北京东部地区地面沉降发育特征分析

结合区域地质背景条件,利用水准测量、分层标地层变形、地下水位动态等监测数据,对北京东部地区地面沉降的发育特征与发展变化规律进行了分析研究。该区域的地面沉降与地下水开采具有显著相关性,深部地层仍是沉降的主要贡献层位;沉降中心地下水具有明显的分层变化规律,深层承压水明显的水位降落漏斗,直接导致深部地层沉降压缩最为显著;地面沉降的区域分布、沉降速率变化与地下水降落漏斗具有一定的时空相关性;南水北调的稳定供水,有效缓解了北京地面沉降快速发展的趋势。     

基于PSInSAR技术的山东半岛蓝黄交迭区地面沉降发育特征与影响因素识别

研究区位于山东半岛蓝色经济区和黄河三角洲高效生态经济区的交迭地带,区位优势明显。地面沉降灾害的发生对该区规划建设和港口防潮堤高程构成了威胁,因此,全面了解该区地面沉降的发育特征,尤其是掌握地面沉降的主要影响因素极其重要。前人在不同时段内应用GPS和水准测量方法对该区局部地段地面沉降开展了相应研究,但未对全区地面沉降状况进行分析评价,尚不能有效支撑区域规划建设及地面沉降防控管理。文章在前人研究基础上,基于PSInSAR遥感技术分析了该区地面沉降速率及其变化状况,并与水准测量成果进行了对比。认为多年来该区地面沉降现象明显,超过75%的区域发生了不同程度的地面沉降,在寿光-广饶交界处、寿光-滨海开发区北部、寿光城区西北部和昌邑-滨海开发区北部等存在多个显著片区,且多年变化总体呈现加重趋势;区内存在16个沉降中心,最大沉降速率达到29~168 mm/a,沉降速率超过40 mm/a的占比达到62%以上,主要分布于研究区西部和西北部;该区地面沉降受区域构造、地层结构、地下水开采和地面荷载等因素影响,其中地下水开采是区域地面沉降发生的主致因素,地面荷载加强了局部地段的不均匀沉降程度,区域构造和地层结构为地面沉降发育和加剧提供了地质背景条件。     

唐山沿海地区地面沉降渗流固结耦合模拟研究

唐山沿海地区经济在迅速发展,沿海地区城市化规模在扩大,地下水开采量增大,地面沉降加剧.文中分析了唐山沿海地区的水文地质条件,概化为3个含水层、3个弱透水层,共6个压缩层.建立了三维地下水流和垂向一维压缩完全耦合模型.采用25a的观测资料校正模型,计算值与实测值拟合较好,模型具有较高的仿真性和适用性.预测了10a末的地面沉降;当地下水以现有开采量开采时,沉降中心累计达1192.3mm, 10a沉降352.3mm,沉降速率为35.23mma-1;当地下水的开采量在现有开采量的基础上增加10%时,沉降中心累计达1260.8mm, 10a沉降420.8mm,沉降速率为42.08mma-1; 当地下水的开采量在现有开采量的基础上减小10%时,沉降中心累计达1088.7mm, 10a沉降247.9mm,沉降速率为24.79mma-1.增大10%的地下水开采量, 10a地面沉降量增加68.5mm;减少10%的地下水开采量, 10a地面沉降量减少104.4mm.因此,控制地下水开采量是控制地面沉降的有效方法.     

川西南甘洛地区中—新生代构造沉降史分析及对铅锌保存的约束

本文通过碎屑岩磷灰石、锆石裂变径迹和炭质泥岩镜质体反射率相结合的办法,重建了甘洛地区中—新生代的构造沉降史,进而探讨了构造沉降史对铅锌保存状态的约束。研究表明:晚三叠世,甘孜-理塘洋盆和西秦岭地区洋盆的闭合作用导致研究区变为前陆环境,并开始迅速接受陆相沉积,埋深迅速增加,增幅达7.6km;晚三叠世至古近纪,甘洛地区经历过多次抬升-沉降作用,总体表现为缓慢抬升,平均抬升速率不高于32.7m/Ma;新近纪,甘洛地区快速差异隆升北部抬升速率高于南部,25.5~10.3Ma期间,平均抬升速度超过295m/Ma;在6Ma至今,平均抬升速率超过667m/Ma。快速隆升过程早于川南马边地区和临沧地区,而明显晚于攀西地区,这在一定程度上支持了青藏高原东部边界晚新生代以来幕式抬升及分步向外扩展的观点。构造沉降史结果表明成矿后的深埋藏作用对原生铅锌矿具有重要的保存作用,并影响到现今矿体的就位深度。     

地面沉降几种致灾模式的初步探讨

提出并探讨了地面沉降的"抬升-塌陷模式、开裂模式、下降模式、漏斗模式、土体结构破坏和地下水流场改变"等6个致灾模式,初步探讨了各种模式致灾的特点,提出了对不同模式开展有针对性的地面沉降治理工作的建议。     

考虑断层效应的高铁列车动荷载对地面沉降影响机理研究——以京张高铁怀来段为例

京张高铁怀来段位于怀涿、延矾盆地复合部位,盆地内土体工程地质特性的差异及隐伏断裂稳滑活动产生的地面沉降无疑会威胁京张高铁的安全运行。依据工程地质钻孔及地球物理探测资料,构建跨活动断层地基土体二维地层结构模型,通过数值模拟手段开展考虑断层效应的高铁列车动载荷对地面沉降的影响机理研究。研究表明:列车动荷载主要影响50 m深度范围内的土体,随车速增加动荷载造成的土体竖向位移降低,随车重增加竖向位移增加;在列车动荷载和断层滑移双重作用下,随深度增加,土体竖向位移以受列车动荷载影响为主转为以断层滑移影响为主,50 m以下土体竖向位移全部由断层滑移所致,且紧邻断层两侧距离相同位置上盘土体竖向位移大于下盘。      

鲁西隆起和济阳坳陷新生代隆坳耦合关系

为探讨鲁西隆起的抬升史,研究鲁西隆起和济阳坳陷之间的隆-坳演化关系,进一步揭示渤海湾盆地的演化特征,主要利用裂变径迹分析和裂变径迹t-T模拟方法建立了新生代鲁西隆起的抬升史和济阳坳陷的沉降史。鲁西隆起三期抬升史分别为62～53Ma、44～37Ma和23～20Ma,济阳坳陷在65～46Ma和46～38Ma期间为快速构造沉降期,构造沉降量大,23Ma左右坳陷抬升。对比研究表明,新生代鲁西隆起的抬升与济阳坳陷沉降之间存在隆-坳耦合关系。鲁西隆起的抬升控制了济阳坳陷烃源岩的形成、油气运移时间和油气分布由南向北迁移,并为济阳坳陷古潜山油藏提供了有效的储集空间。研究还认为,鲁西隆起与济阳坳陷的隆坳耦合关系是渤海湾盆地及周边山系盆山耦合事件的一个组成部分。     

Burial and thermal history of the West Bashkirian sedimentary basins

The GALO system is applied to the numerical reconstruction of burial and thermal histories of the West Bashkirian lithosphere from the Riphean to the present. An analysis of the variation in tectonic subsidence of the basin during its development is utilized to estimate approximately the mantle heat flow variations. Our variant of basin evolution suggests that after cooling in the Early Riphean, the rather weak thermal reactivations have not led to considerable heating of the lithosphere in the study region. Surface heat flow decreased from relatively high values in the Early Riphean (60–70 mW/m² in the eastern area and 40–50 mW/m² in the western part) to present-day values of 32–40 mW/m². In spite of the relatively low temperature regime of the basin as a whole, a syn-rifting deposition of more than 10 km of limestone, shale and sandstone in the Riphean resulted in rather high temperatures (180–190 °C) at the base of present-day sedimentary blanket in the eastern area. In agreement with the observed data, computed present-day heat flow through the sediment surface increases slightly from 32 to 34 mW/m² near the west boundary of the region to 42 mW/m² near the boundary of the Ural Foldbelt, whereas the heat flow through the basement surface decreases slightly from 28–32 to 24–26 mW/m² in the same direction. The mantle heat flow is only 11.3–12.7 mW/m², which is considerable lower than mean heat flow of the Russian Platform (16–18 mW/m²) and comparable with the low heat flow of Precambrian shields.     

U–Pb zircon age of the Walloon Coal Measures in the Surat Basin,southeast Queensland: implications for paleogeography and basin subsidence

The Jurassic Walloon Coal Measures of the Surat Basin were previously estimated to be of Middle Jurassic age, ranging from Aalenian to Callovian, based on an uncalibrated eastern Australian biostratigraphic framework. New U–Pb dates of 162.55 ± 0.05 Ma and 158.86 ± 0.04 Ma obtained from zircons in ash-fall volcanic tuffs now place the Walloon Coal Measures of the Surat Basin in the Upper Jurassic Oxfordian. The new dates have several implications for the interpretation of the Jurassic strata in the Surat Basin. First-order subsidence rates of 61 m/Myr for the Walloon Coal Measures are more akin to those of foreland basins than the previously assumed intracratonic setting. The dates also imply deposition of the Walloon coals in substantially higher latitudes than previously assumed and that they accumulated as peats in mires that experienced more than three months’ continual darkness each winter. Zircon dating of tuffs and associated geochemistry should assist with the correlation of the laterally impersistent coals, fluvial sandstone and mudstone of the Walloon Coal Measures, which are currently difficult to correlate over distances of more than a few kilometres. Dating of the palynostratigraphic zones APJ4.2 to APJ5 (Aequitriradites norrisii Association Zone to Murospora florida Association Zone) will also need to be recalibrated.     

太沙基一维固结理论在软土路基沉降变形初期阶段的开拓应用探讨

结合某高速公路K98 028、K98 470两处路堤完工一年后才开始的断续的前期沉降变形监测成果,利用太沙基一维固结理论,在缺少固结参数而又无法对多层软土路基固结参数分别反演的情况下,通过对地基整体固结参数的反演及数理统计分析,来达到沉降变形和沉降时问预测的目的;并通过与不同方法最终沉降变形预测结果之对比,及沉降预测结果与监测成果之拟合对比,进一步论证了该方法的可行性。