300m级高土石坝心墙直—斜轴线布置型式选择中的渗流和静动力计算分析

Seepage,Static and Dynamic Computation in Selecting Core Type of An abaut 300m High Embankment Dam between Vertical and Sloping Core

据不完全统计,世界上已建和在建的坝高在230m以上的当地材料坝共有12座,其防渗体布置一般采用土质斜心墙和直心墙两种型式。拟建的某心墙堆石坝高310m,属于超高坝,其心墙面临两种轴线布置型式选择。通过渗流有限元计算知,斜心墙型式坝体坡降较直心墙的大,但两种型式坝体和坝基各区域水力坡降均未超过允许渗透坡降。静力计算表明,斜心墙型式的心墙抗水力劈裂性能比直心墙略好,但由于采取了在黏土心墙料中掺砾的措施,两种型式的心墙抗水力劈裂能力都有保证。动力分析表明,两种型式坝体抗震性能相当,由于坝址区的基本烈度并不高,动力反应都不强烈。计算表明,渗流、静力、动力问题都不是心墙型式选择的决定性因素,但斜心墙的基础处理范围、坝体填筑工程量大,导致投资增加,故推荐直心墙方案。

A planed to be built extra-high embankment dam is 310m high,and selection of its core type should be decided considering many facts.By Seepage FEM analysis,the water head gradient of a sloping core is bigger than that of a vertical one,yet the hydraulic gradient in both the dams and their foundation doesn′t exceed the allowable gradient.The static computation shows that the sloping core can better prevent hydraulic fracture yet both the types are safe because the clay core is admixed with gravel.By the dynamic FEM analysis,the two type cores have the equal earthquake resistance,and because the dam site is in an area of low seismic intensity,so dynamic response both of the dams is not intensive.The computation shows that seepage,static and dynamic issues are not the key factors in selecting the core type.For the embankment dam with a sloping core,the scope of foundation treatment and filling quantity are bigger than that with a vertical core,which leads to additional 170 million Yuan investment,so the vertical core is to be adopted.