库岸边坡多场光纤监测技术与稳定性评价研究

发布时间：2018-05-11 23:17

  本文选题：库岸边坡 + 多场　； 参考：《南京大学》2015年博士论文

【摘要】：国内外水库尤其是大型水库工程中,受库水位循环涨落影响而孕育和发生的库岸新老滑坡,相比其他条件下的滑坡影响范围更为广泛,危害形式更加多样化。库岸边坡监测作为研究边坡变形与失稳破坏机理以及预防滑坡灾害的主要手段,对其技术的革新和研发以及据此开展的边坡稳定性研究,具有重要的理论和现实意义。从场的角度来看,库岸边坡是一个由基本场、渗流场、应力场、温度场、变形场等构成的复杂多场系统。传统的岸坡多场监测技术与方法还存在诸多不足,难以达到岸坡多场信息获取、分析与评价的要求。分布式光纤感测(Distributed Fiber. Optic Sensing,简称DFOS)技术突破了传统点式感测技术的局限,可实现岸坡的连续分布式监测,比较全面地获得岸坡多场的变化信息,从而为岸坡的稳定性评价和灾害预警提供基础性资料。本文针对岸坡各场特点,围绕三类分布式光纤感测技术—光纤布拉格光栅技术(FBG),布里渊光时域反射技术(BOTDR)和拉曼光时域反射技术(ROTDR),在室内外试验基础上,比较系统地开展了库岸边坡多场监测技术的研究；结合三峡库区马家沟边坡,建立了岸坡分布式光纤感测系统,已获得了二年的监测数据；在此基础上,采用数据挖掘和数值模拟等方法,分析了岸坡演化过程中多场间的关联性及其对边坡稳定性的影响；最后,采用突变理论,对岸坡的稳定性及变形发展规律进行了评价。论文主要取得如下成果：(1)对三种基于布里渊散射光感测原理的BOTDR、BOTDA和BOFDA解调仪进行了对比试验。测试结果表明：Neubrex公司生产的BOTDA要比fibrisTerre生产的BOFDA解调仪的空间分辨率要高,而测量重复性相近；二者的空间分辨率与测量重复性间呈反比关系,其乘积控制在±0.2MHz*m,折合±4με*m范围以内；BOTDA和BOFDA解调仪均需要感测光纤构成回路,属于双端测量,适合于地质工程结构的精细化监测,但对于复杂条件下的地质体监测存在较大的成活风险；而中国电科四十一所生产的BOTDR的空间分辨率和重复性虽然比BOTDA和BOFDA低,但单端测量的优势,十分适合于地质体及地质灾害的监测。(2)开展了表面粘贴光纤应变感测性能的试验研究。当分布式光纤表面粘贴长度L15.8cm时,低传感段长度可以控制在7cm以内,表明在工程应用中,采用表面粘贴工艺时,光纤应保证有足够的粘贴长度,在采集应变数据时,应舍弃端部低传感段误差较大的数据。(3)理论推导了光纤测管式位移计的误差计算公式,得出位移误差与测试距离的平方成正比,与管径成反比,并在试验中得到了很好的印证。该公式还可适用于在其他梁式类结构中进行位移分布式光纤监测时的误差分析。(4)设计并改进了基于DFOS技术的新型金属基索状应变感测光缆,对课题组研发的基于FBG技术的温度传感器、渗压计、液位计、钢筋应力计和土压力计,开展了一系列试验测试。设计出了库岸边坡多场光纤监测方案,包括不同监测场的DFOS技术及传感器的选择、感测光缆的布设方法、传感器的安装工艺、多场信息数据的表征、处理及分析。(5)建立了三峡库区马家沟边坡多场光纤监测系统,成功获得了岸坡二年的多场信息数据,准确定位了边坡深部滑动面和坡表滑动边界,并定量得到了岸坡的位移变化规律。(6)结合基于Apriori算法的数据挖掘技术,提取了多场信息的关联规则,得到了三峡库水位与马家沟边坡变形间的关联性：整体而言,水位升高边坡变形速率降低；水位处于低位时,边坡变形速率增大。(7)建立了渗流场作用下马家沟边坡安全系数的数值计算模型。计算结果显示,边坡的安全系数与库水位和库水位变化速率有密切的关系。整体而言,高水位下边坡的安全系数高,低水位下安全系数低；库水位及其变化速率不同,边坡的安全系数出现明显的分区现象。当库水位下降到150m水位附近时,安全系数最低；库水位处于152～155m且变化速率在-0.45～0.26m/天时,安全系数出现快速降低。该计算结果也得到了边坡变形监测结果的印证。(8)引入了粒子群优化算法,有效提高了边坡非线性突变动力模型的反演精度。论证了边坡滑面段测管位移与应变作为状态变量进行建模的等价性；建立了马家沟边坡变形发展的非线性动力学方程,并采用突变理论,分析得出马家沟边坡目前整体处在稳定蠕变,尚未进入滑坡突变发展的阶段。
[Abstract]:In comparison with other conditions , the reservoir slope is a complex multi - field system composed of basic field , seepage field , stress field , temperature field , deformation field and so on . Optic Sensing ( DFOS ) technology breaks through the limitation of traditional point sensing technology , and can realize continuous distributed monitoring of bank slope , so as to provide basic data for stability evaluation and disaster warning of bank slope .
The distributed optical fiber sensing system on bank slope has been established and two years of monitoring data have been obtained in combination with the Majigou slope in the Three Gorges Reservoir area .
Based on this , data mining and numerical simulation are used to analyze the correlation of multi - field and its influence on slope stability during the evolution of bank slope .
The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The results are as follows : ( 1 ) The spatial resolution of the BOFDA demodulator manufactured by Neubrex Company is higher than that of BOFDA demodulation instrument produced by Terre , and the measurement repeatability is similar ;
The spatial resolution of the two is inversely proportional to the measurement repeatability , and the product is controlled within 卤 0.2 MHz * m and is within 卤 4 渭蔚 * m range .
It is necessary to sense the optical fiber forming loop , which belongs to the double - end measurement , which is suitable for the fine monitoring of geological engineering structure , but has great survival risk for the monitoring of geological body under complex conditions .
In this paper , a series of tests have been carried out in this paper , which is based on the data mining technology based on the Apriori algorithm , and the relationship between the water level of the three gorges reservoir and the deformation of the Majigou slope is obtained .
The results show that the safety factor of the slope is high and the safety factor is low under the low water level .
The water level and its rate of change are different , and the safety factor of the slope has obvious zoning phenomenon . When the water level of reservoir falls to the water level of 150 m , the safety factor is the lowest ;
When the water level is 152 锝，

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