發(fā)布時間：2018-06-09 13:29

  本文選題：土質(zhì)埂坎 + 紫色土�。� 參考：《重慶師范大學(xué)》2017年碩士論文

【摘要】：埂坎通過分割坡長和降低坡面坡度控制坡耕地土壤侵蝕,具有較好的水土保持效果。在三峽庫區(qū)坡耕地整治、高標(biāo)準(zhǔn)基本農(nóng)田建設(shè)等工程中,土質(zhì)埂坎因其造價低、施工方便、生態(tài)適宜、調(diào)控侵蝕效果較好,仍占較大比例,與石質(zhì)埂坎同等重要,但確保土質(zhì)埂坎的穩(wěn)定是保護坡耕地的前提。經(jīng)野外大量調(diào)查后選取了典型紫色土埂坎分層采集土壤樣品,利用激光粒度分析儀、應(yīng)變控制式直剪儀測試埂坎土壤物理、力學(xué)參數(shù),運用應(yīng)力變形分析法模擬不同規(guī)格埂坎應(yīng)力應(yīng)變分布特征,采用極限平衡分析法計算不同規(guī)格埂坎在自然工況和土壤吸水飽和工況條件下的穩(wěn)定性系數(shù),構(gòu)建了穩(wěn)定性系數(shù)對埂坎高度和外邊坡坡度的響應(yīng)模型。主要研究結(jié)果如下:(1)紫色土坡耕地土質(zhì)埂坎與坎后土壤基本物理性質(zhì)沒有顯著性差異。自然工況下,埂坎上層土壤抗剪強度大于中層和下層。埂坎和坎后土壤吸水飽和后,抗剪強度均降低。(2)紫色土坡耕地埂坎基部至頂部,最大總應(yīng)力逐漸減小。埂坎高度一定時,隨著外邊坡坡度增加,腰部和基部最大總應(yīng)力呈變大趨勢,頂部變化趨勢不明顯。埂坎頂部和腰部X 總應(yīng)力均隨埂坎外邊坡坡度的增加而減小,基部則變大。埂坎外邊坡坡度一定時,隨著埂坎高度增加,最大總應(yīng)力和X 總應(yīng)力均呈變大趨勢。(3)紫色土埂坎高度一定時,隨著外邊坡坡度增加,X 位移最大值逐漸從埂坎基部下方掩埋區(qū)移動到埂坎基部上方臨空面。埂坎外邊坡坡度一定時,隨著埂坎高度增加,X 位移沒有發(fā)生特別明顯的重分布,位移最大值區(qū)域相對較固定。(4)紫色土坡耕地土質(zhì)埂坎穩(wěn)定性系數(shù)隨高度增加或外邊坡坡度變陡而降低,但高度與外邊坡坡度的交互效應(yīng)對穩(wěn)定性的影響不顯著。埂坎土壤吸水飽和后,穩(wěn)定性系數(shù)顯著降低,其中,“低緩”型土質(zhì)埂坎穩(wěn)定性系數(shù)降低更明顯。(5)紫色土坡耕地土質(zhì)埂坎的潛在滑動面主要有直線形和圓弧形兩種,“高陡”型埂坎潛在滑動面多為直線形,“低緩”型埂坎潛在滑動面多為圓弧形。土壤吸水飽和對潛在滑動面形態(tài)沒有明顯影響。
[Abstract]:The ridge has better soil and water conservation effect by dividing slope length and reducing slope gradient to control soil erosion of sloping land. In the three Gorges reservoir area slope cultivated land regulation, high standard basic farmland construction and other projects, because of its low cost, convenient construction, ecological suitability, good control and erosion effect, it still occupies a large proportion, and is as important as the stone ridge. But to ensure the stability of the ridge is the premise to protect the sloping land. After a large number of field investigations, soil samples were collected from typical purple ridge ridges. The soil physical and mechanical parameters were measured by laser particle size analyzer and strain-controlled direct shear apparatus. The stress and strain analysis method is used to simulate the stress and strain distribution of the ridge with different specifications, and the stability coefficient of the ridge with different specifications under natural conditions and saturated soil water absorption conditions is calculated by using the limit equilibrium analysis method. The response model of stability coefficient to ridge height and slope is constructed. The main results were as follows: (1) there was no significant difference in the basic physical properties of the soil between the ridge and the back of the purple soil. Under natural conditions, the shear strength of the upper layer of the ridge is higher than that of the middle layer and the lower layer. The shear strength of soil decreased after water absorption and saturation of ridge and ridge. 2) the maximum total stress gradually decreased from the base of ridge to the top of ridge in purple soil. When the height of ridge is constant, the maximum total stress of waist and base increases with the increase of slope, but the change trend of top is not obvious. The total stress at the top of the ridge and at the waist decreases with the increase of slope gradient outside the ridge, but the base becomes larger. With the increase of ridge height, the maximum total stress and X ~ (+) total stress of the slope outside the ridge show a trend of increasing when the slope gradient is constant) when the height of the purple ridge is constant, the maximum total stress and the total X _ (+) stress are increased. With the increase of slope of the outer slope, the maximum displacement is gradually moved from the buried area below the ridge base to the empty surface above the ridge base. When the slope gradient outside the ridge is constant, with the increase of the height of the ridge, there is no obvious redistribution of the displacement. The maximum displacement region is relatively fixed. 4) the stability coefficient of slope ridge in purple soil is decreased with the increase of height or steepness of external slope, but the interaction effect between height and slope is not significant. The stability coefficient of "low slow" type ridge is significantly decreased after the soil water absorption saturation. Among them, there are two kinds of potential slip surface of purple soil sloping land ridge: linear shape and circular arc shape, and the decrease of stability coefficient of "low slow" type ridge is more obvious than that of "low slow" type soil ridge. The potential slip surface of "high and steep" ridge is mostly linear, and the potential slip surface of "low and slow" type ridge is mostly circular arc. Soil water absorption saturation has no obvious effect on the morphology of potential sliding surface.
【學(xué)位授予單位】：重慶師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S157

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相關(guān)期刊論文 前10條

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本文編號：1999886