断层土壤气CO_2含量快速测定法关键问题探讨

Study on Rapid Determination Method of CO_2 Content in Fault Soil

为了提高断层土壤气CO2含量观测数据的映震效能,从测点选择、装置布设、观测方法、辅助测项4个方面对断层土壤气CO2含量快速测定法的关键问题做了全面研究,得出结论:(1)断层土壤气CO2含量测点应选择在活动断层破裂带上或紧邻破裂带的敏感地带,在测点选择时应结合地质资料和钻孔资料对预选址的地下岩石结构及其破裂程度进行研究或有效探测,不宜仅为了观测方便在现有地震台站随便选址;(2)断层土壤气CO2含量快速测定法的装置要尽可能布设得深入地下,至少应使测定孔深度超过地表以下0.5m,最好能够选择深入地表以下2.0m以上的深度,以尽量减少或不受地表生物层的影响,但在装置布设时也要充分考虑地下水位的变化情况;(3)在使用断层土壤气CO2含量快速测定法观测CO2含量变化的过程中应努力消除人为因素的影响,避免主观随意性,特别是应将CO2含量快速测定管放置到靠近测定孔的孔底位置,快速测定管底部开口应尽量保持一致且要使开口口径最大化,避免快速测定管触底;(4)测定孔内温度与断层土壤气CO2含量变化呈正相关,降雨量对断层土壤气CO2含量测值有负面的影响,同步进行测定孔内温度和降雨量辅助观测是必须的。鉴于气压变化与断层土壤气CO2含量变化有较强的负相关,建议在机理上进一步研究其影响,同时还应引入湿度作为断层土壤气CO2含量观测的辅助测项。

In order to improve the earthquake-reflecting ability of the fault soil gas CO2 content data, criti- cal issues from 4 aspects of test point selection, equipment layout, observation method, auxiliary items rapid determination method of fault soil gas CO2 content was studied, the conclusion： （1） the fault soil gas CO2 content measuring points should be selected in the rupture of active fault zone or adjacent to the crack sensitive zone, study or the effective detection of underground rock structure in the test point selection should be combined with the data of geological data and drilling on the location and the rupture of degree, not choose CO2 content measured point in the existing seismic stations only for observation convenient; （2） device used in the determination method of the fault soil gas CO2 content should layout as deeper as possi- ble in underground, measure hole depth should be deeper than 0.5 m below the surface, the beset depth is 2.0 m or more so as to minimize or avoid the affection of surface biological layer, the underground water level should be taken into account, After the completion of the plant layout backfill soil compaction is nec- essary; （3） Artificial factors should be eliminated, especially the rapid determination tube should be placed near the bottom of the measuring hole but should not get in touch with the bottom, to rapid determination pipe bottom caliber should be consistent with each other so as to maximize the caliber; （4） Temperature of measuring hole and fault soil gas CO2 changes were positively correlated, rainfall values have a negative in- fluence on fault soil gas CO2 content, temperature and rainfall aided synchronization observation is necessa- ry. In view of changes in air pressure and fault soil gas CO2 content has a strong negative correlation; fur- ther study on the mechanism of this effect is suggested. At the same time, the humidity should be meas- ured as auxiliary observation of fault soil gas CO2.