【摘要】：汶川5·12地震誘發(fā)大量山體滑坡,在震后形成數(shù)量巨大的滑坡堆積體,據(jù)估計滑坡堆積體有19.7萬之多�；露逊e體多為土石混合介質(zhì),其結(jié)構(gòu)松散,孔隙率大,表面植被覆蓋率低,且廣泛分布于江河兩岸。一方面滑坡堆積體在外力作用下易發(fā)生次生災(zāi)害,毀壞城鎮(zhèn)、道路、水利等基礎(chǔ)設(shè)施,危害當(dāng)?shù)鼐用裆敭a(chǎn)安全；另一方面在降雨、徑流、地震等外力作用下,滑坡堆積體極易產(chǎn)生水土流失,對震區(qū)生態(tài)環(huán)境恢復(fù)造成極大困難,同時流失泥沙進(jìn)入河道影響河流水質(zhì),對岷江下游流域生態(tài)環(huán)境造成潛在威脅,可見開展滑坡堆積體研究工作對災(zāi)區(qū)震后生態(tài)環(huán)境重建具有重要意義。本文從土壤侵蝕角度出發(fā),以汶川震區(qū)滑坡堆積體為研究對象,應(yīng)用土壤侵蝕、土壤學(xué)、水文學(xué)等理論,對震區(qū)滑坡堆積體水土流失展開模擬研究。實地調(diào)查汶川縣滑坡堆積體分布及幾何特征,分析滑坡堆積體坡面物質(zhì)組成等物理性質(zhì),采用室內(nèi)人工模擬降雨方法,研究滑坡堆積體坡面土壤侵蝕規(guī)律,探討土石比、雨強(qiáng)、坡度對坡面土壤侵蝕的影響。主要研究結(jié)果如下：(1)研究區(qū)滑坡堆積體呈線性分布,廣泛分布在岷江兩岸,汶川縣東部滑坡堆積體數(shù)量較多,海拔高度多在2000m以下,滑坡堆積體分布與當(dāng)?shù)鼐用窨臻g分布具有一定相似性。88.8%滑坡堆積體坡度在30°～40°之間,高度從幾米至幾百米不等,80%以上堆積體高度在10-150m之間,堆積體剖面不同層細(xì)土(2mm)含水率差異明顯,含水率隨著深度增加有增大趨勢,增大倍數(shù)分別為2.83、1.38、1.03倍,0-10cm層含水率明顯小于非滑坡堆積體0-10cm層,其他層含水率與非滑坡堆積體對應(yīng)層相比差異不大。堆積體不同層含土量隨著深度增加而增大,0-1 Ocm層含土量小于非滑坡堆積體表層,10-20cm、20-30cm層大于非滑坡堆積體對應(yīng)層。10-20cm層合土量從坡頂至坡底有增大趨勢,其他層隨坡長變化無明顯規(guī)律�；露逊e體10-20cm、20-30cm層級配良好,其他層級配不好,滑坡堆積體不同層顆粒粒徑組成中均以中碎石(60-10mm)為主,占50%以上,細(xì)土(2mm)以沙粒為主,占70%左右。(2)人工降雨條件下,堆積體坡面入滲過程隨土石比不同而不同,土石比為1：4時,3種雨強(qiáng)條件下降雨均全部進(jìn)入堆積體,土石比為1：1、1：2時入滲過程較-致,隨著降雨的進(jìn)行,入滲率不斷減小,到一定時間后達(dá)到穩(wěn)定入滲率。土石比、坡度對穩(wěn)定入滲率的影響較復(fù)雜。地表徑流量隨著雨強(qiáng)的增大而增大,土石比為1：4時,地表無徑流產(chǎn)生,土石比為1：2時,小雨強(qiáng)1.0mm/min條件下,地表也無徑流產(chǎn)生,說明土石比存在某一臨界點(diǎn),小于此閥值,無論雨強(qiáng)多大地表無徑流產(chǎn)生,大于此閥值,雨強(qiáng)較小時也無地表徑流產(chǎn)生。地表徑流含沙量在不同雨強(qiáng)條件下,隨時間變化過程曲線不一致,35°土石比為1：1,雨強(qiáng)為1.5mm/min時,含沙量開始有增大的趨勢,后逐漸減小,其他條件下,含沙量均隨著降雨歷時逐漸減小,但減小幅度有差異,同一雨強(qiáng)下,地表徑流平均含沙量隨著土石比減小而減小。地表產(chǎn)沙率變化過程分兩個階段：快速增大階段和波動變化階段,平均產(chǎn)沙率均隨著土石比、雨強(qiáng)的減小而減小。地表時段徑流量和產(chǎn)沙量、累積徑流量和產(chǎn)沙量之間均可用冪函數(shù)關(guān)系表示,R2分別在0.8504～0.9848和0.9962～0.9993之間。(3)壤中流徑流量隨時間變化過程存在峰值,但峰值持續(xù)時間隨土石比、雨強(qiáng)不同而不同,累積壤中流與時間之間可用線性關(guān)系表示,R2均在0.94以上,雨強(qiáng)較小時,壤中流平均徑流量隨土石比減小而增大。壤中流含沙量隨時間逐漸減小,含沙率變化在10min時存在突變,壤中流產(chǎn)沙率總體呈減小趨勢,并逐漸達(dá)到穩(wěn)定,。壤中流累積產(chǎn)沙量與時間關(guān)系隨土石比不同而不同,土石比為1：1、1：2時,呈對數(shù)函數(shù)關(guān)系,土石比1：4時呈線性關(guān)系。壤中流時段徑流量與產(chǎn)沙量之間關(guān)系復(fù)雜,開始時,產(chǎn)沙量隨著徑流量增大而增大,到一定時間后,時段產(chǎn)沙量又隨著時段徑流量減小而減小。壤中流累積徑流量與產(chǎn)沙量之間與地表徑流相同,可用冪函數(shù)表示,R2在0.9086～0.9995之間。(4)地表產(chǎn)流時間隨雨強(qiáng)的增大而減小,隨土石比減小而增大,壤中流產(chǎn)流時間與土石比、雨強(qiáng)之間無明顯規(guī)律,壤中流產(chǎn)流時間均在10min以內(nèi),地表徑流產(chǎn)流時間最短2.7min,最長達(dá)38.9min,地表徑流產(chǎn)流時間多數(shù)長于壤中流產(chǎn)流時間。堆積體徑流總量隨著雨強(qiáng)的增大而增加,相同土石比條件下,地表徑流和壤中流對徑流總量的貢獻(xiàn)隨雨強(qiáng)不同而不同,土石比為1：1和1：2時,在雨強(qiáng)2.0mm/min時,地表徑流貢獻(xiàn)大于壤中流,而在雨強(qiáng)為1.0mm/min時,壤中流貢獻(xiàn)大于地表徑流,土石比為1：4時,無地表徑流產(chǎn)生,徑流總量僅來自壤中流。土石比、坡度對徑流總量的影響不大,隨土石比減小,壤中流貢獻(xiàn)增大,坡度對地表徑流和壤中流的貢獻(xiàn)規(guī)律較復(fù)雜,土石比為1：1時,隨坡度增大,地表徑流貢獻(xiàn)逐漸增大,土石比為1：2時,隨坡度增大,地表徑流貢獻(xiàn)逐漸減小。堆積體產(chǎn)沙總量隨著雨強(qiáng)的增大而增加,地表泥沙和壤中流泥沙對泥沙總量的貢獻(xiàn)規(guī)律與徑流表現(xiàn)一致。產(chǎn)沙總量隨著土石比的減小而減小,地表泥沙對泥沙總量的貢獻(xiàn)隨著土石比的增大而增大。土石比為1：1時,產(chǎn)沙總量隨著坡度增大而增加,土石比為1：2時,產(chǎn)沙總量隨坡度增大有減小的趨勢。
[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 擄 and 40 擄, 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 擄 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.
【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：S157.1

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