大裂隙堵漏剂在神农架矿区复杂地层钻进中的试验应用

通过大裂隙堵漏剂在神农架矿区复杂地层钻进的试验应用,论述了该堵漏剂堵漏性能参数及堵漏机理,总结了用该堵漏剂堵漏的操作方法;简述了野外施工试验的应用过程及应用效果。     

新疆比勒提地区断裂构造磁异常信息提取及解释

比勒提地区位于新疆西南天山,以该区1：50000高精度磁测数据为基础,采用解析延拓、方向导数等技术手段提取与断裂构造有关的磁异常信息,对区域内构造进行识别,结合标本物性参数统计,对引起磁异常的原因进行分析。对区域磁异常向上延拓及求一阶导数后进行对比,圈定4个特征异常带A1-A4,结合地质资料,识别出4条断裂构造FW1-FW4,FW1和FW2对应喀拉铁克断裂及其次级断裂,FW3为构造动力作用产生的强片理化带,FW4为隐伏断裂,表明高精度磁法测量在本区能有效识别断裂并反映其分布。     

利用重力异常的小波模方法识别断层

利用小波特性可以提取航空重力异常的重要信息,笔者采用小波分析方法建立三维地质体模型,讨论了小波模与地质体边界的对应关系。以我国某海域航空重力资料为例,利用小波模极大值识别了断裂信息,并与航空布格重力异常及其方向导数识别的断裂进行对比分析。结果表明,利用小波模不仅可以识别断裂构造,在航空布格异常和方向导数识别模糊的地区效果更为明显。     

招平断裂带中段断裂成矿有利度分析

招平断裂带是我国著名的金矿成矿带。断裂的空间展布形态特征对寻找断裂构造控矿型金矿床具有重要作用。通过断裂的遥感解译,研究了招平断裂带主断裂的走向、主断裂地表破碎带宽度以及主断裂起伏程度等成矿有利度指标,构建了基于断裂距离场的成矿有利度分析模型,并圈定研究区域成矿远景区11处,为区域地质、物化探等勘查工作提供了指导性意见。     

鞍本地区EW向深大断裂地质特征

在“鞍本地区沉积变质型铁矿控矿条件及找矿模型研究”工作中,尝试在GIS平台上对鞍本地区进行区域地质、航磁、重力、化探、地热泉等资料进行综合分析,发现该区存在一条近EW向展布的航磁和重力水平一阶导数负值异常带,该带南北两侧的地磁场、重力场和地球化学场具有明显的差异.研究成果显示,这条EW向断裂带具有控岩、控矿作用.该断裂自新太古代以来一直有活动迹象,新太古代时,可能是火山喷发的重要通道,已知大型或特大型沉积变质型（鞍山式）铁矿床均分布在断裂北侧长约90 km、宽约20 km的带状区域内;元古宙—古生代时,断裂带对沉积环境具有明显的制约,断裂带两侧的沉积环境不尽相同;中生代时,一系列中酸性侵入岩沿该断裂侵入（局部为隐伏岩体）;新生代沿该断裂出露有一系列平行带状展布的地热泉.     

云南大红山矿区梳状断裂构造系及其控矿作用

大红山铜（铁）矿床的形成与分布受控于康滇地轴早元古代裂陷海槽背景下发育的梳状断裂构造系;梳状断裂构造系通过控制沉积盆地、曼岗河组沉积作用、火山活动等间接控制了铜（铁）矿空间展布和定位.大红山矿区外围找矿首先应沿着同沉积断裂寻找古海底洼地.在康滇地轴基底大红山群及同时代含矿火山-沉积建造普遍被中生界覆盖的情况下,同沉积断裂相对于其他标志可能更易于识别,因而可作为区内勘查大红山式铜（铁）矿的重要准则.     

矿山开发中的含水层破坏评估方法初探——以白山市恒基煤矿为例

本文以白山市恒基煤矿为例,在阐述矿区地质环境基础上,探讨了矿山开采中的含水层结构破坏评估方法,含水层水位、水量变化、和采矿活动对含水层水质造成的污染。最后提出了防治措施,为矿山地质环境恢复治理提供科学依据,也为其他矿山开采提供参考。     

Simulation of hydraulic fracture propagation near a natural fracture using virtual multidimensional internal bonds

A virtual multidimensional internal bond (VMIB) model developed to simulate the propagation of hydraulic fractures using the finite‐element method is formulated within the framework of the virtual internal bond theory (VIB) that considers a solid as randomized material particles in the micro scale, and derives the macro constitutive relation from the cohesive law between the material particles with an implicit fracture criterion. Hydraulic pressure is applied using a new scheme that enables simulation of hydraulically driven cracks. When the model is applied to study hydraulic fracture propagation in the presence of a natural fracture, the results show the method to be very effective. It shows that although the in situ stress ratio is the dominant factor governing the propagation direction, a natural fault can also strongly influence the hydraulic fracture behavior. This influence is conditioned by the shear stiffness of the fault and the distance to the original hydraulic fracture. The model results show that when the fault is strong in shear, its impact on hydraulic fracture trajectory is weak and the hydraulic fracture will likely penetrate the fault. For a weak fault, however, the fracture tends to be arrested at the natural fault. The distance between the fault and the hydraulic fracture is also important; the fault influence increases with decreasing distance. The VMIB does not require selection of a fracture criterion and remeshing when the fracture propagates. Therefore, it is advantageous for modeling fracture initiation and propagation in naturally fractured rock. Copyright © 2010 John Wiley & Sons, Ltd.     

Influence of size on the constitutive equations of concrete or rock dowels

The numerical fracture analysis of non‐homogeneous rock or concrete dowels subjected to shear and compression is described in detail. The method of analysis allows the consideration of scale and rate effects due to material non‐homogeneity and fracture. The proposed approach is verified by comparing numerical predictions with experimental results reported in the literature for a series of small rock samples, since experimental evidence for large bodies is not yet available (2007). Results generated by Monte Carlo simulation using the so‐called discrete element method to model the dowels suggest that a simple three parameters law can be used to predict the relationship between tangential stress at the base and lateral distortion. It is observed that the larger the size of the cubes, the smaller both the peak tangential stress and the rupture distortion. Size effects are also evaluated in samples with vertical restraint. The influence of loading rate is likewise numerically assessed for two sample sizes. The effect is compatible with experimental evidence available for concrete using small samples. Copyright © 2008 John Wiley & Sons, Ltd.     

Cohesive‐frictional model for bond and splitting action of prestressing wire

This paper presents a numerical procedure for bond between indented wires and concrete, and the coupled splitting process of the surrounding concrete. The bond model is an interface, non‐associative, plasticity model. It is coupled with a cohesive fracture model for concrete to take into account the splitting of such concrete. Bond between steel and concrete is fundamental for the transmission of stresses between both materials in precast prestressed concrete. Indented wires are used to improve the bond in these structural elements. The radial component of the prestressing force, increased by Poisson's effect, may split the surrounding concrete, decreasing the wire confinement and diminishing the bonding. The combined action of the bond and the splitting is studied with the proposed model. The results of the numerical model are compared with the results of a series of tests, such as those which showed splitting induced by the bond between wire and concrete. Tests with different steel indentation depths were performed. The numerical procedure accurately reproduces the experimental records and improves knowledge of this complex process. Copyright © 2010 John Wiley & Sons, Ltd.