各类泥化夹层的剪切破坏机制与强度特征

THE CHARACTER OF STRENGTH AND THE FAILURE MECHANISM OF CLAY INTERCALARY STRATA

许多研究表明,泥化夹层的力学强度与其物质组成关系极为密切,尤以粒度成分对强度的影响更为显著。作者曾依据粒度成分将泥化夹层分为粘泥型、泥夹碎屑型、碎屑——碎屑夹泥型、泥夹粉砂和粉砂夹泥型等各种类型[1]。并对黄河小浪底水库工程的各类夹泥进行了大量的中型试件剪切试验研究和电子显微镜观察,进一步探讨了夹泥粒度成分与力学强度之关系。

The grain composition of clay intercalary strata is closely related to its mechanical strength.According to the grain composition,the authors divide the clay intercalary strata into four forms, i.e. clay form, clastic clay from, clayey clasolite-clasolite form and silty clay form.The mechanism of shear failure and strength value are vary different for different forms of clay intercalation.The character of deformation of clay form presents as a plastic material and the stress-strain curve is plastic.Its strength value is low. Usually the values of fp are about 0.2-0.25.The character of deformation of the clasolite-clayey clasolite form presents as a brittle material and the stress-strain curve is obviously quasiplastic-quasibrittle,with a higher strength.Usually the fp values are as high as 1.5-2.0 times of that of the clay form.The deformation character and strength of the other clay intercalations are between those of the two forms.The strength of all the clay intercalations are also controlled by its thickness and the undulation of the strata.So we must consider all the different kinds of affecting factors when adopting the strength value of clay intercalation in engneering practice.