某倾倒边坡开挖下的变形特征及加固措施分析

以皖南某高速公路一个反倾边坡为例,在详细地质调查基础上分析了边坡以倾倒-滑移为主要特征的倾倒变形力学机理。调查结果显示在边坡原有倾倒变形的基础上,开挖爆破等工程扰动首先使开挖面顶部出现倾倒变形并伴有后缘拉裂隙,同时坡体内部断续结构面逐渐贯通,最下级台阶面出现外鼓等。上述现象的出现显示出边坡具有整体失稳破坏的趋势。在上述地质概念模型基础上,应用离散单元法对边坡变形全过程进行模拟,验证上述变形破坏机理,并揭示了边坡在深度方向上的变形分区现象,即倾倒-折断区、强烈倾倒区、倾倒影响区和正常岩层区。     

古王陵变形破坏机理及稳定性研究——以国家重点文物高句丽太王陵为例

本文在现场工程地质条件及变形破坏特征勘察的基础上,对高句丽太王陵的稳定性进行了研究,并用三维有限差分程序FLAC3D对陵体在自重和渗流场藕合作用下的应力和变形规律进行了研究。研究表明:(1)太王陵出现的条石内倾、条石拉开等变形是由其本身的结构特点及其在自重作用下形成的;(2)持力层承载力不足,地基失稳是引起该国家重点文物破坏的主要原因;(3)陵坡滑移是由于本身安全储备较低,在地基失稳和地震等的共同作用下引发的。     

港湾广场（一期）深基坑变形监测与分析

深基坑施工变形监测是信息化施工的重要内容,以广州港湾广场(一期)深基坑工程为例,通过对开挖过程中土体水平位移、支护结构侧向位移、支护结构内应力、沉降等监测,结合围护结构的强度检测,采用反演分析对基坑变形进行数值模拟,预测不同开挖深度时基坑的位移变形量,实际监测结果与预测值基本一致,为基坑的设计和施工提供可靠的依据。     

软弱土路基沉降变形控制研究

从理论分析着手,建立路基沉降变形控制系统模型。根据室内试验成果,对路基沉降进行数值分析。模拟不同参数对沉降的影响,研究不同工况中路基沉降的控制效果。地基弹性模量对沉降影响大,提高地基弹性模量,沉降将减小,并且减小的幅度很大;填料密度对沉降影响较大,降低填料密度,沉降将减小,并且减小的幅度很大;路基累积沉降量与路基本体高度之间存在近似线性正相关关系;路基累积沉降量与地基处理深度之间存在近似线性负相关关系。     

根据2001年Mw 78可可西里强震InSAR同震测量结果反演东昆仑断裂两侧地壳弹性介质差异

利用2001年 Mw 78 可可西里强震InSAR同震测量结果，反演了青藏高原北部东昆仑断裂两侧地壳弹性介质差异.InSAR测量结果显示断层南侧的同震位移比北侧的大20％～30%.根据人工地震反射剖面建立岩石圈模型，以断层两侧杨氏模量差异和震源破裂深度为反演变量，通过有限元方法模拟实测得到的同震位移剖面.反演得到最佳断层破裂深度为20～22km，断层南侧杨氏模量相对北侧比值为81%～92%.结果表明，断层两侧弹性介质性质存在明显差异，由于构造运动作用，断层南部地壳不及北部地壳坚硬.前人利用地震层析成像和大地电磁测深等手段推断青藏高原内昆仑山断裂以南可可西里－羌塘地块地壳内广泛发育低速高导层，我们通过形变场力学分析得到与此相一致的结果.     

青藏铁路冻土区土体冷生过程对路基变形影响

一般地区路基土体变形主要受土体压密过程控制,青藏铁路冻土路基变形则主要是受土体冷生过程影响和控制。通过对填土路基修筑后土体冷生过程以及工程实测数据分析,指出冻融过程不同阶段冻土路基变形与土体冷生过程有着密切关系。认为控制填土路基冷生过程稳定时间和填土路基地温场形态,是减少冷生过程和铁路长期运营过程中路基变形、保证冻土区路基工程长期稳定性的有效途径。此认识已经在青藏铁路冻土区路基工程建设实践中得到证明。     

“醉汉林”作为滑坡和边坡变形特征标志的意义——以陕西陇县地区为例

“醉汉林”一般被当做滑坡存在的一种标志。在陕西宝鸡地区进行地质灾害详细调查的过程中,发现变形边坡也有“醉汉林”分布。对陕西陇县郭家庄变形边坡“醉汉林”的树木倾斜角与边坡的倾角进行了测量,并结合几何学分析,认为树木倾斜角反映了边坡倾角的变化,并得出边坡倾角不断变陡是该地区边坡变形的一种主要方式的结论。研究结果表明,“醉汉林”有着多样而具体的指示意义:“醉汉林”记录了边坡变形的历史,可以作为区分滑坡与变形边坡的标志,“醉汉林”可以指示滑坡及边坡的状态,还可以判断滑坡剪出口是否存在。     

北京周口店豹皮灰岩的变形特征

周口店地区广泛分布的寒武纪地层府君山组底部灰岩因其具典型的豹斑状构造而被称为豹皮灰岩。本文主要以出露于周口店黄院地区的豹皮灰岩为研究对象。组成豹皮灰岩的物质成分有2种,一为白云质成分的豹斑,其余部分为泥灰质。在露头尺度上,豹皮灰岩中的豹斑发生了明显的旋转变形并具有一定的定向性,而泥灰质成分则具有清晰的韧性变形特征,为较典型的碳酸盐糜棱岩;在微观尺度上,构成豹斑的白云石矿物未发生韧性变形,而泥灰质成分中的方解石具有明显的细粒化、拉长和定向。豹皮灰岩变形发生时岩石所处的温度介于200～250℃之间。豹皮灰岩的形成经历了原岩形成和后期构造变形改造2个阶段,于寒武纪由沉积作用形成了岩石的物质组分和原生层状构造,在前印支期受水平剪切作用形成岩石的豹斑状构造。     

Experimental Investigation of Eclogite Rheology and Its Fabrics at High Temperature and Pressure

Eclogite plays an important role in mantle convection and geodynamics in subduction zones. An improved understanding of processes in the deeper levels of subduction zones and collision belts requires information on eclogite rheology. However, the deformation processes and associated fabrics in eclogite are not well understood. Incompatible views of deformation mechanism have been proposed for both garnet and omphacite. We present here deformation behaviour of eclogite at temperatures of 1027–1427 °C, confining pressures of 2.5–3.5 GPa, and strain rates of 1 × 10^?5 s^?1 to 5 × 10^?4 s^?1. We obtained a power‐law creep for the high temperature and pressure deformation of a ‘dry’ eclogite (50 vol.% garnet, 40% omphacite and 10% quartz) with A = 10^{3.3 ± 1.0}, n = 3.5 ± 0.4, ΔE =403 ± 30 KJ mol^?1 and ΔV = 27.2 cm³ mol^?1. The two principal minerals of eclogite have greatly different strengths. Progressive increase of garnet results in a smooth increase in strength. Analysis by electron back‐scattered diffraction shows that: (1) garnet displays pole figures with near random distributions of misorientation angle under both dry and wet conditions; (2) omphacite shows pronounced lattice preferred orientations (LPOs), suggesting a dominant dislocation creep mechanism. Further investigation into the water effects on eclogite show: (3) water content does not influence the style of omphacite fabric but increases slightly the fabric strength; (4) grain boundary processes dominate the deformation of garnet under high water fugacity or high shear‐strain conditions, yielding a random LPO similar to that of non‐deforming garnet, despite the strong shape preferred orientation (SPO) observed. {110} [001] slip may dominate the deformation of rutile. Quartz displays complicated and inconsistent LPOs in eclogite. These results are remarkably similar to observations from deformed eclogites in nature.     

Outgoing long wave radiation variability from IR satellite data prior to major earthquakes

Our analysis of the continuous outgoing long wave earth radiation (OLR) indicates anomalous variations prior to a number of medium to large earthquakes. The most recent analysis of OLR is from the M9.0 Sumatra Andaman Islands mega trust event. We compared the reference fields for December 2001 to 2004 and found OLR anomalous values, > 80 W/m², (2σ) within the epicentral area on Dec 21, 2004, 5 days before the event. We used the NOAA/IR daily (one degree) and monthly (two and half degree) gridded data to differentiate between the global and seasonal variability and the transient local anomalies. The cause of such anomalies is not fully understood; one possible explanation is the existence of thermal outgoing radiation as a result of near ground air ionization and latent heat change due to change of air humidity and temperature. This phenomenon is hypothesized to be part of a relationship between tectonic stresses, electrochemical and thermodynamic processes in the atmosphere and increasing mid IR flux, all part of a family of electromagnetic (EM) phenomena related to earthquake activity. The time scale of the observed variations is a few weeks before the onset of the seismic event. In comparison with several years of data, the observed time-series preceding the earthquake had unusually high OLR. The OLR anomaly corresponds to a large area of ground coverage and coincides with the main epicentral zone. The significance of these observations is explored using data from most recent East Asian earthquake swarm of December 2004 and three other earthquakes.