Unsaturated groundwater flow and pollutant migration in EDZ of tunnels excavated in soft rock for nuclear waste disposal

软岩核废料处置隧道EDZ非饱和地下水流及污染物迁移

基本信息

批准号：
14350251
负责人：
WATANABE Kunio
金额：
$ 8.77万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

项目摘要

Tertiary sedimentary rock that is classified as a kind of soft rock has been thought as a potential host rock for isolating hazardous nuclear waste. The biggest problem should be studied before constructing disposal site is to make clear the hydraulic feature of excavation damaged zone(EDZ) that is formed near tunnel wall due to the stress change and drying. In this research, the unsaturated flow in the EDZ was basically evaluated by using the evaporation logging equipment that was newly developed in this project. The accuracy of the evaporation measurement from the bore-hole wall was validated by the laboratory tests, then, this equipment was applied in some actual bore-holes.The major items of this research works in this project are as follows :^*Development of evaporation logging equipment that can measure the little in-flow into a bore holes.^*Development of a new permeability estimation technique from the measured result by the evaporation logging equipment^*Application of the equipment and the permeability estimation technique to tunnels in two sites, the Mt.Terri Under ground Research Lab. (Switzerland) and the Rokkasho Nuclear Waste Disposal Site (Japan).^*Laboratory test for evaluating the fracturing process due to the drying of soft rock.Results obtained are as follows ;(1)Evaporation from bore-hole wall could be well measured by using the new evaporation logging equipment when the air discharge passing through the bore-hole was less than 101/min.(2)Estimation of the hydraulic conductivity of the rock just behind the bore-hole wall was successfully performed. The hydraulic conductivity values estimated for the Opalinus Clay of the Mt. Terri Laboratory were in the order of 10^<-12>cm/s.(3)It was clearly found that the evaporation logging equipment could be well applied to the actual problems.(4)The volumetric change of some kinds of soft rock specimen due to the drying was measured with observing the occurrence of fractures.

第三纪沉积岩被归类为一种软岩，被认为是隔离危险核废料的潜在母岩。处置场建设前应研究的最大问题是明确因应力变化和干燥而在隧道壁附近形成的开挖损伤区(EDZ)的水力特征。本研究主要利用本项目新研制的蒸发测井设备对EDZ内的非饱和流进行评价。通过实验室测试验证了钻孔壁蒸发测量的准确性，然后将该设备应用于一些实际钻孔。本项目的主要研究工作如下：^*开发蒸发测井设备，可以测量进入钻孔的少量流入。^*根据蒸发测井设备的测量结果开发新的渗透率估算技术^*该设备和渗透率估算技术在两个地点的隧道中的应用，特里山地下研究实验室。（瑞士）和六所村核废料处理场（日本）。^*评估软岩干燥导致的破裂过程的实验室测试。获得的结果如下；(1)可以很好地测量钻孔壁的蒸发当通过钻孔的排气量小于101/min时，采用新型蒸发测井设备。(2)对钻孔壁后岩石的导水率进行了估算成功执行。对Mt. Terri实验室的Opalinus Clay估算的水力传导率值在10^<-12>cm/s量级。(3)清楚地发现蒸发测井设备可以很好地应用于实际问题。 (4)通过观察裂缝的发生情况，测量某些软岩试件因干燥引起的体积变化。