本文選題：晚新生代　切入點：地面沉降　出處：《巖土力學(xué)》2014年09期

【摘要】：天津濱海地區(qū)地處渤海灣西岸,晚新生代沉積了巨厚的松散沉積物。地下水位下降、地層自然固結(jié)、地表載荷的加速增長等復(fù)合因素造成了嚴(yán)重的地面沉降。利用在天津濱海新區(qū)塘沽地區(qū)施工的一眼1 226 m全取芯鉆孔,通過原狀樣品測試分析,系統(tǒng)研究了晚新生代土層的物理力學(xué)性質(zhì)、黏性土固結(jié)特征,并結(jié)合欠固結(jié)黏性土層沉降量計算等方法闡述了土層固結(jié)狀態(tài)空間特征,探討了土層固結(jié)特征與地面沉降的相關(guān)關(guān)系。結(jié)果表明:該地區(qū)0~100 m深度土層具有低天然密度、高孔隙比、高含水率、高壓縮性等特點,表現(xiàn)出軟土的性質(zhì),在地表荷載增大的情況下,易發(fā)生地面沉降;100~550 m的黏性土大都處于超固結(jié)和微超固結(jié)狀態(tài),主要是由于過去地下水的大量開采造成的;550 m以下的黏性土多為正常固結(jié),局部存在欠固結(jié)黏性土夾層。鉆孔中存在合計約218 m的欠固結(jié)黏性土夾層,這些欠固結(jié)黏性土夾層在自重應(yīng)力下的最終沉降量為1 985 mm,沉降量最大的土層對應(yīng)于第1、6含水組,分別達614 mm和665 mm,這一沉降過程完成所需時間為數(shù)十年甚至上百年。
[Abstract]:The coastal area of Tianjin is located in the west coast of Bohai Bay. The late Cenozoic deposited extremely thick loose sediments.The decrease of groundwater level, the natural consolidation of strata and the accelerated growth of surface load have resulted in serious land subsidence.The physical and mechanical properties and clay consolidation characteristics of the late Cenozoic soil layer were systematically studied by using the 1 226 m full coring borehole constructed in Tanggu area of Binhai New area of Tianjin, and through the test and analysis of the undisturbed samples.Combined with the method of calculating the settlement of underconsolidated clay soil, the spatial characteristics of soil consolidation state are expounded, and the correlation between soil consolidation characteristics and land subsidence is discussed.The results show that the 0 ~ 100m depth soil layer in this area has the characteristics of low natural density, high void ratio, high moisture content and high compressibility.Most of the 100 ~ 550m clay soils prone to ground subsidence are in the state of overconsolidation and micro-overconsolidation, mainly due to the fact that most of the clay soils below 550 m caused by the massive exploitation of groundwater in the past are normally consolidated, and there is an underconsolidated clay intercalation in the local area.A total of 218 m underconsolidated clay intercalation exists in the borehole. The final settlement of these underconsolidated clay intercalations under gravity stress is 1 985 mm, and the soil layer with the largest settlement corresponds to the first water bearing group,It takes several decades or even hundreds of years to complete the settlement process, which reaches 614 mm and 665 mm respectively.
【作者單位】： 天津地質(zhì)礦產(chǎn)研究所;北京大學(xué)工學(xué)院水資源研究中心;中國地質(zhì)大學(xué)(武漢)環(huán)境學(xué)院;
【基金】：中國地質(zhì)調(diào)查局項目(No.1212011120170,No.1212011120089)資助
【分類號】：TU432

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