本文選題：植物護(hù)坡 + 根土復(fù)合體�。� 參考：《中南林業(yè)科技大學(xué)》2014年碩士論文

【摘要】：邊坡的失穩(wěn)破壞是一種常見的、多發(fā)的自然地質(zhì)災(zāi)害。我國(guó)南方多為丘陵地帶,近20年來(lái),高速公路、高速鐵路等基礎(chǔ)設(shè)施建設(shè)迅速發(fā)展,導(dǎo)致大量的路基邊坡發(fā)生邊坡失穩(wěn)破壞。傳統(tǒng)剛性邊坡防護(hù)雖能大幅提高邊坡穩(wěn)定性,但造價(jià)高且嚴(yán)重破壞生態(tài)環(huán)境,而采用廉價(jià)的植被恢復(fù)技術(shù)進(jìn)行生態(tài)護(hù)坡日益受到高度重視。種植草皮或根系較淺的植物等早期生態(tài)護(hù)坡方式只適于水土保持和淺層土體的防護(hù),對(duì)于破裂面較大、較深的邊坡效果不明顯。采用工程技術(shù)和林草一體化的生態(tài)技術(shù)相結(jié)合的防護(hù)方法,在邊坡上種植合適的灌木和草本植物,既可防護(hù)和控制表層滑坡,又可以對(duì)深層起到“植物土釘”的錨固作用。它不但可以提高坡體的整體穩(wěn)定性,還可以消除噪音、改善公路周邊的光、熱環(huán)境和生態(tài)環(huán)境。因此,研究林草一體化高穩(wěn)定性生態(tài)護(hù)坡技術(shù),將邊坡防護(hù)工程和生態(tài)效應(yīng)進(jìn)行有機(jī)結(jié)合,具有重要理論價(jià)值和工程意義。 本文基于國(guó)內(nèi)外生態(tài)邊坡相關(guān)理論和先進(jìn)技術(shù),依托國(guó)家自然科學(xué)基金項(xiàng)目“高強(qiáng)度林草混交根系成型機(jī)理與邊坡根系土體加固機(jī)制研究”(項(xiàng)目編號(hào)：31270671)、國(guó)家林業(yè)局948項(xiàng)目“林草一體化高穩(wěn)定性生態(tài)護(hù)坡技術(shù)引進(jìn)”(項(xiàng)目編號(hào)：2012-4-76)、湖南省自然科學(xué)基金資助項(xiàng)目“植物防護(hù)邊坡力學(xué)特性研究”(項(xiàng)目編號(hào)：12JJ5015)、以及中南林業(yè)科技大學(xué)“研究生科技創(chuàng)新基金資助項(xiàng)目”(項(xiàng)目號(hào)：CX2012824)等開展相關(guān)研究。通過(guò)試驗(yàn)研究和理論分析,探討了林草混交根土復(fù)合體的力學(xué)特性,研究工作的主要內(nèi)容和取得的創(chuàng)新成果如下。 研究工作的主要內(nèi)容： 1、設(shè)計(jì)了不同的植株密度和邊坡坡度,在室外模型箱內(nèi)種植了草本植物香根草和灌木植物小葉女貞。 2、通過(guò)一年的培育后,對(duì)不同含根量、不同含根比和不同含水量等條件下的香根草和小葉女貞混交根系根土復(fù)合體進(jìn)行了直剪試驗(yàn),探索了在不同情況下混交根系根土復(fù)合體的抗剪強(qiáng)度規(guī)律。 3、對(duì)林草混交根系根土復(fù)合體進(jìn)行了三軸剪切試驗(yàn),進(jìn)一步分析了混交根系根土復(fù)合體的抗剪強(qiáng)度特性。 4、在試驗(yàn)研究的基礎(chǔ)上,通過(guò)模型分析和參數(shù)選擇,對(duì)混交根系根土復(fù)合體的強(qiáng)度規(guī)律和本構(gòu)模型等進(jìn)行了理論研究。 研究工作取得的主要?jiǎng)?chuàng)新成果： 1、草本植物香根草根系發(fā)達(dá),根系直徑一般為0.8-0.9mmm,80%的根系分布于距地表60cm深度以內(nèi)。木本植物小葉女貞有明顯主根,主根直徑較大,豎直深入土壤深層,其側(cè)根在地表中、上層生長(zhǎng)繁密,且沿水平向延伸。 2、直剪試驗(yàn)研究結(jié)果表明,當(dāng)土樣中的含根量以及含根比一定時(shí),在相同的豎向應(yīng)力下,含水量越高,根土復(fù)合體的抗剪強(qiáng)度越低。且隨著含水率的增加,無(wú)根土體和含根土體的抗剪強(qiáng)度均呈不同程度的降低,但含根土體的抗剪強(qiáng)度降低的程度較小。 3、當(dāng)含水率一定,研究發(fā)現(xiàn)土壤粒徑均勻程度和含根量對(duì)復(fù)合體的抗剪強(qiáng)度均有影響。相同含根量條件下,土壤粒徑越均勻,根土復(fù)合體的抗剪強(qiáng)度越高；相同粒徑條件下,植物根系含量越高,根土復(fù)合體的抗剪強(qiáng)度越高。 4、對(duì)草本或者木本植物根系根土復(fù)合體的抗剪強(qiáng)度采用二乘法進(jìn)行擬合,其一次和二次擬合曲線均接近線性關(guān)系,表明草本或木本植物單一根系根土復(fù)合體的抗剪強(qiáng)度符合庫(kù)倫強(qiáng)度理論。同樣對(duì)林草混交根系根土復(fù)合體的抗剪強(qiáng)度進(jìn)行一次和二次擬合,其一次二次擬合曲線均也均呈線性關(guān)系。因此,可以認(rèn)為,林草混交根系根土復(fù)合體的抗剪強(qiáng)度亦符合庫(kù)倫強(qiáng)度理論。 5、系列直剪試驗(yàn)表明,香根草和小葉女貞的根系均可明顯提高根土復(fù)合體的抗剪強(qiáng)度。但二者對(duì)復(fù)合體抗剪強(qiáng)度指標(biāo)的貢獻(xiàn)是不同的,香根草系根的存在主要是提高了復(fù)合體的粘聚力,而小葉女貞系根的存在則主要提高了復(fù)合體的內(nèi)摩擦角。 6、通過(guò)對(duì)根土復(fù)合體的內(nèi)摩擦角與小葉女貞含根比進(jìn)行非線性擬合,發(fā)現(xiàn)內(nèi)摩擦角隨小葉女貞含根比的增大而呈冪函數(shù)形式增長(zhǎng),從而建立了根土復(fù)合體的內(nèi)摩擦角與小葉女貞含根比的冪函數(shù)關(guān)系式,且冪函數(shù)的系數(shù)是與含水率和含根量相關(guān)的常數(shù)。 7、通過(guò)對(duì)林草混交根土復(fù)合體進(jìn)行三軸剪試驗(yàn)研究,得到了不同圍壓條件下林草混交根土復(fù)合體的應(yīng)力-應(yīng)變曲線。通過(guò)分析復(fù)合體的應(yīng)力-應(yīng)變曲線發(fā)現(xiàn),在不同圍壓下,偏應(yīng)力和軸向應(yīng)變之間均較好地符合雙曲線關(guān)系,且軸向應(yīng)變-偏應(yīng)力之比與軸向應(yīng)變之間具有較好的線性關(guān)系,符合鄧肯張模型特點(diǎn)�；卩嚳蠌埬Ｐ�,本文建立了鄧肯張E-B模型形式的林草混交根系根土復(fù)合體的本構(gòu)模型,并提出了新模型參數(shù)的具體確定方法。 以上研究為探索林草混交根土復(fù)合體的力學(xué)特性,開發(fā)并應(yīng)用高穩(wěn)定性的林草護(hù)坡技術(shù),具有重要的理論價(jià)值和廣闊的工程應(yīng)用前景。
[Abstract]:The instability failure of the slope is a common and multiple natural geological hazard. In the south of China, the hilly area is mostly in the south. In the past 20 years, the construction of the basic facilities, such as highway and high speed railway, has developed rapidly, causing a large number of roadbed slopes to be unstable and unstable. Although the traditional rigid slope protection can greatly improve the stability of the slope, the cost is high and strict. The ecological environment is seriously damaged, and the ecological slope protection is paid more and more attention by the cheap vegetation restoration technology. The early ecological slope protection methods such as planting grass skin or the shallow roots are only suitable for soil and water conservation and shallow soil protection. For the larger fracture surface and the deeper slope, the integration of engineering technology and forest grass integration is not obvious. The protection method combined with ecological technology, planting suitable shrubs and herbaceous plants on the slope, not only protects and controls the surface landslides, but also plays the role of anchoring the "plant soil nailing" in the deep layer. It can not only improve the stability of the slope, but also eliminate the noise sound, improve the light, thermal environment and the ecological environment around the highway. Therefore, it is of great theoretical value and engineering significance to study the high stability ecological slope protection technology of forest grass integration and to combine the slope protection engineering with the ecological effect.
Based on the domestic and foreign ecological slope theory and advanced technology, relying on the National Natural Science Foundation Project "high strength forest and grass mixed root forming mechanism and the soil reinforcement mechanism of slope root system" (project number: 31270671), the national forestry bureau 948 project "integration of forest grass integration and high stability ecological slope protection technology introduction" (project compilation) 2012-4-76), Hunan Natural Science Fund funded project "study on mechanical characteristics of plant protection slope" (project number: 12JJ5015), and Central South University of Forestry and Technology "graduate science and technology innovation fund funded project" (project number: CX2012824) to carry out related research. Through experimental research and theoretical analysis, the mixed forest and grass were discussed. The main contents and achievements of the research work are as follows.
The main contents of the research work are as follows:
1, we designed different plant density and slope gradient, and planted herbaceous vetiver and shrubs in the outdoor model box.
2, after one year of cultivation, a direct shear test was carried out on root soil complex of root soil of vetiver and Ligustrum Lucidum with different root content, different root ratio and different water content, and the shear strength of root soil complex of mixed root system under different conditions was explored.
3, three axis shear tests were conducted on the root soil complex of mixed forest and grass, and the shear strength characteristics of the root soil complex of mixed roots were further analyzed.
4, based on the experimental research, the strength law and constitutive model of the root soil complex of mixed roots were studied theoretically through the model analysis and parameter selection.
The main innovative achievements of the research work:
1, the root system of herb root is developed, the root diameter is generally 0.8-0.9mmm, and the root of 80% is distributed within the depth of the surface 60cm. Ligustrum lucidum has obvious main root, the main root diameter is larger, the root is deep deep in the soil, its lateral roots are in the surface, the upper layer grows dense and extends horizontally.
2, the results of direct shear test show that the shear strength of root soil composite is lower when the content of root and the ratio of root ratio is certain, the higher the water content is, the lower the shear strength of the root soil complex is under the same vertical stress. The shear strength of the root soil and the root soil decreases with the increase of water content, but the shear strength of the soil containing the root soil decreases. The degree is small.
3, when the water content is certain, it is found that the soil particle size uniformity and the root content have influence on the shear strength of the complex. Under the same root content, the more uniform the soil particle size is, the higher the shear strength of the root soil complex, the higher the plant root content, the higher the shear strength of the root soil complex.
4, the shear strength of root soil complex of herbaceous or woody plants was fitted with two multiplications, and the first and two fitting curves were close to linear relation, indicating that the shear strength of the root soil complex of herbaceous or woody plants accorded with the Kulun strength theory. The two fitting curves of the one and two times are all linear. Therefore, it is considered that the shear strength of the mixed root soil complex of the mixed forest grass is also in line with the Kulun strength theory.
5, a series of direct shear tests showed that the roots of vetiver and Ligustrum lucidum could obviously improve the shear strength of the rhizosphere complex. But the contribution of the two to the shear strength index of the complex was different, and the existence of the root of vetiver was mainly enhanced by the cohesion of the complex, while the existence of the Ligustrum virginity was mainly improved in the complex. Angle of friction.
6, through the nonlinear fitting of the internal friction angle of the root soil complex and the root ratio of Ligustrum lucidum, it is found that the internal friction angle increases with the increase of the root ratio of Ligustrum lucidum, and establishes a power function relation between the internal friction angle of the root soil complex and the ratio of the root of Ligustrum lucidum, and the coefficient of power function is with water content and content. The constant of the root quantity.
7, the stress strain curve of the mixed root soil complex under different confining pressure was obtained by the three axial shear test of the mixed root soil complex of the forest and grass. The stress strain curve of the composite was found by the analysis of the stress strain curve of the complex. The relationship between the partial stress and the axial strain was better under the different confining pressure. There is a good linear relationship between the stress ratio and the axial strain, which conforms to the characteristics of the Duncan tension model. Based on the Duncan tension model, this paper establishes the constitutive model of the root soil complex of the mixed roots and grass roots in the form of Duncan Zhang E-B model, and puts forward a specific method for determining the parameters of the new model.
In order to explore the mechanical properties of the mixed root soil complex of forest and grass, the development and application of high stability forest grass slope protection technology has important theoretical value and broad engineering application prospects.
【學(xué)位授予單位】：中南林業(yè)科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU43

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