国道219线桑桑-拉孜公路改建工程曲布桑大桥桥基砂土液化初步评价     

柏永岩  崔春龙 《中国地质灾害与防治学报》2004,15(1):49-51

曲布桑大桥工区位于青藏高原。该区地震活动频繁。桥下地基饱水的粉、细砂层较发育。文章根据《抗震设计规范》GB11-89的标准，通过标准贯入实验分析了曲布桑大桥在埋深15m内的地基具有发生砂土液化的可能性，并计算了液化指数，划分了液化等级。为防止砂土液化的发生，对桥下地基处理提出了建议。  相似文献   

A Comparative Evaluation of Indirect Methods to Estimate the Compressive Strength of Rocks   总被引：7，自引：3，他引：7  

M. Fener  S. Kahraman  A. Bilgil  O. Gunaydin 《Rock Mechanics and Rock Engineering》2005,38(4):329-343

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Controls on basalt terrace formation in the eastern Lesotho highlands     

Stefan Grab  Craig van Zyl  Nicholas Mulder 《Geomorphology》2005,67(3-4):473-485

The objective of this study is to ascertain the relative importance of lithological controls and geomorphological processes in the development of Drakensberg basalt terraces. Various hypotheses for terrace formation are considered, including geological controls, macroscale geomorphology, and climatic–geomorphological controls. The variations in strength and relative age differences for scarp surface exposures on two slopes of varying aspect are determined, so that a comparison can be made between various scarp outcrops and relative rates of weathering. Scarp outcrops were measured for their rock mass strength, rock surface roughness, and percentage lichen cover. The ethylene glycol test was performed on prepared rock samples to determine susceptibility to tensional breakup. A satellite image depicting the distribution of late-lying contemporary snow was used to assist in the construction of topo-climatic linkages with scarp terrace localities. Findings show that terraces are most common on southeast-facing aspects, and coincide with the major joint strike direction. Lithological factors are thus considered the primary control to such terrace development. It is suggested that a different set of geomorphological processes operates on various slope-altitudinal and slope-orientational positions at any given time.  相似文献   

Developments in a non-destructive method of determining rock strength     

Robert J. Allison 《地球表面变化过程与地形》1990,15(6):571-577

Material strength is an important variable for any study of the relationships between rock mass geomechanical characteristics and landform development. Standard field and laboratory tests for measuring strength present a variety of problems to the geomorphologist. Recent studies (Allison, 1988) have described a laboratory based non-destructive method for indirectly determining material strength, by measuring Dynamic Young's Modulus. Data presented here suggest that the same apparatus can be used as a field technique. Tests have been conducted on the Devonian limestone of the Napier Range, Western Australia. Laboratory results obtained using the non-destructive ultrasonic apparatus have a high correlation with triaxial Hoek Cell tests. Results from on-site tests have much greater accuracy than data collected using the Schmidt hammer, which is currently the most widely used geomorphological field technique for determining rock strength.  相似文献   

The micro-erosion meter: Use and limitations     

A. P. Spate  J. N. Jennings  D. I. Smith  M. A. Greenaway 《地球表面变化过程与地形》1985,10(5):427-440

Detection of anomalies in measurements of low rates of limestone surface lowering with a traversing micro-erosion meter (MEM) led to temperature-controlled laboratory and field investigations of some sources of error in the method. Regressions for the correction of temperature change in the instrument and in the stud-rock interface were obtained. Probe erosion tests permitted a correction to be devised and also provided information whereby a measure of operational irregularity was adopted. Corrections and error terms were applied to field measurements from two southern New South Wales karsts and a collection of Australian limestone slabs exposed at one site. Examination of these results and of published MEM rates from other parts of the world validated the MEM method. Marine platforms are lowered at such gross rates that these error sources may be neglected there. However limestone lowering in terrestrial environments cannot be assumed to proceed at rates which permit this and recommendations are made about procedures to ensure that investigations are prosecuted within the limitations of the method.  相似文献   

液动回转冲击钻进中管道液流动态及气囊蓄能器的应用     

李世忠  李洵  石智军 《地球科学》1985,(3)

本文计算和论述了回转冲击钻进中管道液流产生的水击及其影响。使用蓄能器可以改善管道液流动态、提高冲击器的工作能力、减少水击能量的损失。凡冲击器的基础频率越低,蓄能器的安装距离则越大,否则效果相反。从管道各部水压变化实测证明蓄能器确能减小管道压力波动幅值,提高冲击器频率。利用热力学原理可以计算蓄能器每次蓄释的能量。  相似文献   

关于振动锤设计理论中几个问题的探讨     

黄振群  吴晓芳  彭贯民 《地球科学》1985,(3)

在工程地质勘察用的多功能钻机的振动锤的设计中,基本参数的确定是一个关键问题,本文通过对振动锤力学模型和振动方程的分析,探讨了在保证振动锤有一定寿命、有最佳工作效果、受外界因素影响最小的最佳工况时,基本参数(i、ε、λ、R)的组合规律。从振体处于一定位置时弹簧压缩量考虑,探讨了振动锤弹簧设计中,上、下弹簧刚度的分配问题。  相似文献   

Some Attempts for Estimating Rock Strength and Rock Mass Classification from Cutting Force and Investigation of Optimum Operation of Tunnel Boring Machines     

K. Fukui  S. Okubo 《Rock Mechanics and Rock Engineering》2006,39(1):25-44

Summary. Tunnel face and wall collapse are common during excavations performed by tunnel boring machines (TBMs) due to the difficulty of correctly identifying the properties of the excavated rock. This identification, however, can be simplified by using the cutting force to estimate rock strength, a method that has already proved quite successful in Japanese tunnel excavations. This paper summarizes knowledge relating to the cutting force obtained through tunnel excavation experience, and the relationship between rock strength and TBM operation is discussed. Although TBM operators rely on intuition to set the cutter head speed appropriately, this decision process represents a logical method of operation that takes advantage of the variable speed capability of the cutter head. Selection of appropriate support methods for the excavated face is also a critical issue in tunnel excavation. This selection process is based on the condition of the rock, which is difficult to determine quickly and accurately during tunnel excavation. The present paper uses the excavation of two tunnels to demonstrate that it is possible to assign rock mass classifications accurately based on rock strength when boring a uniform rock type. It is also shown that the rock mass can be classified from the rock strength normalized by the uniaxial compressive strength when boring through mixed rock types.  相似文献   

扩底灌注CFG桩在北京某地基处理工程中的应用     

郑伟龙  邓才雄  周军红 《岩土工程技术》2007,21(5):269-270,F0003

在地基处理施工中,扩底灌注CFG桩以其施工方法简便、单桩承载力高、施工质量易控制,且改善桩间土性能、提高桩间土承载力、工程费用低等优点在工程中得到应用。  相似文献   

网格对潜孔锤钻头球齿冲击过程数值模拟的影响     

瞿叶高卜长根  刘宝林 《探矿工程》2007,34(6):10-13

潜孔锤钻头冲击钻进的过程是一个高度非线性、大变形、破坏的过程。对这一复杂过程的研究，目前主要是利用实验方法。应用非线性显式三维有限元求解程序LS—DYNA3D，采用与岩石性质较接近的混凝土模型，对潜孔锤钻头硬质合金球齿冲击混凝土板的过程进行了仿真计算，讨论了不同网格尺寸对冲击力、冲击速度及破碎坑深度的影响等。  相似文献