Surface motion of a cylindrical hill of circular-arc cross-section for incident plane SH waves   总被引：2，自引：0，他引：2  

Xiaoming Yuan  Zhen-Peng Liao 《Soil Dynamics and Earthquake Engineering》1996,15(3):189-199

A closed-form solution of two-dimensional scattering of plane SH waves by a cylindrical hill of circular-arc cross-section in a half-space is presented using the wave functions expansion method. The solution is reduced to solving a set of infinite linear algebraic equations, using the auxiliary functions and the exterior region form of the Graf's addition theorem. Numerical solutions are obtained by truncation of the infinite equations and their accuracies are demonstrated by convergence of the numerical results and by the extent to which the numerical results fit the exact boundary conditions with increasing the truncation order. The numerical results for some typical cases are then presented for checking accuracies of various numerical methods. The effects of the height-to-width ratio of the hill on surface ground motion are finally illustrated.  相似文献   

Placement Optimization Method of FPSO Gas Detectors Based on Leakage Risk     

KANG Jichuan  SUN Chongwen  JIN Peng  YAN Fasuo  SUN Liping 《中国海洋大学学报(英文版)》2022,21(1):49-61

As the first step of the fire/gas-detection systems of floating production storage and offloading(FPSO)units is to iden-tify leakage accidents,gas detectors play an important role in controlling the leakage risk.To improve the leakage scenario detection rate and reduce the cumulative risk value,this paper presents an optimization method of the gas detector placement.The probability density distribution and cumulative probability density distribution of the leakage source variables and environmental variables were calculated based on the Offshore Reliability Data and the statistical data of the relevant leakage variables.A potential leakage sce-nario set was constructed using Latin hypercube sampling.The typical FPSO leakage scenarios were analyzed through computational fluid dynamics(CFD),and the impacts of different parameters on the leakage were addressed.A series of detectors was deployed according to the simulation results.The minimization of the product of effective detection time and gas leakage volume was the risk optimization objective,and the location and number of detectors were taken as decision variables.A greedy extraction heuristic algo-rithm was used to solve the optimization problem.The results show that the optimized placement had a better monitoring effect on the leakage scenario.  相似文献   

应用于二维倾斜仪中的圆弧柱面差动电容理论分析     

胡远旺  邹彤  马武刚 《大地测量与地球动力学》2022,42(5):545-550

介绍了基于圆柱摆体和圆弧柱面极板的二维倾斜仪模型,并对其圆弧柱面差动电容电路进行理论分析。结果表明,提高倾斜仪的观测灵敏度需适度增加圆柱摆体半径与高度及吊丝长度,减小圆弧柱面极板圆心角,缩小动极板与定极板间隙距离;减少倾斜仪的输出非线性需适度增加圆柱摆体半径和动极板与定极板间隙距离,减小圆弧柱面极板圆心角、圆柱摆体高度及吊丝长度。依据该原则,选取一组典型参数,计算得到倾斜仪理论灵敏度为0.028 5 V/(″),非线性度为0.001 2%。  相似文献   

高铁站场中不同类型桩基沉桩顺序研究     

秦晓光  杨龙才  何太洪 《岩土工程技术》2011,25(2):101-105

沪宁高铁某站场改建工程在咽喉区的狭窄区域同时出现PHC桩、CFG桩、水泥搅拌桩等多种地基处理方式,为克服PHC桩挤土效应对其他桩的可能影响．分别采用圆孔扩张理论、有限元分析方法及“等量桩”简化方法对PHC桩施工的单桩挤土效应、双桩挤土效应及群桩挤土效应进行了计算分析,获得不同条件下的挤土位移和挤土应力分布规律,进而对该区域基桩的合理施工顺序提出了建议。  相似文献   

Elastic Solution for Deep Tunnels. Application to Excavation Damage Zone and Rockbolt Support   总被引：1，自引：1，他引：0  

A. Bobet 《Rock Mechanics and Rock Engineering》2009,42(2):147-174

Summary  A new formulation is presented for deep circular tunnels in rock with cylindrical anisotropy. The formulation is an exact solution since it satisfies equilibrium, strain compatibility, and the anisotropic constitutive model. Complete solutions have been found for two scenarios: tunnel with excavation damage zone, and tunnel with rockbolt support. The solution is based on the assumption of a deep, circular tunnel in a medium with two homogeneous zones: an inner zone surrounding the tunnel, which is either isotropic or anisotropic, and an outer zone, for the remainder of the medium, which is isotropic. Plane strain conditions, elastic response of rock, rockbolts and support, and simultaneous excavation and support installation are also assumed. For tunnels surrounded by an excavation damage zone with reduced rock properties, the tangential stresses and the radial deformations at the tunnel wall are very sensitive to both the magnitude of stiffness reduction of the damaged rock and the size of the damaged zone. The effect of the rockbolts on the rock is approximated by treating the rockbolt-rock composite as a material with cylindrical anisotropy with stiffnesses related to the properties of the rock and rockbolts, and spacing of the rockbolts. Comparisons between the analytical solution and a numerical method show small differences and provide confidence in the approach suggested.  相似文献   

杭州湾附近海域三个海底柱状岩芯重矿物分布与组成     

孟建国  金秉福  苗丽华  潘振 《华南地质与矿产》2009,(1)

对东海沿岸陆架CJ08-630、CJ08-923、CJ08-1185三个柱状岩心56个重矿物样品63-125μm粒级重矿物的研究表明,重矿物种类有56种,最高含量可达53.1%;平均含量较低,为8.5%,;矿物组成以闪石类、帘石类、辉石类、片状矿物、自生黄铁矿及金属矿物磁铁矿、褐铁矿等等为主.重矿物来源复杂多样,包括陆源、自生等各种来源的矿物.其中沿岸河流输入物是主要陆源矿物来源;此外还有沿岸和岛屿等的剥蚀物、冲刷物.沉积环境是影响重矿物分布的主要因素.  相似文献   

杭州湾附近海底柱状岩心重矿物分布研究     

孟建国 《地质学报》2009,83(8):812-819

摘 要： 对东海沿岸陆架CJ08-630、CJ08-923、CJ08-1185三个柱状岩心56个重矿物样品63-125μm粒级重矿物的研究表明,重矿物种类有56种,最高含量可达53.1%;平均含量较低,为8.5%,;矿物组成以闪石类、帘石类、辉石类、片状矿物、自生黄铁矿及金属矿物磁铁矿、褐铁矿等等为主。重矿物来源复杂多样,包括陆源、火山、自生等各种来源的矿物。其中沿岸河流输入物是主要陆源矿物来源;此外还有沿岸和岛屿等的剥蚀物、冲刷物。沉积环境是影响重矿物分布的主要因素。  相似文献   

基于广义SMP准则及应力路径法的柱孔扩张分析     

郝冬雪  陈榕  许成顺  刘春城 《岩土力学》2013,34(10):2781-2789

柱孔扩张理论广泛用于旁压试验机制分析、沉桩挤土效应等岩土工程问题中。基于经典的Vesic孔扩张理论,采用能够考虑中主应力效应的广义SMP屈服准则,并结合有限应变理论对均质土体中柱孔扩张问题进行分析,根据应力路径假设提出确定塑性区平均体应变的解析步骤。通过大量变参数计算给出具有不同刚度指标 、泊松比 和内摩擦角 的土中柱孔扩张极限状态下的塑性区平均体应变、孔扩张半径比和孔扩张系数。分析结果表明, 、 、 越大,塑性区平均体应变越小,塑性区半径比越大,孔扩张系数越大;随着 增加, 的变化对孔扩张系数的影响更显著。同时,将结果与基于Mohr-Coulomb准则的孔扩张解答进行比较,探讨不同土性参数时中主应力效应对孔扩张系数的影响。文中分析方法及给出的考虑中主应力效应的柱孔扩张系数表可为原位试验分析及桩侧摩阻力估算提供参考。  相似文献   

K0固结饱和土柱孔扩张问题弹塑性分析   总被引：2，自引：0，他引：2  

刘时鹏  施建勇  雷国辉  林海 《岩土力学》2013,34(2):389-394

采用K0固结各向异性土体本构模型,将柱孔扩张后周围土体分为弹性区和塑性区,根据柱孔扩张理论和边界条件,推导出K0固结状态下饱和天然土体柱孔扩张问题弹塑性区的应力、塑性区半径以及超孔隙水压力的理论解答。同时,通过算例与修正剑桥模型解答进行对比分析,结果表明,土的不同初始固结状态对柱孔扩张后孔周围的应力和超孔隙水压力产生很大影响,采用考虑K0固结诱发各向异性土体本构模型所得到的应力和超孔隙水压力解答大于修正剑桥模型的解答,但塑性区影响半径却明显小于后者。  相似文献   

基于SMP准则柱孔扩张问题相似解   总被引：3，自引：0，他引：3  

刘时鹏  施建勇  雷国辉 《岩土力学》2012,33(5):1375-1380

以柱孔扩张理论为基础,将柱孔扩张后塑性区半径b作为时间刻度,引入扩孔速度概念,将塑性区内任意一点的应力、应变描述成塑性区半径b和柱孔扩张后扩张体单元距孔心距离r的函数,采用平面应变条件下无黏性土的SMP准则和不相关联流动法则,考虑到无黏性土的剪胀性,推导出柱孔扩张后极限扩张力 的相似解。通过参数分析表明,土体强度和剪胀性对塑性区半径和极限扩张力产生很大的影响,即随着土体强度和剪胀性的增加,极限扩张力明显增加,相应塑性区半径却随之减小。通过与基于摩尔-库仑准则解答进行对比分析表明,考虑中间主应力影响的SMP准则所得到的极限扩张力明显高于基于摩尔-库仑准则的解答。该解答为无黏性土中进行静力触探（CPT）试验和静压桩等岩土工程问题提供必要的理论依据。  相似文献