虎跳峡龙蟠右岸土石混合体野外试验研究

STUDY ON FIELD TEST OF ROCK-SOIL AGGREGATE ON RIGHT BANK OF LONGPAN IN TIGER-LEAPING GORGE AREA

土石混合体是一种力学性质极其复杂的特殊的工程地质体,它的存在会对工程带来极大的危害。由于其物理力学性质较为复杂且试样难以采集,目前对它的研究还不够深入。为进一步研究土石混合体的变形破坏特征,对虎跳峡龙蟠右岸地区分布的土石混合体选取6个试验点分别进行了天然状态下(3个)和浸水条件下(3个)的原位大型水平推剪试验,取得一些有意义的研究成果。通过现场试验,得出了该区土石混合体在不同条件下的强度特征和应力–应变曲线,在此基础上归纳出土石混合体在天然状态下的全应力–应变曲线。同时对各试样的粒径级配关系辅以三维滑动面分析对土石混合体的变形破坏机制进行了探讨,解释这种特殊的地质体的内摩擦角偏高的内涵所在。提出在计算强度参数时应采用平均滑动面和对土石混合体的黏聚力起重要作用的关键粒径的概念。最后,对研究区分布的土石混合体的强度参数提出合理的参考值,为变形体的三维稳定分析奠定基础。

Rock-soil aggregate is a special kind of engineering geological body, its mechanical characters are very complicated. It has huge influence on engineering projects. For it has very complicated physico-mechanical properties and the collection of its samples is very difficult, the study has not been sufficient so far. In order to make more study on the distortion and destruction characters of the rock-soil aggregate, six test sites on the right bank of Longpan in Tiger-leaping Gorge reservoir area are selected. In these six test sites, six horizontal push-shear in-situ tests were done, which include three non-water immersion tests and three water immersion tests, and some significant results were obtained. Through these in-situ tests, the strength characteristics and the complete stress-strain curves under various states were obtained. At the same time, by analyzing the group of block size and the three-dimensional sliding face, the mechanism of distortion and destruction of rock-soil is discussed to explain why the friction angle is on the high side in such kind of special geological body, and the conception of the average sliding surface which is used in calculating the strength parameters and the conception of the key diameter which is very important in determining the value of the cohesion are put forward. At the end, a reasonable reference value on the strength parameters of rock-soil aggregate in the study area is proposed to establish the foundation of the 3D slope stability analysis.