汶川震区滑坡堆积体坡面水蚀模拟研究
发布时间：2019-06-09 15:16
【摘要】：汶川5·12地震诱发大量山体滑坡,在震后形成数量巨大的滑坡堆积体,据估计滑坡堆积体有19.7万之多。滑坡堆积体多为土石混合介质,其结构松散,孔隙率大,表面植被覆盖率低,且广泛分布于江河两岸。一方面滑坡堆积体在外力作用下易发生次生灾害,毁坏城镇、道路、水利等基础设施,危害当地居民生命财产安全；另一方面在降雨、径流、地震等外力作用下,滑坡堆积体极易产生水土流失,对震区生态环境恢复造成极大困难,同时流失泥沙进入河道影响河流水质,对岷江下游流域生态环境造成潜在威胁,可见开展滑坡堆积体研究工作对灾区震后生态环境重建具有重要意义。本文从土壤侵蚀角度出发,以汶川震区滑坡堆积体为研究对象,应用土壤侵蚀、土壤学、水文学等理论,对震区滑坡堆积体水土流失展开模拟研究。实地调查汶川县滑坡堆积体分布及几何特征,分析滑坡堆积体坡面物质组成等物理性质,采用室内人工模拟降雨方法,研究滑坡堆积体坡面土壤侵蚀规律,探讨土石比、雨强、坡度对坡面土壤侵蚀的影响。主要研究结果如下：(1)研究区滑坡堆积体呈线性分布,广泛分布在岷江两岸,汶川县东部滑坡堆积体数量较多,海拔高度多在2000m以下,滑坡堆积体分布与当地居民空间分布具有一定相似性。88.8%滑坡堆积体坡度在30°～40°之间,高度从几米至几百米不等,80%以上堆积体高度在10-150m之间,堆积体剖面不同层细土(2mm)含水率差异明显,含水率随着深度增加有增大趋势,增大倍数分别为2.83、1.38、1.03倍,0-10cm层含水率明显小于非滑坡堆积体0-10cm层,其他层含水率与非滑坡堆积体对应层相比差异不大。堆积体不同层含土量随着深度增加而增大,0-1 Ocm层含土量小于非滑坡堆积体表层,10-20cm、20-30cm层大于非滑坡堆积体对应层。10-20cm层合土量从坡顶至坡底有增大趋势,其他层随坡长变化无明显规律。滑坡堆积体10-20cm、20-30cm层级配良好,其他层级配不好,滑坡堆积体不同层颗粒粒径组成中均以中碎石(60-10mm)为主,占50%以上,细土(2mm)以沙粒为主,占70%左右。(2)人工降雨条件下,堆积体坡面入渗过程随土石比不同而不同,土石比为1：4时,3种雨强条件下降雨均全部进入堆积体,土石比为1：1、1：2时入渗过程较-致,随着降雨的进行,入渗率不断减小,到一定时间后达到稳定入渗率。土石比、坡度对稳定入渗率的影响较复杂。地表径流量随着雨强的增大而增大,土石比为1：4时,地表无径流产生,土石比为1：2时,小雨强1.0mm/min条件下,地表也无径流产生,说明土石比存在某一临界点,小于此阀值,无论雨强多大地表无径流产生,大于此阀值,雨强较小时也无地表径流产生。地表径流含沙量在不同雨强条件下,随时间变化过程曲线不一致,35°土石比为1：1,雨强为1.5mm/min时,含沙量开始有增大的趋势,后逐渐减小,其他条件下,含沙量均随着降雨历时逐渐减小,但减小幅度有差异,同一雨强下,地表径流平均含沙量随着土石比减小而减小。地表产沙率变化过程分两个阶段：快速增大阶段和波动变化阶段,平均产沙率均随着土石比、雨强的减小而减小。地表时段径流量和产沙量、累积径流量和产沙量之间均可用幂函数关系表示,R2分别在0.8504～0.9848和0.9962～0.9993之间。(3)壤中流径流量随时间变化过程存在峰值,但峰值持续时间随土石比、雨强不同而不同,累积壤中流与时间之间可用线性关系表示,R2均在0.94以上,雨强较小时,壤中流平均径流量随土石比减小而增大。壤中流含沙量随时间逐渐减小,含沙率变化在10min时存在突变,壤中流产沙率总体呈减小趋势,并逐渐达到稳定,。壤中流累积产沙量与时间关系随土石比不同而不同,土石比为1：1、1：2时,呈对数函数关系,土石比1：4时呈线性关系。壤中流时段径流量与产沙量之间关系复杂,开始时,产沙量随着径流量增大而增大,到一定时间后,时段产沙量又随着时段径流量减小而减小。壤中流累积径流量与产沙量之间与地表径流相同,可用幂函数表示,R2在0.9086～0.9995之间。(4)地表产流时间随雨强的增大而减小,随土石比减小而增大,壤中流产流时间与土石比、雨强之间无明显规律,壤中流产流时间均在10min以内,地表径流产流时间最短2.7min,最长达38.9min,地表径流产流时间多数长于壤中流产流时间。堆积体径流总量随着雨强的增大而增加,相同土石比条件下,地表径流和壤中流对径流总量的贡献随雨强不同而不同,土石比为1：1和1：2时,在雨强2.0mm/min时,地表径流贡献大于壤中流,而在雨强为1.0mm/min时,壤中流贡献大于地表径流,土石比为1：4时,无地表径流产生,径流总量仅来自壤中流。土石比、坡度对径流总量的影响不大,随土石比减小,壤中流贡献增大,坡度对地表径流和壤中流的贡献规律较复杂,土石比为1：1时,随坡度增大,地表径流贡献逐渐增大,土石比为1：2时,随坡度增大,地表径流贡献逐渐减小。堆积体产沙总量随着雨强的增大而增加,地表泥沙和壤中流泥沙对泥沙总量的贡献规律与径流表现一致。产沙总量随着土石比的减小而减小,地表泥沙对泥沙总量的贡献随着土石比的增大而增大。土石比为1：1时,产沙总量随着坡度增大而增加,土石比为1：2时,产沙总量随坡度增大有减小的趋势。
[Abstract]:In Wenchuan 5.12, a large number of landslides were induced, and a large number of landslide piles were formed after the earthquake, and it is estimated that the landslide has a large amount of 19.7 million. The landslide accumulation is a soil-rock mixed medium, its structure is loose, the porosity is large, the surface vegetation coverage is low, and it is widely distributed on both sides of the river. on the one hand, the landslide accumulation body is easy to generate secondary disasters under the action of external force, and the infrastructure of towns, roads, water conservancy and the like is damaged, and the life and property safety of the local residents is endangered; on the other hand, under the action of rainfall, runoff, earthquake and the like, the landslide accumulation body is extremely easy to generate water and soil loss, It is very difficult to recover the ecological environment in the earthquake area, and at the same time, the loss of the sediment into the river channel affects the water quality of the river, and the potential threat to the ecological environment in the lower reaches of the Minjiang River is very important to the reconstruction of the ecological environment after the earthquake in the disaster area. In this paper, from the angle of soil erosion, the study of soil erosion, soil erosion, soil science, hydrology and so on is applied to the study of soil erosion, soil erosion, soil science, hydrology and so on. In this paper, the distribution and the geometric characteristics of the landslide in the Wenchuan county are investigated. The physical properties of the material composition and other physical properties of the slope are analyzed. The soil erosion of the slope is studied by the method of indoor artificial rainfall, and the effect of the soil-rock ratio, the rain intensity and the slope on the soil erosion on the slope is studied. The main results are as follows: (1) The landslide accumulation body in the study area is in a linear distribution, and is widely distributed on both sides of the Minjiang River. There is a certain similarity between the distribution of the landslide and the spatial distribution of the local population. The slope of the 88.8% landslide is between 30 掳 and 40 掳, the height of the landslide is from several meters to several hundred meters, the height of the accumulation body above 80% is between 10 and 150 m, and the difference of water content of the fine soil (2 mm) of the accumulation section is obvious. The water content increases with the increase of the depth, the increase is 2.83, 1.38, 1.03 times, and the water content of the 0-10 cm layer is obviously smaller than that of the 0-10cm layer of the non-landslide accumulation body, and the water content of the other layers is less than that of the corresponding layer of the non-landslide accumulation body. The soil content of different layers of the pile is increased with the increase of the depth. The soil content of the 0-1Ocm layer is smaller than that of the non-landslide accumulation body, and the layer of 10-20cm and 20-30cm is larger than the corresponding layer of the non-landslide accumulation body. The amount of the 10-20cm laminated soil increases from the top to the bottom of the slope, and the other layers have no obvious regularity with the change of the length of the slope. The landslide accumulation body is 10-20cm, the level of 20-30cm is good, the other level is not good, the particle size composition of the grain of different layers of the landslide accumulation is mainly the medium-broken stone (60-10mm), accounting for more than 50%, and the fine soil (2 mm) is mainly of sand, accounting for about 70%. (2) Under the condition of artificial rainfall, the infiltration process of the surface of the accumulation body varies with the soil-rock ratio, and the soil-rock ratio is 1:4, and the rainfall all enters the pile body under the condition that the soil-rock ratio is 1:1 and 1:2, the infiltration process is more-and the infiltration rate is reduced as the rainfall is carried out, And the stable infiltration rate is achieved after a certain time. The influence of soil-rock ratio and slope on the steady infiltration rate is more complicated. The surface runoff is increased with the increase of the rainfall, the earth-rock ratio is 1:4, the surface is not run-off, the earth-rock ratio is 1:2, the surface is not generated by the runoff when the soil-rock ratio is 1:2, and the soil-rock ratio is less than the threshold value, It is greater than this threshold, and no surface runoff is generated when the rain is strong. The sediment concentration of the surface runoff is not consistent with the time-varying process curve under different rain and strong conditions, the soil-rock ratio of 35 掳 is 1:1, the rain intensity is 1.5 mm/ min, the sediment concentration starts to increase, and then gradually decreases. Under other conditions, the sediment concentration gradually decreases with the rainfall duration, but the decrease of the amplitude is different. In that same rain, the mean sediment concentration of the surface runoff decrease with the decrease of the soil-rock ratio. The change process of surface sand production rate is divided into two stages: the rapid increase stage and the fluctuation change stage, and the average sand production rate decreases with the reduction of the soil-rock ratio and the rain intensity. The power function relation between the runoff and the sediment concentration, the cumulative runoff and the sediment yield of the surface period is expressed by the power function relation, and R2 is between 0.85504 and 0.9848 and 0.9962-0.9993, respectively. (3) There is a peak in the time-varying process of the flow-in-flow, but the duration of the peak is different from the soil-rock ratio and the rain intensity. The linear relation between the flow and time of the accumulated flow is expressed by the linear relation, and the R2 is above 0.94 and the rain is strong for an hour. The average runoff of the stream increases with the decrease of the soil-rock ratio. The sediment concentration decreases with time, and the change of sand-containing rate is at 10 min, and the sand-bearing rate in the flow is generally decreasing, and it gradually reaches the stability. The soil-rock ratio is 1:1 and 1:2, and the soil-rock ratio is 1:1 and 1:2, and the soil-rock ratio is 1:1 and 1:2. The relationship between the runoff and the sediment concentration in the time period is complicated. At the beginning, the sediment concentration is increased with the increase of the runoff, and after a certain period of time, the sediment concentration of the period decreases with the decrease of the runoff. The runoff and sediment concentration of the flow are the same as the surface runoff. The power function is used to show that R2 is between 0.9086 and 0.9995. (4) The time of surface runoff is reduced with the increase of the rain, and with the decrease of the soil-rock ratio, there is no obvious rule between the flow time of the flow and the soil-rock ratio and the rain intensity, the flow time of the runoff is within 10 minutes, the runoff yield of the surface runoff is the shortest of 2.7 min, and the maximum time is 38.9 min. The runoff generation time of the surface runoff is much longer than the flow time of the stream. The total amount of runoff is increased with the increase of the rainfall. Under the same soil-rock ratio, the contribution of the surface runoff and the total flow to the total runoff is different from that of the rain, and the earth-rock ratio is 1:1 and 1:2, and when the rain is strong for 2.0mm/ min, the contribution of the surface runoff is greater than that of the flow, and when the rain intensity is 1.0 mm/ min, When the flow contribution is greater than the surface runoff and the earth-rock ratio is 1:4, no surface runoff is generated, and the total runoff amount is only from the flow. The soil-rock ratio and the slope have little influence on the total runoff, with the decrease of the soil-rock ratio, the flow contribution of the slope is increased, the contribution of the slope to the surface runoff and the soil flow is more complex, the earth-rock ratio is 1:1, the contribution of the surface runoff is gradually increased with the increase of the slope, the earth-rock ratio is 1:2, and the slope is increased along with the slope. The contribution of surface runoff is gradually reduced. The total amount of sediment in the pile is increased with the increase of the rainfall, and the contribution of surface sediment and sediment to the total amount of sediment is consistent with the runoff. The total amount of sand production decreases with the decrease of the soil-rock ratio, and the contribution of the surface sediment to the total amount of sediment is increased with the increase of the soil-rock ratio. When the soil-rock ratio is 1:1, the total amount of sand production increases with the increase of the slope, and the soil-rock ratio is 1:2, and the total amount of sand production increases with the slope.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.1
本文编号：2495649
[Abstract]:In Wenchuan 5.12, a large number of landslides were induced, and a large number of landslide piles were formed after the earthquake, and it is estimated that the landslide has a large amount of 19.7 million. The landslide accumulation is a soil-rock mixed medium, its structure is loose, the porosity is large, the surface vegetation coverage is low, and it is widely distributed on both sides of the river. on the one hand, the landslide accumulation body is easy to generate secondary disasters under the action of external force, and the infrastructure of towns, roads, water conservancy and the like is damaged, and the life and property safety of the local residents is endangered; on the other hand, under the action of rainfall, runoff, earthquake and the like, the landslide accumulation body is extremely easy to generate water and soil loss, It is very difficult to recover the ecological environment in the earthquake area, and at the same time, the loss of the sediment into the river channel affects the water quality of the river, and the potential threat to the ecological environment in the lower reaches of the Minjiang River is very important to the reconstruction of the ecological environment after the earthquake in the disaster area. In this paper, from the angle of soil erosion, the study of soil erosion, soil erosion, soil science, hydrology and so on is applied to the study of soil erosion, soil erosion, soil science, hydrology and so on. In this paper, the distribution and the geometric characteristics of the landslide in the Wenchuan county are investigated. The physical properties of the material composition and other physical properties of the slope are analyzed. The soil erosion of the slope is studied by the method of indoor artificial rainfall, and the effect of the soil-rock ratio, the rain intensity and the slope on the soil erosion on the slope is studied. The main results are as follows: (1) The landslide accumulation body in the study area is in a linear distribution, and is widely distributed on both sides of the Minjiang River. There is a certain similarity between the distribution of the landslide and the spatial distribution of the local population. The slope of the 88.8% landslide is between 30 掳 and 40 掳, the height of the landslide is from several meters to several hundred meters, the height of the accumulation body above 80% is between 10 and 150 m, and the difference of water content of the fine soil (2 mm) of the accumulation section is obvious. The water content increases with the increase of the depth, the increase is 2.83, 1.38, 1.03 times, and the water content of the 0-10 cm layer is obviously smaller than that of the 0-10cm layer of the non-landslide accumulation body, and the water content of the other layers is less than that of the corresponding layer of the non-landslide accumulation body. The soil content of different layers of the pile is increased with the increase of the depth. The soil content of the 0-1Ocm layer is smaller than that of the non-landslide accumulation body, and the layer of 10-20cm and 20-30cm is larger than the corresponding layer of the non-landslide accumulation body. The amount of the 10-20cm laminated soil increases from the top to the bottom of the slope, and the other layers have no obvious regularity with the change of the length of the slope. The landslide accumulation body is 10-20cm, the level of 20-30cm is good, the other level is not good, the particle size composition of the grain of different layers of the landslide accumulation is mainly the medium-broken stone (60-10mm), accounting for more than 50%, and the fine soil (2 mm) is mainly of sand, accounting for about 70%. (2) Under the condition of artificial rainfall, the infiltration process of the surface of the accumulation body varies with the soil-rock ratio, and the soil-rock ratio is 1:4, and the rainfall all enters the pile body under the condition that the soil-rock ratio is 1:1 and 1:2, the infiltration process is more-and the infiltration rate is reduced as the rainfall is carried out, And the stable infiltration rate is achieved after a certain time. The influence of soil-rock ratio and slope on the steady infiltration rate is more complicated. The surface runoff is increased with the increase of the rainfall, the earth-rock ratio is 1:4, the surface is not run-off, the earth-rock ratio is 1:2, the surface is not generated by the runoff when the soil-rock ratio is 1:2, and the soil-rock ratio is less than the threshold value, It is greater than this threshold, and no surface runoff is generated when the rain is strong. The sediment concentration of the surface runoff is not consistent with the time-varying process curve under different rain and strong conditions, the soil-rock ratio of 35 掳 is 1:1, the rain intensity is 1.5 mm/ min, the sediment concentration starts to increase, and then gradually decreases. Under other conditions, the sediment concentration gradually decreases with the rainfall duration, but the decrease of the amplitude is different. In that same rain, the mean sediment concentration of the surface runoff decrease with the decrease of the soil-rock ratio. The change process of surface sand production rate is divided into two stages: the rapid increase stage and the fluctuation change stage, and the average sand production rate decreases with the reduction of the soil-rock ratio and the rain intensity. The power function relation between the runoff and the sediment concentration, the cumulative runoff and the sediment yield of the surface period is expressed by the power function relation, and R2 is between 0.85504 and 0.9848 and 0.9962-0.9993, respectively. (3) There is a peak in the time-varying process of the flow-in-flow, but the duration of the peak is different from the soil-rock ratio and the rain intensity. The linear relation between the flow and time of the accumulated flow is expressed by the linear relation, and the R2 is above 0.94 and the rain is strong for an hour. The average runoff of the stream increases with the decrease of the soil-rock ratio. The sediment concentration decreases with time, and the change of sand-containing rate is at 10 min, and the sand-bearing rate in the flow is generally decreasing, and it gradually reaches the stability. The soil-rock ratio is 1:1 and 1:2, and the soil-rock ratio is 1:1 and 1:2, and the soil-rock ratio is 1:1 and 1:2. The relationship between the runoff and the sediment concentration in the time period is complicated. At the beginning, the sediment concentration is increased with the increase of the runoff, and after a certain period of time, the sediment concentration of the period decreases with the decrease of the runoff. The runoff and sediment concentration of the flow are the same as the surface runoff. The power function is used to show that R2 is between 0.9086 and 0.9995. (4) The time of surface runoff is reduced with the increase of the rain, and with the decrease of the soil-rock ratio, there is no obvious rule between the flow time of the flow and the soil-rock ratio and the rain intensity, the flow time of the runoff is within 10 minutes, the runoff yield of the surface runoff is the shortest of 2.7 min, and the maximum time is 38.9 min. The runoff generation time of the surface runoff is much longer than the flow time of the stream. The total amount of runoff is increased with the increase of the rainfall. Under the same soil-rock ratio, the contribution of the surface runoff and the total flow to the total runoff is different from that of the rain, and the earth-rock ratio is 1:1 and 1:2, and when the rain is strong for 2.0mm/ min, the contribution of the surface runoff is greater than that of the flow, and when the rain intensity is 1.0 mm/ min, When the flow contribution is greater than the surface runoff and the earth-rock ratio is 1:4, no surface runoff is generated, and the total runoff amount is only from the flow. The soil-rock ratio and the slope have little influence on the total runoff, with the decrease of the soil-rock ratio, the flow contribution of the slope is increased, the contribution of the slope to the surface runoff and the soil flow is more complex, the earth-rock ratio is 1:1, the contribution of the surface runoff is gradually increased with the increase of the slope, the earth-rock ratio is 1:2, and the slope is increased along with the slope. The contribution of surface runoff is gradually reduced. The total amount of sediment in the pile is increased with the increase of the rainfall, and the contribution of surface sediment and sediment to the total amount of sediment is consistent with the runoff. The total amount of sand production decreases with the decrease of the soil-rock ratio, and the contribution of the surface sediment to the total amount of sediment is increased with the increase of the soil-rock ratio. When the soil-rock ratio is 1:1, the total amount of sand production increases with the increase of the slope, and the soil-rock ratio is 1:2, and the total amount of sand production increases with the slope.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.1
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