某水库枢纽工程西域砾岩高边坡处理方案研究

High Slope Treatment of Xiyu Conglomerate in A Reservoir Engineering

分布于天山、昆仑山山麓地带的西域砾岩,成岩时代晚、强度低,遇水易软化、崩解,抗冲刷能力差.新疆巴州境内的某水库工程坝址区出露地层主要有第四系西域砾岩和第三系泥岩夹层,溢洪洞、发电洞、导流兼泄洪冲沙洞的联合进水口前缘岸坡坡度为75° ～87°、坡高84 m,这样的高陡边坡若处理不当,在库水淘蚀下会发生坍塌及岸坡再造,严重时将危及工程安全.根据工程实际,采取了“坡顶削坡减荷、坡脚堆料压重、中部混凝土置换泥岩层、坡面整体喷锚防护”的高边坡综合处理方案.采用二维极限平衡方法,对联合进水口边坡各工况条件下不同滑移模式的稳定状况进行复核计算,并采用三维数值计算方法对其三维稳定状况进行分析评价,验证了高边坡综合处理方案的合理性.

Xiyu conglomerate distributed in the foothills of Tianshan Mountain and Kunlun Mountain,because of late diagenetic age and low intensity,easy to soften and disintegration under the influence of water and anti-erosion ability is poor. Within the territory of Xinjiang Bazhou a reservoir dam site area is the outdoor layer with Quaternary Xiyu conglomerate and Tertiary mudstone interlayer. Bank slope gradient is 75°-87° and slope height is 84 m at joint inlet leading edge of spillway tunnel,power generation water diversion tunnel and the diversion and water flushing tunnel. Such high and steep slope if handled improperly,under the reservoir water scour collapse and bank reengineering will happen,serious will endanger the safety engineering. According to the actual engineering,it took'cutting slope at the top for reducing load,piling up material at the slope toe for weights,concrete replacing mudstone layer at the middle part and shotcrete at overall slope surface for protection'as high slope comprehensive treatment method. Based on the 2D limit equilibrium method and 3D numerical calculation method,the stability of the intake slope of various working conditions of different sliding mode was analyzed and evaluated,so verified the rationality of the design. At the same time,by calculating the high slope stability of the mudstone interbed of Xiyu conglomerate layer,using the concrete plug,concrete beam displacement and closed treatment to avoid mudstone interbed's influence to the overall slope stability.