降雨诱发浅层冻土区边坡土剥落颗粒流模拟:以G214线典型冻土区路基边坡为例  

Particle Flow Simulation of Slope Soil Spalling Induced by Rainfall Inshallow Permafrost Zone:Taking the Subgrade Slope of Typical Frozen Soil Area of G214 Line as an Example

作　　者：蔡沛辰 毛雪松[1] 何沛 郑盛超 运志辉 CAI Pei-chen;MAO Xue-song;HE Pei;ZHENG Sheng-chao;YUN Zhi-hui(Highway of College,Chang'an University,Xi'an 710064,China;Sichuan Jiuma Expressway Co.,Ltd.,Aba 624000,China)

机构地区：[1]长安大学公路学院,西安710064 [2]四川久马高速公路有限责任公司,阿坝624000

出　　处：《科学技术与工程》2024年第26期11423-11431,共9页Science Technology and Engineering

基　　金：国家自然科学基金(51878064)。

摘　　要：为明确降雨诱发浅层冻土区边坡土剥落机理,以G214线典型冻土区路基边坡为例,基于颗粒流和等效降雨法,模拟不同坡度和冲刷速度下边坡坡面土的剥落过程,从边坡形态、颗粒运移规律、力链演化规律和剥落量等方面详细进行探究。结果表明:浅层冻土区边坡土受到雨水冲刷后,仅在坡面浅层部位出现坑槽,并提出边坡形态系数(τ)来定量化表征边坡形态的凹凸程度。边坡形态总体变化态势可概括为:笔直平坦(1.0≤τ<1.40)、粗糙不整(1.40≤τ<1.50)和凹凸不平(1.50≤τ)。土颗粒间接触力演化主要发生在降雨冲刷作用初期,冲刷过程中接触力演化特征并不明显。随循环次数增加,冲刷速度越大接触数量总体越少,但最终稳定状态下的接触数量近乎相同。此外,边坡浅层土在冻融循环作用下结构疏松是导致冻土区坡面土易被雨水冲刷剥落和坡面易形成冲沟的本质原因。To clarify the mechanism of slope soil spalling induced by rainfall in shallow permafrost zones,a typical roadbed slope of the G214 lines in a permafrost area is taken as an example.The spalling process of slope surface soil under different slope angles and erosion velocities was simulated using the particle flow and equivalent rainfall method.Detailed exploration was conducted from aspects such as slope shape,particle transport law,force chain evolution law,and spalling amount.The results show that after the slope soil in the shallow permafrost zone is washed by rainwater,only the shallow part of the slope surface displays grooves.A slope shape coefficient(τ) was proposed to quantitatively characterize the degree of concave and convex slope shape.The overall change trend of slope shape is summarized as follows:straight and flat(1.0≤τ<1.40),rough and uneven(1.40 ≤τ< 1.50),and concave-convex uneven(1.50 ≤τ).The evolution of the contact force of soil particles mainly occurs in the early stage of rainfall erosion,and the evolution characteristics of the contact force are not obvious during the erosion process.As the number of cycles increases,the larger the erosion velocity,the fewer the overall number of contacts,but the number of contacts in the final stable state is almost the same.Additionally,the loose structure of shallow soil on slopes under freeze-thaw cycles is the fundamental reason for the susceptibility of slope soil in permafrost zones to erosion and spalling by rainwater,leading to the formation of gullies on the slope surface.

关 键 词：浅层冻土区 路基边坡 降雨冲刷 剥落 颗粒流 

分 类 号：U416.14[交通运输工程—道路与铁道工程]