土难
土难-
红粘土原状土样难予进行长期有效的保护。
It is difficult to effectively preserve undisturbed sample of red clay in a long term .
-
然而，保存完好的古水稻土剖面极难获得。
However , it is extremely difficult to obtain a well-preserved ancient paddy soil profile .
-
在沿海平原和辽河流域盐碱土上很难种植旱地作物。
It was difficult for upland crops to grow on the saline-alkali soil in the coastal plain and Liaohe river regions .
-
有限元分析法在理论上较成熟，但因其存在土体模型和土性参数难确定等困难，难以实际应用。
The finite element method is mature in theory , but it is difficult to fix the earth model and the soil parameters , so being difficulty to be practice applied .