胶东半岛现今地应力特征与分布预测

Characteristics and distribution prediction of present-day in-situ stress field in the Jiaodong Peninsula

现今地应力对区域地质稳定性分析、油气资源勘探开发以及矿床开采等方面具有重要意义。本研究在前人实测地应力数据的约束下,分析现今地应力与深度关系,构建有限元数值模型,揭示现今地应力分布规律及应力机制,结果表明:(1)胶州半岛现今地应力方向具有WNW-ESE优势方位,三轴主应力均为挤压应力,呈现S_(Hmax)>S_(v)>S_(hmin)大小关系,表明现今地应力为走滑型应力机制,侧压系数为0.92~1.70,反映以水平应力为主导的现今地应力状态。(2)胶东半岛内隆起区的现今地应力值相对较高,断层带和盆地区地应力值较低,其主要受岩性、断层等差异发育分布控制。(3)胶东半岛现今地应力状态受太平洋板块、欧亚板块以及菲律宾板块之间相互作用控制,应力具地表值小、梯度大的特点,近地表水平构造作用较弱。研究结果可为胶东半岛地质稳定评价、矿区安全建设与开采提供地质参考。

The present-day in-situ stress field indicates great implications for regional geological stability analysis,oil and gas exploration and development,and mine exploitation.In this study,the relationship between present-day in-situ stress and depth was analyzed based on previous measured stress data.The distribution of in-situ stresses and stress regime were analyzed according to the established finite element numerical models.The results indicate:(1)The dominant present-day in-situ stress orientation is WNW-ESE in the Jiaodong Peninsula.The horizontal maximum principal stress(S_(Hmax)),horizontal minimum principal stress(S_(hmin))and vertical stress(Sv)are all indicative of compressional stress,and follow the relation S_(Hmax)>S_(v)>S_(hmin),indicating a strike-slip faulting stress regime.The stress lateral coefficient ranges between 0.92 and 1.70,suggesting that horizontal stresses are the dominant in the Jiaodong Peninsula.(2)In the uplift zones of Jiaodong Peninsula,stress magnitudes are relatively high,while in basin zones and fault belts,the stress values are low,which is largely controlled by lithol⁃ogy difference and fault distribution.(3)The present-day in-situ stress state in the Jiaodong Peninsula is controlled by multiple actions among the Pacific Plate,Eurasian Plate and Philippine Plate.Stress magnitudes are low near the surface,but the gradient is high,indicating that the action of horizontal stress is weak around the ground surface.The results can provide geological references for geological stability assessment and mine safety construction and exploitation.