摘要
与一般圈椅状倾向直线式滑坡形态不同,受断层控制滑坡呈侧缘结构差异明显的平面旋扭式滑移,难以划出连续滑面且向临空面单向变形量不突出,给边坡破坏模式判识和稳定性分析带来困难。以梅州市大埔韩江高陂水利枢纽尾水渠右岸边坡为例,据工程地质勘察和变形监测数据,分析该风化花岗岩边坡地质结构特征及不同开挖阶段监测点位移,发现2019年2月24日该边坡出现裂缝以来滑动受构造控制:断裂控制后缘拉裂缝、节理密集带控制东侧缘沟谷、与斑状花岗岩伴生的辉绿岩脉控制西边界。断层与岩脉联合控制边坡发生顺时针右旋滑移破坏:滑体西边界上拉下压,上部压剪和下部扩容使边缘裂缝近直立且光滑平直,平面上呈右列式断续分布,在公路内侧和下部坡脚出现集中线状排泄泥流;东边界上压下拉,内侧界限不明显,公路内侧坡厚重钢筋砼挡墙拉剪破坏。整个斜坡和沟谷呈“S”形地貌形态,说明历史上曾发生过此类侧旋滑移而使坡体倾角异常变缓、滑体堆积物变密实。基于上述科学认识采取封闭中部公路、裂缝覆盖充填、补充边坡地质勘探、加强变形体监测、滑体中上部快速削方卸载等抢险措施;随后采取保护西缘辉绿岩脉之下起抗剪支撑作用的块状斑状花岗岩体、减少西侧缘坡脚开挖范围并及早回填砼挡土墙、滑坡前缘从两边向中间(西侧剪出口)合拢而逐步加固的包饺子式开挖等加固处理措施,取得预期效果,保证了坡脚尾水渠挡土墙下挖期间施工安全,为工程按期完工赢得时间。变形监测结果显示该边坡总体变形已趋稳定。多方论证后该路段2019年7月20日开始通车。
Different from the general shape of the chair-like and linear slipping landslide,the fault-controlled landslide has a plane twist slip with obvious lateral structure difference.It is difficult to draw a continuous slip subsurface,the unidirectional deformation to the vacant surface is not prominent,and the slope is destroyed.Thus,pattern identification brings difficulties for identification and stability analysis of slopes.Taking the right bank slope of the tailrace of Gaobei Water Control Project in Dapu,Meizhou City as an example,the geological structure of the weathered granite slope and the displacement of the monitoring points in different excavation stages were analyzed,Based on the detailed engineering geological survey and deformation monitoring data in the slope,it was found that on Feb.24,2019,the sliding of the cracks on the slope is controlled by the geological structure:a fault led to the crack at the trailing edge,the dense joint zone controlled the eastern marginal gully,and the diabase vein that associated with the porphyrite dominated the western boundary.The joint action of fault and veins controlled the clockwise dextral slippage of the slope:the west boundary of the sliding body was pulled in the upper part and pressed in the lower part.The edge fractures were nearly vertical and smooth due to the upper press-shear and lower dilatancy;dextrally and intermittently distributed on the plane,and concentrated linear discharge muds on the inner side of the road and the lower slope.For the east boundary,it was under press in the upper part and pull in the lower part,making the inner boundary blurred and the heavy-thick retaining wall was sheared.The entire slope and valley presented S-shaped landform,indicating that such lateral rotation once occurred in the history,so that the inclination of the slope is dipping gently and the accumulation of the sliding body was densified.Based on our observation and slope structure model,preventative measures were recommended including to close the central highway
作者
刘震涛
邵鹏
尚彦军
LIU Zhen-tao;SHAO Peng;SHANG Yan-jun(Engineering Construction Management Department of Gaobei Water Control Project of Hanjiang River at Dapu of Meizhou,Meizhou 514011,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学技术与工程》
北大核心
2020年第25期10190-10197,共8页
Science Technology and Engineering
基金
国家自然科学基金面上项目(41772324)。
关键词
高陂水利枢纽工程
右岸边坡
构造控制
辉绿岩脉
旋扭式蠕滑
精细化施工
Gaobei Water Control Project
right bank slope
geological structural control
diabase vein
torsional creep
fine construction
