摘要
我国已建成的特高拱坝逐渐由设计施工期过渡到蓄水运行期,其试验及监测成果表明,开挖、蓄水等扰动将加快拱坝枢纽区山体边坡的流变变形,这些长期变形对拱坝安全构成严重威胁。提出岩质高边坡长期变形对拱坝安全的影响分析方法,采用黏弹–塑性流变本构模型,计算锦屏一级左岸边坡在运行期的长期变形。以此变形为基础,引入极限分析的思想,提出基于边界位移法和变刚度的强度折减法,对边坡变形对拱坝的影响进行分析评价。边界位移法是在模型边界解除约束,施加固定位移,模拟边坡长期变形;变刚度的强度折减法是基于弹塑性和流变模型之间的内在联系,同时降低刚度和强度,来模拟边坡变形对拱坝影响,具有完备的理论基础。对锦屏一级拱坝左岸高边坡的长期变形进行分析预测,评价了拱坝承受边坡长期变形的安全度。研究表明,左岸边坡长期变形在一定程度上对坝体有益,流变稳定时,坝体屈服区、塑性余能范数都有减小,应力状况得到改善;拱坝可承受6倍以上的边界位移超载。因此,应重点关注应力集中等建基面局部区域对拱坝长期稳定性的影响。
Gradually,most of the completed super high arch dams in China are stepping into operation. Experimental results and monitoring records demonstrate that excavating,impounding and other perturbations can quicken the creep deformation of rock slope in junction areas. This long-term deformation may seriously threaten the safety of arch dams. New analytical methods of dam body safety under long-term deformation of high-slope are proposed. The creep deformation of high-slope has been calculated and analysed by viscoelastic-plastic rheological constitutive models. The evaluating methods for long-term stability of arch dam based on boundary displacement method（BDM） and stiffness and strength reduction method（SSRM） are proposed while limit analysis is introduced to estimate the capacity of dam body bearing the long-term deformation of slope. Boundary constrains are replaced by exerting fixed displacements to simulate long-term displacement field in BDM. SSRM has a complete theory based on the internal relationships between the elastic-plastic model and the creep model with reducing stiffness and strength at the same time. The above methods are applied in evaluating the capacity of Jinping I arch dam bearing the long-term deformation of the left bank slope. The results indicate that the long-term deformation of the left bank slope is beneficial to Jinping I arch dam body in some extent. The yield zone volume and plastic complementary energy norm both decrease while the stress state improves when the creep deformation is stable. The dam body could bear more than 6 times boundary displacement. Hence, more attentions should be focused on the local stress concentration in the base surface damaging the long-term stability of Jinping I arch dam.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2016年第A02期4040-4052,共13页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金面上项目(51479097
11172150)
清华大学水沙科学与水利水电工程国家重点实验室科研项目资助(2016–KY–02)~~
关键词
边坡工程
拱坝
长期变形
变刚度的强度折减
锦屏一级拱坝
slope engineering
arch dam
long-term deformation
stiffness and strength reduction
Jinping Ⅰ arch dam
