采空区临界安全顶板预测的厚度折减法

借鉴强度折减法计算边坡安全系数的思路，提出采空区安全顶板预测的厚度折减法.不断调整顶板厚度，直到其达到临界破坏状态，此时对应的顶板厚度即为安全顶板厚度.当顶板达到临界状态时，其位移将发生突变，计算不收敛，因此，将静力平衡方程组是否有解、计算是否收敛作为顶板破坏的标准.采用同时考虑拉伸和剪切破坏的Mohr-Coulomb准则，对某一采空区顶板安全厚度进行预测，并对采空区周围的应力和变形进行分析，结果表明：当采空区跨度分别为4，7，10，15，20，25 m时，顶板安全厚度为2.1，5.2，9.2，12.3，16.6，22.9 m；采空区跨度较小时，塑性区范围较小，顶板主要破坏形式为冲切破坏；随着跨度的增大，塑性区面积增加，破坏形式转变为垮落；当顶板发生破坏时，计算的不平衡力无法收敛，位移不断发展，位移最大值区域位于采空区正上部.     

Testing study of subcritical crack growth velocity and fracture toughness of marble

Subcritical crack growth of double torsion specimens made of marble was studied using Instron1342 type electro hydraulic servo test machine. The relations of the mode-Ⅰ stress intensity factor KI versus the subcritical crack growth velocity V and the fracture toughness KIC were obtained by the double torsion constant displacement load relaxation method. The behavior of subcritical crack growth was analyzed. The results show that IgKI-IgV relations of marble measured by this method accord with linear rule, i.e.the relations between subcritical crack growth velocity Vand stress intensity factor KI have a power law, which is in good agreement with Charles theory. The testing results provide a basis for time-dependency of rock engineering stability.     

分级加卸载下节理软岩流变试验及模型

采用分级增量循环加卸载方式，对金川有色金属公司 Ⅲ 矿区软弱节理矿岩进行蠕变试验，按瞬时弹性应变、滞后黏弹性应变、瞬时塑性应变与黏塑性应变对流变试验数据进行分析，探讨了软弱节理矿岩的黏弹塑性变形特性；引入2种非线性元件--裂隙闭合体和非线性牛顿体，并将它们和描述衰减蠕变特性的开尔文体及描述瞬弹性的虎克体相结合，得到了一种新的复合元件流变模型，以研究复杂条件下节理软岩的黏弹塑性变形特性.试验结果表明,复合元件流变力学模型能很好地描述节理软岩在不同应力水平下的蠕变特性,特别是裂隙闭合阶段和加速蠕变阶段的特性，金川Ⅲ 矿区矿岩蠕变试验曲线与理论曲线较为吻合.     

Mechanism analysis on pillar instability induced by micro-disturbance under critical condition

A simplified mechanical model of ultra-high pillar was established and its potential energy expression was derived under axial load on the basis of energy theory. Under critical conditions according to the nonlinear theory, the critical behaviors and the forming mechanism of pillar instability were discussed by external disturbance , such as stresses waves by blasting , axial force eccentricity ratherish and imperfections in pillar. The results show that the micro-disturbances attenuate with time and they are independence each other when pillar is in the stability state. Their effects on the stability of system are inessential. The correlation degree of disturbances increases sharply and various micro-disturbances are relative and nested reciprocally when the system is in critical state and they also cooperate with each other, which induces system to reach a new state.     

Test of subcritical crack growth and fracture toughness under water-rock interaction in three types of rocks

The subcritical crack growth and fracture toughness in peridotite, lherzolite and amphibolite were investigated with double torsion test. The results show that water-rock interaction has a significant influence on subcritical crack growth. With water-rock interaction, the crack velocity increases, while the stress intensity factor declines, which illustrates that water-rock interaction can decrease the strength of rocks and accelerate the subcritical crack growth. Based on Charlse theory and Hilling & Charlse theory, the test data were analyzed by regression and the correlation coefficients were all higher than 0.7, which shows the correlation is significant. This illustrates that both theories can explain the results of tests very well. Therefore, it is believed that the subcritical crack growth attributes to the breaking of chemical bond, which is caused by the combined effect of the tensile stress and the chemical reaction between the material at crack tip and the corrosive agent. Meanwhile, water-rock interaction has a vital effect on fracture toughness. The fracture toughness of samples under atmospheric environment is higher than that of samples immersed in water. And water-rock interaction has larger influence on fracture toughness in amphibolite than that in peridotite and lherzolite.     

基于PFC2D的冬瓜山铜矿爆破参数优化

以铜陵冬瓜山铜矿采场爆破为研究对象,基于矿山爆破设计参数,建立了PFC^2D数值爆破模型,对拟定的12组不同爆破参数进行模拟优化试验,通过分析不同参数下模拟爆破效果及监测点的应力值,得出最优爆破参数为: 排距2.5 m、孔距2.5 m;现场生产实践证实,采用此爆破参数时能达到良好的爆破效果,验证了PFC^2D数值程序模拟爆破的可行性。     

软弱复杂矿岩亚临界裂纹扩展机制分析

采用双扭试件常位移松弛法,对某矿软弱复杂矿岩进行了亚临界裂纹扩展试验研究,测得其断裂韧度值和应力腐蚀下限值,并按Charles理论与Hillig & Charles理论对试验结果进行了线性回归,确定了采场矿岩亚临界裂纹扩展速度与应力强度因子之间的关系,试验复相关系数分别为0.9254和0.9247,均在显著性水平0.01上.试验结果表明,该矿软弱复杂矿岩的应力腐蚀亚临界裂纹扩展是拉应力和裂纹尖端物质与环境中的腐蚀介质发生化学反应,使化学键断裂这两种机制联合作用的结果;应力强度因子与亚临界裂纹扩展速度对数关系能很好地呈线性.     

Directly searching method for slip plane and its influential factors based on critical state of slope

In order to determine the slip plane of slope directly by the calculation results of strength reduction method, and analyze the influential factors of slope stability, a numerical model was established in plane strain mode by FLAC3D for homogeneous soil slope, whose parameters were reduced until the slope reached the critical state. Then FISH program was used to get the location data of slip plane from displacement contour lines. Furthermore, the method to determine multiple slip planes was also proposed by setting different heights of elastic areas. The influential factors for the stability were analyzed, including cohesion, internal friction angle, and tensile strength. The calculation results show that with the increase of cohesion, failure mode of slope changes from shallow slipping to the deep slipping, while inclination of slip plane becomes slower and slipping volume becomes larger; with the increase of friction angle, failure mode of slope changes from deep slipping to shallow slipping, while slip plane becomes steeper and upper border of slip plane comes closer to the vertex of slope; the safety factor increases little and slip plane goes far away from vertex of slope with the increase of tensile strength. Foundation item: Project(20060533071) supported by the Doctoral Program Foundation of Higher Education of China; Project (20060400264) supported by China Postdoctoral Science Foundation; Project (50774093) supported by the National Natural Science Foundation of China; Project (1343-74236000014) supported by Graduate Student Innovation Foundation of Hunan Province, China     

基于SURPAC的FLAC3D三维模型自动构建

为了将岩土工程分析软件FLAC^3D在数值计算方面的独特优势和矿山工程软件SURPAC在三维建模方面的优势相结合．研究了2种软件单元数据之间的关系,提出数据之间的转换方法;采用Fortran语言编制了SURPA C-FLAC^3D的接口程序,并通过某大型铁铜矿区建模实例说明程序实施的具体步骤．结果表明：提出的转换方法以及相应的接口程序能够实现SURPAC模型到FLAC^3D模型的转换,使FLAC^3D建模快捷化,拓展了FLAC^3D和SURPAC的应用空间．     

强度折减法在Hoek-Brown准则中的应用

为了在Hoek-Brown准则中实施强度折减法，并使其得到的结果与Mohr—Coulomb准则中强度折减法得到的结果等效，首先，通过理论推导确定Hoek-Brown准则参数m，s，σci与粘结力c和内摩擦角φ之间的关系；然后，进一步得到在Hoek—Brown准则中实施强度折减法时，m，s和σci的折减系数以及它们之间的关系；最后，由FLAC3D软件建立计算模型，采用所确定的折减方法计算边坡的安全系数，并将该结果与Mohr—Coulomb准则得到的结果进行对比，结果表明：参数m，s和σci的折减系数须满足一定关系，强度折减法在Hoek-Brown准则和Mohr-Coulomb准则中得到的安全系数的差别为3．54％，差别微小，从而验证了所确定的折减方法的可靠性。