侧限状态下高压实高庙子膨润土非饱和渗透性的试验研究
Laboratory test on unsaturated hydraulic conductivity of densely compacted Gaomiaozi Bentonite under confined conditions
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摘要: 高放废弃物深地质处置库中,由高压实膨润土形成的人工屏障,起着阻障围岩中地下水渗入内库并引起核素迁移以及库内高放废物的辐射扩散的作用。因此,有必要研究侧限状态下高压实膨润土的非饱和渗透性能。采用瞬时截面法试验研究了侧限状态下高压实高庙子膨润土的非饱和渗透特性。结果表明:侧限状态下,干密度为1.7g/cm3的高压实高庙子膨润土的非饱和渗透系数,数值为1.13×10-13～8.41×10-15m/s,且与土中吸力呈非单一增减关系。当土中吸力约为68MPa时,非饱和渗透系数最小;吸力大于68MPa时,其非饱和渗透系数随着吸力的增加而增加;而当吸力小于68MPa时,非饱和渗透系数随着土中吸力的增加而减小。Abstract: In deep geological disposal for high-level radioactive waste,the engineering barrier made by densely compacted bentonite is used to prevent the groundwater infiltrating and the radioactive waste diffusing.It is necessary to study the unsaturated hydraulic conductivity of densely compacted bentonite under the confined conditions.The instantaneous profile method is employed to study the unsaturated hydraulic permeability of densely compacted Gaomiaozi bentonite under the confined conditions.Results show that the coefficient of unsaturated hydraulic conductivity of Gaomiaozi bentonite is between 1.13×10-13 and 8.41×10-15 m/s,and it does not vary linearly with the soil suction.The coefficient of hydraulic permeability is the lowest at the suction of 68 MPa.And when the suction is higher than 68 MPa,the hydraulic conductivity increases with the increase of the suction;but it is reverse when the suction is below 68 MPa.
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