本文選題：紅層滑帶土 + 蠕變�。� 參考：《南華大學(xué)》2014年碩士論文

【摘要】：大量邊坡工程表明：邊坡失穩(wěn)部分由滑動(dòng)帶的剪切蠕變破壞造成，因而研究其滑動(dòng)帶的剪切蠕變特性和其長(zhǎng)期強(qiáng)度尤為重要。紅層呈軟硬互層的特點(diǎn)，軟弱夾層是其滑帶土形成的物質(zhì)基礎(chǔ)，當(dāng)軟弱夾層的含水量變化時(shí)對(duì)邊坡穩(wěn)定性影響非常明顯。湘南紅層邊坡常因?yàn)槿斯ら_(kāi)挖及排、防水處理不當(dāng)，導(dǎo)致失衡形成滑坡。對(duì)滑帶土的流變特性及長(zhǎng)期強(qiáng)度已有許多科研工作者做了大量的研究工作，但專(zhuān)門(mén)針對(duì)湘南紅層滑帶土剪切蠕變特性的研究報(bào)告尚不多見(jiàn)。本文通過(guò)對(duì)湘南某紅層滑坡滑帶土直剪蠕變?cè)囼?yàn)，研究該滑帶土在不同垂直荷載、含水率條件下，分級(jí)施加水平剪力之后的蠕變特性，得出其剪切位移—時(shí)間關(guān)系曲線及剪切位移—剪應(yīng)力曲線，為確定滑帶土長(zhǎng)期強(qiáng)度及計(jì)算邊坡變形提供依據(jù)，主要取得了以下進(jìn)展。 (1)本文通過(guò)對(duì)湘南紅層滑帶土進(jìn)行了室內(nèi)直剪蠕變?cè)囼?yàn)，初步探討了該土在不同垂直荷載、含水率下的蠕變特性。試驗(yàn)結(jié)果表明：由于紅層滑帶巖層破碎，水沿紅層裂隙下滲至滑動(dòng)帶，使其軟化，加速了其剪切蠕變的發(fā)展；當(dāng)剪切應(yīng)力達(dá)到滑帶土長(zhǎng)期極限抗剪強(qiáng)度時(shí)，當(dāng)含水率一定，若垂直荷載較小，滑帶土則表現(xiàn)為突然剪破；當(dāng)垂直荷載足夠大，滑帶土則以穩(wěn)定的加速蠕變發(fā)展；當(dāng)含水率和垂直荷載一定時(shí)，隨著剪切應(yīng)力的增大，土體的剪切位移逐漸增大，整個(gè)蠕變階段逐漸呈現(xiàn)；衰減蠕變，等速蠕變、加速蠕變?nèi)齻�(gè)蠕變階段。在剪切應(yīng)力、垂直荷載一定的條件下，，含水率越大，滑帶土的非線性流變特征越明顯，產(chǎn)生的總剪切位移也越大。 (2)通過(guò)對(duì)直剪蠕變?cè)囼?yàn)結(jié)果中紅層滑帶土的剪應(yīng)力—剪切位移等時(shí)曲線的研究分析，得出其變化規(guī)律及特性，以此提出了流變模型中紅層滑帶土的兩個(gè)流變參數(shù)，蠕變變形速率和剪切模量。經(jīng)試驗(yàn)發(fā)現(xiàn)：紅層滑帶土的剪應(yīng)力—剪切位移等時(shí)曲線呈明顯的非線性流變特點(diǎn)，表現(xiàn)為：隨著剪應(yīng)力和時(shí)間的持續(xù)增加，曲線將逐漸朝應(yīng)變軸靠攏；在同一含水率情況下，紅層滑帶土的剪切模量的變化與時(shí)間及剪切水平的變化呈反比特點(diǎn)。 (4)將長(zhǎng)期強(qiáng)度理論與土體在蠕變?cè)囼?yàn)中的破壞準(zhǔn)則相結(jié)合，建立了湘南紅層滑帶土的冪函數(shù)形式的長(zhǎng)期強(qiáng)度方程。該方程較好的描述了土體在長(zhǎng)期荷載作用下所經(jīng)歷的三個(gè)蠕變狀態(tài)，完成了對(duì)湘南紅層滑帶土長(zhǎng)期強(qiáng)度特征的模擬，為紅層滑帶邊坡的變形問(wèn)題、強(qiáng)度問(wèn)題和穩(wěn)定性問(wèn)題的分析提供了理論依據(jù)。
[Abstract]:A large number of slope projects show that the failure of slope stability is caused by the shear creep failure of the slip zone, so it is very important to study the shear creep characteristics and long-term strength of the slip zone. The red layer is soft and hard interbedded, and the weak intercalation is the material foundation of the soil in the slip zone. When the water content of the weak intercalation changes, the slope stability is obviously affected. The red bed slope in southern Hunan is often caused by artificial excavation and drainage and improper waterproof treatment, which leads to the imbalance of landslide. Many researchers have done a lot of research on the rheological characteristics and long-term strength of sliding zone soils, but there are few reports on the shear creep characteristics of red bed soils in southern Hunan. In this paper, the creep characteristics of a red layer landslide sliding zone soil under different vertical loads and moisture content are studied by means of direct shear creep test. The shear displacement-time relation curve and shear displacement-shear stress curve are obtained, which provide the basis for determining the long-term strength of sliding zone soil and calculating the slope deformation. In this paper, the creep characteristics of the red layer sliding zone soil under different vertical loads and moisture content are preliminarily discussed by means of indoor direct shear creep test. The test results show that due to the breakage of the rock layer in the red layer slip zone, water seeps down along the red bed fissure to the slip zone, which softens it and accelerates the development of its shear creep, and when the shear stress reaches the ultimate shear strength of the sliding zone soil for a long time, the moisture content is constant. If the vertical load is small, the slip zone soil appears to be suddenly shearing; when the vertical load is large enough, the sliding zone soil develops steadily and accelerates creep; when the moisture content and vertical load are constant, the shear stress increases with the increase of shear stress. The shear displacement of the soil gradually increases and the whole creep stage gradually appears; the decay creep, the constant velocity creep and the accelerated creep are three creep stages. Under the condition of shear stress and vertical load, the higher the moisture content is, the more obvious the nonlinear rheological characteristics of sliding zone soil are, and the larger the total shear displacement is. 2) through the study and analysis of shear stress-shear displacement isochron curve of red layer sliding zone soil in direct shear creep test results, the variation law and characteristic are obtained, and two rheological parameters of red layer slip zone soil in rheological model are put forward. Creep deformation rate and shear modulus. The experimental results show that the shear stress-shear displacement isochron curve of red layer slip zone soil shows obvious nonlinear rheological characteristics, which shows that with the increasing of shear stress and time, the curve will gradually close to the strain axis, and under the same water content, The variation of shear modulus of red layer slip zone soil is inversely proportional to time and shear level. 4) combining the long-term strength theory with the failure criterion of soil in creep test, the long-term strength equation of the soil in the form of power function of the red layer slip zone in southern Hunan is established. The equation well describes the three creep states experienced by soil under long-term load, and completes the simulation of the long-term strength characteristics of the red bed slip zone soil in southern Hunan Province, which is the deformation problem of the red bed slip zone slope. The analysis of strength problem and stability problem provides theoretical basis.
【學(xué)位授予單位】：南華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TU411

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