海底管道沉箱基础的复合承载力包络面研究     

周素静  张艳  王栋 《海洋通报》2019,38(6):727-733

当负压沉箱被用作深水管汇或管道终端基础时,其长径比常介于1～2之间,而目前的沉箱复合承载力包络面表达式大都针对长径比不超过1的情况,少数覆盖长径比大于1的研究又不适用于土体表层强度非零的情况。采用有限元方法,模拟竖向力、水平力和弯矩共同作用下沉箱基础的响应,采用Probe加载模式获得沉箱的复合承载力包络面。进行大量变动参数分析,针对长径比为1～2的沉箱,讨论了长径比和土体强度分布对单向承载力和包络面的影响,并给出了预测沉箱复合承载力的归一化表达式。  相似文献   

Modeling progressive failures in rock slopes with non‐persistent joints using the numerical manifold method     

Xinmei An  Youjun Ning  Guowei Ma  Lei He 《国际地质力学数值与分析法杂志》2014,38(7):679-701

Rock slope failure is a complex process that usually involves both opening/sliding along pre‐existing discontinuities as well as fracturing of intact rock bridges. Discontinuity persistence is an important factor governing rock slope instabilities. However, traditional slope failure analysis assumes persistent discontinuities, and rock slope fails along a predefined persistent continuous potential failure surface because of the limitations of the analysis tools. This paper proposes the numerical manifold method (NMM) incorporated with a Mohr–Coulomb criterion‐based fracturing algorithm to simulate the progressive failure of rock slopes with non‐persistent joints. Detailed fracturing algorithm is first presented. Then, the NMM enabling fracturing is calibrated through simulating an edge‐cracked plate and the Brazilian test. Lastly, the developed code is applied to investigate the failure process of rock slopes involving non‐persistent joints. Numerical results indicate that the proposed method can capture the opening/sliding along existing discontinuities, the fracturing in intact rock bridges and the final kinematic release. Progressive slope failure is well exhibited. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Extension of numerical manifold method for coupled fluid flow and fracturing problems     

Zhijun Wu  Louis Ngai Yuen Wong 《国际地质力学数值与分析法杂志》2014,38(18):1990-2008

The present study extends the numerical manifold method to include the hydro‐mechanical model to investigate the effect of water flow in fractures on the stability of rock structures, particularly slopes. The proposed flow model is verified by a simple 2‐D flow problem in a homogeneous aquifer. Combining the water flow model with the earlier developed fracture evolution technique, the entire failure process of the rock slope due to a heavy rain is simulated. The results illustrate that the developed numerical manifold method can not only determine the trigger factor of the crack initiation but also model the failure processes related to crack initiation, propagation, block formation, detachment and sliding due to the water effect successfully. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

球坐标下数值流形方法有限单元覆盖的单元矩阵表达式     

刘经南  陈庭  许才军  易长荣 《武汉大学学报(信息科学版)》2005,30(12):1035-1038,1043

为将数值流形方法从平面扩展到球面,推导了球面上数值流形方法的有限单元覆盖的应变矩阵及刚度矩阵、初应力矩阵、点荷载矩阵、体荷载矩阵、惯性力矩阵和固定点矩阵的具体公式。  相似文献   

在线膜过滤流动注射-分光光度法直接测定废水中酚     

郭伟林守麟  胡圣虹 《岩矿测试》2005,24(4):245-248

采用一种预装的流动注射功能块流路,以4-氨基安替比林为显色剂,流动注射-分光光度法测定了水样中的酚。提出流动注射固定化和标准化流路硬件,依靠软件程序选择流路参数的优化方法,并采用一种在线膜过滤装置过滤混浊样品,直接进行测定。这种过滤装置不堵塞,可连续运行30 h以上。所拟定的方法酚的质量浓度在0.1~8.0 mg/L与吸收值呈线性关系,相关系数为0.999,方法的检出限为0.05 mg/L(3σ,n=11)。样品平行测定的相对标准偏差(RSD,n=5)<2.1%,回收率为97.0%~104.3%,采样频率为60/h以上。用此法测定油田水及管道废水中酚的结果与常用蒸馏法结果相符。  相似文献   

广义相对论的时空及参照系的数学模型     

黄孝华 《华东地质学院学报》1987,(3)

本之运用拓朴学及流形几何的概念,给出一般时空应具备的几个数学条件,结合相应的物理含义加以说明,并给出了参照系的数学定义及物理意义.  相似文献   

Non-Existence of Five Dimensional Perfect Fluid Cosmological Model in Lyra Manifold     

G. Mohanty  K. L. Mahanta  R. R. Sahoo 《Astrophysics and Space Science》2006,306(4):269-272

In this paper we have taken an attempt to construct a five dimensional perfect fluid cosmological model within the framework of Lyra manifold. It is found that neither perfect fluid nor dust distributions survive. Finally the exact solutions of the vacuum field equations are obtained.  相似文献   

The Tetrahedral 4‐Body Problem with Rotation     

Claudio Vidal 《Celestial Mechanics and Dynamical Astronomy》1998,71(1):15-33

We consider four bodies in space with same masses forming two binaries, each one symmetric with respect to a fixed axis and moving under Newtonian gravitation in opposite directions about this axis. It is given a direct proof that all singularities of this model are due to collisions, and it is proved that the singularities due to simultaneous double collisions are regularizable. The set of equilibrium points on the total collision manifold is studied as well as the possible connections among them. We show that the set of initial conditions on a given energy surface going to quadruple collision is a union of twenty submanifolds: twelve of them have dimension 2 and the others have dimension 3. Similarly for ejection orbits from quadruple collision. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Motions close to escapes in the rhomboidal four body problem     

Ernesto A. Lacomba  Ernesto Pérez-Chavela 《Celestial Mechanics and Dynamical Astronomy》1993,57(3):411-437

In this work we study escape and capture orbits in the planar rhomboidal 4-body problem in a level of constant negative energy. There are only two different values of the masses here. By using numerical analysis, we show certain transversal intersections of the invariant manifolds of parabolic orbits. We then introduce Symbolic Dynamics when the mass ratio is small, and when it is close to one. In the first case the escapes or captures predominate in the direction of one of the diagonals of the rhombus, while in the second case we find solutions escaping or being captured in the direction of both possible diagonals.  相似文献   

近井口高压管汇布置结构设计及选材优化研究          下载免费PDF全文

谭建国  洪毅  张所邦  王勇 《探矿工程》2022,49(5):163-170

为了研究和改善油气资源钻井工程中高压管汇系统受到流固体冲蚀的影响,本文根据近井口常规管汇布置情况,建立了0°、45°、90°三种角度弯管模型,并根据计算流体力学基本理论,结合实际工况,对压裂弯管内部流场进行数值模拟,最后设计了0°与45°压裂安装角度管汇布置结构,并根据此3种弯管安装角度及弯管材料选用,进行了室内冲蚀试验研究,得出了如下结论：（1）在不同的安装角度下,随着冲次增大,流体出口速度越大,在任何安装角度下,弯管部位会发生较大的速度波动,因此速度波动太大弯管部位会受到严重冲蚀;（2）高速流体冲蚀区域主要分布在近井口压裂头部位的管道入口位置,在两种错位情况下,管汇整体流体速度由出口到入口逐渐变小;（3）压裂头部位5个出口部位存在较大的冲蚀速度,速度和压力呈现阶梯状的变化,中间有压力和速度稳定时期,速度大的位置压力小。当安装角度为0°和45°时,流体的冲击速度会较小;（4）42CrMo防冲蚀能力较强,管道材料选用42CrMo有助于延长管道使用寿命。  相似文献