基于钻屑形态特征的岩体结构复原方法研究

In non-core drilling，cuttings which came from borehole by rock fragmentation was true reflection of geological mass. This study object was cuttings from pneumatic downhole hammer drilling. This project followed with cutting collection, character statistic, index option and law search as study process on the science peoblem that geometrical character of different rock structure framentation under percussive rotary loads.At first，First,bulit modle with PFC3D which is a discrete element method based on particle flow,according to the calculation results, established definition of the noeven broken cuttings which take information of rock mass characteristic,and filtered cuttings from borehole with a specially manufactured screen which design by results. Secondly, uneven broken cuttings based on the different geometrical and apperance characters of symmetrical and asymmetry fragmentation, build defining of asymmetry cuttings, collected cuttings from advance horizontal boring in tunnels, and fine description of tunnel face, made it mutually corresponding of rock structure. Afterwards,choose available cuttings which contain rock structure infromation to build the image model of drill cuttings, rock fracture and structural surface color difference by the original, the identification structure surface, using off the mouth ratio gray scale images after the detection of shadows, gradient to identify and open contour operation determining cuttings, extract cuttings in the geometric characteristics of two-dimensional, three-dimensional, qualitative / quantitative indicators and colour of cuttings. Finally, taking into account a variety of factors, qualitative / quantitative indicators and complex process broken made rock stucture as target, filtered index by Quantification Theory Ⅲ,and built distinguish model by Quantification Theory Ⅰ,to find laws between cuttings and rock stucture to design reasonable sampling interval recovery in rock mass structure. In this way, this project could abundance rock stucture detcetion means, and enlarge non-core drilling applicable fields, support a new method in geological hazard fast exploration.This study can not only promote the development of the theory of the jointed rock mass bottom of the hole impact crusher, and can enrich the rock mass structure type detection means, the promotion of the geological hazard detection and development of information technology, and ultimately provide a more rapid construction method for geological disasters emergency exploration.

本项目拟采用理论研究、图像识别和多元统计的方法，对冲击回转作用下不同岩体结构破碎产物的几何特征进行研究，通过钻屑复原岩体结构中的部分特征。首先，采用基于颗粒流的离散元软件PFC3D数值模拟，提出含有岩体结构信息钻屑--即不均匀破碎钻屑的定义，并设计异形筛网将其筛选出来；然后，建立钻屑的图像模型，通过原岩断口与结构面颜色差异，识别结构面在断口中的比例，利用阴影检测后的灰度图像，进行梯度识别和开操作确定钻屑外形轮廓,提取钻屑几何特征中的二维、三维定性/定量指标；最后，考虑到各种因素的定性/定量指标和破碎的复杂过程，利用数量化理论Ⅰ确定各指标与岩体结构类型的相关程度，提取其中重要指标，利用数量化理论Ⅲ建立岩体结构的判别模型，设计合理的取样间隔复原岩体结构。通过本研究不仅可以推动节理岩体孔底冲击破碎理论的发展，而且可以促进地质灾害探测与信息技术的发展，最终为地质灾害应急勘查提供更加快速的施工方法。

本研究采用理论推导、实验统计和数值模拟的方法，以钻屑特征为主要研究对象，分析了钻屑与岩体结构之间的关系，得到以下结论：.（1）在完整岩体中，气动潜孔锤钻进破碎后钻屑，总体形态为板状、不规则凸边形（五边形、六边形占大多数）为主。在节理岩体中，根据典型采集数据、数值模拟结果，气动潜孔锤破碎形成的钻屑中出现颗粒状的钻屑（四面体、五面体），且出现的比例与结构面的发育比例成正比。.（2）根据现场采集和地质分析，钻屑的原岩色与风化色差异明显，且由于不同性质节理表面存在红褐色（锈染）、乳白色（方解石、石膏）等颜色，可以根据风化的基本定义，从风化色和原岩色钻屑的比例区分岩体风化程度，如果是其他类型具有特殊颜色结构面的区分亦然。.（3）通过分析气动潜孔锤钻孔破碎过程，提出了由于节理参与孔底破碎而产生的携带地质信息的钻屑——不均匀破碎钻屑。并根据其外形特点设计异形筛，通过分析不均匀破碎钻屑破碎位置与节理的组合关系，在合理考虑重复破碎的前提下，可以推测节理与钻进方向的夹角。.（4）建立基于钻屑的岩体结构复原方法。根据突变型岩体结构、渐变型岩体结构的特点，从几何指标、成分指标和施工指标建立一般钻屑描述体系和判别方法，并对不均匀破碎钻屑建立相应指标进行描述，通过钻屑形状差异复原岩体结构。.（5）根据地质环境的差异，将坡体封闭性能分为不同类型：封闭型、突变型、渐变型、临界型、开放型。将岩体结构特征分为现场观察特征、现场测试特征和室内测试特征，根据不同地质体的类型，提出岩体结构复原思路。.（6）对于一般地质灾害探明推荐采用如下步骤，将易于收集的现场观察特征作为三维地质结构的宏观背景，针对典型二维计算剖面进行现场测试特征的收集，并对地质关键位置如地质界面变化、滑面、裂缝附近收集其室内测试特征。而对于诸如地质灾害应急抢险等需要快速施工的项目，考虑到其时效性要求，建议以现场观察的特征为主。