共查询到19条相似文献，搜索用时 906 毫秒
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本文介绍了大型地质力学模型试验中所采用的离散化多主应力面加载及监测系统。该系统是在大型地下厂房洞室群施工稳定性模型试验研究中，国内外首次提出使用的一种能近似模拟复杂三维空间地应力场的加载系统，该系统可将复杂变化的地应力分布场，离散为有限多个微小的单元应力场，然后在每个单元的主应力面上，按照实测和经回归分析确定的单元主应力值进行加载，从而完成整个试验域的原始地应力场的模拟，另外还设计了监测控制系统，以便保持加载系统在整个开挖模拟过程应相对稳定，该试验系统已成功地应用于某大型水电站地下厂房洞室群的三维地质力学及施工仿真模型试验，取得有价值的成果。 相似文献
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《浙江大学学报(A卷英文版)》2016,(10)
目的:地下洞室群区域地应力分布繁杂多变,勘测点因数量有限难以反映初始地应力场空间分布特征。考虑工程区域内的地质构造、地形地貌及河谷的发育演化史等因素,提出综合反映工程区复杂地质条件及地层剥蚀过程的地应力场二次反演方法,揭示工程所在区域的三维地应力场分布特征,为地下工程的开挖加固设计提供更加准确的基础资料。创新点:1.基于地应力场反演基本理论,建立逐步回归-差异进化-支持向量机模型(SR-DE-SVM)的二次反演非线性模型;2.通过SR-DE-SVM算法计算流程,成功模拟工程区域地应力场分布。方法:1.通过工程勘测分析,推导出构造运动对工程区域地应力场分布产生的影响(表5和图13);2.基于智能反演方法,构建SR-DE-SVM的二次反演非线性模型(公式(10)),得到SR-DE-SVM算法的计算流程(图2);3.通过数值仿真模拟,结合地质历史的发展过程,验证所提出的二次反演方法的可行性和有效性(图10和11)。结论:1.工程区域内初始地应力水平属中等,主要受到岩体自重与构造运动的双重影响。2.SR-DESVM二次反演方法可更加清楚地明确初始地应力形成的主导成因,且更加准确、高效和真实地模拟工程区域三维地应力场的分布规律;3.围岩类别对黄登地下洞室群区域内的初始地应力场影响不大,仅在断层带及III、IV类凝灰岩夹层带切割部位有显著的应力释放效应。 相似文献
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对山西省万家寨引黄入晋工程总干线7号隧洞开挖和蓄水运行的几种工况进行了非线性有限元分析．主要内容包括采用分级堆填过程模拟风积黄土层的初始应力场；应用：Duncan释放荷载思想和弹性理论面力公式进行开挖卸荷计算；采用Goodman节理单元模拟衬砌管片的接缝；应用Terzaghi松动土压力理论施加管片上压力；确定土的Duncan-Chang模型参数时，分别取原状土进行了卸载和加载试验，并比较了用2种试验获得的模型参数进行有限元变形分析的结果，多种工况的有限元分析得到了一些合理的结果． 相似文献
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对新奥法在大型地下洞室施工中的二次支护时间的现有判据进行分析,发现其考虑因素欠全面,主要以变形量或变形速率为主,洞室位移相对值不适应大型洞室.以围岩变形为研究对象,提出大型洞室围岩变形达到总变形的80%、洞室周边水平收敛速度小于0．2 mm/d、顶拱或者底板垂直位移速率小于0．1 mm/d、隧洞周边水平收敛速度以及拱顶或底板垂直位移速度明显下降、位移加速度应基本接近于0作为大型地下洞室最佳支护时间的判据.为了验证该判据的合理性,选择了向家坝大型地下洞室一个断面,按照实际开挖顺序,计算了不同开挖层的最佳支护时间.向家坝地下洞室该断面处围岩拱顶、不同开挖层上下游侧边墙最佳支护时间在8~18 d之间,较好地符合了向家坝实际支护时间. 相似文献
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微型高精度多点位移计的设计及在三维模型实验中的应用 总被引：9，自引：1，他引：9
岩体力学模型试验是研究复杂岩体内部建筑物稳定及破坏的一种重要方法。在各种地质，边界和荷载条件下，地下洞室群周围岩体的应力，变形以及破坏机理等十分复杂。超大型水电站地下厂房洞室群以其规模巨大，洞室结构形式多样，围岩稳定问题复杂而备受关注，但是许多制约因素使得这类试验难以实现，其中包括试验过程中内部物理量的量测问题，本文就为解决模型试验中的位移量测问题而进行的微型高精度多点位移计设计，埋设和安装等有关问题进行了探索，并介绍了它在溪洛渡水电站地下厂房洞室群模型试验中的成功应用。 相似文献
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介绍了采用FLAC30内嵌功能较强的FISH语言对初始地应力场生成方法的改进,建立了三维非线性地应力反演分析数值模型.模拟了断层及裂隙密集带,并采用此方法构造神经网络样本,采用神经网络结构分析的方式,对不同深度的侧向系数进行反演.通过正分析的计算结果与现场实测值对比,满足精度要求,表明所获得的岩体地应力场是基本合理的. 相似文献
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研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。 相似文献
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蓄能电站地下厂房洞室群埋藏较深、开挖面积较大,地下岩体变形参数在工程设计过程中是至关重要的,根据深圳蓄能电站地下厂房系统岩体的特殊性与重要性,在现期勘察的地下厂房系统主探洞内进行现场岩体变形试验,对试验数据经过科学的分析与总结,建立合理的变形参数,并对同一岩性不同地理位置的岩体变形参数进行对比,在此特提供给大家参考。 相似文献
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用MSC.Marc软件建立螺栓接头的三维接触有限元模型,计算得到了螺栓接头中螺纹段最大等效应力随预紧力的变化曲线、残余预紧力和螺纹段最大等效应力随被连接件所受轴向外力的非线性变化曲线,提出了基于这些曲线设计高强度螺栓接头预紧力和允许外力的方法。 相似文献
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应用三维有限元程序,考虑地下通道非柔性结构及其结构缝的存在,结合某城市地下通道之下的隧道暗挖实例,模拟隧道断面分步开挖、超前加固、初期支护、接近既有结构施工的复杂空间过程。有限元分析过程显示：采用三维有限元法模拟隧道施工对现有结构的影响,可得到与实际施工更为接近的结构沉降与应力结果,从而为隧道结构设计提供更准确的依据。同时模拟分析还表明：通道项部地表和底板的沉降非常接近,可依据通道底板的拉应力增量,参考通道结构在隧道施工前的应力状态评价通道安全。 相似文献
13.
Environmental effects induced by excavation 总被引：1，自引：0，他引：1
Based on 3D Biot＇s consolidation theory and nonlinear Duncan-Chang＇s model, a 3D FEM （finite element method） program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit deformations of the former are larger than those of the latter, so that the result without considering the variation of water head difference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit. 相似文献
14.
《浙江大学学报(A卷英文版)》2021,(3)
Water curtain systems(WCSs) are key components for the operation of underground oil storage caverns(UOSCs) and their optimization and design are important areas of research.Based on the time series monitoring of the first large-scale underground water-sealed storage cavern project in China,and on finite element analysis,this study explores the optimum design criteria for WCSs in water-sealed oil caverns.It shows that the optimal hole spacing of the WCS for this underground storage cavern is 10 m in order to ensure seal effectiveness.When the WCS is designed with a 10-m horizontal hole spacing and a water curtain pressure(WCP) of 80 kPa,a water curtain hole(WCH) has an influence radius of approximately 25 m.The smaller the vertical distance is between a WCH and the main cavern,the greater the water inflow into the main cavern.The vertical hydraulic gradient criterion can be satisfied when this distance is 25 m.It shows that the optimal WCP is 70 kPa,which meets sealing requirements. 相似文献
15.
MIDAS/Civil在预应力空心板简支梁桥结构抗震分析中的应用 总被引：1，自引：0，他引：1
以有限单元法基本理论为基础,介绍了有限元通用软件MIDAS/Civil在预应力空心板简支梁桥结构抗震计算中的应用问题.采用三维有限元法,实现了预应力空心板简支梁桥的动力特性模拟,分析了在E1、E2地震作用下,桥梁各控制截面的抗弯能力、抗剪能力,以及支座厚度和抗弯稳定性等抗震性能,并提出切实可行的抗震措施,为桥梁施工质量控制提供必要的理论指导与技术支持. 相似文献
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本文采用三维杆系力学分析模型对钢结构框架进行分析,避免了传统的有限元方法要对构件大量划分网格进行计算而导致的计算自由度巨大,计算耗时的缺点。对于杆件单元,本文采用了一种变刚度的杆单元模型,建立了考虑塑性铰分布长度影响的构件单元刚度矩阵。在此基础上对经典的算例模型进行了静力全过程分析。 相似文献
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Based on elastoplastic model, 2D and 3D finite element method (FEM) are used to calculate the stress and displacement distribution in the soft clay slope under gravity and uniform load at the slope top. Stability analyses indicate that 3D boundary effect varies with the stress level of the slope. When the slope is stable, end effect of 3D space is not remarkable. When the stability decreases, end effect occurs; when the slope is at limit state, end effect reaches maximum. The energy causing slope failure spreads preferentially along y-z section, and when the failure resistance capability reaches the limit state, the energy can extend along x-axis direction. The 3D effect of the slope under uniform load on the top is related to the ratio of load influence width to slope height, and the effect is remarkable with the decrease of the ratio. 相似文献
18.
Establishing an accurate in situ stress field is important for analyzing the rock-mass stability of the underground cavern at the Huangdeng hydropower station in China. Because of the complexity and importance of the in situ stress field, existing back analysis methods do not provide the necessary accuracy or sufficiently recognize nonlinear relations between the distribution of the in situ stress field and its formative factors. Those factors are related to the geological structures of high compressive tectonic stress regimes, including geological faults and tuff interlayers. The new two-stage optimization algorithm proposed in this paper is a combination of stepwise regression (SR), difference evolution (DE), support vector machine (SVM), and numerical analysis techniques. Stepwise regression is used to find the set of unknown parameters that best match the modeling prediction and determine the range of parameters to be recognized. Difference evolution is used to determine the optimum parameters of the SVM. The SVM is used to create the DE-SVM nonlinear reflection model to obtain the optimal values of the parameters from measured stress data. We compare the new two-stage optimization algorithm to other two popular methods, a multiple linear regression (MLR) analysis method and an artificial neural network (ANN) method, to estimate the in situ stress field for the actual underground cavern at the Huangdeng hydropower station. The two-stage optimization algorithm produces a more realistic estimate of the stress distribution within the investigated area. Thus, this technique may have practical applications in realistic scenarios requiring efficient and accurate estimations of the in situ stress in a rock-mass. 相似文献
19.
Penetration of disk fragments following impact on thin plate 总被引：1，自引：0，他引：1
Juan-juan Li Hai-jun Xuan Lian-fang Liao Wei-rong Hong Rong-ren Wu 《浙江大学学报(A卷英文版)》2009,10(5):677-684
To investigate the ballistic resistance and failure pattern of aeroengine casing following the impact of disk fragments, and to determine the optimum case structure, the phenomena of a 1/3rd disk fragment impact on single and double-layered thin plate targets were simulated using nonlinear dynamical analysis software MSC.Dytran. Strain rate effect was introduced in a Johnson-Cook （JC） material model for the disk fragment and the plate. Impact modeling was based on the Arbitrary Lagrange-Eulerian method, and simulated using explicit finite element method （FEM）. Simulation results showed that the major failure pattern of the plate is shearing and tensile fracture with large plastic deformation. It was also concluded that the ballistic limit velocity increases with the standoffdistance when it is beyond a certain value, and that greater resistance is obtained when the front plate has either a proportionately low or high thickness. The impact resistance of a double-layered plate may exceed that of a single plate if the thicknesses and standoff distance of the two plates are set appropriately. 相似文献