Interpretation of borehole impulse tests at Haut Glacier d’Arolla, Switzerland
Interpretation of borehole impulse tests at Haut Glacier d’Arolla, Switzerland
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瑞士达罗拉上冰川钻孔脉冲测试的解释
DOI：
10.3189/s0260305500012507
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发表时间：
1997
影响因子：
2.9
通讯作者：
B. Hubbard
中科院分区：
文献类型：
--
作者：
B. Kulessa;B. Hubbard
1995年7月和8月，在瑞士的Haut Glacier d 'Arolla密集钻孔阵列中进行了116次脉冲试验。脉冲试验响应压力振荡在相对幅值衰减、振荡频率和净水位位移三个参数上有显著变化。对充水钻孔响应信号的分析表明：(i)单个钻孔的响应在几十分钟内是可重复的；（二）对弹塞插入（“弹塞试验”）和移除（“保释金试验”）的反应相似，但不完全相同；（iii）信号振幅衰减随记录压力传感器位于井眼的深度而变化；（iv）所有三个响应参数的相干最小值与已知的优先冰下水流路径的位置一致。这种对应关系表明，首先，充满水和无波动的钻孔与Haut冰川d 'Arolla的冰下含水层建立了联系；其次，可以通过相对较低的响应信号频率、响应信号衰减和净水位位移来识别局部传输的基底沉积物。因此，脉冲试验充水钻孔有能力提供有关冰下含水层当地水文地质特性的信息。在43个案例中，记录了与被测钻孔相邻的钻孔的水位，以便确定可能的冰下联系。未检测到此类连接。
One hundred and sixteen impulse tests were conducted in a dense borehole array at Haut Glacier d’Arolla, Switzerland, during July and August 1995. Impulse-test response pressure oscillations reveal marked variations in three parameters: relative amplitude decay, oscillation frequency and net water-level displacement. Analysis of response signals from water-filled boreholes indicates that (i) responses from individual boreholes are reproducible over some tens of minutes; (ii) responses are similar, but not identical, for slug insertion (“slug tests”) and removal (“bail tests”); (iii) signal amplitude decay varies with the depth at which the recording pressure transducer is located in a borehole; and (iv) coherent minima in all three response parameters coincide with the location of a known preferential, subglacial water-flow pathway. This correspondence suggests, first, that water-filled and non-fluctuating boreholes have established a link to the subglacial aquifer at Haut Glacier d’Arolla and, secondly, that locally transmissive basal sediments may be identified by relatively low response-signal frequencies, response-signal decays and net water-level displacements. Impulse testing water-filled boreholes therefore has the capacity to provide information relating to the local hydrogeological properties of subglacial aquifers. In 43 cases, water levels in boreholes adjacent to those being tested were recorded in order to identify possible subglacial linkages. No such connections were detected.