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据不完全统计,至今我国已有90余个城市和地区相继发生不同程度的地面沉降,长江、黄河、珠江三角洲、华北平原、松辽平原及沿海许多地区,地面沉降正在发生和发展之中,尤其以上海为中心的长江三角洲及以天津为中心的华北平原,成为我国两片最大的沉降地区。地面沉降对这些地区社会和经济的可持续发展带来严重影响。几十年来,这些地区一直将“调整地下水开采层次”作为控制地面沉降措施之一。该文章认为“调整地下水开采层次”并非一种理想的控沉措施,不仅值得商榷,甚至为应该被否定的控沉措施。依据:①一般情况下,随深度增加,地层的压缩性会渐下;但是开采同量的地下水,其水位下降的速率及幅度深部含水组比浅部含水组要大的多,两者引起的沉降量不会有明显的差别;②从地下水开采资源组成与地面沉降关系分析,含水层深度越深,其中的压密释水量所占的比例也越大,造成的地面沉降也越严重;③地层的物理力学性质及固结状态,随深度的增加,也不完全是越来越好。
According to incomplete statistics, up to now, more than 90 cities and areas in China have occurred land subsidence in varying degrees. The land subsidence is taking place in the Yangtze River, the Yellow River, the Pearl River Delta, the North China Plain, the Songliao Plain and many coastal areas. In particular, the Yangtze River Delta centered on Shanghai and the North China Plain centered around Tianjin have become the two largest subsidence areas in the country. Land subsidence has a serious impact on the social and economic sustainability of these areas. For decades, “adjusting the level of exploitation of groundwater” has been one of the measures taken to control ground subsidence in these areas. The article believes that “adjusting the level of exploitation of groundwater” is not an ideal control measures, not only open to question, or even control should be denied. According to: ① Under normal circumstances, as the depth increases, the compressibility of the formation will gradually decrease; However, the exploitation of the same amount of groundwater, the rate and amplitude of the water level decline in deep water than shallow water group is much larger, both caused There is no obvious difference between the settlement amount and the subsidence amount. (2) According to the analysis of the relationship between the composition of groundwater resources and the land subsidence, the deeper the aquifer depth is, the greater the proportion of the tight water discharge is and the more serious the land subsidence is. The physical and mechanical properties of strata and the consolidation state, with the depth increase, is not entirely better and better.