摘要
汶川震区滑坡堆积体土石结构松散,在降雨径流作用下易产生剧烈沟蚀,导致严重的水土流失,研究堆积体水流泥沙输移运动规律具有重要意义。根据野外调查结果,采用4种石土比(质量比分别为0∶1、1∶3、1∶2和1∶1),3级流量(4、8、12 L min-1),在近临界休止角34°和36°条件下进行放水冲刷试验,研究汶川震区滑坡堆积体土壤侵蚀率和水动力学参数的变化特征及其关系。结果表明:随着冲刷时间的推延,土壤侵蚀率、水流功率和单位水流功率逐渐减小,水流剪切力先增加后减小,过水断面单位能量先减后增再减小。全土以及石土比分别为1∶3和1∶1条件下,土壤侵蚀率、水流剪切力、水流功率和过水断面单位能量随流量的增加而增大;在石土比1∶2条件下,土壤侵蚀率随流量的增加而增大,水流剪切力、水流功率和过水断面单位能量随流量的增加,变化规律不稳定。水流剪切力、水流功率和过水断面单位能量对土壤侵蚀率的影响均可用幂函数方程描述,而单位水流功率的影响不显著。该结果可为汶川震区滑坡堆积体坡面土壤侵蚀模型的建立奠定基础。
Landslide accumulations in the earthquake area of Wenchuan are formed typically of mixtures of rock fragments and soil,loose in structure. Drastic rill or gully erosion tends to occur with rainfall runoff,thus leading to grave soil and water loss. Therefore it is of great importance to launch a study on rules of water and sediment transport with runoff on landslide accumulation slopes. Based on field investigation,an indoor scouring experiment,designed to have 4 treatments in rock fragment and soil ratio（0∶1,1∶3,1∶2 and 1∶1）,3 treatments in water flow rate（4,8 and 12 L min-1）and 2 treatments in nearest dwell angle（34° and 36°）was carried out to study variations of soil erosion rate and hydrodynamic parameters and their relationships on landslide accumulation slopes in the Wenchuan earthquake area. Results show that with the souring experiment going on,the soil erosion rate,flowing power and specific flowing power gradually decreased,while water flow shear force increased at first then decreased,and specific energy at water flow cross-section decreased at first,then increased and decreased at last. On slopes,0∶1,1∶3 and 1∶1 in rock/soil ratio,soil erosion rate,water flow shear force,flowing power,and specific energy at water flow cross-section,increased with increasing water flow rate,but on slopes,1∶2 in rock/soil ratio,only soil erosion rate increased with increasing water flow rate and the other indices varied irregularly. In this study,the effects of water flow shear force,flowing power and specific energy at water flow cross-sectionon soil erosion rate could all be described with power function equations,and the effect of specific flowing power was not so obvious. All the findings in this study may help lay down a foundation for establishment of a model for predicting soil erosion on landslide accumulation slopes in the earthquake areas of Wenchuan.
出处
《土壤学报》
CAS
CSCD
北大核心
2016年第2期375-387,共13页
Acta Pedologica Sinica
基金
国家自然科学基金项目(41271291)资助~~
关键词
汶川震区
土石混合
土壤侵蚀率
水动力学参数
Wenchuan earthquake
Earth-rock mixture
Soil erosion rate
Hydrodynamic parameters
