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注浆材料介电常数在雷达图像识别中的应用 总被引:3,自引:0,他引:3
利用探地雷达(GPR)方法探测软土盾构隧道盾尾壁后注浆分布效果时,电磁波在介质中的传播速度是准确识别介质界面的关键。在估计波速时常常将介质的介电常数假设为固定不变的常数,这不符合实际情况。为保证探测图像识别的精度,首次利用网络分析仪对不同配比、不同探测频率和不同龄期下软土隧道壁后注浆材料的介电常数进行了测定,对测定结果进行了基于射线追踪原理的GPR数据二维正演分析,并将分析结果与模拟的探地雷达隧道壁后注浆分布探测结果进行了比较。结果表明,针对不同的探地雷达探测频率而采用相应的介质介电常数来进行探地雷达探测图像的准确识别是十分必要的。 相似文献
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THE HOLOCENE ACTIVITY AND STRIKE-SLIP RATE OF THE SOUTHERN SEGMENT OF XIAOJIANG FAULT IN THE SOUTHEASTERN YUNNAN REGION,CHINA
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The southern segment of the Xiaojiang Fault (SSXF) is located at the intersection of the Xianshuihe-Xiaojiang Fault and Red River-Ailao Shan fault systems in the southeast margin of the Tibetan plateau. Based on the interpretation of remote sensing image, the SSXF clearly shows the linear feature and continuous distribution as a single, penetrating fault. It has a total length of about 70km, trends generally about 20° to the northeast and protrudes slightly in the middle to the east. A typically geomorphologic phenomenon about the synchronous left-lateral dislocation of ridges and gullies can be found at Liangchahe, Longtan Village along the SSXF. The distribution of faults, the sedimentary features, attitude variance and the primary dating results of the offset strata in the trench section across fault sag ponds reveal three paleoseismic events rupturing obviously the surface, which demonstrates that the SSXF has the ability of recurrence of strong earthquakes. High-precision topographic map about two gullies and the platform between them with synchronous dislocation is acquired by using the Trimble 5800 GPS real-time difference measurement system. The dislocation is (18.3±0.5)m. As the top geomorphologic surface between the above two gullies and their adjacent area, the terrace surface T2 stopped accepting deposits at ~2606a, based on the linear regression analysis of three dating data. According to the geological method, a sinistral strike-slip rate of (7.02±0.20)mm/a on the SSXF in the Holocene is obtained, which has a good consistency with the results provided by using GPS data. The preliminary results about the Holocene activity and slip rate of the SSXF demonstrate that the southward or south-southeast motion of the Sichuan-Yunnan block in the SE Yunnan region has not been absorbed by the possible shortening deformation and the sinistral strike-slip rate of the SSXF has not been drastically reduced. The SSXF is a Holocene fault with obvious activity. This preliminary understanding provides some basic geological data for the seismic risk evaluation of the SSXF in the future, and for the establishment and inspection of the seismotectonic model about the Sichuan-Yunnan block. 相似文献
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The relationship between the latest activity of active fault and seismic events is of the utmost importance. The Tan-lu fault zone in eastern China is a major fault zone, of which the active characteristics of the segments in Jiangsu, Shandong and Anhui has been the focus of research. This study takes the Dahongshan segment of the Tanlu Fault in Sihong County as the main research area. We carried out a detailed geological survey and excavated two trenches across the steep slope on the southwest side of the Dahongshan. Each trench shows fault clearly. Combining the comparative analysis of previous work, we identified and cataloged the late Quaternary deformation events and prehistoric earthquake relics, and analyzed the activity stages and behavior of this segment.
Fault gonge observed in the trench profiles shows that multiple earthquake events occurred in the fault. The faulting dislocated the Neogene sandstone, black gravel layer and gray clay layer. Brown clay layer is not broken. According to the relations of dislocated stratums, corresponding 14C and OSL samples were collected and dated. The result indicates that the Dahongshan segment of the Tanlu Fault has experienced strong earthquakes since the late Quaternary. Thrust fault, normal fault and strike-slip fault are found in the trenches. The microscopic analysis of slices from fault shows that there are many stick-creep events taking place in the area during the late Quaternary. Comprehensive analysis shows that there have been many paleoearthquakes in this region since the late Quaternary, the recent active time is the late Pleistocene, and the most recent earthquake event occurred in(12~2.5ka BP).
The neotectonic activity is relatively weak in the Anhui segment(south of the Huaihe River)of Tanlu fault zone. There are difficulties in the study of late Quaternary activity. For example, uneven distribution of the Quaternary, complex geological structure, larger man-made transformation of surface and so on. The progressive research may be able to promote the study on the activity of the Anhui segment of Tanlu fault zone. 相似文献
448.
郯庐断裂带山东段的中新生代构造演化特征 总被引:2,自引:0,他引:2
本文在总结郯庐断裂带的最新研究成果的基础上,对郯庐断裂带山东段深部构造特征、运动学特征和内部结构特征进行了分析,并对郯庐断裂带山东段的中新生代构造演化过程进行了研究。在华南华北碰撞造山时期,郯庐断裂带山东段发生了显著的左旋走滑剪切变形。郯庐断裂带山东段在晚侏罗至早始新世(50Ma前)的左旋走滑直接受控于古太平洋板块向东亚大陆的俯冲,板块俯冲边界的应力直接传递到郯庐断裂带导致其发生走滑运动;早白垩世中期至古近纪,郯庐断裂带山东段内部及两侧盆地的伸展则受控于深部岩石圈减薄、地幔底辟导致的裂陷作用。 相似文献
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针对Hough变换不能检测直线段的缺点,提出了一种改进的Hough变换用于影像中矩形建筑物的半自动提取。同传统Hough变换相比,改进的Hough变换充分利用了Hough变换的参数空间数据,将Hough变换的“投票”过程和直线段的检测过程融为一体,获得直线段的端点坐标。根据直线段的端点坐标消除虚假直线段的过连接,并根据直线段的角度、距离条件合并直线段。最后通过直线段上的若干点利用最小二乘法拟合出一条最佳直线,通过计算最佳直线的交点确定建筑物的角点坐标,完成影像中建筑物的半自动提取。实验结果表明:用改进的Hough变换算法提取出的航空影像中建筑物边缘结果是正确的,定位精度较高。 相似文献
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六盘山东麓断裂南段断裂沟槽韵律沉积特征对最新活动时代的限定 总被引:2,自引:0,他引:2
六盘山位于华北断块西部鄂尔多斯块体与青藏块体祁连断褶带之间的构造转换部位。前人对六盘山东麓断裂南段进行过一定程度的研究,根据地貌特征推断六盘山东麓断裂南段晚更新世以来不活动。根据断裂特征,大致可将六盘山东麓断裂划分为北段、中段和南段。活动断裂带上的断裂沟槽沉积物表现为由多个粗粒层与细粒层交替的韵律层序结构,韵律沉积特征与断裂活动有直接关系。在六盘山东麓断裂南段冶家村西发现一个断裂沟槽韵律沉积剖面,共鉴别出三期韵律沉积组合。通过分析认为本剖面所反映的韵律沉积特征应为构造成因。对断裂沟槽沉积物采样测年的结果表明,该段断层分别在约500 a BP后、6 ka BP后和15 ka BP前有过明显的地质活动。确认六盘山东麓断裂南段晚更新世以来有过多次活动,是一条活动断裂带。 相似文献