刚性桩与柔性桩复合地基共同作用研究现状     

胡仁众 《华南地质与矿产》2007,(2):62-65

刚性桩与柔性桩共同作用的复合地基是一项新的地基处理技术,是现在学术界和工程界研究的热点。本文通过对其特性、设计参数、理论研究和工程实践等各个方面进行了讨论,提出了自己的一些观点。  相似文献   

The decrease in shear stress and increase in transport rates subsequent to an increase in sand supply to a gravel-bed channel     

Joanna C. Curran 《Sedimentary Geology》2007,202(3):572-580

It is generally accepted that a gravel-bed river will aggrade if the supply of sediment to the river is increased. In a series of flume experiments using constant discharge and gravel feed rate, sand feed rates were increased to 6.1 times that of gravel. The slope of the bed decreased with increasing sand supply, indicating that the increased sediment load could be transported at the same rate due to a decrease in shear stresses. These results extend previous experiments to a wider range of boundary conditions. A recent surface transport model is used to predict the changes in bed composition and transport using the same sediment supply composition and feed rates as in the laboratory experiments. This model reasonably predicts a decrease in the reference shear stresses of the sand and gravel fractions as the sand supply is increased. An increase in sand supply can increase the mobility of gravel fractions in the stream bed, which can lead to bed degradation and preferential evacuation of these sediments from the river.  相似文献   

苏通长江公路大桥试验钻孔施工工艺          下载免费PDF全文

杨宗仁 《探矿工程》2007,34(1):21-23

苏通长江公路大桥主塔基础采用巨型群桩基础，施工前要模拟水上钻孔桩进行钻孔工艺试验，试验钻孔的技术要求高于现行规范要求。介绍了试验钻孔施工技术及取得的成果。  相似文献   

CFG桩复合地基桩土应力比分析     

陈春霞  赵其华  赵跃平 《四川地震》2007,(4):26-30

根据工程软弱土层进行复合地基处理后的静载荷试验结果,对CFG桩、桩间土荷载分担及桩土应力比随外荷载的变化规律进行了分析,提出了本次试验的极限桩土应力比。这些试验结果和分析结论对指导西南地区软弱土地基处理与加固有一定的参考价值。  相似文献   

CG型全套管冲抓成孔设备及施工工艺          下载免费PDF全文

宋志彬冯起赠  王年友张金昌 《探矿工程》2007,34(9):48-52

简述了国家重点新产品“CG型全套管冲抓成孔设备”的研发历程,以及设备的组成、特点和参数;分析了全套管灌注桩、咬合桩、置换桩的施工工艺及特点;总结了该设备的应用实例和发展前景。  相似文献   

广西地矿局科技业务楼深基坑施工实例          下载免费PDF全文

韦漠  苏力才  梁官华  李世新  周葛源 《探矿工程》2006,33(8):11-16

介绍了广西地矿局科技业务楼深基坑桩锚+高压旋喷止水帷幕联合支护形式、渗透系数试验、锚索试验，以及施工质量控制措施。  相似文献   

Sedimentology and stratigraphy of a transgressive, muddy gravel beach: Waterside Beach, Bay of Fundy, Canada     

SHAHIN E. DASHTGARD  MURRAY K. GINGRAS  KARL E. BUTLER † 《Sedimentology》2006,53(2):279-296

Sediments exposed at low tide on the transgressive, hypertidal (>6 m tidal range) Waterside Beach, New Brunswick, Canada permit the scrutiny of sedimentary structures and textures that develop at water depths equivalent to the upper and lower shoreface. Waterside Beach sediments are grouped into eleven sedimentologically distinct deposits that represent three depositional environments: (1) sandy foreshore and shoreface; (2) tidal‐creek braid‐plain and delta; and, (3) wave‐formed gravel and sand bars, and associated deposits. The sandy foreshore and shoreface depositional environment encompasses the backshore; moderately dipping beachface; and a shallowly seaward‐dipping terrace of sandy middle and lower intertidal, and muddy sub‐tidal sediments. Intertidal sediments reworked and deposited by tidal creeks comprise the tidal‐creek braid plain and delta. Wave‐formed sand and gravel bars and associated deposits include: sediment sourced from low‐amplitude, unstable sand bars; gravel deposited from large (up to 5·5 m high, 800 m long), landward‐migrating gravel bars; and zones of mud deposition developed on the landward side of the gravel bars. The relationship between the gravel bars and mud deposits, and between mud‐laden sea water and beach gravels provides mechanisms for the deposition of mud beds, and muddy clast‐ and matrix‐supported conglomerates in ancient conglomeratic successions. Idealized sections are presented as analogues for ancient conglomerates deposited in transgressive systems. Where tidal creeks do not influence sedimentation on the beach, the preserved sequence consists of a gravel lag overlain by increasingly finer‐grained shoreface sediments. Conversely, where tidal creeks debouch onto the beach, erosion of the underlying salt marsh results in deposition of a thicker, more complex beach succession. The thickness of this package is controlled by tidal range, sedimentation rate, and rate of transgression. The tidal‐creek influenced succession comprises repeated sequences of: a thin mud bed overlain by muddy conglomerate, sandy conglomerate, a coarse lag, and capped by trough cross‐bedded sand and gravel.  相似文献   

Environmentalism and Natural Aggregate Mining     

Drew  Lawrence J.  Langer  William H.  Sachs  Janet S. 《Natural Resources Research》2002,11(1):19-28

Sustaining a developed economy and expanding a developing one require the use of large volumes of natural aggregate. Almost all human activity (commercial, recreational, or leisure) is transacted in or on facilities constructed from natural aggregate. In our urban and suburban worlds, we are almost totally dependent on supplies of water collected behind dams and transported through aqueducts made from concrete. Natural aggregate is essential to the facilities that produce energy—hydroelectric dams and coal-fired powerplants. Ironically, the utility created for mankind by the use of natural aggregate is rarely compared favorably with the environmental impacts of mining it. Instead, the empty quarries and pits are seen as large negative environmental consequences. At the root of this disassociation is the philosophy of environmentalism, which flavors our perceptions of the excavation, processing, and distribution of natural aggregate. The two end-member ideas in this philosophy are ecocentrism and anthropocentrism. Ecocentrism takes the position that the natural world is a organism whose arteries are the rivers—their flow must not be altered. The soil is another vital organ and must not be covered with concrete and asphalt. The motto of the ecocentrist is man must live more lightly on the land. The anthropocentrist wants clean water and air and an uncluttered landscape for human use. Mining is allowed and even encouraged, but dust and noise from quarry and pit operations must be minimized. The large volume of truck traffic is viewed as a real menace to human life and should be regulated and isolated. The environmental problems that the producers of natural aggregate (crushed stone and sand and gravel) face today are mostly difficult social and political concerns associated with the large holes dug in the ground and the large volume of heavy truck traffic associated with quarry and pit operations. These concerns have increased in recent years as society's demand for living space has encroached on the sites of production; in other words, the act of production has engendered condemnation. Many other environmental problems that are associated with dust and noise and blasting from quarry and pit operations have been reduced through the efficient use of technology. Recycling concrete in buildings, bridges, and roads and asphaltic pavements will ultimately reduce the demand for virgin natural aggregate. The impact created by the large holes in the ground required for the mining of natural aggregate can be greatly reduced by planning their reclamation before mining begins.  相似文献   

抗滑桩内力计算“K”法的改进与应用   总被引：4，自引：0，他引：4  

戴自航  彭振斌 《地质与勘探》2002,38(3):79-83

对传统的抗滑桩内力计算“K”法作了一些改进,如建立了滑动面上下统一的坐标系,将桩视为一个整体进行考虑,通过合理的假定,保证了桩身在滑动面处内力和位移的连续性,同时,采用名的MATLAB数学软件设计了“K”法的计算程序,适用于滑坡推力和桩前滑体抗力分布的各种形式以及抗滑桩为刚性桩和弹性桩的情况,实例计算结果表明,较之传统的查表法,该方法有效地提高了抗滑桩内力和位移计算速度和精度,同时可得到理想的可视化计算结果,有助于抗滑桩结构的优化设计。  相似文献   

利用载荷试验研究水泥土搅拌桩的有效桩长   总被引：7，自引：1，他引：7  

徐超  廖星樾  叶观宝  杨晓明 《水文地质工程地质》2005,32(3):105-107

本文根据某高速公路软基处理中不同桩长的水泥土搅拌桩单桩载荷试验结果,探讨了复合地基中水泥土搅拌桩的有效桩长。研究结果表明:水泥土搅拌桩的有效桩长与地基条件和桩身强度直接相关,在设计中考虑有效桩长有其必要性。最后,作者对有效桩长的确定方法提出了建议。  相似文献