淮北煤田太原组灰岩水水文地球化学形成作用及反向模拟研究

Hydrogeochemical formation and inverse simulation of limestone groundwater in Carboniferous Taiyuan Formation of Huaibei coalfield

随着浅部煤炭资源开采殆尽,华北型隐伏煤田的煤炭开采正逐步向深部发展,破坏了地下水系统原有平衡,以致水文地质条件复杂化,从而使深部地下水动力条件和水化学特征发生改变。通过对淮北煤田石炭系太原组灰岩(简称"太灰")含水层地下水化学常规组分进行离子比例分析和主成分分析,探讨该含水层地下水水文地球化学形成作用及其控制因素,并选取淮北煤田南部的临涣矿区太灰含水层为研究示范,应用PHREEQC软件对其进行了反向水文地球化学模拟。研究结果表明:淮北煤田太灰含水层主要水文地球化学形成作用类型为溶滤溶解(包括方解石、白云石、石膏溶滤溶解和黄铁矿氧化)和阳离子交替吸附作用;反向水文地球化学模拟定量分析与离子比例以及主成分定性分析结果基本一致。随时间的延续,采动后淮北煤田南部太灰含水层溶滤溶解作用逐渐减弱,阳离子交替吸附作用逐渐增强,而北部太灰含水层因地层埋藏普遍较浅表现出与之相反的现象。淮北煤田南部太灰含水层水文地球化学形成作用受构造影响表现出较为明显的空间差异;而北部太灰含水层水文地球化学形成作用程度受其径流影响,表现出由东向西逐渐增强的特征。淮北煤田南部的临涣矿区太灰含水层反向水文地球化学模拟验证了水文地球化学形成作用及其空间差异性。

With the exhaustion of shallow coal resources, coal mining is gradually developing into the deeper part to the concealed coalfield in North China, which destroys the original balance of groundwater system, complicates the hydrogeological conditions, and changes the dynamic conditions and hydrochemical characteristics of deep groundwater. The main hydrogeochemical formation and the control factors for the aquifer of Carboniferous Taiyuan formation limestone in the Huaibei coalfield were investigated by the ion ratio analysis and the principal component analysis. Meanwhile, the aquifer of Carboniferous Taiyuan formation limestone in the Linhuan mining area in the south of Huaibei coalfield was studied, and the inverse hydrogeochemical simulation was carried out by PHREEQC. Results show that the main types of hydrogeochemical formation in the aquifer in the Huaibei coalfield are the leaching dissolution(including calcite, dolomite, gypsum dissolution and pyrite oxidation) and the cations alternate adsorption. The quantitative analysis results of inverse hydrogeochemical simulation are basically consistent with the qualitative analysis results of ion ratio and principal component. Affected by mining activities, the leaching dissolution in the aquifer in the south of Huaibei coalfield is gradually weakened with time, while the cation alternate adsorption is gradually strengthened. In contrast, the opposite phenomena are shown because the strata of Taiyuan formation limestone are generally shallow in the north of Huaibei coalfield. The hydrogeochemical formation of the aquifer in the south of Huaibei coalfield presents obvious spatial difference under the influence of structure, while the hydrogeochemical formation in the north of Huaibei coalfield is affected by its runoff, showing the characteristics of gradually increasing from east to west. The inverse hydrogeochemical simulation for the Linhuan mining area in the south of Huaibei coalfield verifies the hydrogeochemical processes and the spatial distribution difference in the aquifer of Carboniferous Taiyuan formation limestone.