本文選題：紅壤 + 坡耕地��； 參考：《西南大學(xué)》2017年碩士論文

【摘要】：土壤抗剪強(qiáng)度與土壤侵蝕關(guān)系非常密切,是表征土壤抗侵蝕性能,土體破壞、埂坎穩(wěn)定性重要力學(xué)指標(biāo),同時(shí)也是土壤耕性的重要參數(shù)。本文以江西進(jìn)賢、云南馬龍、廣西來(lái)賓紅壤坡耕地為研究對(duì)象,研究了耕層土壤理化性質(zhì)和抗剪強(qiáng)度變化特征,通過(guò)Pearson相關(guān)分析法和主成分分析探討影響抗剪強(qiáng)度的因素,采用室內(nèi)模擬實(shí)驗(yàn)對(duì)比研究三種紅壤坡耕地耕層土壤抗剪強(qiáng)度對(duì)土壤含水率、干濕循環(huán)次數(shù)、幅度、土壤容重、粒徑級(jí)配的響應(yīng)特征,以期為紅壤坡耕地耕層土壤水土流失防治、耕層土壤質(zhì)量改善和梯田埂坎穩(wěn)定性提供理論借鑒。主要結(jié)論如下:(1)不同類(lèi)型紅壤坡耕地不同土層土壤理化性質(zhì)差異明顯。江西進(jìn)賢紅壤、廣西來(lái)賓紅壤、云南馬龍紅壤坡耕地不同土層土壤容重和孔隙度差異明顯,土壤容重表現(xiàn)為:耕作層(0—20 cm)心土層(20—40 cm)底土層(40—60 cm),毛管孔隙度和總孔隙度表現(xiàn)為耕作層心土層底土層(P0.05)。耕作層土壤初始入滲率、穩(wěn)定入滲率顯著高于心土層、底土層。不同土層土壤顆粒以粉粒、砂粒為主,土壤質(zhì)地為壤土,土壤機(jī)械穩(wěn)定性團(tuán)聚體以5 mm、5-2 mm粒級(jí)團(tuán)聚體為主,土壤水穩(wěn)定性團(tuán)聚體以0.5-0.25mm和0.25mm粒級(jí)團(tuán)聚體為主,土壤微團(tuán)聚體以0.25~0.05 mm、0.05~0.01 mm粒級(jí)為主。不同土層土壤有機(jī)質(zhì)、全氮、全磷、堿解氮、有效磷含量差異顯著,隨土層深度增加而含量降低,表現(xiàn)為耕作層心土層底土層。綜合野外調(diào)查和試驗(yàn)分析,紅壤坡耕地合理耕層主要特征表現(xiàn)為:土壤容重介于1.11~1.25g/cm-3,總孔隙度56%,土壤穩(wěn)定入滲率5.88~10.18mm/min,土壤質(zhì)地為壤土,有機(jī)質(zhì)含量13.67g/kg。(2)不同類(lèi)型紅壤坡耕地土壤抗剪強(qiáng)度差異明顯,隨土層深度增加而增大,呈現(xiàn)階段性特征,30-40 cm土層時(shí)抗剪強(qiáng)度迅速減小。江西進(jìn)賢紅壤、云南馬龍紅壤Ⅰ階段:0-40 cm耕層,抗剪強(qiáng)度隨深度呈線性遞增,Ⅱ階段:40-60 cm土層,抗剪強(qiáng)度隨土層深度增加趨于出一定的穩(wěn)定性。廣西來(lái)賓紅第Ⅰ階段:0-30 cm土層,抗剪強(qiáng)度隨深度呈線性遞增,Ⅱ階段:30-60 cm土層,抗剪強(qiáng)度增加幅度急劇減小,趨于穩(wěn)定。綜合野外調(diào)查結(jié)果,紅壤坡耕地合理耕層抗剪強(qiáng)度變化范圍為3.58~5.99 kPa根據(jù)Pearson相關(guān)和主成分分析表明,土壤容重、含水率、物理性粘粒、分散系數(shù)、濕篩MWD是與紅壤坡耕地土壤抗剪強(qiáng)度密切相關(guān)的物理性因素,土壤有機(jī)質(zhì)、全氮、全磷、有效磷、堿解氮是與紅壤坡耕地土壤抗剪強(qiáng)度密切相關(guān)的化學(xué)性因素。(3)不同類(lèi)型紅壤坡耕地土壤抗剪強(qiáng)度隨含水率呈非線性衰減,不同垂直荷載下抗剪強(qiáng)度隨含水率衰減路徑差異明顯。江西進(jìn)賢紅壤100 kPa、200 kPa下,隨含水量增加抗剪強(qiáng)度微幅度波動(dòng)衰減,300 kPa、400 kPa下,含水率為11%~19%時(shí),趨于穩(wěn)定,含水率為19%~23%時(shí),抗剪強(qiáng)度劇烈衰減,含水率為23%~27%時(shí),抗剪強(qiáng)度趨于穩(wěn)定。廣西來(lái)賓紅壤200、300、400kPa下,呈非線性階段衰減,含水率為11%~17%時(shí),呈非線性平滑衰減,含水率為17%~27%時(shí),呈非線性波動(dòng)衰減。云南馬龍紅壤抗剪強(qiáng)度隨含水率呈非線性波動(dòng)衰減,含水率25%時(shí),衰減趨勢(shì)減弱并趨于穩(wěn)定。不同類(lèi)型紅壤坡耕地耕層土壤粘聚力隨含水率先增大而后減小,內(nèi)摩擦角隨含水率增大呈非線性波動(dòng)衰減。含水率為11%~21%時(shí),江西進(jìn)賢紅壤粘聚力介于1.02~16.54 kPa,含水率21%時(shí),粘聚力隨含水率增加而減小。含水率11%~23%時(shí),廣西來(lái)賓紅壤、云南馬龍紅壤粘聚力迅速增大,含水率23%時(shí),隨含水率增加逐漸衰減。江西進(jìn)賢紅壤、廣西來(lái)賓紅壤、云南馬龍紅壤含水率低于19%、17%、15%時(shí),內(nèi)摩擦角線性衰減,含水率超過(guò)轉(zhuǎn)折點(diǎn)時(shí),摩擦角波動(dòng)衰減,且趨于穩(wěn)定。(4)江西進(jìn)賢紅壤與云南馬龍紅壤坡耕地耕層土壤抗剪強(qiáng)度、粘聚力隨循環(huán)次數(shù)增加呈非線性衰減,內(nèi)摩擦角呈波動(dòng)式衰減。對(duì)江西進(jìn)賢紅壤與云南馬龍紅壤抗剪強(qiáng)度而言,Ⅰ階段1~3、4次循環(huán),抗剪強(qiáng)度衰減率呈近似線性迅速增加,抗剪強(qiáng)度衰減快,Ⅱ階段3、4~5次循環(huán),抗剪強(qiáng)度逐漸趨于穩(wěn)定值。對(duì)粘聚力而言,Ⅰ階段0~3、4次循環(huán),呈現(xiàn)近似線性地迅速衰減;Ⅱ階段為3、4~5次循環(huán),粘聚力趨于穩(wěn)定。內(nèi)摩擦角隨干濕循環(huán)次數(shù)增加波動(dòng)式衰減,但衰減幅度明顯低于粘聚力。循環(huán)次數(shù)、幅度交互效應(yīng)下,江西進(jìn)賢紅壤粘聚力隨循環(huán)次數(shù)的增大先迅速減小,波動(dòng)范圍為2.65~9.75 Kpa,循環(huán)次數(shù)3次后,粘聚力趨于穩(wěn)定,而循環(huán)幅度對(duì)粘聚力衰減作用不顯著。江西進(jìn)賢紅壤內(nèi)摩擦角隨干濕循環(huán)幅度增大而增大。云南馬龍紅壤粘聚力隨循環(huán)次數(shù)增加而減小,隨循環(huán)幅度變化先微幅增大后減小,峰值出現(xiàn)在Δw=15%附近,內(nèi)摩擦角隨循環(huán)次數(shù)增加而波動(dòng)式減小,隨干濕循環(huán)幅度變化衰減路徑起伏波動(dòng)大,衰減受干濕循環(huán)幅度影響小。(5)江西進(jìn)賢紅壤、廣西來(lái)賓紅壤、云南馬龍紅壤坡耕地耕層土壤粘聚力隨著容重增加呈逐漸增大趨勢(shì)。粒徑級(jí)配對(duì)紅壤坡耕地耕層土壤粘聚力無(wú)顯著影響,內(nèi)摩擦角隨0.05mm細(xì)粒徑顆粒的增加而增大,內(nèi)摩擦分布范圍為7.57°~8.67°、7.38°~8.67°、8.97°~9.33°。容重較小時(shí)(0.9~1.1g/cm3),粘聚力隨容重平穩(wěn)增加,容重較大時(shí)(1.1~1.3g/cm3),粘聚力隨容重陡增。云南馬龍紅壤粘聚力隨容重呈現(xiàn)波動(dòng)式增加,粘聚力分布1.85~3.33 kPa,內(nèi)摩擦角隨著容重增加呈現(xiàn)出逐漸增大趨勢(shì)。
[Abstract]:Soil erosion resistance is very closely related to soil erosion. It is an important mechanical index to characterize soil erosion resistance, soil destruction, and ridge stability. It is also an important parameter for soil tillage. This paper studies the soil physical and chemical properties and shear strength changes of soil in Jinxian, Yunnan, Yunnan, Jiangxi and Guangxi Laibin red soil. By means of Pearson correlation analysis and principal component analysis, the factors affecting the shear strength were discussed. The response characteristics of soil moisture content, dry and wet cycle times, amplitude, soil bulk density and grain size distribution of three kinds of red soil sloping cultivated land soil were studied by indoor simulation experiments, so as to be the soil soil and water soil in red soil slope farmland. The main conclusions are as follows: (1) there are obvious differences in soil physical and chemical properties of different soil layers in different types of red soil, Jiangxi Jinxian red soil, Guangxi Laibin red soil, and the soil bulk density and porosity of different soil layers in the Malone red soil slope farmland in Yunnan, and the soil bulk density The soil layer (0 - 20 cm) soil layer (20 - 40 cm) soil layer (40 - 60 cm), the capillary porosity and total porosity is shown as the soil layer soil layer (P0.05) of the tillage layer. The initial infiltration rate of the tillage soil, the stable infiltration rate is significantly higher than the soil layer, the bottom soil layer. The soil particles in different soil layers are mainly powder and sand, and soil texture is loam soil. Soil water stability aggregates are mainly composed of 5 mm and 5-2 mm granular aggregates, and soil water stability aggregates are dominated by 0.5-0.25mm and 0.25mm particles. The soil microaggregates are mainly 0.25~0.05 mm and 0.05~0.01 mm particles. The soil organic matter, total nitrogen, total phosphorus, alkali hydrolysable nitrogen, and available P content have significant difference with the depth of soil layer. The main characteristics of rational plough in red soil slope arable land are as follows: soil bulk density is 1.11~1.25g/cm-3, total porosity is 56%, soil stable infiltration rate is 5.88~10.18mm/min, soil texture is loam, organic matter content is 13.67g/kg. (2) different types of red soil slope cultivated land. The difference of soil shear strength is obvious, which increases with the depth of soil layer, showing stage characteristics, the shear strength of 30-40 cm soil layer decreases rapidly. Jiangxi Jinxian red soil, Yunnan Malone red soil I stage: 0-40 cm plough layer, the shear strength is linearly increasing with depth, stage II: 40-60 cm soil layer, the shear strength tends to increase with soil depth to a certain extent. The stability of Guangxi Laibin red stage I: 0-30 cm soil layer, the shear strength is linearly increasing with the depth, stage II: 30-60 cm soil layer, the increasing amplitude of shear strength decreases sharply and tends to stability. Comprehensive field investigation results show that the change of shear strength of reasonable plough in red soil slope farmland is 3.58~5.99 kPa based on Pearson correlation and principal component analysis table The soil bulk density, water content, physical clay particles, dispersion coefficient, wet sieve MWD are closely related to the soil shear strength of red soil slope farmland. Soil organic matter, total nitrogen, total phosphorus, effective phosphorus, alkali hydrolysable nitrogen are chemical factors closely related to soil shear strength of red soil slope farmland. (3) soil shear strength of different types of red soil slope farmland There is a nonlinear attenuation with water content, and the difference of shear strength with water content decreases obviously under different vertical loads. Under 100 kPa kPa and 200 kPa, the shear strength decreases with the moisture content increasing, the shear strength decreases, 300 kPa and 400 kPa, when the water content is 11%~19%, and the moisture content is 19%~23%, the shear strength attenuates violently. When the water rate is 23%~27%, the shear strength tends to be stable. Under the 200300400kPa of Guangxi Laibin red soil, the attenuation is nonlinear stage. When the water content is 11%~17%, it is nonlinear and smooth attenuation. When the water content is 17%~27%, it is nonlinear wave attenuation. The shear strength of Malone red soil in Yunnan is attenuated with the moisture content, and the attenuation trend is 25% when water content is water. The cohesive force of the plough soil in different types of sloping farmland is first increased and then decreased with water content, and the internal friction angle decreases with the increase of water content. When the water content is 11%~21%, the cohesion of the red soil in Jinxian, Jiangxi is 1.02~16.54 kPa, and the cohesion decreases with the increase of water content when the water content is 21%. The water content is 11%~23% When Guangxi Laibin red soil, Yunnan Malone red soil cohesive force increased rapidly, when water content was 23%, it gradually attenuated with the increase of water content. The water content of Jiangxi Jinxian red soil, Guangxi Laibin red soil, Yunnan Malone red soil was lower than 19%, 17%, 15%, the internal friction angle linearly attenuated, when water content exceeded the turning point, the friction angle fluctuation attenuated and tended to stabilize. (4) Jiangxi entered The shear strength of the soil of cultivated soil in red soil and Yunnan Malone red soil slope is nonlinear attenuation with the increase of cycle times, and the internal friction angle is fluctuant. For the shear strength of Jinxian red soil and Yunnan Malone red soil in Yunnan, the shear strength attenuation rate is approximately linear and fast increasing, and the shear strength attenuates fast in the Jiangxi Jinxian red soil and Yunnan red soil. As for the 3,4~5 secondary cycle, the shear strength gradually tends to a stable value. For cohesion, the 0~3,4 secondary cycle of stage I is approximately linear and rapidly attenuates; the second stage is 3,4~5 secondary cycle, and the cohesion tends to be stable. The internal friction angle increases with the frequency of dry and wet cycle, but the attenuation amplitude is obviously lower than that of cohesive force. Under the mutual effect, the cohesive force of red soil in Jinxian of Jiangxi rapidly decreases with the increase of cycle times, and the fluctuation range is 2.65~9.75 Kpa. After 3 cycles, the cohesive force tends to be stable, and the cyclic amplitude is not significant to the cohesive force attenuation. The internal friction angle of the red soil in Jinxian of Jiangxi is increased with the increase of the dry and wet circulation amplitude. The cohesion of the red soil in Yunnan Malone soil follows the cohesion of the red soil. The cycle number increases and decreases with the increase of the amplitude of the cycle, the peak appears near the delta w=15%, the internal friction angle decreases with the increase of the cycle number. The attenuation path fluctuates with the dry and wet cycle amplitude, and the attenuation is less affected by the dry and wet cycle. (5) Jiangxi Jinxian red soil, Guangxi Laibin red soil, Yunnan horse The cohesive force of the soil in the cultivated land on the slope of the red soil slope increased gradually with the increase of the bulk density. There was no significant influence on the cohesive force of the soil in the plough layer of the red soil slope. The internal friction angle increased with the increase of the 0.05mm fine particle size, and the distribution range of internal friction was 7.57 ~8.67, 7.38 [8.67], 8.97 [~9.33]. The bulk density was lower (0.9~1.1g/cm3). Cohesion increases steadily with bulk density, the cohesive force increases with bulk density when the bulk density is larger (1.1~1.3g/cm3). The cohesive force of Yunnan Malone red soil increases with the bulk density, and the cohesive force distributes 1.85~3.33 kPa, and the internal friction angle increases gradually with the increase of bulk density.
【學(xué)位授予單位】：西南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：S157

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