共查询到20条相似文献，搜索用时 750 毫秒
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研究了随机地震激励下土层地震反应及土-结构相互作用分析中有限土域的取值范围对计算精度的影响。分别以基岩白噪声谱和杜修力修正基岩谱作为输入,进行了土层随机地震反应分析,探讨了自由边界、固定边界和黏弹性边界3种人工边界条件下土域的取值范围、土介质阻尼和土体长深比（L/H）对土层随机地震反应的影响,给出了侧向人工边界合理位置的具体建议。在此基础上,选取土体的合理边界范围,建立土-结构相互作用分析模型,分别以基岩白噪声谱、杜修力修正基岩谱以及实测地震波功率谱作为输入,进行了土-结构相互作用体系随机地震反应分析,计算结果验证了侧向人工边界取值在土-结构相互作用体系随机地震反应分析中的有效性。 相似文献
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基于Zienkiewicz提出的非饱和多孔介质波动理论,考虑两相流体和固体颗粒的压缩性以及惯性、黏滞和机械耦合作用,采用半解析的方法获得了一类典型边界条件下单层非饱和多孔介质一维瞬态响应解。首先推导出无量纲化后以位移表示的控制方程,并将其写成矩阵形式;然后,将边界条件齐次化,求解控制方程所对应的特征值问题,得到了满足齐次边界条件的特征值和相对应的特征函数。根据变异系数法并利用特征函数的正交性,得到了一系列仅黏滞耦合的关于时间的二阶常微分方程及相应的初始条件。在此基础上,运用精细时程积分法给出了常微分方程组的数值解。最后,通过若干算例验证了结果的正确性并探讨了单层非饱和多孔介质一维瞬态动力响应的特点。该方法可推广应用于其他典型的边界条件。 相似文献
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研究采空区剩余沉降对上覆建（构）筑物造成的危害程度，分层沉降观测是比较直观的方法，但由于基岩内测试环固定困难，大深度采空区上覆岩层中进行分层沉降观测国内未见报道。针对这一情况，在焦晋高速公路采空区优化治理与质量检测研究课题中，研制了专用固环设备，开发了“变径成孔，锚固器固环”的施工工艺，成功解决了采空区上覆岩层分层沉降观测所遇到的技术难题。 相似文献
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《水文地质工程地质》2015,(4)
厚风积沙薄基岩浅埋煤层实现保水开采,关键是煤层开采后在上覆岩层中形成的导水裂隙带是否破坏了含水层底部隔水层的稳定性。在分析含、隔水层的分布特征以及基岩层的物理力学特性的基础上,结合采动岩层内部移动变形规律,推导了岩层层向拉伸变形的计算公式,给出了一种预计导水裂隙带高度的预测方法,并结合相似模拟实验确定了厚风积沙薄基岩浅埋煤层开采覆岩导水裂隙带发育高度,研究成果为保水开采提供了理论指导。 相似文献
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针对某些地质条件导出了离散双重介质二维二相流耦合微分方程,对方程中的渗透率和裂隙宽度进行了Karhunen－Loeve级数展开,对其他参数进行了多项式随机函数的级数展开,同时对截取级数前有限项所产生的误差作了分析．在求解基本未知量的同时也能求解随机变量的特征数。 相似文献
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高文仲 《水文地质工程地质》1985,(2)
非饱和土壤水分运动规律,一般采用简化的数学模型,在定水位条件下,稳定蒸发计算αψ/αt=0,将偏微分方程化为常微分方程求解。在积分中,导水系数κ(θ)及扩散系数 相似文献
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针对某些地质条件导出了离散双重介质二维二相流耦合微分方程,对方程中的渗透率和裂隙宽度进行了Ｋａｒｈｕｎｅｎ－Ｌｏｅｖｅ级数展开,对其他参数进行了多项式随机函数的级数展开,同时对截取级数前有限项所产生的误差作了分析,在求解基本未知量的同时也能求解随机变量的特征数。 相似文献
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成层多孔粘弹性地基在轴对称荷载作用下的解 总被引：1，自引：0，他引：1
给出一种有效的解析方法求解成层多孔粘弹性地基在轴对称荷载作用下的固结问题，通过关于时间t的拉普拉斯变换和关于半径r的亨克尔变换，将控制偏微分方程转化为常微分方程，从而得到用常微分短阵方程形式表示的控制方程，基于矩阵常微分方程的解以及拉普拉斯，亨克尔逆变换，可得到该固结问题的解，该方法理论及计算简捷，通过算例比较了该方法的精度，并研究了地基的粘弹性特性对固结过程的影响。 相似文献
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将土体中的混凝土桩基简化为黏滞介质中的一维黏弹性杆,桩顶部受锤头冲击产生内部应力波。根据杆内微元应力平衡条件建立杆中一维黏弹性应力波传播的控制方程,结合桩顶锤头冲击条件和桩底弹-黏性约束条件给出桩基两端的耦合边界条件。对控制方程和定解条件作Laplace变换并求解变换后的常微分方程,得到变换域的应力像函数解析解。采用数值反变换技术将像函数转变为时间域的应力波形。应用此方法可以较方便地分析桩基中应力波的产生、传播、反射及相互作用过程。 相似文献
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Large strain similarity solution for a spherical or circular opening excavated in elastic‐perfectly plastic media 
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下载免费PDF全文 K.H. Park 《国际地质力学数值与分析法杂志》2015,39(7):724-737
This paper deals with the unloading problem of a spherical or circular opening excavated in elastic‐perfectly plastic media with a nonassociated Mohr–Coulomb yield criterion. A large strain similarity solution, using incremental velocity approach, is presented by replacing partial differential equations from stress equilibrium, constitutive law, consistency condition, and displacement equation with first‐order ordinary differential equations. The classical Runge–Kutta method is used to solve the first‐order ordinary differential equations. Comparisons among small and large strain solutions are made using some data sets of soil and rock. The results show that the displacements by large strain similarity solution are smaller than those by exact small strain solution and somewhat larger than those by large strain solution using total strain approach. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Flexural toppling is a mode of failure that may occur in a wide range of layered rock strata in both rock slopes and large
underground excavations. Whenever rock mass is composed of a set of parallel discontinuities dipping steeply against the excavated
face plane, the rock mass will have the potential of flexural toppling failure as well. In such cases, the rock mass behaves
like inclined superimposed cantilever beams that bend under their own weight while transferring the load to the underlying
strata. If the bending stress exceeds the rock column’s tensile strength, flexural toppling failure will be initiated. Since
the rock columns are “statically indeterminate,” thus, their factors of safety may not be determined solely by equations of
equilibrium. The paper describes an analytical model with a sequence of inclined superimposed cantilever rock columns with
a potential of flexural topping failure. The model is based on the principle of compatibility equations and leads to a new
method by which the magnitudes and points of application of intercolumn forces are determined. On the basis of the proposed
model, a safety factor for each rock column can be computed independently. Hence, every rock column will have a unique factor
of safety. The least factor of safety that exists in any rock column is selected as the rock mass representative safety factor
based on which simple equations are proposed for a conservative rock mass stability analysis and design. As a result, some
new relations are established in order to design the length, cross-sectional area and pattern of fully grouted rock bolts
for the stabilisation of such rock mass. Finally, the newly proposed equations are compared with the results of existing experimental
flexural toppling failure models (base friction and centrifuge tests) for further verification. 相似文献
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岩石物理力学性质指标是反映岩体工程特性的重要参数。通过对鄂西恩施地区典型滑坡区白垩系砂岩、三叠系粉砂岩、三叠系薄层泥灰岩、三叠系粉砂质泥岩、泥盆系石英砂岩和三叠系、二叠系、奥陶系灰岩等岩石单轴抗压强度σc、弹性模量E、泊松比μ、岩块的块体密度ρ和纵波速度Vp等试验数据的聚类和相关分析,表明白垩系砂岩和三叠系粉砂岩、三叠系粉砂质泥岩和二叠系灰岩参数间关联模式完全一致,其中岩块密度和纵波速度的关系最密切,将两者的乘积作为组合参数进行参数关联式拟合可提高拟合精度。分别对各地层岩石拟合出考虑多种因素且形式简明的参数关联式,并对拟合残差进行正态性检验,结果表明拟合出的参数关联式比较合理。 相似文献
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A method for the analysis of the consolidation of a horizontally layered soil under plane conditions is developed. The method depends upon the transformation of the governing equations by a Fourier trasform. This transformation has the effect of reducing the partial differential equations of consolidation to ordinary differential equations. The ordinary differential equations are then solved using a finite layer or finite difference approach. Once the solution in the transformed plane has been found, the actual solution is synthesized by Fourier inversion. The method leads to a considerable reduction in the amount of core storage necessary for solution and enables the solution of quite significant problems to be obtained on a mini-computer. 相似文献
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基于连续介质损伤力学框架,通过损伤张量和有效应力来描述节理岩体的力学性能,自主研发了基于损伤力学模型的有限元程序（CD-FEM）,用于节理岩体等效力学性能研究。同时,采用Karhunen-Loeve（K-L）展开来分解随机输入场,用混沌多项式来表示随机输出场,采用概率配点法生成配点,再由连续损伤有限元分析系统CD-FEM求解确定性方程组,最终得到输出域的统计数据,从而提出了一种将随机分析与基于连续损伤力学模型的数值分析方法解耦进行节理岩体不确定性力学行为分析的方法。利用该方法,对一典型节理岩体在加载条件下的力学行为进行不确定性分析,并与蒙特卡罗方法进行对比,结果表明,所提方法的计算量大大减少,极大地提高了节理岩体力学性能不确定性分析的效率,可应用于对节理岩体在不同载荷条件下的不确定性进行分析。 相似文献
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随着煤矿开采强度的不断增大,矿井逐渐向深部转移,冲击地压灾害日益严峻。而深部冲击地压矿井往往存在一层或多层坚硬厚岩层,这些坚硬顶板厚度较大,整体性强,突然断裂时会释放大量弹性能,易引发冲击地压事故,严重制约矿井安全生产。以陕西彬长矿区孟村矿为例,针对矿区内煤层埋藏深、普遍存在多种坚硬厚岩层的特殊情况,提出针对性治理措施：对顶板上方0～80 m范围内厚度超过10 m的坚硬厚岩层进行破断、弱化处理,对煤层上方0～30 m范围的低位岩层采取顶板深孔爆破预裂措施,对煤层上方30～60 m范围内的中位坚硬岩层采取顶板定向长钻孔水力压裂措施,对煤层60 m以上高位坚硬岩层采取地面水平井分段压裂措施;使高、中、低位顶板产生的裂缝在垂向上实现贯穿,将顶板“切割”成相对规则的“块状”结构,使上覆岩层应力由“硬传递”转化为“软传递”;并结合煤层大直径孔卸压、煤层爆破等煤层卸压措施,形成了区域与局部相结合、煤层与岩层全覆盖的“井上下”立体防治模式。工程实践证明：采用“井上下”立体防治模式后,工作面103 J以上微震事件降低88%,周期来压强度降低23%,来压持续时间缩短61%,防冲效果良好。该技术模式的成功... 相似文献
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A novel procedure associated with the precise integration method (PIM) and the technique of dual vector is proposed to effectively calculate the magnitude and distribution of deformations in a homogeneous multilayered transversely isotropic medium. The planes of transverse isotropy are assumed to be parallel to the horizontal surface of the soil system. The linearly elastic medium is subjected to four types of vertically acting axisymmetric loads prescribed either at the external surface or in the interior of the soil medium. There are no limits for the thicknesses and number of soil layers to be considered. By virtue of the governing equations of motion and the constitutive equations of the transversely isotropic elastic body, and based on the Hankel integral transform and a dual vector formulation in a cylindrical coordinate system, the partial differential motion equations can be converted into first‐order ordinary differential matrix equations. Applying the approach of PIM, it is convenient to obtain the solutions of ordinary differential matrix equations for the continuously homogeneous multilayered transversely isotropic elastic soil in the transformed domain. The PIM is a highly accurate algorithm to solve the sets of first‐order ordinary differential equations, which can ensure to achieve any desired accuracy of the solutions. What is more, all calculations are based on the standard method with the corresponding algebraic operations. Computational efforts can be reduced to a great extent. Finally, numerical examples are provided to illustrate the accuracy and effectiveness of the proposed approach. Some more cases are analyzed to evaluate the influences of the elastic parameters of the transversely isotropic media on the load‐displacement responses. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献