长江漫滩区深大异形基坑施工对紧邻特大型桥梁影响及变形控制研究     

史建升  徐源  李慧  阎长虹  侯珏  俞良晨  赵华新  崔王洪  徐成华  刘刚 《地质论评》2024,70(1):2024010005-2024010005

随着地下空间资源的开发利用,越来越多深基坑呈现出开挖深、规模大、形状不规则等特点,其支护结构设计复杂,施工难度大,具有明显的空间效应。本文以南京地铁某基坑工程为例,分析基坑施工对邻近桥梁的影响。其场区位于长江下游漫滩相二元结构地层分布地段,上部软土层厚度大,下部承压含水层地下水位高、水量丰富,地质条件复杂,该基坑为典型的深大异形基坑,距离某大桥的双曲拱引桥仅为7. 2 m,由于之前桥梁已遭受其他地下工程施工产生的较大变形,所以后续工程对其影响变形控制要求极高。为此,该车站基坑支护结构设计基于地下空间实际功能采用设置分隔墙分区开挖及MJS超深工法墙综合变形控制方案。本文通过有限元数值模拟计算,开展复杂环境下基坑开挖引起的围护结构及桥梁桩基的变形预测分析,计算结果显示,该深大狭长异形基坑开挖对邻近桥梁沉降变形影响显著,通过设置分隔墙分区开挖及MJS工法墙进行变形控制,能够较好地控制基坑的空间效应,减少“长边效应”、“异形效应”等对桥梁沉降变形的影响。通过现场基坑开挖过程实际监测结果,验证这一综合变形控制方案的可行性。该研究成果对于类似复杂地质条件下深大狭长异形基坑的支护及施工设计具有很好的借鉴意义。  相似文献   

The Quaternary Lancaster Sound trough‐mouth fan,NW Baffin Bay     

Gang Li  David J.W. Piper  D. Calvin Campbell 《第四纪科学杂志》2011,26(5):511-522

The development of the Lancaster Sound Trough Mouth Fan (TMF) and glacial history in Arctic Canada were studied using a high‐resolution seismic profile across the entire fan and two piston cores. Stacked tills separated by erosion surfaces on the shelf pass seaward through till deltas into thick transparent glacigenic debris flow (GDF) deposits on the slope, separated by thin, well‐stratified glaciomarine layers. An age model was built by ties to the Ocean Drilling Program Site 645. The deepest GDF on the seismic profile was indicative of the onset of shelf‐crossing glaciation in the Early Pleistocene. The transition of the growth of Lancaster Sound TMF from an aggradational sequence (unit M) to an aggradational–progradational sequence (unit F) occurred at the Middle Pleistocene transition in glacial cyclicity. In the most recent glacial cycle, GDF sheets were deposited during Heinrich events 4 and 2 according to the correlation of the main detrital carbonate beds in two piston cores. The outmost till wedge reflects the maximum advance of the grounding glacier, far seaward of previously proposed Last Glacial Maximum ice extent. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

锡石的晶体结构和形态的关系          下载免费PDF全文

柴钢  王文魁 《岩石矿物学杂志》1988,7(4):374-381

本文对不同成因类型的锡石晶体形态进行了研究,并从PBC(周期性键链)理论出发,讨论了锡石晶体形态与晶体结构的关系。笔者认为,锡石晶体具有三种F面,即s{111}、e{101}、m{110},与Hartman对同样结构类型的金红石晶面性质划分有所差异。据锡石晶面结构性质所推导的理想晶体形态图,与晶体测量所得到的天然晶体形态图总体上相吻合。  相似文献   

中国元古宙地质构造格局演化对于沉积作用的控制          下载免费PDF全文

李汉瑜  安延恺 《沉积与特提斯地质》1989,9(3):32-37

一、五台运动对构造格局的影响五台运动表现的地区,主要是在华北的五台山区、太行山区、冀东、鲁西、豫西地区以及东北的辽东地区,其绝对年龄时限大致为22—23亿年。现已证实,经历五台运动后,华北地区的克拉通化更加明显,被认为属于中国境内克拉通化最早与最完备的地区。在太古宙末期,华北古陆块与西部的塔里木古陆块可能相联的局面至早元古宙末期已逐渐解体;并且这  相似文献   

我国西北部分地区地壳-上地幔电性横向变化特征与地震活动的关系   总被引：4，自引：0，他引：4       下载免费PDF全文

张云琳  安海静  刘晓玲  刘宝勤  贾政 《地震地质》1988,10(2):65

由50余个测点的大地电磁测深资料,讨论了该区的地壳-上地幔电性横向变化特征。按照上地幔第一低阻层顶面埋深,将测区划分为四类地区:浅埋深(55-90公里)、中浅埋深(90-110公里)、中深埋深(110-160公里)和深埋深(160-250公里)。讨论了本区六次大震例的深部电性背景。指出了上地幔顶部的梯度带地区、地壳内电性横向变化剧烈的地区和地壳内存在局部特殊增厚的低阻层地区将可以作为潜在震源区的深部电性判据之一  相似文献   

胆矾的稳定条件及保护方法研究     

杨刚  姚雅娟  沈美冬 《地球学报》1993,14(3):79-86

胆矾为一种含水硫酸盐矿物，晶体美丽，色泽鲜艳，但易风化，本文从分析影响胆矾稳定的环境、湿度等条件入手，通过实验确定常温下胆矾风化主要是受湿度影响，胆矾稳定定的相对湿度上限为65%．下限为45%。对胆矾矿物的保护，可选用液态湿度缓冲剂，采用湿源密封环境．控制胆矾矿物保存环境湿度。  相似文献   

1989 Datong-Yanggao Earthquake with Ms=6.1     

Liu Wei  An Weiping  Zhao XinpmgSetomological Bureau of Shanxi Province  Taiyuan  China 《中国地震研究》1994,(3)

In this paper,the basic conditions and characteristics of the Datong-Yanggao earthquake are described in detail.The type of the earthquake,the aftershock activity,the earthquake trend,the characteristics of damage are analyzed and discussed.This earthquake belongs to a sequence of earthquake swarm type and is of the concentratedly occurring characteristics of several main shocks in a time sequence,and the aftershock activity was normally attenuated.Because of the unreasonable design of buildings and repeated vibration by several destructive main shocks within a short period,the damage in the high intensity region was aggravated.The analysis and the prediction procedure of the 1991 Datong-Yanggao earthquake(Ms=5.8)are also briefly given.  相似文献   

An object-oriented knowledge representation structure for exploration data integration     

P. An  W. M. Moon  G. F. Bonham-Carter 《Natural Resources Research》1994,3(2):132-145

Knowledge representation structure and reasoning processes are very important issues in the knowledge-based approach of integrating multiple spatial data sets for resource exploration. An object-oriented knowledge representation structure and corresponding reasoning processes are formulated and tested in this research on the knowledge-based approach of integrating spatial exploration data. The map-based prototype expert system developed in this study has self-contained knowledge representation structure and inference mechanisms. It is important to distinguish between lack of information and information providing negative evidence for a map-based system because the spatial distribution of data sets are uneven in most cases. Error and uncertainty estimation is also an important component of any production expert system. The uncertainty propagation mechanisms developed here work well for this type of integrated exploration problem. Evidential bellef function theory provides a natural theoretical basis for representing and integrating spatially uneven geophysical and geological information. The prototype system is tested using real mineral exploration data sets from the Snow Lake area, northern Manitoba, Canada. The test results outline the favorable exploration areas successfully and show the effectiveness of the knowledge representation structure and inference mechanisms for the knowledge-based approach.  相似文献   

西太平洋热带海域厄尔尼诺年和非厄尔尼诺年期间湍流通量输送的不同特征     

曲绍厚  安磊明 《大气科学》1993,17(4):415-423

本文根据海洋科考船“实验三号”1986—1989年在西太平洋热带海域、使用系留气艇探测系统观测的140多次温度、湿度和风等廓线资料,利用Monin-Obukhov相似理论的半经验通量-廓线关系,计算给出该海域的动量通量M(特别是曳力系数C_D)、感热通量H_S和潜热通量H_L以及海表温度T_S和Richardson数Ri.结果表明:它们有明显的年际变化;感热通量H_S和潜热通量H_L与海表温度T_S呈明显正相关;曳力系数C_D与风速和Richardson数Ri也有明显相关关系,当风速一定时,C_D值随着Ri值的减少(Ri<0时的不稳定情况)而增加,而当Ri值不变时,C_D值随着风速值的增加而增加.  相似文献   

太阳活动,大气臭氧和平流层温度相关分析研究   总被引：1，自引：4，他引：1  

言穆弘  华贵义 《高原气象》1993,12(3):302-311

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