1. Prices have reached ( the ) hardpan.

2. The microstructure of hardpan is described through observation of electronic microscope and its effect on the mechanical properties is analyzed.

3. Soils with clay and hardpan can hold water and expand when they freeze and slide when wet .

4. But on the hardpan or sands, pipe-drived pile has almost same or lower number compared with bored pile because of sand's liquefaction.

5. The limestone–and–clay and sand-and-clay soil over a hardpan and iron–dross subsoil allows excellent draining.

6. In this paper, the hardpan roughness of paddy field was measured, autocorrelation and power density spectrum were analyzed.

7. The study provided the variation range of paddy field hardpan roughness and the effective frequency of the hydraulic copying system.

8. For the need of earthquake microzonation some studies on the dynamic properties of hardpan in west Anhui were conducted.