高拱坝与坝肩开挖边坡的相互作用研究

STUDY OF INTERACTION BETWEEN HIGH ARCH DAM AND ABUTMENT EXCAVATED SLOPE

我国西南地区特殊的地质构造,以及水利枢纽的高拱坝、高边坡特点,使得边坡和坝体的相互作用问题在该地区尤为突出。在弹塑性理论的基础上,提出以塑性余能范数为指标的结构稳定分析方法;指出在一定荷载作用下,弹塑性结构在失稳情况下,总是趋向于塑性余能范数最小的状态。如果塑性余能范数等于0,则表明存在同时满足平衡条件和屈服条件的协调应力场,结构稳定;如果塑性余能范数大于0,则表明不存在同时满足平衡条件和屈服条件的应力场,结构失稳。同时,基于大荷载步长下的弹塑性本构积分算法,进行岩体结构的非线性有限元分析。以锦屏一级拱坝左岸坝肩开挖边坡为对象,计算分析边坡与拱坝的相互作用。结果表明,在一定程度上拱坝拱端推力对边坡的整体稳定是有利的;边坡降强在超过1.5倍以后才会对拱坝的受力性态和整体稳定产生影响。

In southwest district of China,a number of high arch dams are being built or going to be built. Due to the complicated geological conditions and features of high arch dams and slopes,the interaction between dams and abutment excavated slopes has become an important issue in this area. On the basis of elastoplastic theory,the analysis method of structure stability using plastic complementary energy as parameter is proposed;and under specified loading conditions,elastoplastic constitutive relation makes the structure whose plastic complementary energy is minimum tend to be stable. It points out that an elastoplastic structure is not stable if it can′t satisfy simultaneously equilibrium condition,kinematical admissibility and constitutive equations under the prescribed loading. If the plastic complementary energy equals 0,which means that the stress field can satisfy equilibrium condition and constitutive equation at the same time,then the structure is stable;if the plastic complementary energy is greater than 0,then it means the structure is unstable. Based on Drucker-Prager criteria,a perfect elastoplastic incremental analysis method is considered in nonlinear finite element computation,which has good convergence for both small and large loading step sizes;then above method is used to study the interaction between slope and dam of Jinping I. Plastic complementary energy curves varying with strength reduction are provided to show the interaction between slope and dam. The results show that the push force coming from the arch dam is of some benefits to the slope′s stability to some extent;and the slope structure strength reduction has little influence on arch dam until the strength reduction rate is larger than 1.5.