| Fenman, as China's first large-scale hydropower hydropower, Dam has been 60 years running, Basically reached the technical life length. Existing low intensity, overall poor, large amount of outstanding problems such as leakage, seriously affecting the plant's safe and reliable operation. In order to fundamentally solve the problems the dam to ensure dam safe and reliable operation and carry out a comprehensive reinforcement Fengman power plant dam project, we have studied on the activity of earthquake and stability of structure about the Fenman dam project.一,Regional seismic tectonic environmentBy analyzing the tectonic setting, geophysical field characteristics, the regional seismic tectonic activity, research Fengman dam regional stability conditions for the Delineation of structural basis for providing the earthquake.The major earthquake in the region in the north-east region, this area Quaternary tectonic activity since the approach to the differences in the main lifting movement, the modern role of subduction led to depression, but also the displacement caused by fault activity. Main seismotectonic: Songliao basin around the fracture, Icho fault, Dunhua - Mishan fault, north-west to the second Songhua River fracture. On the region, the 5 level and above in the strong earthquake frequency and intensity is not high, but most of the major earthquakes along the fault distribution, mainly in the following salient features:1,Earthquake activity along the Great Rift Valley with a large fault zone distribution, such as an earthquake along the Yilan - Yitong fault occurred in 1937, Jilin gangyao 5.0 earthquake.2,Earthquake occurred in the gravity and magnetic field or the Moho gradient zone and the corner, The intersection of the linear anomalies in different directions, as well as the junction of different forms of abnormal, Such as the eastern slope of Songliao Basin, Here is the gravity, aeromagnetic anomalies in a complex area.3,Faulted basins around the fracture,Cross Songliao Basin and Yilan - Yitong graben of NW-trending fault,The intersection of active faults inflection point at the strong earthquake prone, Today small earthquakes are frequent.4,Songliao basin, and in 1119 Qianguo 6 3/4 Earthquake Area in terms of geological structureSince 2003, Matsubara northern areas, small earthquakes are frequent, Earthquake swarm occurred on several occasions, Maximum earthquake is 3.5. Show that seismic activity within the Songliao Basin has been enhanced.Overall, the existence of regional earthquake occurred about six geological conditions.Correlation studies have shown that The occurrence of strong earthquakes the largest possible lots of different directions of the intersection of active tectonic zones.The active fault in the, North-west to the second Songhua River fault with the north-east to Yilan - Yitong fault-, Songliao Basin, eastern margin of the fracture, Dunhua - Mishan fault zone in the modern tectonic stress field under the action of, Strong earthquakes are a potential danger zone, this delineation of potential seismic sources of work are taken into account the characteristics of these structures.The seismic activity, seismic conditions, geological structure and geophysical changes in the market is divided into a potential source area basis.二,Regional seismic activityThrough the project site is located on seismic activity in the region in space and time distribution of characteristics, historical earthquake sites to conduct analysis of the effects of, For the Delineation and seismic activity to provide a reliable basis for parameter estimation.1. The study area including the earthquake zone in the Northeast and North China earthquake zone of south-east of the northeast. Within the study area light source, less strong earthquake, Since the year 1119 so far, Only eight times in the strong earthquake records, 8 mid-strong earthquake occurred four times more than 5 earthquake, the largest earthquake of 1119, Jilin Qianguo 6 3/4 earthquake.Seismic activity controlled by regional faults, which have obvious non-uniform spatial distribution characteristics.2. Northeast earthquake area: Northeast China is located in the northeast border of China's history to Kuang were rare, so the historical seismic data is obviously insufficient, So difficult to be carved out of the statistical significant seismic zone, and therefore correlation analysis of earthquake zone will be the northeast seismic belt as a unified analysis. Northeast earthquake zone is a relatively small area of shallow earthquakes, seismic activity is characterized by six or more relatively small number of shallow earthquake, more than five-strong earthquakes along the fault and fracture junction of a larger place, the largest earthquake for the 1119 Jilin Qianguo 6 3/4 earthquake. The last century, 70 years since the establishment of stations and networks, the recorded small earthquakes are frequent, mostly in the North East and North-west-trending fault and its interchanges.Northeast Seismic Zone earthquakes are unevenly distributed over time, the earthquake took place alternating quiet and active period of the Northeast earthquake zone of the seismically active period of about 20 years or so, the Northeast has entered another active earthquake zone section.3. In North China seismic zone earthquake zone Tanlu : Tanlu seismic belt and the Tan-Lu fault zone Spread broadly consistent with the scope, is the strongest earthquake activity in eastern China's earthquake zone. The Tan-Lu Fault Zone developed a long history, large-scale across the different geological units, with a significant section of. The distribution of seismic activity are also the corresponding section of.Of time, seismic activity with 300 years of activity cycle, the study area in North China earthquake zone while the south, but the entire North China earthquake zone and the relative Tanlu weak seismic activity seismic zone.However, affected, seismic activity within the study area in recent decades to a century may still be in third during that period.4. Historical earthquakes on the site of the most influential is the 1119 Jilin Qianguo 6 3/4-class, in 1937 Jilin gangyao 5.0 and 1960 Jilin elm 5.8 earthquake, the greatest impact of V degree of intensity.5. Through the eastern part of Liaoning, Jilin tectonic stress field in south-central region, characteristics of study found in North China, Northeast earthquake focal mechanism solutions are basically the same.The study area of maximum principal compressive stress direction of NEE-SWW direction in the NEE-SWW direction of maximum principal compressive stress (average P-axis) and the NNW-SSE direction of minimum principal compressive stress (average T-axis) under, NNE, and NWW 2 directions on the faults of the most vulnerable to the activities of the study area tectonic earthquakes in the two directions is easy to produce rock fracture and dislocation.三,Near-field seismic activity and seismic structural evaluation of Of engineering site as the center, a radius of not less than 25Km range as the near-field zone, the near-field zone of E126.37°-127.00°, N 43.49°-43.94°. Near-field region to study the seismic structure on the basis of field visits, with reference to 1:20 million regional geological investigation report and other results of the work. The main purpose of this chapter is to study the near-field area and the venues fault activity for the division of potential source areas and provide a basis for seismic response analysis of soil.Near-field zone faults, mainly the north east and north-west to the two sets of faults, including the north west of the Second Songhua River as the main fault rupture. These faults cross-cut each other constitute a more complex geological tectonic background.North-west to the second Songhua River fault to what is found in two sites Department, in the region, a length of about 51Km. On the whole, the fracture was 330°-340°North-West to the extension of the fault is an activity in the Pleistocene, the fracture had not seen signs of activity since the late Pleistocene. Venue not found fault since the Late Pleistocene. |
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