模拟试验法确定桩基承载力   总被引：3，自引：0，他引：3  

亓宾  佴磊  江娟 《吉林大学学报(地球科学版)》2004,(Z1)

通过室内中型剪切摩擦试验确定桩与地层间的C、Φ值,依据莫尔—库仑准则确定桩侧摩阻力。桩侧法向应力采用桩土上部荷载引起的作用于桩身的侧向应力,桩端承载力通过室内三轴试验确定,两者之和即为单桩承载力。该方法用于肇源松花江大桥桩基承载力的测试,得出的桩承载力与实测值吻合较好,取得了预期的效果。  相似文献   

A new method of testing pile using dynamic P-S-curve made by amplitude of wave train     

Hu Yi-li  Xu Jun  Duan Yong-kong  Xu Zhao-yong  Yang Run-hai  Zhao Jin-ming 《地震学报(英文版)》2004,17(6):725-734

A new method of detecting the vertical bearing capacity for single-pile with high strain is discussed in this paper. A heavy hammer or a small type of rocket is used to strike the pile top and the detectors are used to record vibration graphs. An expression of higher degree of strain (deformation force) is introduced. It is testified theoretically that the displacement, velocity and acceleration cannot be obtained by simple integral acceleration and differential velocity when long displacement and high strain exist, namely when the pile phase generates a whole slip relative to the soil body. That is to say that there are non-linear relations between them. It is educed accordingly that the force P and displacement S are calculated from the amplitude of wave train and (dynamic) P-S curve is drew so as to determine the yield points. Further, a method of determining the vertical bearing capacity for single-pile is discussed. A static load test is utilized to check the result of dynamic test and determine the correlative constants of dynamic-static P(Q)-S curve. Foundation item: Key projects of the tenth Five-year Plan of Yunnan Province (documented Yunnan district [2002]54-02-02) and Geophysical Society of Yunnan Province.  相似文献   

Interactive behavior of soil–pile-superstructure system in transient state to liquefaction by means of large shake table tests     

Shintaro Yao  Koichi Kobayashi  Nozomu Yoshida  Hiroshi Matsuo 《Soil Dynamics and Earthquake Engineering》2004,24(5):572-409

Shaking table tests were conducted by means of a large-scale laminar box with 4 m in length, 2 m in width and 2 m in height in order to investigate behavior of a soil-pile-superstructure system in liquefiable ground. A model two-storey structure, supported by a pile group, was set in a saturated sand deposit, and subjected to a sinusoidal base motion with increasing amplitude. Discussions are focused on the transient behavior until soil liquefaction occurs. Main interests are characteristics of springs used in a sway-rocking model and a multi-freedom lumped mass (MFLM) model that are frequently used in soil–pile interaction analysis. The spring constant in the sway-rocking model is represented by restoring force characteristics at the pile head, and that in the MFLM system is represented by an interaction spring connecting the pile to the free field. The transient state prior to soil liquefaction is shown to be important in the design of a pile because dynamic earth pressure shows peak response in this state. The reduction of the stiffness due to excess porewater generation and strain dependent nonlinear behavior is evaluated.  相似文献   

In-plane and anti-plane strong shaking of soil systems and structures     

G. Gudehus  R. O. Cudmani  A. B. Libreros-Bertini  M. M. Bühler 《Soil Dynamics and Earthquake Engineering》2004,24(4):319-342

The concept of in-plane and anti-plane shaking is introduced with a rigid block on a plane surface with Coulomb friction. Using a hypoplastic constitutive relation to model the mechanical behaviour of the soil, numerical solutions for a rigid block on a thin dry or saturated soil layer are obtained. The coupled nature of dynamic problems involving granular materials is shown, i.e. the motion of the block changes the soil state—skeleton stresses and density—which in turn affects the block motion. Motions of the block as well as soil response can be more realistically calculated by the new model. The same constitutive equation is applied to the numerical simulation of the propagation of plane waves in homogeneous and layered level soil deposits induced by a wave coming from below. Experiments with a novel laminar shake box as well as real seismic records from well-documented sites during strong earthquakes are used to verify the adequacy of the hypoplasticity-based numerical model for the prediction of soil response during strong earthquakes. The response of a homogeneous earth dam subjected to in-plane and anti-plane shaking is investigated numerically. In-plane and anti-plane shaking is shown to cause nearly the same spreading of a sand dam under drained conditions, whereas under undrained conditions anti-plane shaking causes stronger spreading of the dam. The dynamic behaviour of a breakwater founded on rockfill and soft clay during the 1995 Kobe earthquake is back-calculated to show the good performance of the proposed numerical model also with a structure. Section 9 deals with buildings on mattresses of densified cohesionless soils or fine-grained soils with granular columns, slopes with ‘hidden’ dams and structures on piles traversing clayey slopes to show the suitability of hypoplasticity-based models for the earthquake-resistant design and safety assessment of geotechnical systems.  相似文献   

A new method for testing pile by sin- gle-impact energy and P-S curve     

许昭永  段永康  王彬  胡毅力  杨润海  许峻  赵晋明 《地震学报(英文版)》2004,17(Z1)

Introduction Through many year's practices by vast numbers of scientific and technological workers andefforts from all aspects, the dynamic testing method of high-low strain has formally entered intothe technical code of foundation pile test of construction at last (The Industry Standards of thePeople's Republic of China, 2003). The striking mode of the dynamic testing method of high strainis stipulated as hammer in the code, the striking of rocket can also be used. The latter is widely…  相似文献   

大气边界层湍流能量交换特征研究进展     

李富余张宏升  陈家宜 《气象科技》2004,32(5):305-310

从一维湍流能量平衡方程出发,回顾了近几十年湍流能量平衡方程中的各项以及Karman常数k的研究成果,总结了大气边界层湍流能量交换特征的研究概况和热点问题,并对今后发展趋势做了展望。实验研究表明,湍流能量平衡方程中的各项在不同条件下有不同的形式;传统的能量产生和耗散的局地平衡假设存在不足,特别是在不稳定条件下,垂直的湍流输运和压力脉动对湍流能量收支起了非常重要的作用。Karman常数与Rossby数和Reynolds数无关,在比较光滑的下垫面上k近似等于040±001。  相似文献   

探地雷达在公路灌注碎石桩检测中的应用     

韦瑞表 《物探与化探》2004,28(6):553-556

介绍了应用探地雷达检测公路灌注碎石桩的基本方法,包括数据的采集、处理与解释,指出了探地雷达检测技术能够定性分析碎石桩的桩身完整性,并在公路工程实践中取得了良好的效果.  相似文献   

路堤下现浇薄壁管桩复合地基工作特性分析   总被引：15，自引：7，他引：15  

费康  刘汉龙  高玉峰 《岩土力学》2004,25(9):1390-1396

现浇薄壁管桩和土工格栅加筋碎石垫层所组成的复合地基加固软弱路基具有经济合理，施工时间短，承载力高，沉降减小明显等优点。采用非线性有限元对路堤荷载作用下的现浇薄壁管桩复合地基的工作特性进行了分析，结果表明：在路堤荷载作用下，路堤填土材料中的拱效应、土工格栅的拉膜效应或加筋垫层的刚性垫层效应、桩土间刚度差异引起的应力集中效应保证了大部分荷载由桩承担，有效地减小了总沉降和不均匀沉降。同时对荷载传递机理的影响因素做了分析.  相似文献   

组合桩型复合地基计算与应用分析   总被引：14，自引：2，他引：14  

周德泉  张可能  刘宏利 《岩土力学》2004,25(9):1432-1436

为完善组合桩型复合地基设计理论，以单一桩型复合地基计算方法为基础，给出了其承载力和沉降量计算方法，提出了静载试验结果的尺寸修正方法，并与测试结果进行了验证。结果表明：经修正后，承压板下组合桩型复合地基承载力试验值与采用本文公式所得计算值吻合；采用桩间土的压缩模量乘以承载力的提高幅值，所得复合压缩模量计算组合桩型复合地基，最终沉降满足工程要求。  相似文献   

水泥土桩单桩荷载传递及临界桩长研究   总被引：7，自引：0，他引：7  

吴雄志 《岩土力学》2004,25(9):1491-1494

将克拉夫-邓肯模型作为传递函数，对水泥土桩荷载传递规律及临界桩长进行了研究，描述了桩周摩阻力的分布及发展规律，并详细讨论了临界桩长的确定标准及各种因素对临界桩长的影响。结果表明，该方法是可行的，该方法同样适用于其它形式的柔性桩。  相似文献