海域天然气水合物稳定带厚度与其影响因素的半定量研究

海底沉积物中蕴含着大量的天然气水合物资源。水合物稳定带(HSZ)反映了海底天然气水合物的成矿作用和分布规律,稳定带厚度的影响因素决定了天然气水合物的蕴藏量。水合物稳定带的影响因素有很多种,但每种因素对其的影响程度不同。为探讨水合物稳定带厚度的分布规律,从分析海底天然气水合物相平衡影响因素入手,着重研究了影响稳定带厚度的水合物气体组分、地温梯度、海水深度、海底温度及孔隙水盐度等重要参数,并使用CSM Gem程序对这些影响因素进行模拟计算;然后利用模拟计算所得到的结果数据进行曲线拟合,直至得到较为可信的相平衡曲线;最后根据此相平衡曲线,结合相应条件下的地温梯度曲线方程求得稳定带厚度。通过对预设各条件值与相应得到的稳定带厚度值进行回归分析,得出稳定带厚度与各个影响因素的关系以及这些因素对稳定带厚度的影响程度。     

青藏高原山区某公路滑坡滑动机理及其稳定性分析

以青海省南部省道红土山段滑坡为例,在分析区域地质概况和滑坡特征的基础上,对滑坡机理及影响滑坡的因素进行分析,确定滑坡滑动模式;选取合理的计算参数进行滑坡稳定性计算,根据计算结果对滑坡稳定性进行分析。得到以下结论:产生滑坡体病害的主要原因是滑坡所处区域冻土深度较大,区域冬夏温差大,地表水下渗后冻胀,次年夏初消融,这使粘性土及泥岩泥化,粘聚力降低,周而复始,滑体不断蠕动下滑。采用传递系数法对滑坡在不同工况下的稳定性进行计算,结果表明,在天然状态下滑坡浅层滑面处于蠕动变形状态,深层滑面基本稳定;在考虑暴雨和地震的条件下,滑坡处于不稳定状态。      

Optimization of slope angle and its seismic stability: A case study for the proposed open pit coalmine in Phulbari, NW Bangladesh

The present study reflects upon the results of substantial program of two-dimensional Finite Element Method （FEM） numerical analyses of the open pit that links to slope angle optimization associated with the safety factor of the pit slope of a coal mine in Bangladesh. In the present analyses, two types of models have been presented. The first model estimates safety factor without seismic effect on the overall pit slope of the model; the second model incorporates safety factor with seismic stability of the model. The calculated optimum slope angle of the first model is 31% with a rational safety factor of 1.51, prior to the seismic effect. However, the value is reduced to 0.93, 0.82, and 0.72, after we applies the seismic effect in the second model with M6, M6.5, and M7, respectively. Finally, our modeling results emphasize that for the case of the proposed Phulbari coalmine, there is extremely high prospect for causing massive slope failure along the optimum pit slope angle with 31% if the mine area felt seismic shaking, like the Sikkim （in northern India） earthquake with M6.9 on September 18, 2011.     

济南市燕翅山铁矿采空区稳定性分析评价

济南燕翅山铁矿已闭坑多年,遗留大量的采空区潜在地面塌陷、山体崩塌及裂缝隐患,对当地人民群众生命财产安全构成威胁。该文对采空区稳定性进行了分析计算,并根据研究区实际,提出了主要地质灾害治理方法和措施建议。     

Analysis of implicit HHT‐α integration algorithm for real‐time hybrid simulation

Real‐time hybrid simulation is a viable experiment technique to evaluate the performance of structures equipped with rate‐dependent seismic devices when subject to dynamic loading. The integration algorithm used to solve the equations of motion has to be stable and accurate to achieve a successful real‐time hybrid simulation. The implicit HHT α‐algorithm is a popular integration algorithm for conducting structural dynamic time history analysis because of its desirable properties of unconditional stability for linear elastic structures and controllable numerical damping for high frequencies. The implicit form of the algorithm, however, requires iterations for nonlinear structures, which is undesirable for real‐time hybrid simulation. Consequently, the HHT α‐algorithm has been implemented for real‐time hybrid simulation using a fixed number of substep iterations. The resulting HHT α‐algorithm with a fixed number of substep iterations is believed to be unconditionally stable for linear elastic structures, but research on its stability and accuracy for nonlinear structures is quite limited. In this paper, a discrete transfer function approach is utilized to analyze the HHT α‐algorithm with a fixed number of substep iterations. The algorithm is shown to be unconditionally stable for linear elastic structures, but only conditionally stable for nonlinear softening or hardening structures. The equivalent damping of the algorithm is shown to be almost the same as that of the original HHT α‐algorithm, while the period elongation varies depending on the structural nonlinearity and the size of the integration time‐step. A modified form of the algorithm is proposed to improve its stability for use in nonlinear structures. The stability of the modified algorithm is demonstrated to be enhanced and have an accuracy that is comparable to that of the existing HHT α‐algorithm with a fixed number of substep iterations. Both numerical and real‐time hybrid simulations are conducted to verify the modified algorithm. The experimental results demonstrate the effectiveness of the modified algorithm for real‐time testing. Copyright © 2011 John Wiley & Sons, Ltd.     

基于区间方法的岩质边坡稳定性非概率可靠性分析

在综合分析岩土参数区间性的基础上,通过引入区间分析方法和非概率可靠性思想,建立岩质边坡稳定的非概率可靠性模型,并针对区间运算结果扩张问题,引入区间截断法和区间优化法,对边坡非概率可靠性指标进行较为精确的求解。然后,以湖北某岩质高边坡为实例,进一步探讨了岩体参数变异性对岩质边坡稳定的非概率可靠性指标的影响规律。     

湖北省三峡库区秭归县头道河Ⅱ号滑坡特征及稳定性评价

针对湖北省三峡库区秭归县头道河Ⅱ号滑坡现状条件下的明显变形迹象,本文对该滑坡进行了综合的分析和研究,详细介绍了该滑坡的地质背景及滑坡特征。采用剩余推理法,对滑坡体在各种不同工况下的稳定性作了科学分析,并对滑坡体在三峡水库蓄水以后的稳定性作了合理评价。结果表明,滑坡体在目前状态下基本稳定,三峡水库蓄水以后,将对滑坡体稳定性产生较大影响,极有可能导致滑坡体失稳,据此结合工程实际提出了一些可行的防治措施及建议。     

Finite element analysis of steep excavation slope failure by CFS theory

The distribution of Coulomb failure stress (CFS) change in the steep excavation slope is calculated by finite element method in this paper, and the failure mechanics under different conditions have been investigated. Comparing the CFSs before and after the slope excavation (stress loading and unloading processes), the dangerous internal zone and the most likely failure external area are attained. Given the shear cracks on the top surface while tensile stress or cracks along the toe of the slope, we analyze the high cutting-angle steep slope in Kaixian county of the Three Gorges Reservoir region. We bring forward that the peak value of CFS after excavation can reach to the order of 0.1 MPa, which is greatly higher than that of before. Our preliminary results are useful for optimizing the reinforcement structure during the steep slope stabilization engineering.     

青藏铁路路基稳定性模型的GIS集成工作环境应用研究

为了发挥GIS在青藏铁路冻土路基稳定性研究中有力的支持作用, 在已经建成的青藏铁路数字路基GIS平台的基础上, 探讨了一种基于过程集成模式的模型与GIS集成方法, 研究建立专业冻土路基模型与GIS平台集成的可视化"模型GIS集成工作环境", 研究重点为专业冻土路基稳定性模型模块在此"模型GIS集成工作环境"中的集成技术手段、 模型管理模式以及模型调用模式. 作为研究成果, 实现了一个实用原型系统.     

内蒙古乌里雅斯太凹陷南洼槽坡折带粗砾斜坡扇沉积特征

斜坡扇沉积属重力流事件沉积,在我国陆相断陷湖盆中也有发育,是一种重要的相类型.针对乌里雅斯太凹陷南洼槽东部坡折带发育一套厚度大、粒级粗和相变快的砾岩体,通过精细的岩心观察,结合测井、3D地震,以及岩石分析资料等,认为该砾岩体应属于低位体系域重力流成因机制的斜坡扇沉积,并论述了研究区内的斜坡扇相带的划分,分析了其平面的相分布特征,建立了该研究区沉积相模式,为研究区岩性油气藏的进一步勘探开发提供了依据.