PP織物袋在陜北淤地壩滲透破壞治理中的試驗研究
發(fā)布時間：2019-06-21 06:26
【摘要】：淤地壩是小流域綜合治理的重要水保工程措施之一,既可以增加耕地面積、提高農(nóng)業(yè)生產(chǎn)力,又可以防止水土流失。上世紀70到80年代由于當?shù)厣笆先狈?建設經(jīng)費不足,陜北靖邊、定邊地區(qū)所建淤地壩絕大多數(shù)未布設反濾材料,導致淤地壩產(chǎn)生滲透破壞而成為病險壩,這一問題目前一直未得到很好地解決,給當?shù)赜俚貕喂こ處韲乐氐陌踩[患。壩后滲透破壞已成為制約當?shù)赜俚貕谓ㄔO的一個重要問題。論文以陜西省榆林市靖邊縣高家溝鄉(xiāng)淤地壩的筑壩土料粉砂質(zhì)壤土為研究對象,通過室外模擬原淤地壩在滲流作用下的滲透破壞現(xiàn)象及過程,并用PP織物袋裝填原狀土作為反濾體對比其對滲透歷時和浸潤線的影響。對滲透破壞之后的壩體土樣用掃描電子顯微鏡研究壩體土樣的微觀結構和孔隙特征,用馬爾文激光粒度儀分析滲透破壞過程中的滲流泥沙顆粒級配,分析PP織物袋對滲透破壞的防治效果,為陜北靖定地區(qū)產(chǎn)生滲透破壞的淤地壩進行除險加固提供理論依據(jù)和技術支持,該項研究具有重要的工程實踐意義。本論文的主要結論有:(1)筑壩土料的常規(guī)土工試驗結論試驗分析結果表明,該筑壩土料屬于中粉質(zhì)壤土,土樣類別為低液限黏土。土料粒徑分布不均勻,不均勻系數(shù)CU=6.12,CC=0.90,不能同時滿足CU5及CC=1~3的條件,因此屬于不良級配的土樣,土壤較大土粒間的孔隙在滲流的作用下可被較小土粒較容易通過而造成滲透破壞。(2)PP織物袋的基本性質(zhì)測定試驗結論試驗分析結果表明,PP織物袋一方面可以更好地與砂性土結合,并保證整個袋體的穩(wěn)定性,另一方面,它抗拉伸和抗撕裂程度大,再加之袋體半身孔徑較小,水流易通過,而土壤較大顆粒不易通過,所以PP織物袋適合作為淤地壩壩后防止?jié)B透破壞的反濾材料。(3)壩后滲透破壞模擬試驗結論1)隨著滲透破壞的發(fā)生,兩個模擬壩壩體內(nèi)各個部位的水位高度逐漸增加到一定數(shù)值后達到穩(wěn)定,即當前區(qū)域土體達到飽和,壩體內(nèi)水位高度從壩前向壩后總體呈降低趨勢。2)由于PP織物袋袋體孔徑只容許水流和小顆粒土壤通過,因此PP織物袋裝填原狀土作為反濾體在防治滲透破壞時,可以減緩壩體內(nèi)各個部位水位升高的速率并降低最大水位高度,使得壩體相對較難發(fā)生滲透破壞。另一方面,可以將壩體內(nèi)多余水分排出,降低壩體浸潤線,減緩滲透破壞的發(fā)生。3)壩體的滲透破壞過程大體可以分為:壩坡下游表層浸濕階段、滲透破壞的發(fā)生發(fā)展階段和滲透破壞階段三個階段。并且兩個模擬壩的滲透破壞過程和現(xiàn)象相似,但是PP織物袋裝填原狀土作為反濾體的淤地壩滲透破壞發(fā)生的三個階段的開始發(fā)生時間都要比原土壩晚且滲流泥沙量要比原土壩小,說明PP織物袋雖不能真正地解決發(fā)生破壞的問題,但在一定程度上可以減緩滲透破壞的發(fā)生時間和破壞規(guī)模。4)兩個模擬壩的滲流量隨著滲透破壞的發(fā)生均呈現(xiàn)線性增長的趨勢,并且越往后增長的幅度越大,即先緩慢增加后顯著增加,最后趨于穩(wěn)定,直至壩體被完全破壞;PP織物袋作為反濾體的淤地壩要比原淤地壩的滲透破壞歷時要長;原淤地壩的滲流效果遠差于PP織物袋裝填原狀土作反濾體的淤地壩的滲流效果。(4)滲透破壞試樣微觀研究結論1)處于壩體浸潤線以下的土樣的孔隙率和孔隙平均直徑都要比原土料和壩體其他部位土樣大,顆粒平均直徑都要比原土料和壩體其他部位土樣小,而孔隙圓度和粒徑圓度的變化規(guī)律不明顯。處于壩體最底部的土樣從壩前向壩后孔隙率依次減小,且PP織物袋作反濾體的淤地壩土樣的孔隙率的增大程度不及原淤地壩。2)原筑壩土料和兩個模擬壩的滲流泥沙顆粒分布區(qū)間主要為20μm-100μm,原淤地壩滲透破壞過程中通過顆粒的重新分布,土體細小顆粒和部分骨架大顆粒較易流失。而PP織物袋一方面起到了防止土體較大顆粒流失的作用,在一定程度上保證了壩體的穩(wěn)定性。
[Abstract]:The silt dam is one of the important water conservation engineering measures for the comprehensive treatment of the small watershed, which can not only increase the cultivated area, improve the agricultural productivity, but also prevent the water and soil loss. In the 1970s and 1980s, because of the lack of local sand and gravel, the construction of sand and gravel in the Jingbian and Dingbian areas of northern Shaanxi had not been put into the anti-filter material, which led to the seepage and destruction of the silt dam and became a risk dam. The problem has not been well solved. It is a serious safety hazard to the local silt dam project. The seepage and destruction of the dam has become an important problem to restrict the construction of the local silt dam. In this paper, the seepage and damage phenomena and the process of the silt loam of the dam in Gaojiagou, Jingbian county, Yulin City, Shaanxi Province, are studied, and the infiltration and destruction of the original silt dam under the seepage of the original silt dam are simulated. The effect of the original soil as the filter body on the infiltration duration and the infiltration line was compared with the PP fabric bag. The micro-structure and pore characteristics of the soil sample of the dam body were studied by means of scanning electron microscope, and the grain gradation of the seepage and sediment in the process of seepage failure was analyzed by the Marvin laser granulometer, and the control effect of the PP fabric bag on the penetration failure was analyzed. It is of great practical significance to provide the theoretical basis and technical support for the risk removal and reinforcement of the silt dam that produces the seepage and destruction in the Jingding area of northern Shaanxi. The main conclusions of this paper are as follows: (1) The test and analysis results of the conventional geotechnical test for dam-building materials show that the dam-building material belongs to the medium-silty soil, and the soil sample belongs to the low-liquid limit clay. The particle size distribution of the soil is not uniform, the non-uniform coefficient CU = 6.12, CC = 0.90, the condition that the CU5 and CC = 1 to 3 cannot be met at the same time, therefore, the soil sample with bad grading and the pore between the large soil particles can be more easily adopted by the small soil particles under the action of the seepage, so that the seepage and the damage can be caused. (2) The test results of the basic properties of the PP fabric bag show that the PP fabric bag can be better combined with the sandy soil in one hand, and the stability of the whole bag body is ensured, and on the other hand, the PP fabric bag has the advantages of high tensile strength and tear resistance, and small aperture of the body of the bag body, The water flow is easy to pass, and the large particles of the soil are not easy to pass, so the PP fabric bag is suitable to be used as an anti-filtration material for preventing the seepage from being damaged after the dam of the silt dam. (3) After the dam, the seepage failure simulation test (1) increases to a certain value after the level of the water level in the two simulated dam bodies is gradually increased to a certain value with the occurrence of the seepage failure, that is, the soil body in the current region is saturated, because the pore diameter of the PP fabric bag body is only allowed to pass through the water flow and the small particle soil, the PP fabric bag is filled with the original soil as the anti-filter body, The rate of water level rise in various parts of the dam body can be reduced and the maximum water level height is reduced, so that the dam body is relatively difficult to penetrate and destroy. On the other hand, the excess water in the dam body can be discharged, the infiltration line of the dam body is reduced, and the occurrence of seepage failure is reduced. and the seepage failure process and the phenomenon of the two analog dams are similar, It is indicated that the PP fabric bag can not really solve the problem of failure, but it can slow the occurrence time and the destruction scale of the penetration failure to a certain extent. and the larger the amplitude of the later growth, that is, the increase is obviously increased after the slow increase is first, and finally is stable until the dam body is completely destroyed; the silting dam of the PP fabric bag as an anti-filter body needs to be longer than that of the original silting dam; The seepage effect of the original silt dam is far from that of the silt dam in which the PP fabric bag is filled with the original soil as an anti-filter. (4) The porosity and the average diameter of the soil sample below the infiltration line of the dam body are larger than that of the original soil and the other parts of the dam body, and the average diameter of the particles is smaller than that of the original soil and the other parts of the dam body, And the variation law of the circularity of the pore and the roundness of the particle diameter is not obvious. The porosity of the soil sample at the bottom of the dam body is reduced in sequence from the front of the dam to the rear of the dam, and the increase of the porosity of the soil sample of the silt dam of the PP fabric bag as an anti-filter body is less than that of the original silt dam. The re-distribution of the particles, the fine particles of the soil and the large particles of the part of the skeleton can be easily lost during the infiltration and destruction of the original silt dam. And the PP fabric bag plays an important role in preventing the large particle loss of the soil body, and the stability of the dam body is ensured to a certain extent.
【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S157.31
本文編號：2503862
[Abstract]:The silt dam is one of the important water conservation engineering measures for the comprehensive treatment of the small watershed, which can not only increase the cultivated area, improve the agricultural productivity, but also prevent the water and soil loss. In the 1970s and 1980s, because of the lack of local sand and gravel, the construction of sand and gravel in the Jingbian and Dingbian areas of northern Shaanxi had not been put into the anti-filter material, which led to the seepage and destruction of the silt dam and became a risk dam. The problem has not been well solved. It is a serious safety hazard to the local silt dam project. The seepage and destruction of the dam has become an important problem to restrict the construction of the local silt dam. In this paper, the seepage and damage phenomena and the process of the silt loam of the dam in Gaojiagou, Jingbian county, Yulin City, Shaanxi Province, are studied, and the infiltration and destruction of the original silt dam under the seepage of the original silt dam are simulated. The effect of the original soil as the filter body on the infiltration duration and the infiltration line was compared with the PP fabric bag. The micro-structure and pore characteristics of the soil sample of the dam body were studied by means of scanning electron microscope, and the grain gradation of the seepage and sediment in the process of seepage failure was analyzed by the Marvin laser granulometer, and the control effect of the PP fabric bag on the penetration failure was analyzed. It is of great practical significance to provide the theoretical basis and technical support for the risk removal and reinforcement of the silt dam that produces the seepage and destruction in the Jingding area of northern Shaanxi. The main conclusions of this paper are as follows: (1) The test and analysis results of the conventional geotechnical test for dam-building materials show that the dam-building material belongs to the medium-silty soil, and the soil sample belongs to the low-liquid limit clay. The particle size distribution of the soil is not uniform, the non-uniform coefficient CU = 6.12, CC = 0.90, the condition that the CU5 and CC = 1 to 3 cannot be met at the same time, therefore, the soil sample with bad grading and the pore between the large soil particles can be more easily adopted by the small soil particles under the action of the seepage, so that the seepage and the damage can be caused. (2) The test results of the basic properties of the PP fabric bag show that the PP fabric bag can be better combined with the sandy soil in one hand, and the stability of the whole bag body is ensured, and on the other hand, the PP fabric bag has the advantages of high tensile strength and tear resistance, and small aperture of the body of the bag body, The water flow is easy to pass, and the large particles of the soil are not easy to pass, so the PP fabric bag is suitable to be used as an anti-filtration material for preventing the seepage from being damaged after the dam of the silt dam. (3) After the dam, the seepage failure simulation test (1) increases to a certain value after the level of the water level in the two simulated dam bodies is gradually increased to a certain value with the occurrence of the seepage failure, that is, the soil body in the current region is saturated, because the pore diameter of the PP fabric bag body is only allowed to pass through the water flow and the small particle soil, the PP fabric bag is filled with the original soil as the anti-filter body, The rate of water level rise in various parts of the dam body can be reduced and the maximum water level height is reduced, so that the dam body is relatively difficult to penetrate and destroy. On the other hand, the excess water in the dam body can be discharged, the infiltration line of the dam body is reduced, and the occurrence of seepage failure is reduced. and the seepage failure process and the phenomenon of the two analog dams are similar, It is indicated that the PP fabric bag can not really solve the problem of failure, but it can slow the occurrence time and the destruction scale of the penetration failure to a certain extent. and the larger the amplitude of the later growth, that is, the increase is obviously increased after the slow increase is first, and finally is stable until the dam body is completely destroyed; the silting dam of the PP fabric bag as an anti-filter body needs to be longer than that of the original silting dam; The seepage effect of the original silt dam is far from that of the silt dam in which the PP fabric bag is filled with the original soil as an anti-filter. (4) The porosity and the average diameter of the soil sample below the infiltration line of the dam body are larger than that of the original soil and the other parts of the dam body, and the average diameter of the particles is smaller than that of the original soil and the other parts of the dam body, And the variation law of the circularity of the pore and the roundness of the particle diameter is not obvious. The porosity of the soil sample at the bottom of the dam body is reduced in sequence from the front of the dam to the rear of the dam, and the increase of the porosity of the soil sample of the silt dam of the PP fabric bag as an anti-filter body is less than that of the original silt dam. The re-distribution of the particles, the fine particles of the soil and the large particles of the part of the skeleton can be easily lost during the infiltration and destruction of the original silt dam. And the PP fabric bag plays an important role in preventing the large particle loss of the soil body, and the stability of the dam body is ensured to a certain extent.
【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S157.31
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