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由四个工程提供的资料可见,池塘粘土衬砌的渗透系数大大超过根椐室内渗透试验予计的数值。粘土衬砌的实际渗透系数通常为在室内用原状土样或扰动土样作的渗透试验值的10-1000倍。这是由于室内试验很难得到有代表性的试验土样。再击实的扰动土样或小尺寸的原状土样都不可能包含有代表性的干缩裂缝、裂隙、滑面或其他在衬砌中可能存在的水力缺陷分布。在四种情况记载中,三种作了现场渗透试验,所得渗透系数与实际的相比较为一致。看来,现场渗透试验比室内试验能取得更准确的结果。这四个工程有某些共同点:(1)都具有很高的渗透率,衬砌都很薄(小于24英寸或0.6米);(2)除一种情况外,其余都受到某种程度干缩的影响;(3)在所有情况中,都未进行广泛的施工质量检查。
From the data provided by the four projects, it can be seen that the permeability coefficient of the clay lining of the pond exceeds the value predicted by the penetration test in the chamber. The actual permeability coefficient of a clay lining is usually 10-1000 times the penetration test value of an undisturbed soil sample or disturbed soil sample. This is because it is difficult to obtain representative test soil samples in laboratory tests. The reconstructed disturbed soil sample or the small-sized undisturbed soil sample may not contain representative shrinkage cracks, cracks, sliding surfaces, or other hydraulic defect distributions that may exist in the lining. In the four case records, three kinds of in-situ penetration tests were conducted, and the obtained permeability coefficient was consistent with the actual one. It appears that on-site penetration tests can yield more accurate results than indoor tests. The four projects have some things in common: (1) they all have high permeability, the linings are all very thin (less than 24 inches or 0.6 meters), and (2) except for one case, the others are subject to some degree of dryness. (3) In all cases, extensive construction quality inspections have not been conducted.