土石混合料的工程综合分类法研究[J].岩土力学,2007,28(1):179-184.(DONG Yun,CHAI He -jun.Study on engineering synthetical cla -ssification of rock-soil aggregate mixture[J].Rock and Soil Mechanics,2007,28(1):179-184.(in Chinese))
[8] 金磊,曾亚武.块石形状对土石混合体力学行为影响的颗粒流模拟[J].计算力学学报,2016,33(5):753-759.(JIN Lei,ZENG Ya-wu.Particle flow simulation for effects of rock block shape on mechanical behavior of soil-rock mixture[J].Chinese Journal of Computational Mechanics,2016,33(5):753-759.(in Chinese))
[9] 赵明华,刘建军,罗宏,等.土石混填体抗剪强度特性及影响因素的试验研究[J].岩土力学,2017,38(4):965-972 (ZHAO Ming-hua,LIU Jian-jun,LUO Hong,et al.Experimental studies of shear strength characteristics and influencing factors of soil-rock aggregate mixture[J].Rock and Soil Mechanics,2017,38(4):965-972.(in Chinese))
[10] Zhang Z P,Liu L F,Yuan Y D,et al.A simulation study of the effects of dynamic variables on the packing of spheres[J].Powder Technology,2001,116(1):23-32.
[11] Jia T,Zhang Y W,Chen J K,et al.Dynamic simulation of granular packing of fine cohesive particles with different size distributions[J].Powder Technology,2012,218(1):76-85.
[12] 张世良,戚力,高伟,等.分子模拟中常用的结构分析与表征方法综述[J].燕山大学学报,2015,39(3):213-220.(ZHANG Shi-liang,QI Li,GAO Wei,et al.Summary of methods for structural analysis and characterization in molecular modeling[J].Journal of Yanshan University,2015,39(3):213-220.(in Chinese))
[13] Lochmann K,Oger L,Stoyan D.Statistical analysis of random sphere packings with variable radius distribution[J].Solid State Sciences,2006,8(12):1397-1413.
[14] 崔之久.混杂堆积与环境[M].河北科学技术出版社,2013.(CUI Zhi-jiu.Diamicton and Environment[M].Hebei Science & Technology Press.(in Chinese))
[15] 孙其诚,金峰,王光谦,等.二维颗粒体系单轴压缩形成的力链结构[J].物理学报,2010,59(1):30-37.(SUN Qi-cheng,JIN Feng,WANG Guang-qian,et al.Force chains in a uniaxially compressed static granular matter in 2D[J].Acta Physica Sinica,2010,59(1):30-37.(in Chinese))