不同粒径砒砂岩剪切力学性能试验研究

发布时间：2018-09-12 10:08

【摘要】：砒砂岩为陆相碎屑岩系,由于其上覆岩层厚度小,压力低,造成其成岩程度低,砂粒间胶结程度差,结构强度低,最大特点是遇水如泥,遇风成砂,造成严重的水土流失。近年来,内蒙古鄂尔多斯砒砂岩区水利工程建设逐年递增,深入研究砒砂岩的力学性能显得刻不容缓；同时,在进行滑坡体稳定性计算时,许多滑坡在滑动前一般要逐渐发展形成一个滑动面,此滑动面上抗剪强度已由峰值强度降到残余强度,所以残余强度也是必须要研究的问题；考虑到含水率对砒砂岩的影响极为重要且不同粒径砒砂岩的抗侵蚀能力存在显著差异。综合上述,针对不同粒径和不同含水率共同作用下砒砂岩重塑土进行反复直剪试验,探讨了峰值强度和残余强度的变化规律。在第一次剪切中,不同粒径范围试样应力-应变曲线均出现明显峰值,粒径范围为0.5-0.25mm试样的抗剪强度最低,工程特性最差,较大粒径范围试样的颗粒破碎明显,在较高含水率作用下,相对较粗颗粒更易破碎,而细小颗粒含量随着含水率降低而增高。不同粒径范围试样的抗剪强度随着含水率的增大而线性下降,在较低法向应力作用下,含水率对抗剪强度的影响更剧烈；粘聚力和内摩擦角均随含水率的增大而减小,但粘聚力减小的幅度更明显。三种粒径范围下试样残余粘聚力随含水率的增大基本呈线性下降,其中粒径范围为0.5-0.25mm试样突变较明显。在剪切开始阶段,试样表现出减缩特性,随着剪切位移的增大,表现出剪胀性。采用R. simon剪胀模型有一定的缺陷,不能描述初始剪缩现象。所以,本文用SAS软件进行回归分析,得到一个新的剪胀回归方程,试验值和拟合值有良好的拟合度。
[Abstract]:The soft sandstone is a continental clastic rock series. Because of its low overlying layer thickness and low pressure, it has low diagenetic degree, poor cementation degree between sand grains and low structural strength. The biggest characteristic is that it meets water such as mud and wind-formed sand, which results in serious soil erosion. In recent years, the construction of water conservancy projects in the Ordos soft rock area of Inner Mongolia has been increasing year by year, so it is urgent to study the mechanical properties of the soft rock in depth, and at the same time, when calculating the stability of the landslide body, Many landslides generally develop into a sliding surface before sliding, and the shear strength on the sliding surface has been reduced from peak strength to residual strength, so the residual strength is also a problem to be studied. Considering the influence of water content on the Pisha sandstone, there are significant differences in the corrosion resistance of different size Pisha sandstone. Based on the above, repeated direct shear tests were carried out for the remolded soil under the combined action of different particle size and different moisture content, and the variation law of peak strength and residual strength was discussed. In the first shear, the stress-strain curves of samples with different particle size range show obvious peak value. The range of particle size is the lowest shear strength of 0.5-0.25mm specimen, and the worst of engineering properties. Under the action of higher water content, relative coarse particles are more easily broken, while the content of fine particles increases with the decrease of water content. The shear strength of samples with different particle size ranges decreases linearly with the increase of moisture content. Under the action of lower normal stress, the effect of water content on shear strength is more intense, and the cohesion and internal friction angle decrease with the increase of moisture content. But the decrease of cohesion is more obvious. The residual cohesion of the samples decreases linearly with the increase of moisture content in the three particle size ranges, in which the 0.5-0.25mm sample mutation is obvious in the particle size range. At the beginning of shearing, the specimen showed the property of reducing shrinkage, and with the increase of the shear displacement, the specimen showed the dilatancy of shear. The R. simon shear expansion model has some defects and can not describe the initial shearing shrinkage. In this paper, a new regression equation of shear expansion is obtained by regression analysis with SAS software, and the test value and fitting value have good fitting degree.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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