Temporal and spatial evolution of layered subsidence in Hengshui City and its response mechanism to environmental factors
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摘要: 受气候变化及人类活动的影响,衡水地区地下水资源常年处于超采状态,从而直接诱发了严重的地面沉降,这已成为该地区主要的地质灾害问题之一。本文以分层标监测获取的衡水市主城区2009年1月-2022年12月的累积沉降量作为基础,对三个压缩层位(从浅至深依次为F1、F2、F3层)的地面沉降机理进行分析和研究;首先用Gompertz模型分别拟合三个压缩层位的累积沉降量,对拟合结果进行一阶求导得到各层位的沉降速率,并以0.5mm做为阈值,得到各层位沉降生、沉降速率快速增长、沉降速率递减及沉降趋于稳定的时段;然后采用零生长(ZG)模型将各层位的沉降量区分为不可逆的沉降期(GRC)序列和可逆的回弹期(SWD)序列,分析沉降期和回弹期的波动特征;最后,采用线性混合模型(LMM)分析降水、蒸散发、浅层地下水位和深层地下水位等环境因子对各层位沉降期压实沉降 (GRC_rate)的贡献。结果表明:(1) 各层位的累积沉降量拟合曲线均呈“ S”形,沉降速率曲线呈单峰模式,并表现出“慢-快-慢”的趋势,各层位的主要沉降期开始时间、结束时间、累积沉降量和沉降速率均有所差异;(2)在累积沉降量和月沉降增量幅度上,整体呈现出F3层>F2层>F1层,在回弹幅度上,总体呈现F1层>F2、F3层;(3) 蒸散发和浅层地下水位对F1、F2层的压实沉降贡献最大,浅层地下水位和深层地下水位对F3层的压实沉降贡献最大。Abstract: [Objective]Affected by climate change and human activities, the groundwater resources in Hengshui area are in an over-exploited state all year round, which directly leads to severe ground subsidence, which has become one of the main geological disaster problems in this region. [Methods]Based on the accumulated settlement data of the main urban area of Hengshui City from January 2009 to December 2022 obtained from layered monitoring, this paper analyzes and studies the ground subsidence mechanism of three compression layers (F1, F2, F3 layers from shallow to deep). Firstly, the Gompertz model is used to fit the cumulative settlement of each compression layer. The first-order derivative of the fitting results is obtained to obtain the settlement rate of each layer. With 0.5mm as the threshold, the settlement growth, rapid settlement rate growth, slow settlement rate decline and stable settlement period of each layer are obtained. Then, the zero growth (ZG) model is used to divide the settlement of each layer into irreversible settlement period (GRC) sequence and reversible rebound period (SWD) sequence, and analyze the fluctuation characteristics of settlement and rebound periods. Finally, the linear mixed model (LMM) is used to analyze the contribution of environmental factors such as precipitation, evapotranspiration, shallow groundwater level and deep groundwater level to the compression settlement (GRC_rate) during each layer's settlement period. [Result]The results show that: (1) The cumulative settlement fitting curves of each layer show an "S" shape, and the settlement rate curve shows a single peak pattern, with a "slow-fast-slow" trend. The main settlement period start time, end time, cumulative settlement and settlement rate of each layer are different; (2) In terms of cumulative settlement and monthly settlement increment amplitude, F3 layer>F2 layer>F1 layer. In terms of rebound amplitude, F1 layer>F2, F3 layer; (3) Evapotranspiration and shallow groundwater level contribute most to the compression settlement of F1 and F2 layers, while shallow groundwater level and deep groundwater level contribute most to the compression settlement of F3 layer.
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Key words:
- layered settlement /
- settlement period /
- rebound period /
- contribution
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