摘 要
本文通过收集研究分析前人的大量研究成果，结合自己的工作经验，归纳了我国北方奥陶系古风化壳的形成过程，古生代加里东构造的3 期6 幕次运动是早古生代海相盆地形成古风化壳的关键。加里东构造运动的中、晚期，碳酸盐岩地层直接暴露到地表，形成构造控制的暴露面。在表生成岩作用的影响下，大气降水、浅层地下水（包括上升水）、混合水构成的循环体系，形成地质历史时期的溶蚀系统，使奥陶系暴露到地表的碳酸盐岩地层不断遭受溶解。地层孔隙度增加，渗透性增大，组构的表生岩溶发育带多呈面状展布。奥陶系灰岩暴露到地表，在接受大气降水淋滤、溶解、溶蚀碳酸盐岩的同时部分大气降水形成地表水流顺地势向地形低洼处径流，其余则沿奥陶系灰岩的裂隙和原生孔隙进行渗流。当降水渗流至古潜水面及其下以后，水头流向变成以横向潜流为主。经过一定的时期后，在大气降水的不断淋滤、溶蚀下，碳酸盐岩表面及浅部的原生孔隙岩溶裂隙扩溶空间增大，形成一定范围和规模的地表水、浅层地下水循环流动的体系，其连通性也渐次增强，形成早期的岩溶初始发育带。其后，在大气降水与浅部地下水形成的溶蚀系统的共同作用下，早期形成的岩溶带持续发育，形成了连通性良好的孔、洞、缝系统，并促进了奥陶系碳酸盐岩地层的进一步溶解、溶蚀，形成后期的岩溶成熟发育带。其后由于构造运动的影响奥陶系地层接受来至石炭系-二叠系的泥沙岩沉积充填。形成了奥陶系的古风化壳。
总结了古风化壳的岩溶发育的控制因素主要是构造与古隆起、古气候、岩石性质与结构。构造作用为古风化壳岩溶储层发育中必不可少的因素，不管是碳酸盐台地的整体抬升亦或者是局部的构造断裂，都对岩溶发育起到积极的作用。对霍州矿区的岩溶发展史研究表明：李雅庄煤矿所处的霍州矿区晚奥陶后，华北断块上升奥陶系顶部遭受剥蚀、溶蚀，形成了古岩溶风化壳。古气候对风化壳岩溶的发育有重要影响，降水量与温度具有非常重要的作用，与碳酸盐岩的溶解、溶蚀作用呈现出正向关系。同时碳酸盐岩的非均质性和各向异性，不同碳酸盐岩的类型决定其溶蚀作用的能力。
在区域构造演化史分析基础上，结合古岩溶平面分布规律，初步将我国北方（以华北盆地为例）奥陶系灰岩岩溶演化模式划分为以三个阶段。加里东运动期、海西运动期、燕-喜山运动期。加里东时期，华北地台的陆表海沉积为特征的碳酸盐岩地层在构造运动的作用下抬升，经历了长期的风化剥蚀，形成了一个大型区域性古侵蚀面作用下抬升，经历了长期的风化剥蚀，形成了一个大型区域性古侵蚀面。大气淡水对地表碳酸盐岩地层的溶解、侵蚀，造成易溶碳酸盐岩的溶解，形成各种地表岩溶，如溶蚀沟，溶蚀坑等。在海西期华北地台在海西运动影响下开始缓慢沉降，形成海陆交互相—大型陆相盆地。奥陶系风化壳地层被更年轻的
地层覆盖，早期形成的孔隙被部分充填。在石炭系，二叠系地层压实的早期，压释水含有大量有机质而呈酸性，压释水具有很强的溶蚀能力，孔、洞、缝进一步发展。随着风化壳地层的进一步埋深，原来含大量有机质的酸性水在溶解了碳酸盐岩后变为碱性，逐渐饱和碳酸盐，其溶蚀性降低并可沉淀，充填先前已形成的孔、洞、缝。中生代受燕山运动影响，我国东部大洋板块相对大陆板块作左旋压挤运动，引起地壳拱曲和张裂。造成古老脆性岩石发育大量裂缝，促进了岩溶的发育和对早期充填物的溶解。
指出了古风化壳自身厚度及充填程度、含水层的富水性以及地质构造是制约古风化壳隔水能力的制约因素。在压力的一定的条件下，隔水层的厚度越大突水的危险性越小。充填程度是指对风化形成的裂隙带的充填程度，充填越密实，隔水性能较强。充填越松散，隔水性能较差。前人从地质学角度论证顶部碳酸盐岩隔水层的存在性，该隔水层可分为单一充填型和充填–岩溶不发育型。奥陶系含水层的富水性对古风化壳的隔水能力有重要的影响。奥陶系含水层的富水性越强，越容易溶蚀古风化壳，久久而久之，古风化壳溶蚀空间被水充填形成含水层，所谓的原始导高。反之含水层的富水性越差，水动力条件越弱。古风化壳发育越完整。后期的地质构造运动对地层具有―重塑―作用。断层、褶皱、陷落柱等地质构造不仅对古风化壳本身有重要影响。后期的构造对含水层也起到了控水的作用，影响含水层的水文地质条件。成为影响古风化壳的动力因素。后期的断裂构造影响主要有2各方面：1、后期构造具有控水性，能够影响地下水富水条件。在断层等构造发育地段有利于地下水的富集。含水层的富水性教好。2、断裂构造可以破坏古风化壳的结构，形成一定的破碎带，由于地下水的溶蚀作用。在二者共同作用下，古风化壳的隔水性能大大降低。
结合作者的工作经历总结了古风化壳厚度的确定方式：奥灰古风化壳是主要是指奥套系古侵蚀面之上风化残迹层，以铝质泥岩、铝土岩为主。水文地质钻探过程中通过岩芯鉴定、水位、消耗量观测来确定古风化壳是否存在，由于风化壳的成分复杂，以铝质、铁铝质沉积为主与奥套系石灰岩存在明显差别，极易鉴别。鉴定角度而言极易辨认。同时二者富水性差异，通过水位、消耗量的变化可以确定古风化壳与奥灰之间界面。对于测井曲线而言，石炭系泥质岩主要成分为高岭石；古侵蚀面之下的奥陶系则以伊利石为主。石炭系风化残积层自然伽马曲线呈特高峰状突起，深侧向电阻率显极低值(1-158m.Ω)，密度曲线底部为特高值段；奥陶系岩溶段则为低伽马、低时差、中高电阻率、中高密度值。古侵蚀面上、下的测井曲线特征明显不同，易于识别。
采用中国矿大（北京）武强教授的“脆弱性指数法”分析评价古风化壳在李雅庄煤矿突水危险性评价方面的作用。中奥陶统灰岩风化壳发育与充填情况确定为主控因素之一。李雅庄煤矿位于霍州矿区处于山西六大泉域之一的郭庄泉域径
流区，构造复杂，地下水富水性存在不均一性。通过对李雅庄煤矿水文地质条件的分析确定：（1）峰峰组含水层水压（2）峰峰组含水层富水性（3）有效隔水层等效厚度（4）矿压破坏带下脆性岩厚度（5）古风化壳厚度（6）陷落柱分布（7）断层褶皱的分布（8）断层规模指数（9）断层褶皱交点和端点的分布九个因素作为10#煤层底板奥灰突水脆弱性评价的主控因素。通过主控因素的分析研究确定了主控因素的权重值。其中古风化壳的权重值为0.027。通过突水主控因素的权重分析研究表明：底板突水受控于多种的因素的共同作用的结果，古风化壳是其影响因素之一，同时古风化壳受控于含水层的富水性及构造的发育程度。表明古风化壳对煤层底板带压开采的主要影响作用，古风化壳可以作为隔水层作为复合关键隔水层，对下组煤带压开采具有积极意义。
关键词：李雅庄煤矿,古风化壳,隔水性,突水危险性
Abstract In this paper, the research collected by the analysis of the previous researches, combined with their own work experience, summed up the North China Ordovician weathering crust formation process. The Paleozoic Era Garito structure 6 stage 3 act movement is the key to early Paleozoic marine basin formation of ancient weathering crust, the carbonate rocks in the middle and late period of the Garito tectonic movement are exposed to the surface, and the formation of the structural control of the storm. Under the influence of surface generation, the atmospheric precipitation, shallow groundwater (including the rising water), mixed water constitute the circulatory system, the formation of the geological history of the dissolution system, so that the exposed surface of the Ordovician carbonate rock continued to suffer. The formation porosity and permeability increase, the formation of the structure of the surface of the karst development zone is more than the surface. Ordovician limestone exposed to the surface in an atmospheric precipitation leaching, dissolution, dissolution of carbonate rocks and some precipitation formed surface water Shun lying to the low-lying terrain runoff and the rest along the Ordovician limestone fractured primary pores and seepage. The formation porosity and permeability increase, the formation of the structure of the surface of the karst development zone is more than the surface. Ordovician limestone exposed to the surface in an atmospheric precipitation leaching, dissolution, dissolution of carbonate rocks and some precipitation formed surface water Shun lying to the low-lying terrain runoff and the rest along the Ordovician limestone fractured primary pores and seepage. When the water seepage to the water table and later, head to become a horizontal subsurface
flow. After a certain period of time, in continuous leaching of meteoric water, corrosion, surface of carbonate rocks and shallow primary pore karst fissure expansion solution space increases, the formation of a certain scope and scale of surface water and shallow groundwater circulation flow system, the connectivity is also enhanced gradually, the formation of early stage of karst is the initial development zone. Subsequently, in the common action of the dissolution system of the atmospheric precipitation and shallow groundwater, the early formation of Karst Zone continued to develop, forming a good connectivity of hole, hole, fracture system, and promote the further dissolution of the Ordovician carbonate formation, dissolution, formation of late maturing and development zone. Then due to the influence of tectonic movement of Ordovician formation to accept Carboniferous Permian sedimentary rock sediment. The formation of the Ordovician weathering crust.
Summarizes the control factors of karst weathering crust is the main tectonic and paleo uplift, paleoclimate, rock properties and structure. Tectonic action for antiquity of crust karst reservoir development essential factor, regardless of the overall uplifting of the carbonate platform or is partial rupture of the structure of karst development and play a positive role. In Huozhou mining area of karst development history research show that the Liyazhuang coal mine of Huozhou mining area in the late Ordovician, North China fault block at the top of the Ordovician suffered denudation, dissolution, formation of the ancient karst weathering crust. The ancient climate has an important influence on the development of weathering crust karst, and it has a very important effect on the precipitation and temperature, and it has a positive relationship with the dissolution and dissolution of carbonate rocks. At the same time, the heterogeneity and anisotropy of the carbonate rocks, the different types of carbonate rocks determine the ability of its dissolution.
Based on the analysis of regional tectonic evolution history and the distribution law of ancient rock dissolution, the evolution pattern of Ordovician limestone karst in North China is divided into three stages. Caledonian movement, Hercynian Himalayan movement period, yan. The Caledonian period, the land of the North China platform table sea depositional characteristics of carbonate rocks in tectonic movement under the action of uplift and experienced a long period of weathering and erosion, forming a large regional fossil erosion surface uplift, experienced a long period of weathering and erosion, formed a large regional erosion surface. The dissolution and erosion of the atmospheric fresh water on the surface carbonate rocks,
resulting in the dissolution of soluble carbonate rocks, the formation of a variety of surface karst, such as corrosion, corrosion pits, etc.. Slow subsidence in the Hercynian Hercynian movement began in the North China platform under the influence, the formation of large paralic continental basin. The weathering crust of Ordovician is covered by a much younger strata, and the porosity of the formation of the early formation is partially filled. In the Carboniferous, early Permian strata compaction. Press release water contains a lot of organic matter is acidic, pressure release water has a strong dissolution ability, holes, seams for further development. With the further depth of the weathering crust, the acidic water, which contains a large amount of organic matter, becomes alkaline and gradually saturated with carbonate, which is gradually saturated with carbonate, which can be reduced and precipitated. Mesozoic Yanshan movement, China Eastern oceanic plate relative to the continental plate for left-hand squeeze motion, causing crustal doming and rifting. A large number of fractures are caused by the development of ancient brittle rocks, which promotes the development of karst and the dissolution of early filling materials.
It is pointed out that the paleoweathering crust thickness and filling degree, aquifer water rich and geological structure is restricted palaeoweathering crust across water capacity constraints. Under the pressure of a certain condition, the greater the thickness of the water, the smaller the risk of water inrush. Filling degree is the degree of filling of fractured zone formed by weathering, the more dense the filling, the stronger the water separating performance. The more loose the filling, the less water performance. From the perspective of geology, the existence of the top carbonate rock is demonstrated by the predecessors, which can be divided into a single filling type and filling the karst is not developed. Has the important influence of water rich Ordovician aquifer water resisting capability of weathering crust. The stronger the Ordovician aquifer water rich, more prone to corrosion weathering crust, for a long time and for a long time, solution space of paleoweathering crust is water filling into the aquifer, the so-called original guide. In the contrary, the poor water in the aquifer, the weaker the water power condition. Palaeoweathering crust more complete. The geological tectonic movement in the later period has the function of the formation of the formation. Faults, folds, tectonic collapse columns not only on the palaeoweathering crust itself has an important influence. The later period of the structure of the aquifer also plays a role in controlling water, affecting the hydrogeological conditions of the aquifer. A dynamic factors influencing weathering crust. Faults affect later there are 2 main aspects: 1, with the late tectonic controlling
water, underground water can affect the water conditions. The enrichment of groundwater in the development of fault and so on. The rich water of the aquifer is good. 2, the structure of faults can destroy the palaeoweathering crust, forming a fracture zone, due to groundwater corrosion. In the two together, the water resisting property of weathering crust is greatly reduced.
Combined with the author's work experience the palaeoweathering crust thickness determined: Ordovician weathering crust is mainly refers to the Austrian ancient erosion surface weathered remnant layer, aluminum mudstone, aluminous rocks. Hydrogeological drilling process through the core identification, water level, consumption quantity observation to determine the existence of paleo weathering crust, due to the complexity of the composition of the weathering crust, aluminum, iron aluminium sedimentary based and Ordovician system limestone are obviously different, is very easy to identify. Identification point of view is very easy to identify. At the same time the two water rich difference, the water level, consumption changes can determine the interface between weathering crust and Ordovician limestone. For the log curves, the main components of the Carboniferous mudstone are kaolinite, and the Ordovician in the paleo erosion area is dominated by illite. Carboniferous weathering eluvial natural gamma curve showed a peak shaped protrusions, deep lateral resistivity show very low values (1-158m. omega), the density curve at the bottom for extra high value section; Ordovician Karst Section for Bagama, low jet lag, high resistivity, in high density value. The characteristics of well logging curves in the paleo erosion surface are obviously different, which is easy to be identified.
Use of CUMT (Beijing) Wuqiang professor "vulnerability index method" to evaluate paleoweathering crust in Liyazhuang mine inrush water risk assessment on the role of analysis. One of the main controlling factors for the development of the weathering crust of Ordovician limestone weathering crust and filling. In Liyazhuang coal mine in Huozhou mining area is one of six big spring field in Shanxi Province of guozhuangquan basin runoff area, complex structure, underground water yield property exists inhomogeneity. Determined through analysis of the Liyazhuang coal mine hydrogeological conditions: (1) the peak group containing water pressure (2) Fengfeng Group effective vibration and equivalent water thickness (4) mine pressure damage morbid brittle rock thickness (5) paleoweathering crust thickness (6) subsided column distribution (7) fault fold distribution (8) fault scale index (9) faults, folds the intersection point and the endpoint of the distribution of nine factors as 10# coal seam floor Ordovician limestone water inrush vulnerability evaluation of main controlling
factors including water enrichment of water (3). Through the analysis of the main control factors, the weight values of the main control factors are determined. The weight of the paleocrust value is 0.027. Through the main control factors of water inrush of weight analysis, and the results show that the water inrush from floor controlled on the results of the interaction of many kinds of factors, the paleo weathering crust is one of the influencing factors, and paleoweathering crust is controlled by the degree of development of the aquifer water rich and its tectonic. Show that the paleoweathering crust on coal seam floor with pressure mining of the major impact, the palaeoweathering crust can be used as water resisting layer as a compound key aquifuge, of lower group coal mining with pressure has a positive meaning.
Key Words: Liyazhuang coal mine, ancient weathering crust, Water-resisting property, Water inrush risk