本文選題：植被　切入點：滲透破壞　出處：《天津大學(xué)》2015年博士論文

【摘要】：內(nèi)河航道土質(zhì)岸坡常年受滲流、船行波和降雨的作用,其穩(wěn)定性受到威脅。為了防止岸坡失穩(wěn)現(xiàn)象的發(fā)生,維護通航安全,必須對危險岸坡采取治理措施,以提高其穩(wěn)定性。而植被護坡作為一項兼顧岸坡加固及環(huán)境保護的工程技術(shù),在近幾十年間被廣泛應(yīng)用于岸坡整治工程。對于多因素作用下植被對岸坡穩(wěn)定影響的研究,目前的研究成果尚未涉及根系對岸坡淺層穩(wěn)定影響的判別以及船行波作用下草根加筋土動力特性研究。此外,滲透對土體結(jié)構(gòu)性破壞的影響、船行波作用下岸坡的強度折減以及植被覆蓋對降雨工況下岸坡穩(wěn)定影響的相關(guān)分析也是不完善的。本文采用土工試驗與數(shù)值模擬相結(jié)合的手法,對植被護坡前后航道土質(zhì)岸坡在滲流、船行波和降雨作用下的穩(wěn)定性進行分析研究。內(nèi)容如下:(1)開展原狀素土和重塑素土的三軸滲透剪切試驗,研究滲透破壞對土體有效應(yīng)力強度指標(biāo)的影響,得出滲流作用后土體內(nèi)摩擦角不變,粘聚力降低。在此基礎(chǔ)上,本文通過莫爾-庫侖準(zhǔn)則將此破壞作用以“等效圍壓降低”的形式量化表述。此外,還推導(dǎo)出以指數(shù)函數(shù)的形式來表征滲透工況下的有效應(yīng)力強度隨水力坡降變化的公式。(2)開展重塑草根加筋土的三軸滲透剪切試驗,研究根系的存在對土體滲透性和強度的影響,并推導(dǎo)出考慮滲流對草根加筋土強度破壞影響范圍的計算公式。(3)開展重塑素土和重塑草根加筋土的動三軸試驗,研究其孔壓和殘余應(yīng)變隨循環(huán)次數(shù)增長的變化規(guī)律。通過對比得出根系在抵抗動力破壞的過程中發(fā)揮的作用是降低循環(huán)荷載作用過程中孔壓的增長和殘余應(yīng)變的累積。此外,推導(dǎo)出循環(huán)后草根加筋土的抗剪強度折減率隨動應(yīng)力比變化的公式。(4)在試驗的基礎(chǔ)上建立了考慮滲透破壞對土體有效應(yīng)力強度影響的修正Duncan-Chang本構(gòu)模型,并以危險滑動區(qū)能量積分變化來作為岸坡整體失穩(wěn)判別準(zhǔn)則。此外,針對草本植被根系作用深度較淺而對岸坡整體穩(wěn)定性基本無影響的特點,提出以岸坡表層植被根系作用區(qū)的變形能量總和作為判斷根系作用的指標(biāo)。該研究對全面分析岸坡在滲流作用下的整體及局部穩(wěn)定性提供了理論依據(jù)。(5)結(jié)合試驗得出的素土與草根加筋土的抗剪強度折減率隨動應(yīng)力比的變化公式,通過對軟件二次開發(fā),建立了岸坡不同區(qū)域內(nèi)土體抗剪強度指標(biāo)的弱化模型。此外,提出以岸坡表面最大位移突變作為船行波作用下的岸坡失穩(wěn)判別準(zhǔn)則,從而計算出岸坡在不同船行波荷載作用下所產(chǎn)生的不同的失穩(wěn)模式。從而對分析船行波作用下草本植被保護岸坡在抵抗動力荷載破壞方面的研究提供了理論依據(jù)。(6)建立了全面考慮坡面流沖刷強度與植被覆蓋影響的降雨工況下植被對岸坡穩(wěn)定影響的數(shù)值分析模型,提出以岸坡發(fā)生圓弧滑動失穩(wěn)之前表層塑性區(qū)的發(fā)展來表征降雨對岸坡穩(wěn)定的影響。(7)利用本文提出的多因素作用下植被對岸坡穩(wěn)定影響的分析方法,進一步分別對不同滲流、船行波和降雨工況作用下的內(nèi)河航道土質(zhì)岸坡進行穩(wěn)定性分析,得出:根系在抵抗?jié)B流對岸坡表層變形擾動方面起到了作用;船行波作用后岸坡會在水位線附近和坡腳產(chǎn)生大變形,所以需要著重對這兩個區(qū)域加強生態(tài)和工程保護措施;隨植被覆蓋率的降低和降雨時間的延長,表層破壞的范圍加大,所以需要對岸坡表層塑性破壞區(qū)域加強生態(tài)及工程保護措施。
[Abstract]:Inland waterway perennial soil slope seepage, rainfall and ship wave function, its stability is threatened. In order to prevent the occurrence of slope instability, maintaining the safety of navigation, we must take measures on bank risk, to improve its stability. And the slope vegetation as a both slope reinforcement and environmental protection engineering in in recent years has been widely used in slope remediation projects. For the study of multiple factors affecting the vegetation on the slope stability, the results of the present study does not involve root Slope Shallow stability discrimination and ship waves of grassroots reinforced soil dynamic characteristics research. In addition, osmotic effect on soil structural damage to the ship. The traveling wave effect of strength reduction and the bank under the vegetation coverage analysis of the impact on the slope stability under the condition of rainfall is not perfect. This paper uses soil test and numerical model The combination of tactics, the vegetation and the waterways in the soil slope seepage, analyze the stability of the ship wave and the effect of rainfall. The contents are as follows: (1) shear test three axial penetration undisturbed soil and remolded in soil, study the seepage failure impact effect on soil strength index, the seepage after the action of the internal friction angle of soil constant, cohesive strength reduced. On this basis, the Mohr Coulomb criterion will damage to the "quantitative form of equivalent confining pressure to reduce the statement. In addition, is derived in the form of exponential function to characterize the permeability of effective stress intensity changes with the hydraulic gradient formula under the condition of. (2) shear tests of three axis penetration to carry out remodeling of grassroots reinforced soil, influence study of root on soil permeability and strength, and deduces the seepage of grass-roots strength of reinforced soil damage influence scope Formula (3). Three triaxial test is carried out to reshape the soil and remodeling of grassroots reinforced soil, the variation of pore pressure and residual strain of research with the number of cycles of growth. By comparing the root plays in the process of dynamic damage resistance effect is reduced accumulation of cyclic loading process of pore pressure and growth the residual strain. In addition, the shear strength reduction rate with dynamic stress ratio formula is derived. After GRS (4) on the basis of experiments considering seepage damage constitutive models of modified Duncan-Chang effective stress intensity effect on soil was established, and the energy of dangerous sliding area integral change as the overall slope instability criterion. In addition, according to the characteristics of herbaceous vegetation root depth is shallow and has no effect on the overall stability of slope, the slope surface is proposed to root zone and the total deformation energy As a judge of root index. The research provides a theoretical basis for the comprehensive analysis of slope under seepage action of the overall and local stability. (5) the shear strength reduction rate changes with the formula of dynamic stress ratio with experimental results for soil and GRS, through the two development software. The weakening model of shear strength index of soil slope in different areas. In addition, the maximum displacement of slope surface under the action of mutation as the ship wave slope instability criterion to calculate the slope generated under different load under different ship wave instability mode. Thus the slope vegetation protection of ship wave under the effect of the herbs in the dynamic load resistance provides a theoretical basis for the destruction of the study. (6) the establishment of a comprehensive consideration of the vegetation on the slope stability influence of overland flow erosion intensity and vegetation cover affects rainfall conditions The numerical analysis model, proposed effects of instability before development of the plastic zone surface to characterize the rainfall on the slope stability of slope with circular slip occurred. (7) using the analysis method of influence of vegetation on the slope stability under the action of multiple factors, further respectively on the different seepage flow effect of ship wave and rainfall condition the inland waterway soil slope stability analysis, the seepage on the slope surface of root in resistance to deformation disturbance plays a role of slope; will produce large deformation in the water near the line and slope ship wave action, so the need to focus on ecological and engineering protection measures of the two areas to strengthen; with the vegetation coverage rate and reduce the rainfall time prolonged, the increase range of surface damage, so the slope surface plastic damage area to strengthen ecological and engineering protection measures.

【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：U617

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