| 坡度对碎屑流冲击立式拦挡墙力学特征的影响 |
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| 引用本文： | 肖思友,苏立君,姜元俊,李丞,刘振宇. 坡度对碎屑流冲击立式拦挡墙力学特征的影响[J]. 岩土力学, 2019, 40(11): 4341-4351. DOI: 10.16285/j.rsm.2018.1577 |
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| 作者姓名： | 肖思友 苏立君 姜元俊 李丞 刘振宇 |
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| 作者单位： | 1. 中国科学院成都山地灾害与环境研究所，山地灾害与地表过程重点实验室，四川 成都 610041；2. 中国科学院大学，北京 100049；3. 中国科学院青藏高原地球科学卓越创新中心，北京 100101 |
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| 基金项目： | 中科院“百人计划”；中国科学院战略先导A项目（No. XDA 20030301）；中科院西部之光“一带一路”国际合作团队项目。 |
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| 摘 要： | 由坡度和挡墙倾角的改变造成碎屑流冲击力学模型的改变是目前被忽略的问题。在碎屑流冲击倾式拦挡墙物理试验的基础上，利用离散元数值计算方法研究了坡度对碎屑流冲击立式拦挡墙（墙面与地面的夹角为90°）力学特征的影响，依据死区颗粒堆积特征，流动层颗粒冲击特征以及二者的相互作用特征提出了两种新力学模型：由倾斜冲击挡墙向坡面堆积转变的力学模型和考虑流动层对死区冲切摩擦作用的水平直接冲击力学模型。对不同冲击力学模型进行了验证分析，结果表明：坡度和挡墙倾角改变了死区的堆积特征从而改变了流动层的冲击方向和冲击力大小。当坡度小于40°时，碎屑流流动层首先沿死区上覆面倾斜冲击挡墙，在最大冲击力作用时刻，流动在坡面层状堆积，最大法向冲击合力可按静土压力公式估算。随着坡度的增大，在最大冲击力时刻，流动层颗粒直接冲击挡墙，但由于死区颗粒对流动层颗粒具有摩擦缓冲减速作用，大幅降低了流动层对挡墙的直接冲击力。此时死区对挡墙的作用力主要包括3个部分：流动层沿坡面冲击死区，由死区传递至挡墙的冲击力、流动层对死区的冲切摩擦力以及死区自重的静土压力。死区对挡墙作用力占最大法向冲击合力的比例增大至90%左右。当坡度由40°增大到50°时，在最大法向冲击合力作用时刻，流动层对死区的冲切摩擦力占最大冲击力的比例由15%增大到49%，流动层与死区之间的摩擦系数由滚动摩擦系数转变为静摩擦系数。提出的流动层对死区的冲切摩擦力为碎屑流冲击刚性挡墙力学计算模型提供了新的研究思路。
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| 关 键 词： | 碎屑流 拦挡墙 冲击力 离散元方法 冲切摩擦 |
| 收稿时间： | 2018-08-29 |
Influence of slope angle on mechanical properties of dry granular flow impacting vertical retaining wall |
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| XIAO Si-you,SU Li-jun,JIANG Yuan-jun,LI Cheng,LIU Zhen-yu. Influence of slope angle on mechanical properties of dry granular flow impacting vertical retaining wall[J]. Rock and Soil Mechanics, 2019, 40(11): 4341-4351. DOI: 10.16285/j.rsm.2018.1577 |
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| Authors: | XIAO Si-you SU Li-jun JIANG Yuan-jun LI Cheng LIU Zhen-yu |
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| Affiliation: | 1. Key Lab. of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, Sichuan 610041, China; 2. University of Chinese Academy of Sciences, Beijing 100049, China; 3. CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China |
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| Abstract: | The impact mechanical model changes of granular flow caused by the changes in slope angle and rigid wall slope are neglected problem presently. The discrete element method (DEM) is utilized to investigate the influences of slope angles on the impact properties of dry granular flow impacting on the rigid wall, which is based on the laboratory experiment of granular flow impacting on low-angle retaining wall. Two impact mechanical models are proposed according to the accumulation characteristics of dead zone, the impact characteristics of flowing layer and their interaction characteristics. The results show that the slope and the angle of the retaining wall change the accumulation characteristics of the dead zone and change the impact direction and impact force of the flowing layer. The maximum normal impact resultant force (NIRF) can be estimated by the formula of static earth pressure when the slope is less than 40 degrees, since the flow layer impact the retaining wall indirectly at the moment of maximum impact force. With the increasing of slope, the kinetic energy of the flowing layer increases. At the moment of the maximum normal impact force, the flowing layer impacts the retaining wall directly. However, the dead zone has the buffer and deceleration effects on the flowing layer. This leads to decrease of direct impact force on the retaining wall. The load of dead zone on retaining wall mainly includes the direct impact force of the flowing layer on the dead zone along the slope, the shear friction force of the flowing layer on the dead zone and the static earth pressure of dead zone. The ratio of impact force of the dead zone on the retaining wall increases to 90% of the maximum NIRF. When the slope angles increase from 40 to 50 degrees, the ratio of shear friction force increases from 15% to 49% of the maximum NIRF. The friction coefficient between dead zone and flowing layer also changes from rolling friction coefficient to static friction coefficient. The shear friction force by the flowing layer onto the dead zone provides a new research idea for the estimating model of granular flow impacting on rigid retaining wall. |
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| Keywords: | granular flow rigid barrier discrete element method impact friction |
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