三峡二期工程蓄水后的垂直形变场

根据三峡地区的数字高程模型(DEM)，模拟三峡二期工程蓄水位达到135m后的水体负载，利用Farrell提出的质量负荷产生的地球形变理论，推算三峡水库水位达到135m后整个库区的垂直形变，与三峡库区GPS形变监测网获得的蓄水前后的垂直形变图像进行对比分析，结果显示：在三斗坪-巴东库段，两者中都出现了3个相同的、明显的垂直形变集中区。在三峡大坝附近，模拟结果比观测结果大8～15mm，说明坝址附近的花岗岩具有较强的刚性；而在香溪，模拟结果比观测结果要小23mm，且GPS观测到长江两岸的垂直变化差异达到22mm，说明该段地质构造的特殊性和复杂性。综合分析表明，三峡大坝坝址所在地的地质构造和地壳是稳定的。

VERTICAL DEFORMATION AFTER FIRST IMPOUNDMENT OF THREE GORGES PROJECT

In the light of the digital elevation model of the Three Gorges region, the water loading was simulated, which describes the status after the first impoundment water level at 135 m. The vertical deformation of the Three Gorges area was calculated according to the Farrell's globosity deformation theory. Comparing these calculated results with those surveyed by GPS monitoring network of the Three Gorges Reservoir's crustal deformation, we found that in both the results there are three similar and obvious vertical changes areas between Sandoupin and Badong.Near the dam the vertical deformation value is 15 mm larger than GPS results,which shows that the granite structure has strong rigidity in this area. The vertical subsidence value in Xiangxi is 23 mm less than the observed. the GPS results also show that the deformation difference between two bank of the Yangtze River is 22 mm, which reveals the geological structure is especial and complex in this area.Integrated analysis imply that the geological structure and crustal activity at the Three Gorges Dam Area is stable.