岷江某水库蓄水运行期进水口高边坡变形特征模拟研究

岷江某电站库区前期地质勘查资料表明,枢纽区地下水类型主要有第四系覆盖层孔隙性潜水和基岩裂隙水。水库蓄水后水位抬升127m,对条形山脊两侧边坡地下水渗流场产生较大的影响,不仅改变边坡地下水原有渗流场特征及其补、径、排条件,而且由此产生孔隙水压力,对边坡稳定性产生较大的影响。利用地质原型和开挖边坡地质-力学模型(GMD模型),建立水库蓄水过程中,条形山脊地下水的渗流模型及水岩作用模式。进一步考虑蓄水渗流场的变化,对不同蓄水位高边坡的稳定性进行了数值模拟研究,探讨蓄水过程中,条形山脊高边坡形变场特征及其稳定性状况。三维数值仿真显示,水库溢洪道进水口与EL.885m平台下方L11层位(EL.840~852m)与2#泄洪洞的洞脸边坡左上方(EL.833.59~847.50m),为大变形集中部位。水库进水口一侧边坡在库水位上升过程中,岩体的变形范围将随水位的增高逐渐扩大,量级呈递增趋势。受蓄水位的影响,水库进水口边坡的临江(Y方向)位移往山内方向顺层滑移还是朝山外倾倒拉裂不定,层间剪切错动带成为正负位移的"转换断层"效应。

Numerical simulation of high slopes deformation characteristics at intake during reservoir water-storing operation of a reservoir of Minj iang River,China

The previous geological investigation of some hydroelectric power station shows that the groundwater type in the j unction region is mainly the Quaternary overburden pore phreatic water and bedrock fracture water.The water-level elevated 127 m after reservoir water-storing,exerting a great influence on the groundwater seepage field on the bilateral slopes of the strip ridge.This not only changed the pre-existent seepage field characteristics and the recharge, runoff, and drainage conditions of the slope groundwater,but also generated interstitial hydraulic pressure,making an impact on the slope stability.By using the geological-prototype and geological-mechanical model (GMD model )of the excavation slope,the seepage model of the strip ridge groundwater and the water-rock action mode are established during the reservoir water-storing.The seepage field change of the water-storing is further considered.Utilizing the numerical simulation,the high slope stability during different water-storing levels is studied.The deformation field characteristics as well as the stability situation of the high slope of the strip ridge are discussed in the water-storing process.3D artificial simulation shows that the reservoir spillway water inlet,the L11 horizon of EL.885 m platform (EL.840~852 m),and the slope to the left of 2# tunnel are large deformation concentrated areas.The range of the rock mass deformation will be gradually enlarged along with the water-storing level elevating during the reservoir water level rises at the reservoir water inlet side slope.The displacement will be gradually increased.That the river displacement (Y direction)on the reservoir water intake slope is the bedding slip inside or the toppling failure outside is uncertain affected by the storage level.The interlayer shear rupture zone becomes the “transform fault”effect of the positive and negative displacements.