石笼挡土墙的颗粒离散元细观力学模拟研究   总被引：2，自引：0，他引：2  

孟云伟  柴贺军  贾学明 《岩土力学》2010,31(8):2677-2681

针对在施工过程中,石笼挡土墙墙面位移的发展、墙背填土中土应力的变化的问题,从细观层面,采用基于离散单元法的颗粒流程序,通过多组试件的模拟压缩试验,确定了填土、填石、石笼等材料合理的力学参数值,以工程中的实体石笼挡土墙为原型,建立了墙背阶梯式石笼挡土墙数值模拟模型。通过在填土表面施加均布荷载,研究了挡土墙的力学行为。模拟结果显示：填土中的水平应力随深度的增加对均布荷载的敏感性降低,填土深度越浅,应力值越早得到增加,增加幅度越大,这主要是由于石笼挡土墙上部发生了较大的位移,均布荷载的作用大部分消耗在上层填土中,仅有小部分能量传递到较深填土;石笼挡土墙变形主要发生在填土阶段,应加强石笼挡土墙填土阶段的施工管理;无论是在填土阶段,还是均布荷载作用阶段,石笼挡土墙墙面的位移值均是中上部较大,下部较小。由此可推断,墙背阶梯式石笼挡土墙的破坏形式为倾覆式。  相似文献   

饱水状态对岩石冲击倾向性影响的研究     

肖为国  ;贾晓垒  ;崔继生  ;姜振泉 《山东地质》2009,(9):26-28

取菏泽赵楼煤矿岩样进行了饱水前后冲击倾向性指标的对比试验,研究发现饱水状态对岩样弹性能量指数影响明显,动态破坏时间和冲击能量指数亦有影响。对于不同水稳性特征的岩石,饱水前后的冲击倾向性存在明显差异。  相似文献   

张北6.2级地震民房震害与重建措施   总被引：1，自引：0，他引：1  

刁建新  刁桂苓 《华北地震科学》1999,17(3):43-47

根据张北地震现场的实地考察资料,介绍了房屋的震害情况,提出了重建家园应采取的措施,建议,以此次地震为鉴,要加强防震减灾宣传,增强农村干部群众的抗震意识,全面提高农村房屋的抗震能力。  相似文献   

CHARACTERISTICS AND FORMATION MECHANISM OF LARGE ROCK AVALANCHES TRIGGERED BY THE LUDIAN M_S6.5 EARTHQUAKE AT HONGSHIYAN AND GANJIAZHAI          下载免费PDF全文

CHANG Zu-feng  CHANG Hao  YANG Sheng-yong  CHEN Gang  LI Jian-lin 《地震地质》2017,39(5):1030-1047

The 3 August 2014 Ludian, Yunnan M_S6.5 earthquake has spawned more than 1, 000 landslides which are from several tens to several millions and over ten millions of cubic meters in volumes. Among them, the Hongshiya and Ganjiazai landslides are the biggest two with volumes over 1 000×10⁴m³. The Hongshiya and Ganjiazai landslides are two typical landslides, the former belongs to tremendous rock avalanche, and the latter belongs to unconsolidated werthering deposit landslide developed in concave mountain slope. Based on field investigations, causes and formation mechanism of the two landslides are discussed in this study. The neotectonic movement in the area maintains sustainable uplifting violently all the time since Cenozoic. The landform process accompanied with the regional tectonic uplifting is the violent downward erosion along the Jinshajiang River and its tributary, forming landforms of high mountains and canyons, deeply cut valleys, with great height difference. The regional seismo-tectonics situation suggests that:Ludian earthquake region is situated on the southern frontier boundary of Daliangshan secondary active block, and is seismically the strongest active area with one earthquake of magnitude greater than M5.0 occurring every 6 years. Frequent and strong seismicity produces accumulated effects on the ground rock to gradually lower the mechanical strength of slopes and their stability, which is the basis condition to generate large-scale collapse and landslide at Hongshiyan and Ganjiazhai. The occurring of Hongshiyan special large rock avalanche is associated with the large terrain height difference, steep slope, soft interlayer structure and unloading fissures and high-angle joints. The formation mechanism of Hongshiyan rock avalanche may have three stages as follows:Stage 1, when P wave arriving, under the situation of free surface, rocks shake violently, the pre-existent joints(in red)parallel to and normal to the river and unloading cracks are opened and connected. Stage 2, on the basis of the first stage, when S wave arriving, the ground movement aggravates. Joints(in green)along beds develop further, resulting in rock masses intersecting each other. Stage 3, rock masses lose stability, sliding downward, collapsing, and moving over a short distance along the sliding surface to the inside of the valley, blocking the river to form the dammed lake. The special large landslide at Ganjiazhai is a weathering layer landslide occurring in the middle-lower of a large concave slope. Its formation process may have two stages as follows:Firstly, under strong ground shaking and gravity, the ground rock-soil body around moves and assembles to the lower of the central axis of the large concave slope, which suffers the largest earthquake inertia force and firstly yields plastic damage to generate compression-expansion deformation, because of the largest water content and volume-weight within the loose soil of it. Secondly, in view of the steep slope, along with the compression, the plastic deformation area enlarges further in the lower of slope, giving rise to a tensional stress area along the middle of the slope. As soon as the tensional stress exceeds the tensile strength of the weathering layer, a tensional fracture will occur and the landslide rolls away immediately making use of momentum. This two large landslides are the basic typical ones triggered by the M_S6.5 Ludian earthquake, and their causes and mechanism have a certain popular implication for the landslides occurring in this earthquake region.  相似文献   

云南地震地质灾害与资源环境效应问题的初步研究   总被引：2，自引：1，他引：2  

李世成  崔建文  杨润海  杨昆杰  陈宇军 《云南地理环境研究》2003,15(2):9-18

在对历史震害资料浅析的基础上，利用最近40年有现场调查的地震记录，分析了云南省各类地震地质灾害与资源环境破坏影响的一些特征，并结合云南地震时空活动特性，对云南有仪测地震资料近百年间的地震地质灾害与资源环境效应问题进行了反演，表明：（1）云南地区地震地质灾害与资源环境破坏影响具有群体分区特征。（2）云南地区存在时间进程上连续的中强地震活跃背景：地震对资源环境的作用影响具有强度为2级的高背景值。（3）云南资源环境地震破坏影响具有多侧面、长时效和渐微影响的特征。地震对资源环境的破坏，必将恶化人类生存条件，阻碍社会经济的长期与可持续发展。这是资源环境安全防震减灾所面临的新课题。  相似文献   

冷库系统变工况性能的理论分析   总被引：1，自引：0，他引：1  

曾冬琪 《广东海洋大学学报》2009,29(1)

对氨冷库蒸汽压缩制冷系统进行理论分析。通过改变环境温度,改变蒸发器和冷凝器压力降,建模计算了冷库系统的损失、效率和制冷系数COP,结果表明,系统各设备的损失随着环境温度升高而变化,系统设备性能随着压力降升高而变化。认为减少蒸发器和冷凝器的传热温差,减少压缩机内不可逆损失,减少蒸发器的压力降等可以提高系统性能。  相似文献   

新义煤矿底板采动破坏规律及突水危险性研究     

杨志斌 《中国煤炭地质》2012,(4):31-34,41

为了研究新义煤矿煤层底板的突水危险性,分析了矿区的水文地质条件,设计了底板采动破坏的测试方案,结合FLAC数值模拟软件和经验公式对底板采动破坏深度进行了分析,采用考虑矿压影响的斯列萨列夫公式对底板突水危险性进行了评价,为新义煤矿的安全合理开采提供了科学依据。  相似文献   

从华北克拉通中、西部结构的区域差异性探讨克拉通破坏   总被引：16，自引：0，他引：16       下载免费PDF全文

陈凌  危自根  程骋 《地学前缘》2010,17(1)

详细的深部结构信息是深入认识华北克拉通显生宙改造和破坏的重要依据。基于密集流动地震台阵和固定台网记录的远震P波和S波接收函数资料,获得了跨越华北克拉通东、中、西部的3条剖面的岩石圈和上地幔结构图像,揭示了克拉通不同区域深部结构特征的显著差异。与东部普遍减薄的岩石圈(60～100km)相比,中、西部表现出厚、薄岩石圈共存的强烈横向非均匀性,既在稳定的鄂尔多斯盆地之下保留着厚达200km的岩石圈,又在新生代银川—河套和陕西—山西裂陷区存在厚度<100km的薄岩石圈,差异最大的厚、薄岩石圈仅相距约200km。岩石圈厚度在东、中部边界附近的约100km横向范围内显示出20～40km的迅速增加。岩石圈厚度的快速变化与地表地形从东向西的突然改变以及南北重力梯度带的位置大致吻合,并对应于地壳结构、地幔转换带厚度和660km间断面结构的快速变化。这种从地表到上地幔底部深、浅结构的耦合变化特征表明,东西两侧区域在显生宙可能经历了不同的岩石圈构造演化和深部地幔动力学过程。克拉通东部薄的地壳、岩石圈和厚的地幔转换带以及复杂的660km间断面结构可能与中生代以来太平洋板块深俯冲及其相关过程对这一地区岩石圈的改造和破坏有关;而中、西部存在显著减薄的岩石圈这一观测结果,并结合岩石、地球化学资料表明,克拉通岩石圈改造和减薄不仅发生在东部,而且可能影响了包括中、西部在内的更广泛的区域。岩石圈薄于100km的中、西部裂陷区可能与先前存在于岩石圈中的局部构造薄弱带相联系。这些古老岩石圈薄弱带可能经历了后期构造事件的多次改造,并在新生代印度—欧亚陆陆碰撞过程中被进一步弱化、减薄,最终造成地表裂陷。另一方面,中、西部总体较厚的地壳、岩石圈以及正常偏薄的地幔转换带表明,同太平洋深俯冲对东部的作用相比,包括印度—欧亚大陆碰撞在内的多期热-构造事件对该地区的构造演化影响相对较弱,不足以大范围改造和破坏高强度的克拉通岩石圈地幔根,从而造成了该地区现今岩石圈结构的高度横向不均匀。  相似文献   

Formation of a cohesive floodplain in a dynamic experimental meandering river     

Wout M. van Dijk  Wietse I. van de Lageweg  Maarten G. Kleinhans 《地球表面变化过程与地形》2013,38(13):1550-1565

Field studies suggest that a cohesive floodplain is a necessary condition for meandering in contrast to braided rivers. However, it is only partly understood how the balance between floodplain construction by overbank deposition and removal by bank erosion and chutes leads to meandering. This is needed because only then does a dynamic equilibrium exist and channels maintain meandering with low width–depth ratios. Our objective is to understand how different styles of floodplain formation such as overbank deposition and lateral accretion cause narrower channels and prevent chute cutoffs that lead to meandering. In this study we present two experiments with a self‐forming channel in identical conditions, but to one we added cohesive silt at the upstream boundary. The effect of cohesive silt on bank stability was tested in auxiliary bank erosion experiments and showed that an increase in silt reduced erosion rates by a factor of 2. The experiment without silt developed to a braided river by continuous and extensive shifting of multiple channels. In contrast, in the meandering river silt deposits increased bank stability of the cohesive floodplain and resulted in a reduction of chute cutoffs and increased sinuosity by continuous lateral migration of a single channel. Overbank flow led to deposition of the silt and two styles of cohesive floodplain were observed: first, overbank vertical‐accretion of silt, e.g. levee, overbank sedimentation or splays; and second, lateral point bar accretion with silt on the scrolls and in the swales. The first style led to a reduction in bank erosion, while the second style reduced excavation of chutes. We conclude that sedimentation of fine cohesive material on the floodplain by discharge exceeding bankfull is a necessary condition for meandering. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Eclogite-melt/peridotite reaction: Experimental constrains on the destruction mechanism of the North China Craton   总被引：2，自引：0，他引：2  

WANG Chao    JIN ZhenMin  GAO Shan  ZHANG JunFeng & ZHENG Shu State Key Laboratory of Geological Processes  Mineral Resources  China University of Geosciences  Wuhan  China  State Key Laboratory of Inorganic Synthesis  Preparative Chemistry  College of Chemistry  Jilin University  Changchun 《中国科学:地球科学(英文版)》2010,(6)

To study the mechanism of melt-peridotite reaction pertinent to the destruction of the North China Craton (NCC) lithosphere, a series of experiments were performed at a pressure of 2.0 GPa and temperatures from 1250 to 1400°C using Bixiling eclogite and Damaping peridotite as starting materials. The experimental results show that the reaction between eclogite melt and peridotite causes dissolution of olivine and orthopyroxene and precipitation of clinopyroxene in the melt. The experimental run products, cha...  相似文献