静钻根植能源桩承载特性模型试验研究     

李富远  王忠瑾  谢新宇  娄扬  王奎华  方鹏飞  郑凌逶 《岩土力学》2020,41(10):3307-3316

为了研究静钻根植能源桩在热?力耦合作用下的承载特性，采用自行设计模型试验系统，测试模型桩在黏?砂双层地基中的热力响应。试验结果表明：桩体温度沿深度变化并不均匀，对桩周土的温度影响半径为3倍桩径；3次冷热循环后桩顶和桩周土表面均产生累积沉降，在桩顶荷载达到单桩极限承载力的25%时，桩顶累积沉降达到桩径的3.12‰，是桩顶无荷载情况下的1.77倍；模型桩附加温度应力沿深度分布均表现为中间大两端小，位移变化零点（附加温度应力最大处）随着桩顶荷载增大（约束增强）而上移，桩顶荷载较小时降温引起桩身局部产生拉应力。因此，静钻根植能源桩的承载特性与温度变化条件、桩顶荷载大小和桩端约束条件密切相关，在工程设计中需要综合考虑以确保运行安全性。  相似文献   

珊瑚砂地基中膨胀混凝土桩竖向受压承载性能研究     

邓玮婷  丁选明  彭宇 《岩土力学》2020,41(8):2814-2820

为研究珊瑚砂地基下膨胀混凝土桩竖向承载特性，开展了室内单桩竖向静载模型试验，分析了膨胀混凝土桩的单桩荷载-位移曲线以及轴力、桩侧摩阻力等沿桩长分布特性，与PLAXIS 3D软件数值模拟结果进行对比并探究了线膨胀率对承载特性的影响。结果表明：珊瑚砂中膨胀混凝土桩的荷载位移曲线呈现缓变型，在加载过程中，荷载主要由桩侧摩阻力承担，轴力随着深度的增加而减小，桩侧摩阻力随深度先增加后逐渐减小，随荷载的增加逐渐发挥作用。随着膨胀剂用量的增加，桩身线膨胀量逐渐增加，桩-土相互作用更加明显。添加25% HCSA型膨胀剂可提高近20%的极限承载力和56%的极限侧阻力，提高桩体线膨胀率可以有效提高桩的极限承载力和侧摩阻力。该研究可为珊瑚砂桩基工程设计提供参考。  相似文献   

Experimental investigation of single blade and propeller loads by free running model test. Straight ahead sailing     

《Applied Ocean Research》2019

The understanding and the accurate assessment of propeller loads in realistic operative scenario, both design and off-design conditions, is of paramount importance to design low emission and comfortable ships, fulfilling the requirements of structural integrity of the propulsion system, safety and continuity of operations at sea. To this purpose, a deeper characterization of the propeller functioning, in terms of averaged and fluctuating loads, can be attained by means of the quantification of the single blade loads. In this work, a novel set up that allows to monitor the loads developed by a single blade was implemented on a free running, self propelled maneuvering model with the aim to investigate in details the hydrodynamic interactions between the spatially non-homogeneous and time-variant wake of the hull and the propeller and a complete characterization of its performance. This preliminary work introduces the experimental setup and provides a preliminary overview of the results relative to straight ahead motion.  相似文献   

Physical Modeling of a Footing on Soft Soil Ground with Deep Cement Mixed Soil Columns under Vertical Loading     

Jian-Hua Yin  Zhen Fang 《Marine Georesources & Geotechnology》2013,31(2):173-188

Deep cement mixing (DCM) technique is a deep in-situ stabilization technique by mixing cement powder or slurry with soft soils below the ground surface to improve their properties and behavior. Some of DCM treated soft soil grounds are approximately in a plane-strain condition; for example, a fill embankment on DCM improved ground. In this study, a plane-strain physical model was created with instrumentation and used to investigate the bearing capacity and failure mode of a soft soil improved by an end-bearing DCM column group. This study focuses on the observed wedge-shaped shear failure of the model ground and attempts to give an account of the failure. Two different methods are used to calculate the bearing capacity of the model ground, and the computed values are compared with the measured ones. It is found that the simple Brom's method gives a better estimate of the bearing capacity of the present model ground. It is also found that measured data of pore water pressures at different locations in the soft soil indicate coupling between failure of columns and consolidation of the soft soil. This study has presented the first time that a wedge-shaped block failure was observed for pattern of DCM treated soil ground.  相似文献   

Retrieval of Substrate Bearing Strength from Hyperspectral Imagery during the Virginia Coast Reserve (VCR’07) Multi-Sensor Campaign     

Charles M. Bachmann  C. Reid Nichols  Marcos J. Montes  Rong-Rong Li  Patrick Woodward  Robert A. Fusina 《Marine Geodesy》2013,36(2-3):101-116

Hyperspectral imagery (HSI) derived from remote sensing can delineate surface properties of substrates such as type, moisture, and grain size. These are critical parameters that determine the substrate bearing strength. Although HSI only sees the surface layer, statistics can be derived that relate surface properties to the likely bearing strength of soils in particular regions. This information can be used to provide an initial map estimate on large scales of potential bearing strength. We describe an initial validation study at the Virginia Coast Reserve relating airborne HSI to in situ spectral and geotechnical measurements through a spectral-geotechnical lookup table (LUT).  相似文献   

桩-筒组合基础在单层黏土中水平承载性能分析   总被引：2，自引：1，他引：2       下载免费PDF全文

丁红岩  胡彩清  张浦阳  朱东剑 《海洋工程》2014,32(2):30-37

桩-筒组合基础是将单桩基础与筒型基础组合的一种新型海上风电基础形式,其受力模式不同于传统桩基基础,优点是可通过合理减小桩长、桩壁厚等途径提高承载性能。基于极限地基反力法,提出单层黏土中桩-筒组合基础受力模式及水平承载力的计算方法。利用力加载和位移加载两种控制方法进行数值分析,研究水平承载性能的影响因素。结果表明,在一定范围内,桩-筒组合基础水平承载性能随桩入土深度、桩壁厚、筒外径的增大而提高。基于实际工程,对等用钢量的单桩基础与组合基础进行比较计算,结果表明,桩-筒组合基础可有效降低基础倾斜度和位移,提高承载性能。  相似文献   

Determination of partial factors for the verification of the bearing capacity of shallow foundations under open channels     

《Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards》2013,7(3-4):186-194

The limit state design method has been introduced into the design criteria for geotechnical structures. The current paper attempts to apply the reliability-based design method, at Level II, to the bearing capacity of the foundations of open channels from the viewpoint of the limit state design. To examine the applicability of the proposed procedure for practical structures, the reliability index is computed for evaluating the stability of the foundations of existing open channels designed by the conventional method. The conventional design procedure makes excessively safe side design. We applied the FORM to the existing open channels designed by the conventional design procedure, and consequently, large values of reliability index, 3 and 5 were obtained for clayey and sandy soils, respectively. Finally, the partial factors for the soil parameters have been determined, corresponding to the target reliability indices β _t =1, 3 and 4.  相似文献   

浅谈内蒙古查干楚鲁地区的找矿前景     

周阳  胡平  郭鑫 《吉林地质》2013,(4):13-15

介绍了本区所处的大地构造位置、地层、构造、岩浆岩和区内主要金属、多金属矿的赋矿层位。阐述了本区成矿规律。东西向、北东向、北西向基底断裂的＂活化＂,并控制了本区侏罗纪—早白垩世火山-侵入岩浆活动及成矿活动。根据野外工作中的实际情况对该地区的成矿前景进行预测。  相似文献   

无砂垫层真空预压在吹填淤泥软基处理中的效果分析     

吴兴龙  张开伟  徐剑 《岩土工程技术》2013,(6):315-319

新吹填淤泥具有超软、超含水率等不利的工程特性,使得其对后期的地基处理提出了很高的要求.结合某新吹填淤泥工程,对取消排水垫层后的浅层地基处理进行了现场试验研究.同时采用数值模拟方法、理论和规范方法对该现场试验后的承载力进行分析和探讨.结果表明,在取消排水垫层后,采用浅层处理方法对新吹填淤泥进行处理,可使处理深度范围内的吹填淤泥强度得到明显增长.  相似文献   

四川盆地南部下寒武统筇竹寺组页岩沉积微相研究   总被引：10，自引：0，他引：10  

李延钧  赵圣贤 《地质学报》2013,87(8):1136-1148

页岩气是我国未来一个重要的且比较现实的非常规油气资源,加强该领域的基础研究对页岩气油气成藏理论创新、页岩气开采技术运用和资源量的准确计算都非常必要.因此,本文运用野外露头资料、钻取岩芯和测井资料,以及页岩有机地球化学分析化验结果等大量第一手资料,通过详细分析四川盆地南部下寒武统筇竹寺组页岩沉积微相特征及其含气性特征,并结合研究区沉积相标志和测井相特征,明确指出泥质深水陆棚微相是四川盆地南部下寒武统筇竹寺组优质页岩最有利沉积微相带.  相似文献