不连续介质力学分析的块体-夹层模型

基于岩体等不连续介质的实际结构特征，利用约束变分原理，建立了可同时用于不连续介质和连续介质力学分析的块体 夹层模型．该方法利用拉格朗日乘子法和罚函数法把单元间的连续条件作为约束条件引入泛函中，把不连续介质问题和连续介质问题统一处理，既能方便地求解连续介质力学问题，更重要的是能方便地处理不连续介质力学问题，如岩体结构．由块体 夹层模型可导出刚性有限元和弹性有限元（常应变元）的列式，而且块体的形状可以是任意多边形     

利用灰色模型预测巷道围岩变形

利用灰色系统理论，用少量的非等时的实测数据，建立非等时的灰色ＧＭ（１，１）模型，同时将实测数据经拉格朗日插值后形成等时时序，建立等时的灰色ＧＭ（１，１）模型，通过模型预测结果的比较，得到了在利用灰色模型进行巷道围岩变形预测时比较理想的模型。     

Cumulation of Seismic Waves During Formation of Kimberlite Pipes

A possible mechanism of formation of kimberlite pipes is considered. It is shown that they could have formed upon impact of a large cosmic body on the Earth in the impact's antipode region during focusing of seismic surface waves. It is established that convergence of a surface wave to the antipode region is accompanied by an increase in the wave amplitude and the wave energy density. Focusing of such a wave results in an almost vertical rupture of the Earth's crust and formation of a channel diverging to the surface — a burst pipe. Along this channel, kimberlite magma, additionally heated by deep focusing of the other waves, rises to the Earth's surface to form a kimberlite pipe. The absence of ideal cylindrical symmetry due to the inhomogeneity of the Earth's crust along the path of wave propagation leads to wave defocusing and formation of several centers of convergence, i.e., formation of a pipe field.     

Two-Phase Flow Properties Prediction from Small-Scale Data Using Pore-Network Modeling

The objective of this work is to evaluate the prediction accuracy of network modeling to calculate transport properties of porous media based on the interpretation of mercury invasion capillary pressure curves only. A pore-scale modeling approach is used to model the multi-phase flow and calculate gas/oil relative permeability curves. The characteristics of the 3-D pore-network are defined with the requirement that the network model satisfactorily reproduces the capillary pressure curve (P_c curve), the porosity and the permeability. A sensitivity study on the effect of the input parameters on the prediction of capillary pressure and gas/oil relative permeability curves is presented. The simulations show that different input parameters can lead to similarly good reproductions of the experimental P_c, although the predicted relative permeabilities K_r are somewhat widespread. This means that the information derived from a mercury invasion P_c curve is not sufficient to characterize transport properties of a porous medium. The simulations indicate that more quantitative information on the wall roughness and the node/bond aspect ratio would be necessary to better constrain the problem. There is also evidence that in narrow pore size distributions pore body volume and pore throat radius are correlated while in broad pore size distributions they would be uncorrelated.     

Fractal characteristics of rocks fractured under tension

Fractal geometry can be useful for explaining the fracture behavior and rock properties. The fractal properties of rock fracture surface developed under tension were examined. Seven different rock samples were selected for the tests. An automated surface scanning device was used to map the fractured surfaces. Variogram analysis (VA) (for 1D self-affine sets) and power spectral density (PSD) measurement (for 2D self-affine sets) were applied to calculate the fractal dimension. On a comparative basis, there exists a trend between the fractal dimension and loading rate. The profiles in the loading direction yield higher fractal dimensions indicating the anisotropic feature of fractal. The fractal dimensions obtained by PSD and VA display a relationship for grain size and porosity. Higher porosity samples give different fractal dimensions for upper and lower fractures surfaces.     

用双截面应变量测方法研究岩石冲击凿入特性

在一维细长杆中，通过任意不重合的两个截面处的应变测试，就可以计算出杆中任一截面处的应变和质点速度等物理量，并且可以分离出顺波和逆波。本文不但在实验上和理论上对该方法进行了证明，而且成功的将其用于岩石冲击凿入特性的研究，得出了一些有意义的结果     

准静态压力作用下岩体爆破成缝方向与机理的研究

本文在讨论了现有的爆破成缝理论以后,首先将岩体在爆生气体作用下的成缝过程分为开裂、扩展和止裂三个阶段,建立了这三个阶段的力学模型。然后,着重分析了爆破成缝方向和机理,提出了相应的断裂判据。最后,结合在大理石试块上进行的爆破成缝试验,通过计算分析,验证了本文提出的成缝机理。     

岩体原位流变荷载试验的力学参数与模型反演

根据现场岩体原位测试的60m和70m处两试验点的流变变形曲线,首先通过曲线特征筛选出了能够描述其变形特性的流变模型(三参量固体模型,Burgers模型),基于粘弹性分析理论及两步反分析法思路,建立了荷载试验的三参量固体模型、Burgers模型的位移优化反演格式,利用分级加载所获得的瞬时弹性位移,反算出了两试验点处的岩体弹性体积模量K、剪切模量G0和变形模量E0,并由优化反演方法获得了两模型的所有流变参数G1,η1,η2和E1以及长期弹性模量E∞。利用所获得的粘弹性参数分别计算出了在不同载荷下两种模型的理论解析曲线,并与实测曲线进行了分析对比,最终获得了能够较真实地描述试验区域岩体流变变形特性的最佳模型,即三参量固体模型。通过对比分析验证了所用思路及方法的正确性和实用性,文中方法虽然应用于流变荷载实验情况,但其具有一定的普遍意义,可应用于不同状况的流变实验的参数确定和模型反演。     

改进的非定常Bingham岩石蠕变模型及参数辨识

传统Bingham模型适用于描述蠕变的前两个阶段,为了更加准确地描述岩体蠕变的三个阶段,本文提出了一种改进的非定常Bingham蠕变模型,并推导出其蠕变本构方程．该模型在传统Bingham模型的基础上串联一个非定常黏壶元件,并考虑岩体弹性模量及原有黏壶元件蠕变参数的非定常化．基于该模型对泥岩的蠕变试验曲线进行拟合及参数辨识,结果表明该模型具有较高的拟合精度,可以准确地描述泥岩蠕变的三个阶段,并实现了在数值软件中的应用,为实际工程提供了一种简单有效的蠕变本构模型．     

基于非线性统一强度理论的裂隙岩体圆形隧道扩张问题的弹塑性研究

由于节理岩体具有复杂的力学特性,因此节理岩体圆形隧道扩张问题的弹塑性解要复杂得多。节理岩体的力学特性可以很好地用考虑了岩体结构的强度参数m,s和α以及中间主应力影响的非线性统一强度准则来表达。本文根据非线性统一强度准则确定了瞬时摩擦角,强度参数m,s和α是瞬时摩擦角的函数,获得了节理岩体圆形隧道扩张问题的弹塑性解和支护应力的封闭形式的理论解,并给出了算例。