钻孔水力采矿射流喷嘴初步试验研究     

杨倩云  乌效鸣  李云波  胡郁乐 《探矿工程》2003,30(6):31-34

围绕钻孔水力采矿的关键元素——喷嘴，在进行小直径喷嘴试验的基础上，分析研究试验数据，提出喷嘴的设计思路，完成喷嘴的基本选型。针对不同岩层的特性，提出不同的水力采矿方案。研究处在钻孔底高压淹没条件下，水射流的碎岩机理和碎岩能力。  相似文献   

In-situ Measurements of Cutter Forces on Boring Machine at Äspö Hard Rock Laboratory Part II. Characteristics of Cutter Forces and Examination of Cracks Generated     

Z. X. Zhang  S. Q. Kou  P.-A. Lindqvist 《Rock Mechanics and Rock Engineering》2003,36(1):63-83

Summary By means of spectral analysis, the measured normal forces, tangential forces, and side forces acting on two button cutters on the boring machine in ?sp? Hard Rock Laboratory were analysed and the basic characteristics of the cutter forces were determined. After the measurements of the cutter forces, some rock core samples were taken from the bottom and the wall of the test borehole. These samples were cut, polished, and examined by means of a Scanning Electron Microscope (SEM). The lengths of the major cracks in the rock samples were measured, and a relation between the length of the median cracks and the relevant cutter forces was investigated. Received October 5, 2001; accepted June 25, 2002; Published online November 19, 2002  相似文献   

Using the Entropy of Curves to Segment a Time or Spatial Series   总被引：1，自引：0，他引：1  

A. Denis  F. Crémoux 《Mathematical Geology》2002,34(8):899-914

The concept of the thermodynamics of curves is used to analyze change in the variability of time or spatial series. More specifically, the entropy of a curve makes it possible to divide a nonstationary random field, because of a change in variance, into subdomains where data are said to be stationary. It is demonstrated that for time and spatial series the entropy of a curve is the slope of the cumulative sum of absolute differences. Numerical simulations show the efficiency of this tool. It can be shown that the presence of a linear or quadratic trend is without effect on the localization of the stationary subdomains. A practical case is studied with data collected from a tunnel boring machine where several parameters are recorded. This analysis can bring more information on the mechanical behavior of the different geological formations and explain or justify unplanned delays.  相似文献   

The Delivery Tunnel North, Lesotho Highlands Water Project     

P.J.H. De Graaf  F.G. Bell 《Geotechnical and Geological Engineering》1997,15(2):95-120

Summary The Delivery Tunnel North starts in Lesotho and continues into South Africa. It is divided into two sections by the Caledon and Little Caledon rivers. It runs through the mudrocks and sandstones of the Tarkastad Subgroup, and the Elliot and Molteno Formations. The tunnel was excavated by a double-shield tunnel boring machine, except for the sections beneath the two rivers, which were constructed by drill and blast methods. The tunnel boring machine was selected to bore through the anticipated changing ground conditions and also was capable of installing the segmental lining of the tunnel. Boreability tests showed that the sandstones and siltstones had good boreability, but that it was very low in the dolerite dykes. At depth, the weaker mudstones presented the worst tunnelling conditions, giving rise to squeezing ground and to shear failure with accompanying overbreak. Initially a small amount of cracking occurred in the tunnel lining but this was reduced significantly as experience was gained. Cracking was observed predominantly in the weaker rock types, and this was probably associated with overbreak.  相似文献   

利用钻孔资料确定降雨入渗系数   总被引：3，自引：0，他引：3  

陈引锋  王爱玲 《地下水》2008,30(1):37-39

在河北省地下水水资源评价的基础上,提出利用钻孔资料来具体确定降雨入渗系数的大小,从而为区域地下水资源评价的精确计算提供依据。  相似文献   

A fossil record of shell boring: Possible evidence for sea level changes in the Red Sea     

Ehud Spanier   《Estuarine, Coastal and Shelf Science》1987,24(6)

An aggregation of fossil shells of the Indo-Pacific muricid snails Chicoreus ramosus was found in the northern part of the island of Tiran, Red Sea. The site was 7 m above the present mean sea level. Radiocarbon dating of these shells indicated an age of 1570±80 years BP. Some of these shells bore-drilled holes, most of them uncompleted. Biological study revealed that such holes were probably drilled by conspecifics in the absence of alternative food after they had been disconnected from the sea. Since there is no evidence of human activity in this part of Tiran, I suggest that such conditions could be caused only by a physical process that changed the relative water level. In accordance with the character of the drilled holes and the short period which muricids maintain reproductive aggregates, I also postulate that such a physical process must have been a relatively rapid one.  相似文献   

Food Deprivation in the Muricid Drill Ocinebrina edwardsi (Mollusca: Prosobranchia): Histomorphological and Behaviour Research     

A. M. Bolognani  Fantin  P. Nardi    E. Ottaviani    A. Franchini  P. Tongiorgi 《Marine Ecology》1981,2(4):307-316

Abstract. After a starvation period the predation rate in specimens of Ocinebrina edwardsi is less than in animals which feed normally. The closer the prey predator contact during the starvation period, the higher the level of predation when the snails are allowed to resume feeding. The reduction in predation after a long or short fast is obviously the result of changes in the structure and function of the ABO. In the secreting cells of normally fed animals the following enzymatic activities can be distinguished: acid and alkaline phosphatases, carbonic anhydrase and ATPase. Carbonic anhydrase and acid phosphatase activities are not present in starved individuals. Only after the animals have resumed feeding for 10 days does the ABO completely recover its enzymatic functions.  相似文献   

复杂地质条件钢管立柱灌注桩施工技术          下载免费PDF全文

刘波明  郭优腾  李春生 《探矿工程》2016,43(8):77-80

钢管柱逆作法在超大超深基坑中的运用越来越广泛,钻孔桩与钢管柱的有效结合,大大缩短了工期并降低造价,而施工中钢管柱的垂直度控制是钢管柱施工质量的重要指标之一。为使钢管柱的垂直度满足设计要求,保证施工质量,通过采用旋挖钻与冲击钻有机结合在复杂地质条件下的钢管立柱灌注桩施工的工程实例,归纳、总结并提出该技术在钢管立柱灌注桩施工的工艺方法和控制措施等。  相似文献   

Assessment of the effectiveness of natural coral fragmentation as a dispersal mechanism for coral reef‐boring sponges          下载免费PDF全文

Héctor Nava  José Luis Carballo 《Marine Ecology》2016,37(5):1008-1018

Eastern Pacific reefs are mostly made up of interlocking coral branches of Pocillopora, which are easily broken by physical forces associated with heavy swells and winds. In this study we investigated the potential of these coral fragments to enable propagation of boring sponges. For this, we quantified the frequency of occurrence and diversity of boring sponges in fragments of corals recently trapped among the branches of live colonies, and later tested the hypothesis that these sponges colonize new branches of corals. Nearly 80% of the coral colonies investigated had coral fragments among their branches, and 69% of these coral fragments contained boring sponges (11 species), some of these sponges in reproduction (23% of them carried oocytes). To test whether sponges inhabiting coral fragments could colonize new branching corals we transplanted them to healthy branches, and to branches whose living tissue was mechanically eliminated to simulate damage produced by grazing and death after bleaching and other causes of coral tissue mortality. All the transplanted coral fragments cemented to each new colony by means of calcification, and of the three sponge species tested (Cliona vermifera, Cliona tropicalis and Thoosa mismalolli) only C. vermifera was able to colonize both new living branches (26.9%) and cleaned branches (65.5%). The apparent capability of C. vermifera to colonize by direct contact may be another key ability of this species to maintain high frequency of occurrence in Pacific coral reefs. However, although C. tropicalis and T. mismalolli were not able to colonize new coral substrata by direct contact, coral fragments have the potential to contribute to local persistence of these sponges and to their dispersal, both by asexual (fragments) and sexual means (transport of sexual products). The present findings may partly explain the current increase of excavating sponges on deteriorating reefs with a large availability of dead branching corals.  相似文献   

非开挖导向钻进轨迹自动控制系统的研究   总被引：1，自引：0，他引：1  

于基宁  孙友宏  贾栋 《世界地质》2004,23(1):75-78

非开挖导向钻进技术以其施工速度快、适用范围广等优点，得到了广泛的应用。但在目前实际钻进中，对于钻孔轨迹的控制主要是依靠操作人员的经验进行判断，使得钻进速度和效率大大降低。本文通过建立钻孔轨迹的数学计算模型，并利用Visual Basic和AutoCAD实现了钻孔轨迹的可视化，同时将测得实际轨迹与预先设计轨迹在同一界面进行同点比较，纠正超出范围的误差，使钻进轨迹更好的接近设计轨迹，并能顺利穿越地下障碍物完成导向钻进过程。  相似文献