太行山北段岩溶裂隙水的富水性及其电性特征-以保定西部山区为例

Water abundance of karst fissure water and its electrical properties in north Taihang Mountains: A case study of mountainous area in the west of Baoding

为揭示太行山北段岩溶裂隙水富水性分布规律,采用电阻率、极化率、半衰时和偏离度分析不同含水层介质结构、不同含水岩组和不同地下水系统岩溶裂隙水与电性参数的关系,探讨研究区岩溶裂隙水富水性的影响因素及其电性响应特征。结果表明:含水层介质结构按照溶蚀孔洞型→断层型→褶皱型→岩体阻水型的排列顺序,半衰时值分布范围依次降低,而偏离度值分布范围依次升高;四种电性参数对奥陶系含水岩组、蓟县系含水岩组具有较强的分辨能力;极化率、半衰时和偏离度难以识别拒马河、界河-唐河以及瀑河-漕河三种岩溶裂隙地下水系统类型;奥陶系含水岩组的富水性优于蓟县系含水岩组;就含水层介质结构而言,溶蚀孔洞型富水性最佳,断层型和褶皱型次之,岩体阻水型富水性最差。

In north Taihang Mountains, there are mainly located the karst fissure groundwater systems of Juma river,of Puhe river-Caohe river and of Jiehe river-Tanghe river. The water-bearing formation of carbonatite karst fissure in the research area can be divided into the Ordovician and the Jixian water-bearing formations. The Ordovician waterbearing formation is mainly developed with chert zebra dolomite and limestone with holes, solution cracks and fissures and groundwater concentration zones. The Jixian water-bearing formation is made up of chert zebra dolomite with fissures, where water abundance is good. The aquifer medium structures in the research area are divided into corrosion pore type, fault type, fold type and water blocking type of rock mass. Zijingguan fault is a normal fault with relatively fragmented hanging wall. The fissures of dolomite and limestone are developed in the fracture zone with good water abundance. To determine the spatial variation of water abundance of karst fissure water in the northern Taihang Mountains and the electrical characteristics of fissure water, karst fissure water in the northern Taihang Mountains was taken as research object and the data of unit water inflow of 39 boreholes was obtained by pumping tests.According to the characteristic of karst fissure water i.e., obvious induced polarization response, four electrical parameters —resistivity, polarizability, half damping time and deviation degree —were acquired by induced polarization method. Statistical analyses and box-whisker plots were processed by Grapher software. The distribution characteristics of four electrical parameters were studied. The relationships between electrical parameters and water abundance of karst fissure water in different aquifer medium structures, water-bearing formations and groundwater systems were analyzed. Interfering factors of water abundance of karst fissure water in the research area and its electrical response characteristics were discussed. The range delineated by lower box(25%) and upper box(75%) of unit water inflow or electrical parameters reflects the dispersion degree of 50% of the data in the central range, which is indicative of various types of karst fissure water in the research area. Results showed that the structure of aquifer media was arranged in the order of corrosion pore type→fault type→fold type→water blocking type of rock mass. In this sequence, the distribution range of half aging value decreases in turn, while the distribution range of deviation value increases correspondingly. It is difficult to distinguish the four types of aquifer medium structures by resistivity and polarizability. Water-bearing formations of the Ordovician system and the Jixianian system could be identified effectively with resistivity, polarizability, half damping time and deviation degree. It was hard to identify groundwater system types among the Juma river, the Jiehe river-Tanghe river and the Puhe river-Caohe river just by the use of polarizability, half damping time and deviation degree. Water abundance in the Ordovician system is better than its value in the Jixianian system. The best water abundance was found in corrosion pore type, followed by fault type, fold type, and water blocking type of rock mass in sequence.