渤海海峡地应力场研究及地质条件评价

In-Situ Stress Field and Geological Analysis of Bohai Trait

查明渤海海峡处现今地应力状态及断层活动状况,可为渤海海峡跨海通道建设提供科学依据。在通道中轴线上布设6个浅钻钻孔,进行了7个测点的空芯包体地应力测量工作。对测量数据分析后,认为海峡区最大水平主应力、最小水平主应力与垂直主应力均随深度的增加而线性增大;最大水平主应力大于垂直应力,区域内构造力处于主导地位;各测点处均有两个主应力位于近水平方向,其与水平面的夹角平均为7.8°;研究区内地应力各分量值之间相差不大,远远小于区内断层活动应力值的下限,研究区目前处于稳定状态。区域横向上看,海峡区南部地壳浅部的应力状态为σH>σh>σv,有利于逆断层活动,北部的应力状态为σH>σv>σh,有利于走滑断层活动;垂向上看,70m以上的各点应力值受地形影响较大,-70^-130m处的各点处于挤压应力状态中。整个区域处于NE-NEE向的挤压应力场中,在区域应力场的作用下,郯庐断裂带运动状态为右旋压扭,蓬莱-威海断裂带为左旋压扭,黄河口-庙西北断裂带处于拉张走滑运动状态中。

To identify the current state of stress and the active status of fault in Bohai Strait can serve the Bohai strait tunnel construction.Six shallow drilling holes were layouted in the channel axis,and the hollow inclusion stress measurement of seven points was carried in the holes.Based on the analysis of the measurement data,we find that the maximum horizontal principle stress,the minimum horizontal principle stress and vertical principle stress both linearly increases with depth;the maximum horizontal principle stress is higher than the vertical principle stress,and the tectonic stress is outstanding in the region;two principal stress of each measuring point is located near the horizontal plane,the average horizontal angle is 7.8degrees;the difference of stress component values is moderate,and far less than the critical value that can cause fault slip activity,so research area is stable.On horizontal perspective,the stress state of south region in Bohai strait isσH〉 σh〉σv,can conductive thrust fault;the north region isσH 〉σv〉σh,can cause strike slip fault.On vertical perspective,the stress of points above-70 m can affected by topography,the points between-70mand-130 mis in the extrusion stress state.The whole region is in the NE-NEE compressive stress field,the motion state of the Tanlu fault zone is in dextral compressor shear state,Penglai-Weihai fault zone is in sinistral compressor shear state,and Yellow River-MiaoXibei fault zone is in extensional strike slip motion state.