节理岩体体积节理数Jv的新计算公式

岩体体积节理数Jv的定义,按照《工程岩体分级标准》采用节理间距或频率较为恰当;本文研究了岩体内发育一组、二组、三组贯通性节理的情况下,Jv定义的适宜性,指出节理正交的情况下Jv的适宜性最好,推导出Jv的修正系数为K1=|sin(n1,n2[DD(-1][HT5SS]^[HT][][DD)])||cos(n1×n2,n3[DD(-1][HT5SS]^[HT][][DD)])|,研究表明：节理夹角越小,对Jv的影响越大;通过连通率等效途径,断续节理岩体的Jv计算公式为Jv=K1•∑[DD(][]i[DD)]Si•ni(i3)。运用该公式可实现工程岩体裂隙发育程度的科学评价。     

基于监测信息的十三陵抽水蓄能电站引水洞抢险加固设计

北京地区十三陵抽水蓄能电站的引水洞穿过破碎岩体时,因地质条件很差而在开挖初期发生了塌方险情。抢险后及时进行了洞内位移监测。监测结果显示原设计所使用的挂网锚喷加钢拱架组成的支护结构变形较大,特别是在边墙部位,变形更加明显。根据监测结果对引水洞的支护方案进行了重要修改：加密钢拱架和挂网钢筋,并增加喷射混凝土厚度,在洞底增加仰拱。施行上述措施后,洞体位移收敛变小,并趋于稳定,达到了设计和安全使用要求。该可变更设计的成功,充分说明了在工程地质条件复杂,难以准确界定的情况下,信息化施工与可变更设计的重要性。     

充填泥沙裂隙岩石渗流特性的实验研究

对人工充填泥沙裂隙岩石在MTS815.02电液伺服岩石试验系统上进行渗流实验,同时结合岩石孔隙电子显微照片,探讨了泥沙颗粒对裂隙岩石渗透特性的影响规律.实验表明,在泥沙颗粒的作用下,裂隙岩样渗透率明显减小;泥沙颗粒在岩样宏观裂隙中运移达到重新平衡之后,裂隙岩样渗透率随时间逐渐增大并最终趋于稳定.     

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从力平衡的角度,分析了抗滑桩的抗滑阻力与滑体的下滑力之间的依存关系以及传递过程. 利用弹性力学理论,推导出桩后土体应力场的分布函数. 通过绘制应力等值线图, 发现抗滑桩与土体之间产生土拱现象的机制是滑体内的应力状态由不平衡逐渐到 达平衡的结果,属于应力拱的表现形式.     

岩石变形光纤光栅传感检测的应变传递分析

岩石变形过程可以通过光纤光栅的表面粘贴法进行检测。建立了考虑表面凹槽时的应变传递模型,经过力学分析得出了应变传递方程及传递系数的表达式;在MTS伺服机上进行了单轴压缩实验,借助光纤光栅对加载过程进行了测试。结果表明,传递方程与粘贴层厚度均匀分布时的方程形式相同,只是特征值k不同;换算后光栅的轴向应变与MTS位移计吻合很好,相对误差仅为3.2%;环向测试优于MTS的环向应变计,而两种方法都明显地优于应变片。实验验证了所建模型的正确性。经应变传递换算后,通过光纤光栅可以实现岩石变形过程中与MTS精度相当的高精确测试。     

胶磷矿中杂质赋存形式及酸解过程变化

我国中低品位胶磷矿量大、分布广,磷矿中杂质种类及含量对于磷石膏结晶及磷酸品质均有较大影响。以湖北某地区的典型低品位胶磷矿为原料,采用X射线光电子能谱仪、扫描电镜、能谱等方法,分析了磷矿及反应后磷石膏中的主要杂质种类及含量变化,并以此推测湿法磷酸过程中杂质的主要变化。结果表明磷矿中的主要成分是氟磷灰石和石英,杂质组分占比最高的分别是硅、铝、氟、镁,其中硅主要以石英和硅酸钙存在,氟主要存在于氟磷酸钙中,铝是以不同形式的铝硅酸盐存在的,而镁则是以MgF₂和部分硅酸盐存在。通过酸解反应,钙与硫酸根生成磷石膏,硅元素主要存在于固相石膏中,而铝、氟、镁则大部分进入到液相磷酸中,其中存在于固相中的硅则基本以石英形式存在,硅酸钙溶解于酸液中,铝主要以铝硅磷的化合物存在,氟则以氟硅化物形式存在,大部分的MgF₂溶解进入液相,磷石膏中镁主要以镁硅酸盐形式存在。通过磷矿中杂质存在形式及反应过程的变化研究,可以更好的明晰酸解过程中的体系变化,从而为磷石膏结晶过程的考察和控制提供理论基础。     

Feasibility of estimating copper content using visible and near-infrared spectra of bedrock,weathered rock and soil - a case study of the Baogutu stock II,Xinjiang, China

Geochemical anomalies are important symbols for prospecting. To determine a new method for identifying geochemical anomalies rapidly, this study examines the possibility of using visible and near-infrared spectra of bedrock, weathered rock, and soil to assess copper content in the Baogutu stock II, Xinjiang, China. Partial least squares regression was employed to study the relationship between visible and near-infrared spectra and the ore-forming element contents of collected bedrock samples, weathered rock samples, and soil samples. More specifically, our study aims to achieve three objectives. First, to explore the correlations between the contents of different elements and the correlations between the visible and near-infrared spectra and the ore-forming element contents for the three sample types. Second, to evaluate the performance of the reflectance-based partial least squares regression model. The models for iron in bedrock samples and copper in soil samples were chosen for estimating copper content. Third, to assess the effectiveness of data transformation methods in the partial least squares regression model. In our case study, the square root-based models for iron in bedrock samples and copper in soil samples with coefficients of determination for prediction are 0.614 and 0.409 respectively, maximized the model performance. Therefore, it is evident that visible and near-infrared spectra can be an alternative method for estimating ore-forming element contents based on bedrock, weathered rock, and soil samples.     

Evaluating rock mass failure in the vicinity of slot cuts

A comparative analysis of the failure of rock with surfaces of weakness in the vicinity of elongated clot cuts of rectangular cross section was performed using the boundary integral equation method and the Mohr-Kuznetsov strength criterion. The rock failure coefficient was used as the criterion of breaking. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 1, pp. 129–133, January–February, 2008.     

Zonal fracturing mechanism in deep crack-weakened rock masses

The mechanical behaviors of deep crack-weakened rock masses are different from those of shallow crack-weakened rock masses. The surrounding rock in shallow crack-weakened rock mass engineering is classified into loose zone, plastic zone and elastic zone, while the surrounding rock in deep crack-weakened rock mass engineering is classified into fractured zone and non-fractured zone, which occur alternatively. It is assumed that the deep rock masses contain one joint set, in which the probability density function describing the distribution of sizes is assumed to follow the Rayleigh distribution, and the probability density function describing the distribution of spacing is assumed to follow the Weibull distribution. On the basis of strength criterion of deep rock mass, the near-field stress redistribution around circular opening induced by excavation is determined. The strong interaction among cracks is investigated by using the dislocation model. The nucleation, growth, interaction and coalescence of cracks were analyzed based on the strain energy density factor theory. When cracks coalesce, failure of deep crack-weakened rock masses occurs, fractured zone is formed. Then, size and quantity of fractured zone and non-fractured zone are given out. The size and quantity of fractured zone increase with decreasing strength of rock mass. The size and quantity of fractured zone increase with increasing in situ stress. Zonal fracturing phenomenon occurs once value of in situ stress is larger than the unaxial compressive strength of rock masses. The size and quantity of fractured zone decrease with increasing λ when p₂ > p₁. The size and quantity of fractured zone increase with increasing λ when p₂ < p₁.     

岩石变形演化诱致灾变破坏过程的同步实验观测

将试样变形场演化特征与试样的宏观载荷位移曲线的演化特征结合起来研究是揭示非均匀脆性介质变形演化诱致灾变破坏的一个重要途径.本文发展了一套实验系统,通过对试样表面变形场的演化、宏观载荷和位移信号的同步观测,对单轴加载下岩石试样变形演化和灾变破坏的过程进行了实验研究.揭示了试样变形场由加载初期的随机涨落到灾变破坏前出现明显的变形局部化的演化特征现象,试样最终在变形局部化区内形成宏观破裂面.