李家峡拱坝左岸高边坡岩体变位与安全性态分析

ANALYSIS OF HIGH SLOPE ROCK DEFORMATION AND SAFETY PERFORMANCE FOR LEFT BANK OF LIJIAXIA ARCH DAM

实际工程中常遇到山体单薄,地质构造发育,表层岩体卸荷松弛,甚至蠕变或滑移等高边坡安全稳定性问题,因而加强对此类高边坡岩体的变位监测并对实测数据进行及时的处理与分析,对于确保工程安全具有十分重要的意义。据此,以李家峡拱坝左岸高边坡为例,探讨如何通过岩体变位监测资料来全面分析和评价高边坡安全稳定性。在对水库初次蓄水以来的谷幅位移和左岸高边坡岩体变位监测资料进行时空定性分析和变形疑点物理成因分析的基础上,应用最小二乘法建立了岩体变位各测点的逐步回归模型,并以其对测值年变幅的拟合与分离结果,定量分析水压、温度、时效等因子对高边坡变位的影响效应。研究结果表明:(1)在库水位逐步抬升至正常蓄水位的过程中,李家峡左岸高边坡岩体主要产生朝河心方向的下滑变位,但位移量相对较小;(2)库水位在2002年1月趋于相对稳定后,高边坡岩体变位逐步趋于收敛并保持稳定,目前其安全性态基本正常;(3)由于局部岩体仍存在轻微下滑趋势,建议加强对这些部位的监测。

The safety and stability problems of high rock slope, such as weaken massif, fully developed geological conformations, widely unloaded or flabby rock layer, and squirming or sliding rock, are often encountered in engineering practice. So, it is very important to enforce the high slope rock deformation monitoring, and to process and analyze the measuring data timely. The high slope of the left bank of Lijiaxia arch dam is given as an example to search the method of how to analyze and evaluate the safety performance of high slope by utilizing rock deformation monitoring data. Based on space-time qualitative analyses of the dam-site valley breadth, slope rock deformation monitoring data measured after the first reservoir impounding, and physical genesis analysis of doubtful rock deformation points, the progressive regression models of rock deformation survey points were set up by using the least-square method; and the results of model simulation and partition to the variational extension of annual deformation of all surveying points were utilized to analyze the influencing effects of the independent variable factors such as hydraulic pressure, temperature and time-effect related to the high slope rock deformation. The conclusions obtained from synthetical analysis of the deformation monitoring data of the left bank of Lijiaxia arch dam are as follows： （1） the high slope rock principally slided downwards the riverbed during the period of impounding water being escalated to normal reservoir level; （2） the rock deformation of the high slope gradually tended to converge and keep stable after January, 2002, when the impounding water rose to normal reservoir level,and now the safety performance of the left bank is normal： and （3） presently, part of the left bank rock still tends to slide downwards slightly. So, a suggestion is proposed to strengthen the safety monitoring.