發(fā)布時(shí)間：2018-12-06 16:50

【摘要】：非飽和黃土的抗剪強(qiáng)度研究,是為了提供合理的強(qiáng)度進(jìn)行地基承載力、邊坡穩(wěn)定性、擋墻土壓力和圍巖壓力等的估算。本試驗(yàn)研究是為解決工程實(shí)踐問(wèn)題而設(shè)計(jì),希望獲得更適應(yīng)于工程的黃土非飽和抗剪強(qiáng)度估計(jì)的理論指導(dǎo)方案。以陜西涇陽(yáng)典型黃土為研究對(duì)象,取L1、S1、L5、L9層原狀土樣,分別代表地層Q3、Q2和Q1;采用濾紙法進(jìn)行土水特征曲線測(cè)試,直快剪進(jìn)行不同含水率下的抗剪強(qiáng)度測(cè)試,三軸固結(jié)不排水剪、三軸固結(jié)排水剪和直快剪進(jìn)行飽和抗剪強(qiáng)度指標(biāo)測(cè)試,估計(jì)出Bishop模型、Fredlund模型和Vanapalli模型中的參數(shù)。本研究獲得以下結(jié)果:(1)60m埋深時(shí),涇陽(yáng)黃土的飽和度在20-60%,土水特征曲線從L1至L9在該含水區(qū)間內(nèi)變化幅度較大,土體越密實(shí),在相同含水率下基質(zhì)吸力越高。(2)不排水快速剪切試驗(yàn)測(cè)得的飽和有效內(nèi)摩擦角遠(yuǎn)小于排水慢剪試驗(yàn)測(cè)試值,相同的試驗(yàn)方法測(cè)得的有效內(nèi)摩擦角較為接近,并與土樣的干密度關(guān)系甚小,涇陽(yáng)黃土的固結(jié)不排水三軸試驗(yàn)測(cè)得的有效內(nèi)摩擦角各土層在10°左右,而固結(jié)排水剪的結(jié)果達(dá)27°。(3)建立起Vanapalli非飽和抗剪強(qiáng)度預(yù)測(cè)模型中的參數(shù)?與塑性指數(shù)的關(guān)系。建立起采用干密度、塑性指數(shù)和黏粒含量,結(jié)合FredlundXing土水特征曲線方程、Vanapalli抗剪強(qiáng)度模型預(yù)測(cè)非飽和黃土抗剪強(qiáng)度的方案,涇陽(yáng)典型黃土L5層在100kPa壓力下的直快剪結(jié)果對(duì)方案進(jìn)行了有效性檢驗(yàn),誤差在40%以內(nèi)。
[Abstract]:The research on shear strength of unsaturated loess is to provide reasonable strength to estimate the bearing capacity of foundation, slope stability, earth pressure of retaining wall and surrounding rock pressure. This experimental study is designed to solve the practical problems of engineering, hoping to obtain a theoretical guidance scheme for estimating the unsaturated shear strength of loess which is more suitable for engineering. Taking the typical loess in Jingyang, Shaanxi Province as the research object, the original soil samples of layer L _ (1) S _ (1) and L _ (5) and L _ (9) are taken to represent the strata Q _ (3) Q _ (2) and Q _ (1) respectively. The characteristic curves of soil and water were measured by filter paper method, the shear strength under different moisture content was tested by direct quick shear, the saturated shear strength index was tested by triaxial consolidation undrained shear, triaxial consolidation drainage shear and straight fast shear, and the Bishop model was estimated. Parameters in Fredlund model and Vanapalli model. The results are as follows: (1) the saturation of Jingyang loess is between 20 and 60 when the depth is 60 m, and the characteristic curves of soil and water change greatly from L1 to L9 in this water bearing zone, and the soil is more dense. Under the same moisture content, the suction of the matrix is higher. (2) the saturated effective internal friction angle measured by the undrained rapid shear test is much smaller than the measured value of the drainage slow shear test, and the effective internal friction angle measured by the same test method is relatively close. And the relationship between dry density and soil sample is very small. The effective angle of internal friction measured by undrained triaxial test of Jingyang loess is about 10 擄. The result of consolidation drainage shear is 27 擄. (3) the parameters of Vanapalli unsaturated shear strength prediction model are established. The relation with plastic index. A scheme of predicting the shear strength of unsaturated loess by using dry density, plastic index and clay content, combined with FredlundXing soil-water characteristic curve equation and Vanapalli shear strength model, is established. The results of direct fast shear of Jingyang typical loess L5 layer under 100kPa pressure test the validity of the scheme, and the error is less than 40%.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU444

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