川藏铁路金沙江结合带地壳构造动力学效应

The Crustal Tectonic Dynamic Effects of Jinshajiang Combination Zone of Sichuan-Tibet Railway

研究目的:金沙江结合带是川藏铁路必经的超岩石圈断裂,其地壳岩体的应力-形变特征等构造动力学问题,极大地影响和制约着铁道工程。笔者通过对该结合带地质建造-构造特征的现场调查与研究,结合区域地球物理及深部构造资料,建立结合带地壳结构的地质-力学概念模型。采用ANSYS有限元数值模拟方法,分析其地壳岩体应力-应变场特征,进而探讨由此引发的工程效应。研究结论:(1)川藏铁路跨越的是一条以强烈挤压为主的逆冲断裂带;(2)地壳深部两条高导软弱层,以类似'传送带'的动力模式带动上部岩体向NE运移;(3)结合带西侧岩浆岩对结合带的地壳岩体的应力和形变起着一定的'屏蔽'作用;(4)结合带对铁道工程的影响主要是NE向压缩变形、西侧岩浆岩区段隧道工程的高地应力问题以及结合带东侧软岩的大变形问题;(5)本研究成果可应用于川藏铁路等类似铁路的规划与设计。

Research purposes： Jinshajiang combination zone is a lithosphere fracture belt that Sichuan -Tibet railway can not avoid. The activity and stress - strain of crustal rock in fault zone have constrained the railway engineering seriously. Based on field investigation on geology -tectonic features and earthequake, combining regional geophysical and deep tectonic information, a geomeehanics conceptual model of crustal structure of Jinshajiang combination zone was established. The stress, strain and deformation characteristics were analyzed by using ANSYS finite element numerical simulation method. Research conclusions： （ 1 ） Jinshajiang combination zone is a reverse fault with strong compressive property. （2） Two high -conductivity weak layers in the crust flow to NE driving upper rock, forming a dynamic model like ＂ conveyor belt＂. （3）The magmatite on the west of Jinshajiang combination zone breaks the crustal horizontal continuity, plays a shielding role in the stress and movement of crust. （4）The effects of combination zone on railway engineering were compressive deformation along NE, high ground stress of tunnel in the magmatite region, and large deformation of soft rock on the east of combination zone. （5） The research results can be applied to planning and design of Sichuan - Tibet railway and other similar railways.