【作者】 马玉梅；

【导师】 汪家林；

【作者基本信息】 成都理工大学 ， 岩土工程， 2011， 硕士

【摘要】 四川紫坪铺水利枢纽工程是岷江上游一座以灌溉和供水为主,兼有发电、防洪等综合效益的大型水利工程。右岸为一三面被河曲围绕的条形山脊,构造上为一沙金坝向斜,工程水工建筑物均布置于右岸,施工期开挖形成多个高陡岩质边坡。由于边坡内存在断层、层间剪切破碎带等软弱结构面,使边坡的稳定性问题尤为突出。紫坪铺坝区基本地震烈度为Ⅶ度,5.12汶川大地震对距震中仅17km的紫坪铺工程造成了Ⅸ度的影响,各工程边坡均受到了很大的影响,但所有边坡均未产生整体失稳,岩质边坡在强烈地震作用下的变形破坏机理和抗震设计值得研究。本文按边坡地质结构类型将其分类,通过地震后的现场调查并结合边坡内设置的多点位移计、锚索测力计、测斜孔等监测成果,对强震作用下不同地质结构、支护措施边坡的变形差异以及分布特征进行分析。通过地震调查发现,支护边坡整体稳定性较好,仅坡体表面混凝土喷层出现少量裂缝,开挖范围之外未支护边坡出现塌方等现象。各边坡监测成果显示,锚索支护边坡变形量较小,从几毫米到十几毫米,锚杆、挂网喷护或框架梁支护部位坡体变形可达20mm以上,F3断层经过的泄洪洞出口边坡最大变形量达78mm,变形主要发生在主震时期,地震停止后变形即终止。震后多点位移计监测成果显示,边坡变形主要受支护措施、坡高、坡角、地层岩性、与断层带的关系等因素影响。对于反倾向结构边坡、顺层结构边坡,边坡的主要变形区域为层间剪切破碎带等软弱岩层,其他部位岩体随该部位岩体发生同步的变形;中倾横向边坡表面测点的位移增量最大,随孔深的增加位移增量减小,坡体内未出现明显的变形区域;由于存在F3断层,软岩边坡的整体变形均较大;覆盖层边坡变形主要发生在覆盖层内,边坡由基覆界面开始变形,随高程的增加变形逐渐增加,基岩内变形量较小。地震动荷载作用下锚索荷载发生一定的变化,荷载以增大为主,锚索荷载变化主要发生在主震期间,余震及后期的坡体蠕变使锚索荷载变化较小。测斜孔观测成果显示,对于中倾横向边坡,坡体主要发生蠕变变形,变形随高程的增加而增加,孔口累计合位移在20mm以内,坡体在层间剪切破碎带等软弱岩层面附近发生剪切变形;覆盖层边坡变形从基覆界面开始变形,覆盖层内发生蠕滑变形,变形量随高程的增加而增加,基岩内变形较小,测斜孔主要向坡外变形,变形向下游方向。更多还原

【Abstract】 Sichuan Zipingpu water conservancy project, located in the upper stream of the Min Jing River, is a large scale water dam, being build for agricultural irrigation and civil water supply, it also have the functions like power generation, flood prevention, etc. Right bank is a thin and weak ridge, which is surrounded by river on three sides, is a structure of Shajinba syncline. All of the hydraulic structures are arranged in the right bank, a lot of high steep rock slopes are formed during excavating time. Because of the existence of weak structural planes, such as faults, interbeded shearing belts, the stability of slopes are quite obvious. The Wenchuan earthquake has broughtⅨdegrees earth intensity on Zipingpu hydraulic project, which is only 17km from the epicenter, the deformation characteristics and the stability of rock slopes under strong earthquake needed to be studied.In this paper, the author selected several slopes of Zipingpu conservancy project to analysis the influence of earthquake, those slopes contain discharging tunnel slope, water in-take and out-take slope, spillway slope, discharging tunnel slope in left-bank. In those slopes, we stalled multi-point extensometer, load cell, borehole inclinometer, etc. monitoring equipment, according to the monitoring results combine with the geostatistical site investigations, can analysis the deformation characteristics of slopes under different rock structure and support measure.Through the geostatistical site investigation, the stability of slopes with support measure are well, there are only several cracks on the surface of concrete spray layer, several point of collapse occur out the range of excavation and unsupport slopes. According to the monitoring results, the values of anchor supported slopes’s deformation are quite small, from a few millimeter to tens millimeter; the slopes with bolt, nets spray joint and frame beam supporting has a deformation more than 20mm, discharging tunnel slope’s maximum deformation come to 78mm through F3 fault, the deformation mainly occur in the major shock period, it instant stop after earthquake.According to the multi-point extensometer’s monitoring results,antidip stratified rock slope and bedding rock slope has a main deformation region, this is interbeded shearing belts and other weak structural planes, it takes most of deformation and other place has a synchronization with those; medium-dip transverse rock slope’s surface point has a maximum deformation, the values become smaller with the deep of hole become bigger, there aren’t existence the main deformation region; as soft rock slope, because F3 fault’s character are weak, it make the deformation quite big; accumulation slope’s deformation mainly occur in overburden, the deformation started at the interface between rock and overburden, the value ordinarily decreases with height.Anchor load increased under earthquake, the change of anchor mainly occur during the main shock period, aftershock and after creep of slope make a few deformation. Borehole inclinometer monitoring show, medium-dip transverse rock slope take a creep deformation increased with height, the ground displacement is below 20mm, there has a shear deformation during weak structural planes; accumulation slope’s displacement started at the interface of overburden, in overburden has a creep deformation, the displacement increase with height, borehole’s deformate to out of slope, it directed to the lower strctches.更多还原