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1.
苏锡常地区地裂缝形成过程 总被引：8，自引：5，他引：8
苏锡常平原自1989年以来,已有18处发生地裂缝,其中横林、长泾、无锡西郊等6处先后进行了地裂缝勘查工作。本文在苏锡常地区已有的水文地质、工程地质资料和地裂缝灾害勘查成果的基础上,分析了基岩面起伏、地面沉降、土层结构等因素对地裂缝的复合作用及影响方式,对苏锡常地区地裂缝灾害的成因及形成过程进行了较为全面的总结。苏锡常地区的地裂缝主要是地面不均匀沉降的结果,基岩面起伏变化较大为地裂缝孕育了内因条件,超量开采地下水是诱发地裂缝的直接原因,30m以浅的土层条件则影响了地裂缝发育程度。 相似文献
2.
苏锡常地裂缝危险性分区 总被引：1，自引：0，他引：1
地裂缝作为苏锡常地区的一种地质灾害对该区的发展造成了严重危害。由于地裂缝孕育过程的非线性以及各影响因素作用关系的复杂性,使得难以用线性方法进行地裂缝危险性分区。在分析地裂缝发生的主要影响因素--古基岩面的起伏差异、第四纪沉积结构差异、地面沉降的不均一性和地下水的超采的基础上,将该4个因素的6项量化指标--基岩埋深、基岩起伏度、地下水位、地面沉降梯度、含水层导水系数以及粘性土层厚度作为输入量,采用遗传人工神经网络算法,建立了苏锡常地区地裂缝危险性分区模型。结果表明,苏锡常地区地裂缝危险区主要分布在常州东部、无锡中部和江阴南部地段,安全区主要分布在张家港的东北部、常熟市的东部、常州市的北部和西南部,较危险区和次安全区为危险区和安全区的过渡区。 相似文献
3.
苏锡常地区是我国地裂缝地质灾害重灾区之一,给当地群众的生产生活造成了巨大的经济损失。利用灰色关联度理论对苏锡常地区地裂缝进行了分析。通过分析苏锡常地区地裂缝形成条件,选取基岩埋深、基岩面起伏度、第Ⅱ承压含水层厚度、黏性土层厚度、主采层水位埋深、地面沉降梯度作为影响因子指标,计算了各个影响因子的关联程度和影响权重,对整个苏锡常地区地裂缝进行危险性分区。根据区划结果,划分出地裂缝的安全区、过渡区、较危险区以及危险区。通过灰色关联度理论对苏锡常地裂缝分析,达到了对该区地裂缝发育影响因素量化的目的,为地裂缝灾害防治工作提供一定的理论依据。 相似文献
4.
由于长期过量开采地下水,苏州、无锡和常州（苏锡常）的局部地区地裂缝发育,在深层地下水禁采十多年后的今天有些地裂缝还在发展。地裂缝的发育及发展受到诸多因素的影响,其具体力学机制尚不明确。为了查明影响地裂缝发育的因素、确定各因素对地裂缝的影响程度,本文在苏锡常地裂缝发育现状的基础上,利用基于确定性系数计算权重法对苏锡常地裂缝发育危险性进行预测分区。模型考虑了基岩埋深、基岩坡度、累计地面沉降量、沉降坡度、第二含水层厚度、第二含水层厚度变化梯度、第二含水层水位降深、第四纪沉积相等8个主要影响因素,分析结果显示苏锡常地区北部地裂缝易发,东南部发生地裂缝的危险性较小。计算结果与苏锡常地裂缝的分布及发育情况基本一致,验证了该方法在地裂缝预测方面的有效性。本研究对苏锡常地区地下水开采及城市建设规划具有一定的指导意义。 相似文献
5.
6.
苏锡常地区主要地质灾害及防治措施 总被引：1，自引：0，他引：1
汪名鹏 《中国地质灾害与防治学报》2009,20(1):60-65
自20世纪80年代初以来,苏锡常地区由于超量开采深层地下水,相继出现了地面沉降、地裂缝等地质灾害,已造成了大量的经济损失,成为影响本地区经济社会发展的重要制约因素。本文在分析苏锡常地区地质环境条件的基础上,总结出本地区地质灾害主要类型、分布特征以及形成条件等,并对人类活动可能遭受地质灾害的危险性进行分析,进而提出地质灾害的防治措施。 相似文献
7.
基于ANN的苏锡常地裂缝预测研究 总被引：5，自引：0，他引：5
伴随着地面沉降灾害的发生,地裂缝作为一种新的地质灾害出现在苏锡常平原上,已有十多年历史,给地区发展造成严重危害。作者在较详细地阐述区域地质背景基础上,着重分析了地下水位和地面沉降在地裂缝形成中的作用。确定了“起伏的基底外加地下水位和地面沉降作用”这一地裂缝成灾模式。研究认为地裂缝的发生与地下水及地面沉降之间不存在简单的线性关系。而是二者共同作用的结果,同时需要有量的配合。初步确定了水位埋深50m,地面沉降量达500mm这样一个苏锡常地区地裂缝的易发环境。通过文章的研究,使得苏锡常地区地裂缝的产生机制更加清晰。文中一些定性和半定量的分析结论将对该地区地裂缝防治区划产生指导作用。 相似文献
8.
平原区超采地下水引发的地面沉降地质灾害已成为影响这些地区经济可持续发展的重要因素,风险管理是实现灾害防治从被动应对向主动防御转变的标志。根据地面沉降地质灾害自身特点,从其易发性、易损性和抗风险能力三方面进行分析评价,初步构建了地面沉降风险评价指标体系,介绍了常用的数学模型方法和空间分析技术,最后以苏锡常地区为例进行了实例研究。结果表明,决定当前地面沉降区风险分布的首要因素是地区经济发展水平,就相同级别的地面沉降而言,其对经济发达地区所造成的侵害要高于经济欠发达地区;其次才是地面沉降灾害发生程度。由此建议加大抗灾投入,增强区域风险抵御能力。 相似文献
9.
基于GA-ANN的苏锡常地裂缝危险性评价 总被引：4，自引：1，他引：3
文章以苏锡常地区地裂缝危险性评价为例,利用遗传算法(GA)对人工神经网络(ANN)进行改进,先用GA优化BP网络初始权重,再用BP算法修改网络权重,实现不同尺度的同步调整。选择30点的不同地质条件组成样本对所建模型进行训练,评价指标包括:基岩埋深、基岩起伏度、地下水位、地面沉降梯度、含水层导水系数和粘性土层厚度。经过500次GA迭代,得到苏锡常地区地裂缝ANN模型的最佳权重组合,该耦合模型能对全区地裂缝地质条件进行正确分类,精度接近1‰。 相似文献
10.
江阴市河塘镇法裂缝灾害成因分析及防治对策 总被引：2，自引：1，他引：1
苏锡常地区地面沉降及地裂缝灾害较为严重,尤其是地裂缝造成的危害较为明显。本文通过对江阴市河塘镇地裂缝分布区地勘查,从地质条件及人为辞去两方面剖析了地裂缝的形成原因、发展趋势及相应对策,并对地质灾害的勘查工作提出方向性建议。 相似文献
11.
Excessive groundwater withdrawal from an aquifer system leads to three-dimensional displacement, causing changes in the states of stress and strain. Often, land subsidence and sometimes earth fissures ensue. Field investigation indicates that land subsidence and earth fissures in Wuxi, a city in eastern China, are mainly due to excessive groundwater withdrawal, and that they are temporally and spatially related to groundwater pumping. Groundwater withdrawal may cause tensile strain to develop in aquifer systems, but tensile strain does not definitely mean tensile stress. Where earth fissures are concerned, the stress state should be adopted in numerical simulations instead of the strain state and displacement. The numerical simulation undertaken for the Wuxi area shows that the zone of tensile strain occupies a large area on the ground surface; nevertheless, the zone of tensile stress is very limited. The zone of tensile stress often occurs near the ground surface, beneath which the depth to the bedrock surface is relatively small and has considerable variability. Earth fissures often initiate near the ground surface where tensile stress occurs. Tensile stress and earth fissures rarely develop at the centers of land subsidence bowls, where compressive stress is dominant. 相似文献
12.
Earth Fissuring and Land Subsidence in Western Saudi Arabia 总被引：4，自引：0，他引：4
The present investigation deals with the engineering geological evaluation of earth fissuring associated with land subsidence in Wadi Al-Yutamah. The investigations include surface mapping and sampling, in situ and laboratory soil testing, water well inventory, geophysical survey, and monitoring of open fissures and the level of the wadi floor.The earth fissures in the area developed as a result of land subsidence due to man-induced water level declines caused by pumping water from the wadi aquifer above a safe yield. This situation has produced a compaction of underlying unconsolidated sediments and formed hair fissures above ridges and steps of buried surface bedrock. These hair fissures enlarged later after flood erosion and possible enhancement with hydrocompaction.The wadi soil in the study area consists mainly of silt of low plasticity, low density and high void ratio and it was classified as loess like material and collapsing soil. The settlement in the area is greatly increased by excessive wetting under constant pressures. The calculated coefficients of subsidence (collapse) show that the wadi soils were considered to pose moderate problems when wetted.Monitoring of the existing open earth fissures using extensometers indicates that the width of the fissure increases after flooding or rain falls. Monitoring of the ground level using GPS techniques, shows a good relation between the declination of the water table and the subsidence of the ground of the wadi floor. 相似文献
13.
Earth fissures triggered by groundwater withdrawal and coupled by geological structures in Jiangsu Province,China 总被引：3，自引：0，他引：3
Earth fissures in Jiangsu Province, China have caused serious damages to properties, farmlands, and infrastructures and adversely
affected the local or regional economic development. Under the geological and environmental background in Jiangsu Province,
this paper presents the earth fissures caused by excessive groundwater withdrawal and coupled by distinctive geological structures
such as Ancient Yellow River Fault in Xuzhou karst area, and Ancient Yangtze River Course and bedrock hills in Suzhou, Wuxi,
and Changzhou area. Although all the earth fissures are triggered by groundwater exploitation, the characteristics are strongly
affected by the specific geological and hydrogeological settings. In particular, in the water-thirsty Xuzhou city, the cone
of depression caused by groundwater extraction enlarged nearly 20 times and the piezometric head of groundwater declined 17 m
over a decade. As groundwater is extracted from the shallowly buried karst strata in the Ancient Yellow River Fault zone,
the development of earth fissures is highly associated with the development of karstic cavities and sinkholes and their distribution
is controlled by the Ancient Yellow River Fault with all the 17 sinkholes on the fault. On the other hand, in the rapidly
developing Southern Jiangsu Province, groundwater is mainly pumped from the second confined aquifer in the Quaternary, which
is distributed neither homogeneously nor isotropically. The second confined aquifer comprises more than 50 m thick sand over
the Ancient Yangtze River Course, but this layer may completely miss on the riverbank and bedrock hills. With a typical drawdown
rate of 4–6 m per annum, the piezometric head of groundwater in the second confined aquifer has declined 76 m at Maocunyuan
since 1970s and 40 m at Changjing since mid-1980s, and a large land subsidence, e.g., 1,100 mm at Maocunyuan, is triggered.
Coupled with the dramatic change of the bedrock topography that was revealed through traditional geological drilling and modern
seismic reflection methods, the geological-structure-controlled differential settlement and earth fissures are phenomenal
in this area. 相似文献
14.
G. Y. Wang Greg Guanlin You B. Shi S. L. Wu J. Q. Wu 《Environmental Earth Sciences》2010,61(5):1085-1093
Jiangyin County is in the infamous Su–Xi–Chang land subsidence area caused by excessive groundwater withdrawal in Jiangsu
province, China. The maximum accumulated land subsidence reached 1,310 mm near the centre of the subsiding trough in 2006
in southern Jiangyin, and earth fissures of significant vertical offsets have been observed at Changjing, Hetang and Wenlin
which form an arc towards the subsidence trough. An ancient Yangtze River course is found underlying and passing through the
depression in southern Jiangyin, forming a local basin surrounded by outcropped bedrock ridges in the north and south. The
Quaternary stratigraphy demonstrates significant heterogeneities in the basin; the second confined aquifer is much thicker
and deeper and encapsulated inside the basin and absent above the ridges. The development of earth fissures along the Changjing–Hetang–Wenlin
arc might be a combination of an inward rotation of sediments due to a large differential subsidence, an inward movement driven
by seepage force and a steeper slope along the south-eastern shoulder of the basin that facilitates the development of horizontal
tensile strain and/or shear strain necessary for fissuring. The land subsidence has slowed down and no new earth fissure zone
has occurred in the area after the banning of deep groundwater extraction was enacted in 2001. 相似文献
15.
Land subsidence and earth fissures due to groundwater withdrawal in the Southern Yangtse Delta,China 总被引：1，自引：0，他引：1
Yun Zhang Yu-Qun Xue Ji-Chun Wu Jun Yu Zi-Xin Wei Qin-Fen Li 《Environmental Geology》2008,55(4):751-762
Excessive extraction of groundwater has caused severe land subsidence and earth fissures in the Southern Yangtse Delta, China.
Based on field data, the temporal and spatial distribution of land subsidence is investigated and the causes for earth fissures
are analyzed. The areal distribution of the land subsidence is closely related to the cones of depression in the main exploited
aquifers. The compaction of a hydrostratigraphic unit depends on its mechanical behavior, thickness, compressibility, and
the piezometric level changing. The primary subsidence layers in Shanghai have been the first aquitard before 1990 and the
third confined aquifer since then. But the second aquitard unit was the primary subsidence layer in Changzhou. Earth fissures,
trending in several directions, occurred in the Husu tectonic zone. They were mainly caused by differential subsidence and
horizontal displacement that resulted from tensile stress and shear stress in units. The majority of fissures in the study
area are tensile. 相似文献
16.
Earth fissures in Jiangsu Province,China and geological investigation of Hetang earth fissure 总被引：1，自引：0，他引：1
Earth fissures are a geohazard in Jiangsu Province, China. They can be caused by earthquakes and active faults, underground
mining, groundwater extraction and landslides. In order to establish a provincial rehabilitation plan in Jiangsu, a range
of monitoring programs, surveys, geological investigations and modeling have been implemented or planned. One of the focuses
of the project is the land subsidence and earth fissures caused by excessive groundwater withdrawal in Suzhou, Wuxi and Changzhou
(Su-Xi-Chang) area, southern Jiangsu Province. Hetang earth fissure within the Su-Xi-Chang area was first reported in 1995
and a series of investigation has been conducted since then. The site investigations and geophysical survey in 1997 have recognized
the causative factor as the excessive groundwater drawdown coupled by the underlying bedrock ridge. An open trench excavation
in 2007 and a plane strain analysis suggest that Hetang earth fissures may have cracked from the bedrock ridge to ground surface.
Geological drilling in 2007 has further confirmed the existence and configuration of the ridge and extracted soil samples
for laboratory tests to obtain soil parameters for numerical analyses and modeling of land subsidence and earth fissures in
the Su-Xi-Chang area, Jiangsu, China. The laboratory tests are currently in progress and the result of numerical analyses
and modeling is expected to be presented in the near future. 相似文献