近断层地震动作用下混凝土高拱坝损伤特性研究

Study on Damage Characteristics of High Concrete Arch Dams Under Near-fault Ground Motions

我国西部地区已建或拟建一批混凝土高拱坝,其中许多位于结构复杂的地震断裂带,更易发生近场强震,可能引起高拱坝的严重损伤,因而有必要分析近断层地震动作用下高拱坝的损伤特性。考虑拱坝坝体的横缝及塑性损伤,建立某高拱坝的动力非线性有限元模型。从PEER强震数据库选取12条包括破裂前方脉冲、滑冲脉冲和无脉冲的近断层地震动作为输入波,分别从损伤破坏规律、耗能特点和坝顶中点位移响应等方面探讨其对混凝土高拱坝动力响应的规律。研究结果表明,破裂前方脉冲地震动作用下拱坝的损伤破坏、能量耗散及位移响应均最大,无脉冲地震动次之,滑冲脉冲最小;破裂前方脉冲和无脉冲地震动引起的坝体损伤和地震响应较大,应予以重视;滑冲脉冲作用下坝体的损伤破坏可忽略不计。

A number of concrete high arch dams have been built or to be built in Western China,many of which are located in complex seismic fault zones.These areas are more prone to near field strong earthquakes,which may cause serious damage to high arch dams.Therefore,it is necessary to study the damage characteristics of high arch dams under near fault ground motions.Considering the plastic damage and the nonlinearity of transverse joints,the nonlinear dynamic finite element model of a high arch dam is established.Twelve near fault ground motions with forward-directivity pulse,fling-step pulse and pulse-free ground motion are selected as input waves from PEER strong motion database.The dynamic response of high concrete arch dam is studied from the aspects of damage law,energy consumption characteristics and displacement response of the midpoint of the dam crest.The results show that the damage,energy dissipation and displacement response of arch dam under the action of forward-directivity pulse are the largest,followed by pulse-free ground motion,and the fling-step pulse is the smallest;The damage of the dam body and seismic response caused by forward-directivity pulse and pulse-free ground motion are large and should be paid attention;The damage of dam body under the action of fling-step pulse can be ignored.