水保所知识产出(1956---)知识库

为了探究测定时间对定水头法土壤饱和导水率（Saturated soil hydraulic conductivity，K s ）测定结果的影响，采用室内模拟
试验，以关中 塿 土为研究对象，测定原状土（1.5 gcm -3 ）及不同容重（1.2、1.3、1.4、1.5、1.6 gcm -3 ）扰动土长时间序列下（45 d）的饱和
导水率及出流液电导率，并在实验结束后将土样分层用吸管法测定颗粒组成。结果表明：饱和导水率测定值随时间先迅速降低
达到一个拐点（近稳定点）后缓慢降低至最终稳定，对于原状 塿 土，近稳定点（1.33 d）K s 测定值 0.0762 cm h -1 与终稳定点（4.42 d）
K s 值 0.0640 cm h -1 差异不显著（P > 0.05），初步建议测定时间为 1.5 d。原状土比同容重的扰动土先达到稳定且稳定时的 K s 值更
大，随着土壤容重增加，K s 越快稳定（分别 4.92、4.42、2.92、2.5、1.5 d），且稳定时 K s 值越小。不同时刻出流液的电导率与饱和导水
率极显著相关（P < 0.01），试验后粉粒含量随土样深度有所上升，说明土粒的膨胀与迁移对 K s 测定的稳定时间均有影响。

 The effect of measuring time on soil hydraulic conductivity was analyzed by indoor simulation tests on a
long time- dependent (45 d). The soil hydraulic conductivity of undisturbed soil and disturbed soil (artificially
controlling the bulk density with 1.2, 1.3, 1.4, 1.5, 1.6 g cm -3 ) was measured by constant head method, the electrical
conductivity of leaching solution at different time points was measured by conductivity meter, and the composition of
soil particles was measured along the depth by the method of pipette analysis at the end of the experiment. The results
showed that soil hydraulic conductivity dramatically reduced in the beginning till reaching an infection point (the neat
stable point) and slowly reduced subsequently till reaching a stable state. There was not a significant difference (P >
0.05) of the K s values between the near stable point (1.33 d, K s = 0.0762 cm h -1 ) and the final stable point (4.42
d，K s = 0.064 cm h -1 ) of undisturbed soil. In order to obtain accurate and reliable K s value, 1.5 d was initially
recommended as measuring time for Lou soil. The K s of undisturbed soil achieved a sense of stability easier than
disturbed soil while and the infection point showed earlier for larger bulk density of disturbed soil, with 4.92, 4.42,
2.92, 2.5, 1.5 d respectively. As for the K s values at the stable point (both the near and final), undisturbed soil showed
a larger value than disturbed soil under the same bulk density, and there was a negative correlation between the K s
value and the bulk density for disturbed soil. The highly significant correlation (P < 0.01) was also observed between
the electrical conductivity of leaching solution and the saturated hydraulic conductivity value. At the end of the
experiment, the content of silt increased by depth for both of undisturbed and disturbed soil. The expansion and
migration of soil particles affect the stable measuring time of K s