【作者】 胡建平；

【导师】 施斌；

【作者基本信息】 南京大学 ， 水文学及水资源， 2011， 博士

【摘要】 苏锡常地区由于长期过量开采深层地下水,引发了严重的区域性地面沉降和地裂缝灾害。为了控制苏锡常地区的地面沉降,1996年起,省、市政府采取压缩开采量20%的措施,2000年开始该地区实行了深层地下水的限期禁采,2005年底,禁采工作全面完成。禁采以后,从宏观上来看,地面沉降的控制取得了明显的成效,但如何从理论和机理上评价地下水禁采与地面沉降的关系以及地面沉降控制效果,是一个值得深入探讨的课题。本文结合实际观测资料和作者的本职工作,选择这一课题作为博士论文,开展了比较系统的研究工作,取得了一些新的认识和成果,主要表现在以下几个方面：1.系统分析总结了禁采前后地下水位降落漏斗、地面沉降的发生、发展和变化规律,在大量实测数据和分析成果的基础上,论证了地下水开采和地面沉降在时间上和空间上的相关性、一致性。研究表明,禁止开采后地面沉降发育程度具有明显的分区性。地下水补给条件好的地区地下水水位恢复快速,地面沉降减缓也很快,地面沉降滞后时间很短,不少地方甚至出现地面回弹现象,如广大的苏州东部地区和沿江地区。相反地下水补给条件差的地区,地下水位恢复很慢,虽然地面沉降速率也得到了显著控制,但沉降仍在继续,沉降具有明显的滞后作用,较为典型的是无锡西部地区和江阴南部地区。2.比较系统地分析了苏锡常地区地下水位与地面沉降的相互关系,进一步证明了地面沉降临界水位的存在,提出了沉降临界水位与地层中的前期固结压力间的关系。地面沉降临界水位的提出对于科学合理开发地下水资源和控制地面沉降具有重要意义。3.对苏锡常地区禁采地下水后的地面沉降机理进行了探讨,在对地面沉降与地质结构、水文地质条件的关系、沉降与土层承受过的应力历史的关系、沉降与水位关系的分析的基础上,提出了地面回弹概念,并指出地面回弹普遍发生在地下水位上升快速的区域,并且该处的地下水位埋深一般高于沉降临界水位。4.利用大量的监测资料对苏锡常地区原有的地面沉降——地下水流耦合数值模型进行了修正,并分别以禁采和适度开采两种方案对该地区地面沉降进行了预测；以地面沉降控制为约束条件,通过数值模拟获得了该地区的地下水可采资源量,提出了该地区地下水科学开发利用方案,划出了地下水可采区、限采区和禁采区,为今后苏锡常地区地下水合理开发利用和管理提供了科学依据。更多还原

【Abstract】 Long-term excessive deep groundwater withdraw has led to serious geological hazards of regional land subsidence and ground fissures in Suzhou-Wuxi-Changzhou area. In order to slow-down and control the regional land subsidence, the provincial and local government of Jiangsu had taken countermeasure of reducing groundwater pumping quantity by 20% each year since 1996, and the strict ban of the deep groundwater withdrawal has been undertaken within a given period since 2000. By the end of 2005, it has been finished to prohibit the deep groundwater withdrawal in Su-Xi-Chang area. Long term monitoring data show that significant achievement has been made on control of land subsidence from macro viewpoint in the research area, however, further and systematical research work has not been carried out on analyzing the relationship between banning of groundwater pumping and land subsidence, and evaluating the land subsidence effect and subsidence mechanism after Prohibiting Extraction of Groundwater. Based on large number of land subsidence measuring data, the author chooses the land subsidence effect after prohibiting extraction of groundwater in Suzhou- Wuxi- Changzhou area as dissertation research topic to study in detail the mechanism and developing law of land subsidence before and after the prohibition of groundwater withdrawal. Some valuable results are summarized as follows:1. It is analyzed and summarized in detail of the groundwater pumping, groundwater level, and the characteristics and trend of land subsidence before and after the ban of groundwater withdrawal. Based on the large amount of monitoring data and analytical results, it is proved that the relationship between the groundwater pumping and land subsidence is fully consistent in time and space. It is found that there exhibited obvious regionalization of the land subsidence development after ban of groundwater withdrawal. In the area that the groundwater table going up rapidly, the rate of land subsidence slowdown faster, and the time delay of land subsidence is shorter. Even the ground rebound occurred in some site, such as the area in east of Suzhou and near Yangtze River, in the area of better groundwater recharge. While in the area that groundwater recharge condition is bad, the groundwater table rises slowly, which delay is apparent, typically that in west region of Wuxi and south part of Jiangyin, so that the rate of land subsidence can obviously be controlled.2. The relationship between groundwater withdrawal and land subsidence in Su-Xi-Chang area is comprehensively and systematically analyzed. It is further proved that the critical groundwater table of land subsidence exists, and put forward that critical groundwater table is related to the pre-consolidation stress of soil layers, The existence of critical groundwater tablel of land subsidence has great significance in scientific and rational development of groundwater resources and land subsidence controlling.3. The mechanism of land subsidence in Su-Xi-Chang area is further discussed and studied after banning of groundwater pumping. On the basis of relationship analysis between land subsidence and geological structure and hydrogeological condition, and stress history of the strata, and the piezometric head of groundwater, the concept of ground rebound is put forward, which rebound occurred generally in the area of groundwater table rapidly rising, and the groundwater level of which is higher obviously than the critical groundwater level of subsidence.4. A large amount of measuring data in Su-Xi-Chang area is utilized to modify the existing coupled mathematical model of land subsidence and groundwater flow, and the prediction of regional land subsidence is given respectively by two plan of pumping-banning and appropriate pump of the groundwater. Taking land subsidence control as the constraint condition, the allowable groundwater resources of the area is calculated through the numerical modeling. Finally some suggestions and countermeasures have been proposed such as a scientific development scheme of groundwater, zoning of the reasonable groundwater pumping area such as limited extracting zone and prohibited extracting zone. The research achievement of this dissertation provides a scientific basis for the rational development, utilization and management of groundwater in Su-Xi-Chang area.更多还原