山地学报
山地學報
산지학보
JOURNAL OF MOUNTAIN SCIENCE
2015年
3期
365-373
,共9页
董辉%罗潇%史超%罗有为
董輝%囉瀟%史超%囉有為
동휘%라소%사초%라유위
碎石土%滑坡%渗透规律%气阻作用%雨强
碎石土%滑坡%滲透規律%氣阻作用%雨彊
쇄석토%활파%삼투규률%기조작용%우강
gravel soil%landslide%seepage regulation%air entrapment effects%rainfall intensity
降雨过程中,堆积碎石土渗透特性改变是触发滑坡等灾害的主要因素。碎石土中封闭气泡阻碍水相流动,从而对雨水入渗产生影响。通过自制渗流沉降综合测试仪,进行入渗试验,探究不同雨强(1.2 mm/min、1.6 mm/min、2.0 mm/min)下,碎石土的渗透规律与沉降变形。通过Seep/w软件耦合Air/w软件进一步分析不同雨强下气阻作用对湿润锋迁移速度的影响。结果表明:入渗深度-时间曲线存在阶梯状趋势,即湿润锋迁移速度首先随表层土含水率的突增迅速增加至最大值(约30~40 mm/min),然后随气压的增加缓慢减小,最后湿润锋迁移速度随气压减小略微增大,湿润锋平均迁移速率(无积水状态)随雨强的增大趋近线性增长;碎石土沉降变形在入渗过程中经历缓慢增长、急剧增大、逐渐停滞三个阶段,雨强为2.0 mm/min时,碎石土发生急剧沉降变形时间最早(约50 min);碎石土渗透系数与干密度呈线性负相关关系。
降雨過程中,堆積碎石土滲透特性改變是觸髮滑坡等災害的主要因素。碎石土中封閉氣泡阻礙水相流動,從而對雨水入滲產生影響。通過自製滲流沉降綜閤測試儀,進行入滲試驗,探究不同雨彊(1.2 mm/min、1.6 mm/min、2.0 mm/min)下,碎石土的滲透規律與沉降變形。通過Seep/w軟件耦閤Air/w軟件進一步分析不同雨彊下氣阻作用對濕潤鋒遷移速度的影響。結果錶明:入滲深度-時間麯線存在階梯狀趨勢,即濕潤鋒遷移速度首先隨錶層土含水率的突增迅速增加至最大值(約30~40 mm/min),然後隨氣壓的增加緩慢減小,最後濕潤鋒遷移速度隨氣壓減小略微增大,濕潤鋒平均遷移速率(無積水狀態)隨雨彊的增大趨近線性增長;碎石土沉降變形在入滲過程中經歷緩慢增長、急劇增大、逐漸停滯三箇階段,雨彊為2.0 mm/min時,碎石土髮生急劇沉降變形時間最早(約50 min);碎石土滲透繫數與榦密度呈線性負相關關繫。
강우과정중,퇴적쇄석토삼투특성개변시촉발활파등재해적주요인소。쇄석토중봉폐기포조애수상류동,종이대우수입삼산생영향。통과자제삼류침강종합측시의,진행입삼시험,탐구불동우강(1.2 mm/min、1.6 mm/min、2.0 mm/min)하,쇄석토적삼투규률여침강변형。통과Seep/w연건우합Air/w연건진일보분석불동우강하기조작용대습윤봉천이속도적영향。결과표명:입삼심도-시간곡선존재계제상추세,즉습윤봉천이속도수선수표층토함수솔적돌증신속증가지최대치(약30~40 mm/min),연후수기압적증가완만감소,최후습윤봉천이속도수기압감소략미증대,습윤봉평균천이속솔(무적수상태)수우강적증대추근선성증장;쇄석토침강변형재입삼과정중경력완만증장、급극증대、축점정체삼개계단,우강위2.0 mm/min시,쇄석토발생급극침강변형시간최조(약50 min);쇄석토삼투계수여간밀도정선성부상관관계。
During the rainfall,the main factor for triggering landslides and other disasters is the changing of aggre-gate gravel soil permeability. Specifically,the entrapped air in gravel soils impedes aqueous phase flow,thus will have an effect on the rainwater permeability. The experiment of infiltration under different rainfall intensity(1. 2 mm/min,1. 6 mm/min,2. 0 mm/min),investigates the permeability of gravel soil and sedimentation deformation by our own infiltration and sedimentation integrated tester. Then,further research will focus on the relationship between the air entrapment impact with different rainfall intensity and wetting front migration rate through Seep/w and Air/w soft wares. The results show that:there is stepladder trend between wetting front and time curve. More specifical-ly,wetting front migration rate will rapidly increase with the sudden increase of the topsoil moisture to a maximum (30~40 mm/min approximately),then will slowly decrease with increased pressure. Finally the wetting front mi-gration rate will slightly increase with the decreased pressure. The average rate of wetting front migration( without hydrops water)approach linear growth with the increased rainfall intensity. Development of soil settlement deforma-tion passes through three stages:slow growth,sharply rises and gradually stagnation. The minimum time( approxi-mately 50 min)for sharp morph and sedimentation of gravel soil with the rainfall intensity is 2. 0 mm/min. There is a negative linear correlation between the permeability coefficient of gravel soil and the dry density.