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    地球物理方法在城市地质结构精细化探测中最优方法组合研究——以成都市天府新区为例

    The application effect of geophysical method in fine exploration of urban geological structure and study of optimal combination method: A case study of Tianfu New Area in Chengdu, Sichuan Province

    • 摘要:
      研究目的 成都市天府新区属于典型的西南红层地区,其地层结构呈泥岩、粉砂质泥岩、泥质粉砂岩、砂岩互层结构,不同岩性之间的物性差异相对较小,研究浅部地质结构探测方法,有利于实现城市三维精细地质模型的建立。
      研究方法 本文在成都天府新区4个典型试验区,采用多种新的和传统的地球物理方法开展了地质结构精细探测试验。
      研究结果 地质雷达、三分量频率共振具有较高的分辨率,其次是浅层地震勘探、高密度电阻率法、等值反磁通瞬变电磁法、微动勘探;地质雷达和等值反磁通瞬变电磁抗干扰能力最强,浅震、三分量共振、微动勘探受城市噪音干扰比较严重;采用地质雷达、三分量频率共振、高密度电阻率法、等值反磁通瞬变电磁法、浅层地震、微动勘探等方法进行组合探测,可以获得由浅至深不同深度范围内的地质结构分层。
      结论 通过对比分析每种方法的探测深度、分辨率、抗干扰强度、施工效率和经济成本,形成了适应于成都市天府新区不同工况、不同探测深度的地质结构精细探测地球物理方法最优组合方案。

       

      Abstract:
      This paper is the result of urban geological survey engineering.
      Objective Tianfu New Area (TNA) of Chengdu is characterized by a typical red stratigraphy in southwest China, including interbed sedimentary rocks of mudstone, silty mudstone, argillaceous siltstone and sandstone. The difference of physical property among the above rocks is minor. Clarifying the shallow geological structure by geophysical method is favor for constructing the fine three-dimensional geological model of TNA.
      Methods This paper attempts to image fine geological structure in 4 typical sites of TNA through a variety of new and traditional geophysical methods.
      Results Ground penetrating radar (GPR) and three component frequency resonance (TCFR) have higher imaging resolution than that of shallow seismic exploration (SSE), electrical resistivity tomography (ERT), opposing coils transient electromagnetic (OCTEM) and microtremor exploration (ME). Urban noise tends to affect field data quality in SSE, TCFR and ME, but not in GPR and OCTEM. Fine geological structure from shallow to deep depth can be obtained by method assembly for GPR, TCFR, ERT, OCTEM, SSE and ME.
      Conclusions Under comparing and analyzing the detection depth, resolution, anti-urban noise level, construction efficiency, and economic cost of the above methods, the optimal geophysical method assembly to detect fine geological structure with different construction conditions and exploration depths in TNA of Chengdu is summarized.

       

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