基于常规直剪试验的泾阳非饱和黄土抗剪强度研究

发布时间：2018-12-06 16:50

【摘要】：非饱和黄土的抗剪强度研究,是为了提供合理的强度进行地基承载力、边坡稳定性、挡墙土压力和围岩压力等的估算。本试验研究是为解决工程实践问题而设计,希望获得更适应于工程的黄土非饱和抗剪强度估计的理论指导方案。以陕西泾阳典型黄土为研究对象,取L1、S1、L5、L9层原状土样,分别代表地层Q3、Q2和Q1;采用滤纸法进行土水特征曲线测试,直快剪进行不同含水率下的抗剪强度测试,三轴固结不排水剪、三轴固结排水剪和直快剪进行饱和抗剪强度指标测试,估计出Bishop模型、Fredlund模型和Vanapalli模型中的参数。本研究获得以下结果:(1)60m埋深时,泾阳黄土的饱和度在20-60%,土水特征曲线从L1至L9在该含水区间内变化幅度较大,土体越密实,在相同含水率下基质吸力越高。(2)不排水快速剪切试验测得的饱和有效内摩擦角远小于排水慢剪试验测试值,相同的试验方法测得的有效内摩擦角较为接近,并与土样的干密度关系甚小,泾阳黄土的固结不排水三轴试验测得的有效内摩擦角各土层在10°左右,而固结排水剪的结果达27°。(3)建立起Vanapalli非饱和抗剪强度预测模型中的参数?与塑性指数的关系。建立起采用干密度、塑性指数和黏粒含量,结合FredlundXing土水特征曲线方程、Vanapalli抗剪强度模型预测非饱和黄土抗剪强度的方案,泾阳典型黄土L5层在100kPa压力下的直快剪结果对方案进行了有效性检验,误差在40%以内。
[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 掳. The result of consolidation drainage shear is 27 掳. (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%.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU444

【参考文献】