本文選題：碎石土 + 大型直剪試驗(yàn)��； 參考：《中國(guó)地質(zhì)大學(xué)》2015年碩士論文

【摘要】：伴隨著東北老工業(yè)基地振興計(jì)劃的實(shí)施,我國(guó)對(duì)當(dāng)?shù)鼗A(chǔ)設(shè)施的投入力度不斷加大,東北地區(qū)鐵路、公路及橋梁等基礎(chǔ)工程建設(shè)蓬勃發(fā)展。隨著大量的工程建設(shè),人工高邊坡問題逐漸突出,而各種邊坡的失穩(wěn)往往都是由于剪切破壞引發(fā)的,要對(duì)其進(jìn)行穩(wěn)定性分析與治理工程設(shè)計(jì),準(zhǔn)確的把握巖土體強(qiáng)度特性是關(guān)鍵。因此,針對(duì)巖土體的物理力學(xué)性質(zhì)的研究,已成為邊坡穩(wěn)定性分析與災(zāi)害防治中的一項(xiàng)重要任務(wù)。巖土體抗剪強(qiáng)度指標(biāo)是進(jìn)行斜坡穩(wěn)定性評(píng)價(jià)的重要力學(xué)參數(shù),其取值直接決定穩(wěn)定性分析的結(jié)果,通常通過試驗(yàn)的手段來獲取(包括室內(nèi)試驗(yàn)和現(xiàn)場(chǎng)原位試驗(yàn)),然后對(duì)所得的試驗(yàn)數(shù)據(jù)采用回歸統(tǒng)計(jì)分析以獲得其抗剪強(qiáng)度參數(shù)指標(biāo),從而進(jìn)行斜坡穩(wěn)定性評(píng)價(jià)。近期動(dòng)工興建的田師府-桓仁鐵路大前石嶺隧道進(jìn)口段開挖形成人工邊坡,坡體物質(zhì)組成以碎石土、塊石土為主,邊坡一旦失穩(wěn)將嚴(yán)重威脅鐵路運(yùn)營(yíng)及人民的生命財(cái)產(chǎn)安全。碎石土的物理力學(xué)性質(zhì)既不同于通常的土類,也區(qū)別于一般的巖體,而是介于土體和巖體之間的一種特殊的非連續(xù)的高度非均質(zhì)的地質(zhì)體。由于大前石嶺隧道邊坡體土中粗顆粒含量較多,當(dāng)粗顆粒組成不同時(shí),其性質(zhì)差別甚大,進(jìn)行常規(guī)的直剪試驗(yàn)已不能滿足對(duì)其力學(xué)性質(zhì)的完整研究。為此,本文以大前石嶺隧道邊坡碎石土為研究對(duì)象,通過野外現(xiàn)場(chǎng)調(diào)查取樣、室內(nèi)常規(guī)物理力學(xué)試驗(yàn)及室內(nèi)大型直剪試驗(yàn)對(duì)該碎石土的基本物理性質(zhì)、剪切特性、抗剪強(qiáng)度參數(shù)變化規(guī)律、粒度分形特性等方面進(jìn)行研究,可為該邊坡后期的穩(wěn)定性分析和防治提供可靠的巖土參數(shù)。本文主要開展的工作及取得的成果如下：(1)基本物理性質(zhì)研究。通過野外現(xiàn)場(chǎng)測(cè)試和室內(nèi)試驗(yàn)確定了大前石嶺隧道邊坡碎石土的天然密度、天然含水率及其顆粒組成情況等基本物理性質(zhì)參數(shù)。(2)抗剪強(qiáng)度特性研究。以室內(nèi)大型直剪試驗(yàn)為主,常規(guī)直剪試驗(yàn)為輔,對(duì)大前石嶺隧道邊坡碎石土按不同含石量、不同含水率、不同碎石尺寸進(jìn)行重塑樣配制,配制出三組不同含石量(粗粒含量分別為30%,50%,68.53%)、三組不同含水率(含水率分別為9.05%,12.50%,飽和)及三組不同碎石尺寸(三個(gè)區(qū)間粒徑為60～40mm,40～20mm,20～5mm)的碎石土重塑試樣,分別進(jìn)行大型直剪試驗(yàn)和三種不同含水率下的常規(guī)直剪試驗(yàn),建立了其相應(yīng)條件下的抗剪強(qiáng)度庫(kù)倫擬合公式。(3)抗剪強(qiáng)度參數(shù)與含石量變化相關(guān)性研究。根據(jù)三組不同粗粒含量重塑試樣的大型直剪試驗(yàn)結(jié)果,分析了抗剪強(qiáng)度、強(qiáng)度參數(shù)、應(yīng)力-應(yīng)變曲線隨著粗粒含量變化的作用規(guī)律。研究發(fā)現(xiàn),粗粒含量在很大程度上影響著碎石土的抗剪強(qiáng)度。隨著粗粒含量的增大,抗剪強(qiáng)度增大；內(nèi)摩擦角隨著粗粒含量的增加而增大,在粗粒含量為30%-50%之間增幅較快,粗粒含量超過50%后,增幅較慢而呈現(xiàn)逐漸穩(wěn)定的趨勢(shì)；粘聚力隨著粗粒含量的增大先略微下降后急劇上升,在粗粒含量達(dá)到50%時(shí)最低,而后急劇升高。不同粗粒含量下碎石土重塑樣應(yīng)力-應(yīng)變曲線均沒有出現(xiàn)明顯的峰值強(qiáng)度,表現(xiàn)為彈性變形階段、屈服階段和應(yīng)變硬化階段三個(gè)階段。隨著粗粒含量的增加,屈服階段愈為明顯；在同一法向應(yīng)力下,粗粒含量高的碎石土試樣應(yīng)變硬化程度明顯比粗粒含量低的碎石土試樣高。碎石土變形破壞機(jī)制在很大程度上受到其內(nèi)部粗粒含量的影響。(4)抗剪強(qiáng)度參數(shù)與含水率變化相關(guān)性研究。根據(jù)三組不同含水率重塑試樣的大型直剪試驗(yàn)結(jié)果,分析了抗剪強(qiáng)度、強(qiáng)度參數(shù)、應(yīng)力-應(yīng)變曲線隨著含水率變化的作用規(guī)律。研究發(fā)現(xiàn),抗剪強(qiáng)度隨著含水率的增大而降低；內(nèi)摩擦角隨著含水率的增大而降低；粘聚力對(duì)含水率變化的敏感性比內(nèi)摩擦角高,隨著含水率的增大先略微增大后急劇降低；含水率由9.05%上升為12.50%時(shí),粘聚力略有上升,而后粘聚力隨含水率的升高急劇下降。不同含水率下碎石土重塑樣應(yīng)力-應(yīng)變曲線均沒有出現(xiàn)明顯的峰值強(qiáng)度,表現(xiàn)為彈性變形階段、屈服階段和應(yīng)變硬化階段三個(gè)階段。隨著含水率的增大,屈服階段而表現(xiàn)的愈不明顯。在同一法向應(yīng)力下,含水率低的試樣應(yīng)變硬化程度明顯比含水率高的試樣高。(5)大型直剪試驗(yàn)與常規(guī)直剪試驗(yàn)對(duì)比研究。三組不同含水率下大型直剪與室內(nèi)常規(guī)直剪重塑樣的試驗(yàn)結(jié)果對(duì)比分析發(fā)現(xiàn),粘聚力和內(nèi)摩擦角在二種不同的試驗(yàn)方式下的變化規(guī)律基本相同,大型剪切試驗(yàn)得出的粘聚力和內(nèi)摩擦角均高于室內(nèi)常規(guī)小型剪切試驗(yàn),大型直剪試驗(yàn)得到的抗剪強(qiáng)度參數(shù)結(jié)果更貼近碎石土的實(shí)際力學(xué)性質(zhì)。(6)碎石土粒度分形特性研究。引入分形理論,采用顆粒質(zhì)量-粒徑分布分形模型,對(duì)含石量均為50%的重塑試樣進(jìn)行了分維數(shù)的計(jì)算。計(jì)算表明,在粗粒含量相同的情況下,隨著碎石尺寸的相對(duì)增大,分維數(shù)增大；分維數(shù)越大,其顆粒粒度分布越不均勻；分維數(shù)越小,其顆粒粒度分布越均勻。(7)抗剪強(qiáng)度參數(shù)與碎石尺寸相關(guān)性研究。研究表明,在粗粒含量相同時(shí),抗剪強(qiáng)度隨著碎石尺寸的相對(duì)增大而增大,抗剪強(qiáng)度增大的幅度也隨著碎石尺寸的相對(duì)增大而增大；內(nèi)摩擦角隨著碎石土內(nèi)碎石相對(duì)尺寸的增大而增大；而粘聚力呈現(xiàn)相反的趨勢(shì),隨著碎石相對(duì)尺寸的增大而降低。不同碎石尺寸下的碎石土重塑樣應(yīng)力-應(yīng)變曲線均沒有出現(xiàn)明顯的峰值強(qiáng)度,表現(xiàn)為彈性變形階段、屈服階段和應(yīng)變硬化階段三個(gè)階段。在大粒徑區(qū)間組及中粒徑區(qū)間組時(shí),應(yīng)力-應(yīng)變曲線呈現(xiàn)為應(yīng)變硬化型,而小粒徑區(qū)間組在高法向應(yīng)力時(shí),逐漸呈現(xiàn)出弱應(yīng)變軟化型。隨著碎石相對(duì)尺寸的增大,剪應(yīng)力達(dá)到峰值強(qiáng)度前的屈服階段歷時(shí)愈長(zhǎng)。(8)抗剪強(qiáng)度參數(shù)與粒徑分形維數(shù)相關(guān)性研究。研究發(fā)現(xiàn),碎石土抗剪強(qiáng)度和粒度分維數(shù)有一定程度的相關(guān)性。粘聚力隨著分形維數(shù)的增大而減小,而內(nèi)摩擦角呈現(xiàn)相反的趨勢(shì),隨著分形維數(shù)的增大而增大,粘聚力和內(nèi)摩擦角均與粒度分維數(shù)近似呈現(xiàn)拋物線函數(shù)關(guān)系。
[Abstract]:With the implementation of the revitalization plan of the northeast old industrial base, the investment in the local infrastructure is increasing, and the construction of the railway, highway and Bridge in the northeast is flourishing. With the construction of a large number of projects, the problem of artificial high slope is becoming more and more prominent, and the instability of all kinds of slopes is often caused by shear failure. In order to carry on the stability analysis and control engineering design, it is the key to accurately grasp the strength characteristics of rock and soil soil. Therefore, the study of the physical and mechanical properties of rock and soil has become an important task in the analysis of slope stability and disaster prevention and control. The shear strength index of rock and soil is an important mechanics for the evaluation of slope stability. Parameters, which directly determine the results of stability analysis, are usually obtained by means of experiments (including indoor and in-situ test), and then regression statistical analysis is used to obtain the parameters of the shear strength parameters for the obtained experimental data. Thus the slope stability is evaluated. The recent construction of Tian Shi Fu Huanren Railway The entrance section of the great front Shiling tunnel is excavated to form an artificial slope. The material of the slope body is composed of crushed rock soil and block rock. Once the slope is unstable, it will seriously threaten the railway operation and the safety of the people's life and property. The physical and mechanical properties of the gravel soil are different from the ordinary soil, but also different from the ordinary rock mass, but between the soil and the rock mass. A special discontinuous highly heterogeneous geological body. Due to the large amount of coarse particles in the somatic soil of the big front Shiling tunnel slope, the nature of its properties is very different when the composition of coarse particles is different. The conventional direct shear test can not satisfy the complete study of its mechanical properties. Therefore, this paper takes the lithotripsy of the big front Shiling tunnel slope as research. Through field investigation sampling, indoor physical and mechanical test and indoor large direct shear test, the basic physical properties, shear characteristics, changing law of shear strength parameters and fractal characteristics of the shear strength are studied, which can provide reliable rock and soil parameters for the stability analysis and prevention and control of the slope in the later period. The main work and achievements are as follows: (1) basic physical properties study. Through field test and indoor test, the natural density, natural water content and particle composition of the great front Shiling tunnel slope are determined. (2) study on the shear strength characteristics of the rock soil. (2) the indoor large direct shear test As a supplement to the conventional direct shear test, three groups of different rock content (30%, 50%, 68.53%) were prepared from the lithotripsy soil of the slope of the big front Shiling tunnel, with different content of stone, different water content and different size of gravel, and three different water content (water content was 9.05%, 12.50%, saturation) and three different lithotripsy sizes (water content was 9.05%, 12.50%, saturated). The remolded specimens of gravel soil with three intervals of 60 to 40mm, 40 to 20mm and 20 to 5mm are remolded specimens for large direct shear tests and three kinds of conventional direct shear tests under different water content. The fitting formula of the shear strength under the corresponding shear strength under the corresponding conditions is established. (3) Study on the correlation between the shear strength parameters and the variation of the rock content. According to three groups of different coarse particles The effect of shear strength, strength parameter, stress strain curve with the change of coarse grain content is analyzed. It is found that the content of coarse grain affects the shear strength of the gravel soil to a great extent. With the increase of coarse grain content, the shear strength increases, and the internal friction angle increases with the content of coarse grain. When the coarse grain content is 30%-50%, the increase of the coarse grain content is more than 50%, the increase of the coarse grain content is slower and the trend is steady. The cohesive force increases slightly with the increase of the coarse grain content, and then rises sharply at 50% when the coarse grain content is reached, then the stress strain of the crushed stone soil under different coarse grain content is remolded. There is no obvious peak intensity in the curve, which shows three stages of elastic deformation, yield stage and strain hardening stage. With the increase of coarse grain content, the more obvious the yield stage is. Under the same normal stress, the strain hardening range of the rock specimen with high coarse grain content is obviously higher than that of the gravel soil with low content of coarse grain. The deformation and failure mechanism of rock and soil is greatly influenced by its internal coarse grain content. (4) study on the correlation between the shear strength parameters and the change of water content. According to the large direct shear test results of the remolded specimens of three groups of different water content, the effect of the shear strength, strength parameters and stress strain curves with the change of water content is analyzed. It is found that the shear strength decreases with the increase of water content, and the internal friction angle decreases with the increase of water content, and the sensitivity of cohesion to the change of water content is higher than that of the internal friction angle. With the increase of water content, the cohesion is slightly increased after a slight increase. When the water content rises from 9.05% to 12.50%, the cohesive force increases slightly, and then the cohesion is followed with the cohesive force. There is no obvious peak intensity in the stress strain curve of the remolded samples of the crushed rock and soil under the different water content, which shows the three stages of the elastic deformation stage, the yield stage and the strain hardening stage. With the increase of water content, the less obvious the yield stage is. Under the same normal stress, the low water content test The strain hardening degree of sample is higher than that of the sample with high water content. (5) a comparative study of the large direct shear test and the conventional direct shear test. The comparison and analysis of the experimental results of the three groups of large direct shear and indoor conventional direct shear reshaping found that the cohesive force and the internal friction angle are basically the same under the two different test modes. The cohesive force and internal friction angle obtained by the type shear test are higher than that in the conventional small shear test. The results of the shear strength parameters obtained by the large direct shear test are more close to the actual mechanical properties of the crushed rock soil. (6) the fractal characteristics of the gravel soil particle size are studied. The fractal theory is introduced and the particle mass particle size distribution fractal model is applied to the rock content of 50. The fractal dimension calculation shows that the fractal dimension increases with the relative increase of the size of the crushed stone in the case of the same coarse grain content; the larger the fractal dimension, the more uneven the particle size distribution is, the smaller the fractal dimension is, the more uniform the particle size distribution is. (7) research on the correlation between the shear strength parameters and the size of the crushed stone. It is shown that the shear strength increases with the relative increase of the size of the gravel, and the increase of the shear strength increases with the relative increase of the size of the crushed stone, and the internal friction angle increases with the increase of the relative size of the crushed stone in the gravel soil. The stress strain curves of lithotripsy soils under different macadam sizes have no obvious peak intensity, showing three stages of elastic deformation, yield stage and strain hardening stage. In the large particle size interval group and the medium size interval group, the stress-strain curve presents strain hardening type, while the small size interval group is in the area. With the higher normal stress, the weak strain softening type is gradually presented. With the increase of the relative size of the crushed stone, the longer the yield stage before the shear stress reaches the peak strength. (8) the correlation between the shear strength parameters and the fractal dimension of the particle size. The fractal dimension increases and the internal friction angle presents the opposite trend, which increases with the increase of the fractal dimension. The cohesive force and the internal friction angle are approximately parabolic function relation with the particle size fractal dimension.

【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U456

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