闽粤地区花岗岩风化土体粘粒迁移过程的土柱渗流试验  

Soil Solumn Seepage Test on Clay Particles Migration Process of Granite Weathered Soil in Fujian and Guangdong Areas,China

作　　者：王浩[1,2,3] 许少鸿 陈叶健 徐陈灵 黄瑛瑛 WANG Hao;XU Shaohong;CHEN Yejian;XU Chenling;HUANG Yingying(Zijin School of Geology and Mining,Fuzhou University,Fuzhou 350108,China;Key Laboratory of Geohazard,Fujian Province,Geological Engineering Survey in Fujian Provice,Fuzhou 350002,China;Key Laboratory of Geohazard Prevention of Hilly Mountains,Ministry of Natural Resources of China,Fujian Provincial Bureau of Geology and Mineral Exploration and Development,Fuzhou 350002,China)

机构地区：[1]福州大学紫金地质与矿业学院,福州350108 [2]福建省地质工程勘察院福建省地质灾害重点实验室,福州350002 [3]福建省地质矿产勘查开发局自然资源部丘陵山地地质灾害防治重点实验室,福州350002

出　　处：《山地学报》2024年第1期132-142,共11页Mountain Research

基　　金：国家自然科学基金(41972268);福建省高校产学研联合创新项目(2022Y4002);福建省地质灾害重点实验室自主课题(KLGHZ202105)。

摘　　要：花岗岩风化土具有大孔隙结构、级配不良的特性。降雨入渗驱动粘粒迁移导致花岗岩风化土内部孔隙扩张和颗粒粗化,是闽粤地区花岗岩分布区水土流失和边坡变形破坏的主因。本文设计土柱渗流模型试验,研究不同级配条件下花岗岩风化土体的粘粒迁移过程与特征,考察土粒含量、渗流量及水力梯度等指标的变化规律。研究表明:(1)含有较多粘土矿物成分的细粒,尤其是粒径小于5μm的具有良好亲水性的粘粒,在渗流作用下容易发生迁移、集聚、淤堵或再迁移过程,导致渗流量与水力梯度持续变化,逐步出现土体颗粒粗化现象;(2)随着砾粒含量的增加,内部土粒单元发育成形的“混粒性”孔隙-骨架结构更为明显;当砾粒含量从40%增加至60%时,粘粒流失量增加14%,渗流量增加了51%,土体渗流通道增多、土体颗粒粗化,土体结构性逐步丧失;(3)花岗岩风化土中粘粒迁移过程由稳定渗流状态向优势渗流状态转变引起,一旦优势流通道成立,水力梯度增幅可达40%。研究结论可为闽粤地区花岗岩分布区水土流失治理和边坡灾害防治提供科学依据。Granite weathered soil is characterized by large pore structure and poor grading.Rainfall infiltration drives migration of clay particles,accompanying by expansion of internal pores and particle coarsening in granite weathered soil,which was recognized as the main explanation for soil-water loss and slope deformation or failure in granite area of Fujian-Guangdong region,China.In this study,a soil column seepage model experiment was designed to investigate the process and characteristics of clay particle migration in granite weathered soil under different soil grading conditions,in which the variations of soil composition,seepage discharge,and hydraulic gradient were traced for interpretation.(1)0x09Under seepage drive,fine particles with a higher content of clay minerals in the soil,especially clay particles with a particle size smaller than 5μm and good hydrophilicity,were prone to migration,aggregation,clogging,or re-organization processes,leading to continuous changes in seepage discharge and hydraulic gradient,then grain coarsening emerging.(2)0x09With the increase of gravel content in the soil,internal soil particle unit developed into more distinct“mixed-grain”porous skeleton.In case of gravel content increasing from 40%up to 60%,clay particles were leached away up to a 14%of mass of loss,with seepage discharge increases by 51%.More seepage channels developed,more grain coarsening intensified,and progressively soil structure came to collapsing.(3)0x09Clay particle migration in granite weathered soil was caused by the transition from a stable seepage state to a dominant seepage state.Once dominant flow channels were formed,the hydraulic gradient could increase by 40%.This study provides scientific basis for erosion control and slope prevention in granite area of Fujian-Guangdong region,China.

关 键 词：花岗岩风化土 颗粒级配 粘粒迁移 颗粒粗化 闽粤地区 

分 类 号：P642.24[天文地球—工程地质学]