水利学报
水利學報
수리학보
2014年
6期
728-734
,共7页
张常亮%李萍%李同录%张茂省
張常亮%李萍%李同錄%張茂省
장상량%리평%리동록%장무성
水分迁移%入渗深度%体积含水率%非饱和黄土%降雨
水分遷移%入滲深度%體積含水率%非飽和黃土%降雨
수분천이%입삼심도%체적함수솔%비포화황토%강우
water infiltration%infiltration depth%volumetric water content%unsaturated loess%rainfall
已有许多人工降雨试验确定的黄土入渗深度有限，一般很少超过4 m，由此认为降雨难以通过正常渗流途径到达地下水位，而是通过裂隙、落水洞等通道灌入深部补给地下水的。然而调查发现，这种入水通道仅在黄土塬边的卸荷区常见，塬的中部很少。为了了解黄土地区地表水是以何种方式补给地下水的，在甘肃正宁县建立了一个监测站，通过在一深度为10 m的探井井壁上埋设土壤水分计，对天然降雨入渗条件下不同深度黄土层的体积含水率变化情况进行了为期一年的连续监测，同时采用雨量计记录其间的日降雨量。结果表明：2m以内的浅部土层，土壤水分具有周年的背景变化趋势，该趋势和蒸发量的变化趋势吻合。当日降雨量小于18 mm/d时，水分仅在表层循环，对地表以下（>20 cm）的含水率几乎没有影响。当日降雨量大于18 mm/d时，才会引起土壤含水率骤增，降雨量越大，土壤含水率增幅越大，影响深度越大，随着深度增加，增幅减小，时间上渐有滞后。观测点黄土的浸润带约为2 m，2 m以下的非饱和黄土中，水分以非饱和渗流或水汽形式迁移，水汽迁移量很小，但不可忽视，当遇到透水性差的古土壤层时，会在其顶部富集，长期作用则可能形成软弱带，诱发黄土滑坡。
已有許多人工降雨試驗確定的黃土入滲深度有限，一般很少超過4 m，由此認為降雨難以通過正常滲流途徑到達地下水位，而是通過裂隙、落水洞等通道灌入深部補給地下水的。然而調查髮現，這種入水通道僅在黃土塬邊的卸荷區常見，塬的中部很少。為瞭瞭解黃土地區地錶水是以何種方式補給地下水的，在甘肅正寧縣建立瞭一箇鑑測站，通過在一深度為10 m的探井井壁上埋設土壤水分計，對天然降雨入滲條件下不同深度黃土層的體積含水率變化情況進行瞭為期一年的連續鑑測，同時採用雨量計記錄其間的日降雨量。結果錶明：2m以內的淺部土層，土壤水分具有週年的揹景變化趨勢，該趨勢和蒸髮量的變化趨勢吻閤。噹日降雨量小于18 mm/d時，水分僅在錶層循環，對地錶以下（>20 cm）的含水率幾乎沒有影響。噹日降雨量大于18 mm/d時，纔會引起土壤含水率驟增，降雨量越大，土壤含水率增幅越大，影響深度越大，隨著深度增加，增幅減小，時間上漸有滯後。觀測點黃土的浸潤帶約為2 m，2 m以下的非飽和黃土中，水分以非飽和滲流或水汽形式遷移，水汽遷移量很小，但不可忽視，噹遇到透水性差的古土壤層時，會在其頂部富集，長期作用則可能形成軟弱帶，誘髮黃土滑坡。
이유허다인공강우시험학정적황토입삼심도유한，일반흔소초과4 m，유차인위강우난이통과정상삼류도경도체지하수위，이시통과렬극、낙수동등통도관입심부보급지하수적。연이조사발현，저충입수통도부재황토원변적사하구상견，원적중부흔소。위료료해황토지구지표수시이하충방식보급지하수적，재감숙정저현건립료일개감측참，통과재일심도위10 m적탐정정벽상매설토양수분계，대천연강우입삼조건하불동심도황토층적체적함수솔변화정황진행료위기일년적련속감측，동시채용우량계기록기간적일강우량。결과표명：2m이내적천부토층，토양수분구유주년적배경변화추세，해추세화증발량적변화추세문합。당일강우량소우18 mm/d시，수분부재표층순배，대지표이하（>20 cm）적함수솔궤호몰유영향。당일강우량대우18 mm/d시，재회인기토양함수솔취증，강우량월대，토양함수솔증폭월대，영향심도월대，수착심도증가，증폭감소，시간상점유체후。관측점황토적침윤대약위2 m，2 m이하적비포화황토중，수분이비포화삼류혹수기형식천이，수기천이량흔소，단불가홀시，당우도투수성차적고토양층시，회재기정부부집，장기작용칙가능형성연약대，유발황토활파。
By many artificial rainfall tests, the depth of rainfall infiltration in loess area was 4 meters at most. So, it is considered that the rainfall is hard to reach groundwater through the normal leaking way, but through vertical fissures,sinkholes or some other water paths to recharge groundwater. However,accord?ing to our investigation, these water paths only occur in unloading areas which always in the edge of loess tableland, but rare in the center. In order to make clear surface water recharge groundwater in loess area, a monitoring site was set up in Zhengning county, Gansu Province. By using the soil moisture meters which inserted into the wall of a 10-meter-deep exploratory well, the changes of volumetric moisture con?tent of soil layers with different depth were observed continuously for one year under the condition of natu?ral rainfall, the daily precipitation during the monitoring period was also recorded by rain gauge. The re?sults show that the moisture content of the shallow layers within 2 meters changed in annual cycle, and the trend is consistent with the change of evaporation. When the precipitation is less than 18 mm/d,the cir?culation of soil moisture occurs mainly in surface layers, and has little effect on the moisture content be?low 20 centimeters. But when the precipitation is more than 18 mm/d, the moisture content may have a sudden increase. The greater the rainfall, the higher the growth of moisture content and the deeper the af?fected range will be. With the increasing depth, the growth decreases and the change of moisture content lags behind the depth. The infiltration zone of the loess is about 2 meters. In the unsaturated soil below 2 meters, water moves mainly in the form of unsaturated seepage or vapor form, the motion of vapor is very small but cannot be ignored, the water would gather on the surface as encountering paleosol layer with low permeability,weak zone will be formed after long-term accumulation,inducing loess landslides eventually.
