河套灌区暗管外包滤料的透水效果及防淤堵性能研究

Study on the Permeable Effect and Anti-silting Performance of the Filter Material Outside the Subsurface Drainage Pipe in Hetao Irrigation District

为探究不同外包滤料条件下的暗管透水效果、保土和防淤堵性能,设置5种暗管外包滤料方案,分别为砂滤料(A)、68 g/m^(2)土工布(B)、90 g/m^(2)土工布(C)、68 g/m^(2)土工布+砂滤料(D),以及无外包滤料(E)方案作为对照,通过室内渗透试验,田间春灌和秋浇排水过程的监测调查,综合分析不同外包滤料对暗管透水效果、保土和防淤堵性能的影响。结果表明:方案A、B和D的排水流量衰减率平均稳定在5.60%,方案C的衰减率仅次于方案E(15.094%),为11.15%。不同外包滤料达到稳定状态时的渗透系数在7.46×10^(-4)~9.46×10^(-4)cm/s之间,且GR≤3;各方案秋浇的土壤流失量较春灌时平均减少42%,方案D的土壤流失量衰减率仅为35%,低于其他方案(P<0.05),同时方案A~D的流失土壤d90分别为14.8、18.50、9.0和15.50μm与方案E(d90=23.33μm)相较,保土性能显著;B、C和D方案内的淤土量分别为12.54、17.64和7.00 g,方案D的淤土量显著低于其他单一铺设土工布的方案,可见方案D的防淤堵效果最优。综上,针对河套灌区下游土壤性质,推荐优先选择方案D(68 g/m^(2)土工布+砂滤料)作为灌区暗管外包滤料,该研究结果可为河套灌区下游选择适宜暗管外包滤料提供参考。

In order to explore the water permeability effect,soil preservation and anti-silting performance of subsurface drainage pipes under different conditions of outsourced filter material,five types of subsurface drainage pipe outsourced filter material schemes were set up,namely sand filter material(A),68 g/m^(2) geotextile(B),90 g/m^(2) geotextile(C),68 g/m^(2) geotextile+sand filter material(D),and no outsourced filter material(E)scheme as a control.Through the indoor penetration test,the monitoring and investigation of spring irrigation and autumn watering in the field,the influence of different filter materials on the water permeability,soil preservation and anti-silting performance of the subsurface drainage pipe were comprehensively analyzed.The results show that the attenuation rate of the drainage flow of scheme A,B and D was stable at 5.60% on average,and the attenuation rate of scheme C was 11.15%,second only to scheme E(15.094%).The permeability coefficient of different filter media in the stable state ranged from 7.46×10^(-4) cm/s to 9.46×10^(-4) cm/s,and GR≤3;Compared with spring irrigation,the soil loss of each scheme in autumn was reduced by 42%on average,and the soil loss attenuation rate of scheme D was only 35%,which was lower than other schemes(P<0.05).At the same time,the soil loss d90 of scheme A to D was 14.8,18.50,9.0 and 15.50μm,respectively,and the soil preservation performance was significant compared with scheme E(d90=23.33μm);The amount of silted soil in scheme B,C and D was 12.54,17.64 and 7.00 g,respectively,and the amount of silt in scheme D was significantly lower than that in other schemes where only geotextile is laid,indicating that scheme D has the best anti-silting effect.In summary,according to the soil properties of the downstream of Hetao irrigation area,it is recommended to preferentially select scheme D(68 g/m^(2) geotextile+sand filter material)as the filter material for subsurface drainage pipes in the irrigation area.The research results can provide a reference for selecting suitable filter material for subsurface drainage pipes in the downstream of Hetao irrigation area.