【摘要】：近年來,隨著我國西部大開發(fā)戰(zhàn)略的實施,大量鐵路、公路、水利水電等工程項目的施工不可避免開挖出大量的工程邊坡。對于這些工程邊坡不僅要采取必要的支擋措施保證邊坡穩(wěn)定性,而且還應(yīng)對邊坡綠色防護(hù)進(jìn)行進(jìn)一步研究,以有效的恢復(fù)自然生態(tài)環(huán)境。本文主要探討草本植物根系固坡的力學(xué)機理,評價植物根系對土質(zhì)淺層邊坡土體的加固效果,為植物護(hù)坡工程提供充分的理論依據(jù)。由于植物根系有一定的影響范圍,一般小于2m,因此植物護(hù)坡主要是防護(hù)淺層不穩(wěn)定邊坡。本文以草本植物香根草根系為研究對象,探討加入根系后土體的力學(xué)特性,分析根系對邊坡穩(wěn)定性的影響。建立含根系土體的基本力學(xué)模型,并利用有限元方法對含根系土體的直接剪切試驗和抗壓試驗進(jìn)行了大量的數(shù)值模擬,詳細(xì)研究了含根系土體內(nèi)部各力學(xué)參數(shù)的變化規(guī)律,包括不同根系長度、根系分布密度、根系傾斜角度。并對含不同根系形態(tài)的土體粘聚力和內(nèi)摩擦角,與無根系土體的粘聚力和內(nèi)摩擦角進(jìn)行了對比分析,發(fā)現(xiàn)根系垂直分布于土體中且根系數(shù)量越多、長度越長對土體的加固效果越好。通過對粘聚力和內(nèi)摩擦角值的變化規(guī)律研究得到不同根系形態(tài)對土體增加的抗剪強度的影響規(guī)律,以及不同根系形態(tài)下的根-土復(fù)合彈性模量的變化規(guī)律。最后將前面對含根系土體的參數(shù)研究應(yīng)用到實際邊坡中,采用強度折減法對含不同根系形態(tài)邊坡的穩(wěn)定性進(jìn)行分析,進(jìn)一步探討含不同根系形態(tài)土體的力學(xué)參數(shù)變化對邊坡穩(wěn)定性的影響規(guī)律。發(fā)現(xiàn)坡體中含有的植物根系的長度越長、數(shù)量越多,則邊坡穩(wěn)定性越高;根系傾斜角度越大,則邊坡穩(wěn)定性越差。通過對含不同根系形態(tài)的土體模型的基本力學(xué)性能探討,詳細(xì)研究了植物根系護(hù)坡的作用機理,并對根系加固邊坡表層土的實際效果進(jìn)行了分析,為生態(tài)護(hù)坡提供了一定的理論依據(jù)。因此,開展植物護(hù)坡技術(shù)的研究和應(yīng)用具有相當(dāng)重要的意義。
[Abstract]:In recent years, with the implementation of the western development strategy, a large number of railway, highway, water conservancy and hydropower projects inevitably excavated a large number of engineering slopes. For these engineering slopes, not only the necessary retaining measures should be taken to ensure the slope stability, but also the green protection of the slope should be further studied in order to effectively restore the natural ecological environment. In this paper, the mechanical mechanism of herbaceous root system is discussed, and the reinforcement effect of plant root system on soil mass of shallow soil slope is evaluated, which provides sufficient theoretical basis for plant slope protection project. Because the plant root system has a certain influence range, generally less than 2 m, so plant slope protection is mainly to protect shallow unstable slope. In this paper, the root system of vetiver grass was studied, and the mechanical properties of soil were studied, and the influence of root system on slope stability was analyzed. The basic mechanical model of the soil with roots was established, and the numerical simulation of the direct shear test and compression test of the soil containing root was carried out by using finite element method. The variation of mechanical parameters in the soil containing root was studied in detail. It includes different root length, root distribution density and root tilt angle. The cohesive force and internal friction angle of soil with different root forms were compared with those of non-root soil. It was found that the root system distributed vertically in soil and the number of root system increased. The longer the length, the better the reinforcement effect of soil. The influence of different root forms on the increased shear strength of soil and the variation of root-soil composite elastic modulus under different root forms were obtained by studying the change of cohesion and internal friction angle. Finally, the research on the parameters of the soil with roots is applied to the actual slope, and the stability of the slope with different root forms is analyzed by the strength reduction method. The influence of mechanical parameters of soil with different root forms on slope stability was further discussed. It is found that the longer the length and the more the number of the plant roots contained in the slope, the higher the slope stability and the worse the slope stability is. Based on the discussion of the basic mechanical properties of soil models with different root forms, the mechanism of plant root slope protection is studied in detail, and the actual effect of root system reinforcement on the surface soil of slope is analyzed. It provides certain theoretical basis for ecological slope protection. Therefore, the research and application of plant slope protection technology is of great significance.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q948;TU43

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