余姚慈溪养殖场地坪余姚慈溪港口地坪  <联系电话:400-0709-910>

Ground subsidence points tectonic subsidence, settlement and mined-settlement pumping three types.

(1) tectonic subsidence, ground motion caused by the crustal subsidence subsidence phenomenon;
(2) pumping settlement, due to excessive pumping of groundwater (or oil and gas) caused by water (or oil pressure) fall in the less consolidated or semi-consolidated soil distribution, soil compaction caused by the consolidation of large area of ground subsidence phenomenon;
Shanghai County Ground sedigraph
Shanghai County Ground sedigraph
(3) Mined settlement, dish-shaped depressions ground due to underground phenomenon caused big gob of roof (soil) caused by subsidence. Ground subsidence appeared more cities in China.
Press the occurrence of land subsidence geological environment can be divided into three modes:
1, modern alluvial plain models, such as Chinas major plains.
2, delta plain pattern, especially in the modern alluvial delta plains, such as the Yangtze River Delta fall into this category. Changzhou, Wuxi, Suzhou, Jiaxing, Xiaoshan land subsidence occurred in this geological environment.
3, rift basin model, which can be divided into coastal and inland formula type categories. Offshore formula refers to the coastal plain, such as Ningbo; and inland lake alluvial plain style was like Xian, Datong land subsidence as a representative.
3 Causes
Editor

A large area of ground subsidence phenomenon. Land subsidence caused by natural factors is natural tectonic movement of the Earths crust and surface soil
Cartoon
Cartoon
Compaction; artificial extensive land subsidence occurs in some cities a lot of exploitation of groundwater and oil or gas exploration area. Ground subsidence patterns different geological environments have different rules and characteristics, in terms of research methods and forecasting models should also be different.
In addition, according to the reasons of land subsidence occurred can be divided into: (1) pumping ground subsidence caused by groundwater; ground (2) mining of solid minerals caused by subsidence; the ground (3) exploitation of petroleum and natural gas caused by subsidence; (4) Ground subsidence caused by pumping brine; ground (5) ground construction as subsidence caused by underground construction.
4 impact
Editor

Ground subsidence hazards are:
(1) destruction of buildings and production facilities;
(2) is not conducive to the construction and resource development. Area of land subsidence occurred belonging strata unstable zone, during the urban construction and resources development, the need for more capital investment, and the production capacity is limited;
(3) caused by salt water intrusion. Ground subsidence area and more in the coastal zone. Close to the sea when land subsidence, saltwater intrusion will occur, so that the soil and groundwater salinization. Prevention of land subsidence is mainly engineering and take appropriate measures to address the different causes land subsidence.
Ground subsidence will cause harm surface or underground structures; seawater intrusion in coastal areas can cause, harbor facilities failure and other adverse consequences. Anthropogenic land subsidence is mainly mined underground excess liquid or gas, resulting in the storage of these fluids, decreasing trend of pore pressure gas deposits occur, effective stress increase accordingly, resulting in the formation of compaction. Based on the above mechanism, Shanghai in 1965, the use of artificial recharge methods to make the water table to rise, the ground part of the rebound, the more successful control of ground subsidence.

地面沉降分构造沉降、抽水沉降和采空沉降三种类型。
(1) 构造沉降，由地壳沉降运动引起的地面下沉现象；
(2) 抽水沉降，由于过抽汲地下水（或油、气）引起水位（或油、气压）下降，在欠固结或半固结土层分布区，土层固结压密而造成的大面积地面下沉现象；
上海县地面沉降图
上海县地面沉降图
(3) 采空沉降，因地下大面积采空引起顶板岩（土）体下沉而造成的地面碟状洼地现象。　中国出现的地面沉降的城市较多。
按发生地面沉降的地环境可分为三种模式：
1、现代冲积平原模式，如中国的几大平原。
2、三角洲平原模式，尤其是在现代冲积三角洲平原地区，如长江三角洲就属于这种类型。常州、无锡、苏州、嘉兴、萧山的地面沉降均发生在这种地环境中。
3、断陷盆地模式，它又可分为近海式和内陆式两类。近海式指滨海平原，如宁波；而内陆式则为湖冲积平原，如西安市、大同市的地面沉降可作为代表。
3形成原因
编辑

大面积的地面下沉现象。造成地面沉降的自然因素是地壳的构造运动和地表土壤的自然
漫画
漫画
压实；人为的地面沉降广泛见于一些大开采地下水的大城市和石油或气开采区。　不同地环境模式的地面沉降具有不同的规律和特点，在研究方法和预测模型方面也应有所不同。
另外，根据地面沉降发生的原因还可分为：（1）抽汲地下水引起的地面沉降；（2）采掘固体矿产引起的地面沉降；（3）开采石油、气引起的地面沉降；（4）抽汲卤水引起的地面沉降；（5）地面下施工如地铁施工引起的地面沉降。
4产生影响
编辑

地面沉降的危害主要有：
(1)毁坏建筑物和生产设施；
(2)不利于建设事和资源开发。发生地面沉降的地区属于地层不稳定的地带，在进行城市建设和资源开发时，需要更多的建设投资，而且生产能力也受到限制；
(3)造成海水倒灌。地面沉降区多出现在沿海地带。地面沉降到接近海面时，会发生海水倒灌，使土壤和地下水盐碱化。对地面沉降的预防主要是针对地面沉降的不同原因而采取相应的工程措施。
地面沉降会对地表或地下构筑物造成危害；在沿海地区还能引起海水入侵、港湾设施失效等不良后果。人为的地面沉降主要是过开采地下液体或气体，致使贮存这些液、气体的沉积层的孔隙压力发生趋势性的降低，有效应力相应增大，从而导致地层的压密。基于上述机制，上海于1965年以后，采用人工回灌方法，使地下水位回升、地面部分回弹，比较成功地控制了地面沉降。