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751.
752.
当前,随着国民经济的快速发展,地下结构物如地下停车场、地下商场等的开发与利用越来越广泛,其抗浮问题亦日益受到关注。与压重法、摩擦抗浮法、基板延伸法、降排截水法以及大口径抗浮桩(如预应力管桩、钻孔桩、人工挖孔桩)等相比,抗浮锚杆(索)(一般直径小于300mm)由于采用高压注浆工艺,使浆液能渗透到岩土体的空隙与裂隙中,锚杆(索)的侧摩阻力较大,更有利于抗浮,具有受力合理、工期短、造价低、施工便捷、节省建材等诸多优点,已在各大中城市的工程建设中迅速推广使用。文章介绍了锚索抗浮桩在昆明某工程中进行抗拔试验概况,并对试验结果进行分析,得出相关结论并提出适用于下一阶段进行抗浮设计所需的土力学指标及有关施工工艺参数的建议。其锚索抗浮桩试验经验可供同类工程借鉴与参考。 相似文献
753.
Model tests on steel piles embedded in sand were carried out in the laboratory to study the effects of compressive load (i.e.
0, 25, 50, 75, and 100% of their ultimate capacity in compression) on oblique pull-out capacity of piles. The model piles
were of 20 mm × 20 mm cross section, which had an embedded length of 400 and 600 mm. The pull was applied at an inclination
of 0°, 30°, 60° and 90° with vertical axis of the piles. The experimental results indicate that the net oblique pull-out capacity
of piles decreases with increase in % of compressive load and the decrease depends on the magnitude of the compressive load.
Semi-empirical methods, based on experimental results, have been suggested to determine the oblique pull-out resistance of
piles subjected to static compressive loads. A comparison of predicted values of the ultimate oblique resistance by proposed
methods of analysis with experimental values, and also with those reported by others, showed reasonably good agreement. 相似文献
754.
Piles and drilled shafts are commonly used to stabilize potentially unstable natural and engineered slopes. Estimation of
lateral pressures on piles or shafts used to stabilize potentially unstable sites continues to be a fundamental problem in
geotechnical engineering. Several methods are available to estimate the lateral force on piles or drilled shafts used to stabilize
a site. An approximate procedure to estimate the lateral force on drilled shafts supporting structures, i.e., installed at
relatively large spacings on a potentially unstable site with a fixed slip surface is proposed, which is based on a widely
referred theory of plastic deformation. Lateral pressures estimated using the method proposed show good agreement with a more
rigorous method, which in turn has been reported to provide results close to field measurements. An approximate procedure
to estimate a limiting (maximum) value of lateral pressure on shafts or piles when they are installed at close spacings is
also proposed. Although, the limiting pressures estimated using the approximate procedure are in agreement with the pressures
calculated using more rigorous method, verification of both methods with field measurements is recommended. 相似文献
755.
756.
曹安商贸城设计逆作法施工钢立柱桩248根。根据桩标高及垂直度的要求,从钢立柱制作与安装、成孔桩机选择、固定架设计制作与安装等方面采取措施,施工的钢立柱标高及垂直度均符合设计及规范要求。 相似文献
757.
The interaction between soil and rigid piles loaded laterally is analyzed with finite difference method. There is a little difference between computational and experimental value of bearing capacity of rigid piles. Effects of embedding dimensions of piles and mechanical parameters of soil on lateral bearing capacity of rigid piles are studied. It is found that the lateral bearing capacities of rigid piles have important relation with the elastic modulus of soil, have approximate linear relations with the cohesion of soil and the friction coefficient of pile-soil interface and increase obviously with the internal friction angle of soil. But the effects of dilation angle on the lateral bearing capacities of rigid piles are negligible. The relations of bearing capacities of rough piles with smooth piles and the friction coefficient of pile-soil interface are also obtained. 相似文献
758.
三维直角坐标转换的一种阻尼最小二乘稳健估计法 总被引:2,自引:0,他引:2
提出了一种利用阻尼最小二乘原理进行三维直角坐标转换的方法,并在模型中加入了稳健估计进行粗差探测与剔除。该方法的特点是:不依赖7个坐标转换参数初值,计算收敛速度快,计算结果精确稳定可靠,不仅适合于小旋转角而且也适用于任意的大旋转角。通过模拟算例验证了该方法的正确性。 相似文献
759.
Jiu J. Jiao 《Hydrogeology Journal》2007,15(5):1021-1029
In 1973, traces of China’s early Neolithic Hemudu culture (7,000–5,000 BP) were discovered in the village of Hemudu in Yuyao County, Zhejiang Province, in the lower Yangtze River coastal plain. The site has yielded animal and plant remains in large quantities and large numbers of logs secured with tenon and mortise joints, commonly used in wooden buildings and other wooden structures. For hydrogeologists, the most interesting structure is an ancient wooden well. The well is believed to be about 5,600 years old, which makes it the oldest wooden well yet found in China. The well site contains over 200 wooden components and can be divided into inner and outer parts. The outer part consists of 28 piles around a pond. The inner part, the wooden well itself, lies in the middle of the pond. The walls of the well were lined with close-set timber piles reinforced by a square wooden frame. The 28 piles in the outer part of the site may have been part of a shelter for the well, suggesting that the people of the Hemudu culture were already concerned with water hygiene and protection of their water source. 相似文献
760.
利用广义支持函数和限弦函数讨论了弦长分布函数的计算问题,得到正三角形的弦长分布函数的显式表达式,所提供的方法具有普适性. 相似文献