大型复杂采空区注浆效果检测方法研究

大型复杂采空区由于具有分布范围广、多层、厚度及埋深不等和周围岩性复杂等特点,导致其注浆质量检测难度较大,目前尚无可靠的系统检测方法。结合某采空区注浆工程实践,对浆液结石体的电阻率进行了现场试验,得到了浆液结石体的视电阻率范围为93～130m,与采空区及围岩均有较大差异。运用电测深法和电磁波CT对采空区注浆前后进行检测,发现注浆后浅部0～30m范围内,视电阻率普遍得到降低且变得相对均匀稳定; 深部低阻异常在注浆后电阻率也得以减弱,且均匀范围明显扩大; 电磁波吸收系数在40～70m范围内得到提高约25%。钻探取心发现,多数孔内可见注浆结石体; 检测孔的后期注浆中, 10个孔的注浆量均不大于周围相邻4个孔的注浆量平均值的15%。对以上检测结果分析可知:采空区在物性特征上表现为较低的电磁波吸收系数,注浆以后升高; 地下水位之上的采空区表现为较高的电阻率,注浆之后降低,地下水位以下的采空区则反之。注浆前后采空区物探差异明显,本段落采空层的浆液充填效果较好,几种检测方法的结果具有良好的对应关系。同时表明,采用全域检测的电测深和局部详查的电磁波CT相结合的物探方法,与钻探取心结果及检测孔后期注浆数据进行分析对比,可以对大型复杂采空区注浆效果进行有效检测和评价,可为类似采空区提供借鉴。

INSPECTION METHOD FOR GROUTING EFFECT IN TREATING LARGE COMPLICATED CAVITIES DUE TO MINING

Complicated cavities with wide distribution, multi-layers, variable thicknesses and depths as well as the complex surrounding lithology, result in difficulties on their grouting effect test. Therefore, there is no reliable testing system at present. Based on cavities grouting practice, the resistivity of the slurry stones is tested and the apparent resistivity range of 93～130 m has a great difference quantity from cavities and surrounding rocks. Cavities are tested by sounding method and electromagnetic wave CT before and after grouting, showing that: after grouting, in shallow range of 0～30m, the apparent resistivity generally is reduced and becomes relatively uniform and stable; low resistivity abnormity in deep range is mitigated with expanded uniform range; electromagnetic wave absorption coefficient increased by about 25% in 40～70m range. Core drilling indicates that, grouting slurry stone is visible in most boreholes, and 10 detecting holes' grouting volume is not more than 15% of the adjacent four holes grouting average. The above test results show that: the cavities have lower electromagnetic wave absorption coefficient, which rises after grouting; cavities above the water table have high resistivity, which come down after grouting, and cavities below the water table have totally reverse attribute. Before and after grouting the cavities have great difference on the properties, showing the grouting quality is very good and there is a good correspondence between the results of several detection methods. The result indicates that, by comparing with drilling results and detection-hole grouting data, geophysical method of overall electrical sounding detection and partial detailed electromagnetic wave CT,can effectively detect complicated cavities grouting effect. The achievement can be drawn on in other similar cavities.