根土复合体在循环单剪条件下的响应行为及离散元模拟研究（英文）

Cyclic behavior of root-loess composites under direct simple shear test conditions and insights from discrete element method modeling

摘要

植被根系可以提高土体抵抗剪切的能力，抑制浅层滑坡。但是，根系是否可以增强黄土的循环抵抗能力，以及地震荷载下各种因素对根系力学加固效应的影响缺乏相关的研究。通过进行一系列动单剪试验和离散元模拟来探究加根黄土的循环行为。首先调查了初始静剪应力和加载频率对根土复合体试样循环抵抗能力的影响。之后基于离散元方法(PFC^3D),进行常体积循环直接简单剪切模拟，探究根系几何、力学特性及根土间胶结强度对加根黄土循环强度的影响。研究结果表明根系可以有效提高黄土的循环抵抗能力。根土复合体的循环抵抗能力随初始剪应力的增加先下降，后上升，随频率的增加不断提高。模拟结果表明根系弹性模量、根土间胶结强度的增加均可以提升根土复合体的循环抵抗能力。当根系的初始倾斜角度为90°时，根土复合体的循环抵抗能力获得最大值。

Abstract

Plant roots are widely known to provide mechanical reinforcement to soils against shearing and further increase slope stability. However, whether roots provide reinforcement to loess cyclic re-sistance and how various factors affect roots reinforcement during seismic loading have rarely been studied. The objective is to conduct a series of cyclic direct simple shear tests and DEM numerical simulation to investigate the cyclic behaviour of rooted loess. The effects of initial static shear stress and loading frequency on the cyclic resistance of root-soil composites were first investigated. After that, cyclic direct simple shear simulations at constant volume were carried out based on the discrete element method(PFC3D) to investigate the effects of root geome-try, mechanical traits and root-soil bond strength on the cyclic strength of rooted loess. It was discovered that the roots could effectively improve the cyclic resistance of loess. The cyclic resistance of the root-soil composite decreases with the increase of the initial shear stress, then increases, and improves with the increase of the frequency. The simulation result show that increases in root elastic modulus and root-soil interfacial bond strength can all enhance the cyclic resistance of root-soil composites, and the maximum cyclic resistance of the root-soil composite was obtained when the initial inclination angle of the root system was 90°.

关键词

根土复合体 / 动态循环单剪 / PFC~(3D)

Key words

root-soil composite / cyclic direct simple shear tests / PFC~(3D)

Author summay

孙 渊(1999—), 男, 硕士研究生, 主要从事岩土工程防灾减灾研究。E-mail: [e-mail]

基金资助

青海省科技厅科技成果转化专项项目(2022-SF-159)