Elastic-plastic analysis for pile-anchor supporting system of deep foundation pit

By using numerical analysis methods to simulate the deep excavation, a lot of analyses are established on the basis of two-dimensional plane strain, ignoring the fact that foundation pit possesses three dimensions. For soil constitutive relation, people always take linear and nonlinear model, without considering the plastic behavior of soil. Using plastic-elastic hardening model to simulate constitutive relation of soil characteristics, the authors carried out mechanical analysis for pit excavation and support. The results show that the analysis for the stress state of pile anchor system is an effective way which provides theoretical basis for calculation of soil displacement.     

复合型滑坡体系统的工程地质勘察及其稳定性分析

滑坡工程地质勘察及其稳定性分析是滑坡治理工程设计及施工的重要依据.国道316线福建境内K160+840~K161+020山体滑坡是由2个主滑动轴线所构成的复合滑坡体,它具有牵引和推移性质特征,发育2个主滑动面和2个次滑动面.详细论述了复合滑坡体工程地质勘察的内容及侧重点.该滑坡体自然状态下的稳定系数为1.025,处于临界稳定状态,但安全储备极低,必须及早进行工程治理.     

淤泥质地基海塘与水闸不均匀沉降控制措施优化研究

多年的调查与研究表明,建于淤泥质地基上的水闸与海塘等水工建筑物常常因海塘与水闸连接部位产生过大的差异沉降,影响水闸的正常使用,甚至造成连接部位完全破环。在海塘与水闸之间构建连接段则可以有效减小两者过大的差异沉降,进而减小差异沉降对建筑物的不利影响,但单纯设置连接段对于控制过大差异沉降效果极其有限。论文以浙东沿海某海堤围垦工程为背景,基于有限差分数值模拟软件（FLAC3D）,模拟了海塘堆载及流固耦合过程,并考虑通过调节连接段水泥搅拌桩的桩径、桩长及桩间距的连续变化对地基处理措施进行优化,计算出了不同优化措施下水闸与海塘的差异沉降。计算结果表明：基于连接段地基桩桩长的连续变化,再通过调节桩间距的大小可以很大程度控制海塘与水闸之间的差异沉降。     

5•12汶川地震中山区公路桥梁震害及启示

桥梁结构的振动特性受场地条件及土—结相互作用影响显著,为提高桥梁结构的抗震性能,减少因结构破坏而产生的经济损失,进一步开展考虑场地土体非线性以及土—结相互作用对桥梁结构地震反应影响的研究工作十分必要。本文以一典型桥梁结构为例,着重介绍了美国太平洋地震工程研究中心基于性能的桥梁有限元模拟平台BridgePBEE应用中所涉及的地震动选取、桥梁结构建模、土体本构选择以及基于构件的桩—土—桥梁结构体系损伤评估方法,为研究震后桥梁结构经济损失分析方法提供可行性方案。     

胶东半壁店隐伏金矿床综合地球物理探测

胶东半岛是中国重要的金矿集区,金矿床的分布严格受NE—NNE向断裂带控制,招平断裂带是其中规模最大的控矿断裂带。然而,在断裂带中段的招远—道头镇区段(半壁店地区),新生代盖层下尚未发现成规模的金矿床。在总结招平断裂带内金矿床成矿模式和控矿地质体物性差异的基础上,从区域和断裂带尺度对比分析了1:60万和1:20万2种比例尺的布格重力异常特征,厘清了区域构造和岩体分布情况;进而在招平断裂带中段的半壁店地区利用1:1万高精度磁测和代表性剖面1:1万可控源音频大地电磁测量,揭示隐伏控矿地质体的分布情况。区域布格重力异常揭示出近EW向相对低密度正值((0~6)×10-5 m/s2)表征的构造带、团状正密度值(大于2×10-5m/s2)表征的玲珑黑云母花岗岩体和NE—NNE向密度值梯级带表征的招平断裂带;3组赋矿相关地质体的空间相对展布特征显示,玲珑黑云母花岗岩体南边界被近EW向构造带围限,招平断裂带切穿了早期生成的玲珑黑云母花岗岩体。高精度磁测结果反映：①招平断裂带穿切玲珑黑云母花岗岩体;②近EW向低密度、高磁性(相对磁性场值超过100 nT)花岗闪长岩体在深部受控于EW向深大构造带;③NE向串珠状低密度、高磁异常(相对磁性场值超过40 nT)表征了矿床尺度招平次级断裂内的系列花岗岩体(主成矿期之后生成)。可控源音频大地电磁测深和测区中部钻孔均证实,这些花岗岩脉从北向南(指向主断裂方向)埋深逐渐变浅。因此,NE向招平断裂带和近EW向构造带共同控制岩体分布,其交会部位是金矿体产出的有利空间,但上侵花岗岩体本身贫矿。半壁店地区隐伏金矿床形成时间晚于招平断裂主成矿期。研究结果表明,近EW向低密度带内的金矿找矿前景不乐观。     

城镇化与区域工程地质学发展机遇

城镇化是我国现代化进程中的最伟大工程,2001年诺贝尔经济学奖获得者J.Stiglitse把中国的城镇化与美国的高科技并列为影响21世纪人类发展进程的两大关键因素。协调好城市化进程中强大的人类工程活动同复杂的地质环境变化间的关系是我国工程地质工作者的责任与义务,也是工程地质学发展的机遇。充分学习、借鉴地球科学相关学科领域的新观念、新成果、新资料,开展区域工程地质研究,探寻我国区域工程地质环境的形成演化和工程建设与地质环境间的相互作用规律,实现城镇化与地质环境的和谐。     

Sequestration of CO2 in geological media: Criteria and approach for site selection in response to climate change

The well-developed coal electricity generation and coal chemical industries have led to huge carbon dioxide (CO₂) emissions in the northeastern Ordos Basin. The geological storage of CO₂ in saline aquifers is an effective backup way to achieve carbon neutrality. In this case, the potential of saline aquifers for CO₂ storage serves as a critical basis for subsequent geological storage project. This study calculated the technical control capacities of CO₂ of the saline aquifers in the fifth member of the Shiqianfeng Formation (the Qian-5 member) based on the statistical analysis of the logging and the drilling and core data from more than 200 wells in the northeastern Ordos Basin, as well as the sedimentary facies, formation lithology, and saline aquifer development patterns of the Qian-5 member. The results show that (1) the reservoirs of saline aquifers in the Qian-5 member, which comprise distributary channel sand bodies of deltaic plains, feature low porosities and permeabilities; (2) The study area hosts three NNE-directed saline aquifer zones, where saline aquifers generally have a single-layer thickness of 3‒8 m and a cumulative thickness of 8‒24 m; (3) The saline aquifers of the Qian-5 member have a total technical control capacity of CO₂ of 119.25 × 10⁶ t. With the largest scale and the highest technical control capacity (accounting for 61% of the total technical control capacity), the Jinjie-Yulin saline aquifer zone is an important prospect area for the geological storage of CO₂ in the saline aquifers of the Qian-5 member in the study area.     

辽东兰花岭地区古元古代I型花岗岩类与辽吉A型花岗岩对比研究

辽东半岛是华北克拉通胶-辽-吉古元古代活动带的重要组成部分,古元古代经历了复杂的构造演化过程,并记录了多期岩浆-变质作用,约2.2 Ga的辽吉A型花岗岩和1.89~1.85 Ga的巨斑状花岗岩、正长岩分别标志着辽东古元古代造山作用的开端和结束。最新研究显示,2.20~2.15 Ga的岩浆作用形成了2种不同类型的花岗岩,它们可能具有不同的岩石成因和构造意义。在青城子铅锌矿集区北部采集的兰花岭、白砬子花岗闪长岩和黄泊辉绿岩,锆石U−Pb年龄分别为2177±19 Ma、2129±36 Ma、1876±29 Ma。花岗闪长岩的岩石成因类型、地球化学特征与典型的约2.2 Ga的辽吉A型花岗岩明显不同,属于弱过铝质、低钾钙碱性—碱性岩石,Zr、Hf、Nb、Rb含量较低,K2O/Na2O值、稀土元素总量极低,为典型的I型花岗岩类。根据锆石Lu−Hf同位素分析,εHf (t)值为−5.1~9.0,二阶段Hf模式年龄tDM2为2089~2817 Ma,岩浆源区为约2.5 Ga的太古宙地壳物质和少量软流圈地幔物质。兰花岭地区花岗闪长岩具备岛弧或活动大陆边缘的地球化学亲缘属性,可能形成于弧岩浆俯冲挤压环境;结合形成于伸展环境的A型条痕状花岗岩特征,认为约2.2 Ga辽东地区古元古代活动带呈现总体伸展、局部挤压的构造环境,为洋壳板块向龙岗地块俯冲碰撞过程中或碰撞后的弧后盆地。     

Inelastic seismic behavior of soil–pile raft–structure system under bi-directional ground motion

Performance based design of structure requires a reasonably accurate prediction of displacement or ductility demand. Generally, displacement demand of structure is estimated assuming fixity at base and considering base motion in one direction. In reality, ground motions occur in two orthogonal directions simultaneously resulting in bidirectional interaction in inelastic range, and soil–structure interaction (SSI) may change structural response too. Present study is an attempt to develop insight on the influence of bi-directional interaction and soil–pile raft–structure interaction for predicting the inelastic response of soil–pile raft–structure system in a more reasonably accurate manner. A recently developed hysteresis model capable to simulate biaxial interaction between deformations in two principal directions of any structural member under two orthogonal components of ground motion has been used. This study primarily shows that a considerable change may occur in inelastic demand of structures due to the combined effect of such phenomena.     

基于空间语义的地质剖面自动连接算法

地质条件的复杂性决定了地质剖面图完全自动连接的准确性较低。提出一种基于空间语义关系的空区域搜索算法,通过人机交互方式将专家知识应用于剖面连接过程,实现了融合人工编辑的剖面自动化连接方法。该算法通过读入交互结果获得专家知识,在此基础上对剖面地层进行自动化连接。通过语义分解的策略,可以针对实际情况任意组合需要的连接命令。