In recent years many slope lands have been relentlessly cultivated or developed and result in the soils of the slope lands cannot withstand a great amount rainwater seeping into the earth. Consequently the slope lands often crumple to form landslides that become a great threat or cause great damages to people living in the slope land area.
One of the measures to protect people living in the slope area is to construct retaining structure on the slope land. The conventional retaining structure usually is built in the form of embankment. Because of geographic and space constraints, the retaining structure often is constructed by a half-excavation and half-filling approach. And it generally is a man-made platform or construction space. These days many buildings are located on the slope land or below the slope land. Hence the slope land retaining structure becomes very important. A lot of slope land damage cases indicate that prior to the damage occur or pending to occur, many unstable symptoms such as small or obvious inclination or dislocations or cracking take place. However due to the present regulations do not have mandatory decree or budget constraint, no monitor systems or continuous monitoring have been established for those unstable slope lands. As a result, crumpling or dislocation of the slope land often aggravates and finally inflicts a great damage or disaster.
Therefore to establish a safety monitor structure or system for the community on the slope land area is an urgent issue.
To ensure the stability of the slope land retaining structure, besides giving additional reinforcement to the retaining structure, setting up a monitor apparatus on the slope land retaining structure to monitor the slope land condition also is important. FIG. 1 illustrates a conventional monitor system for such purpose. It includes a building gradient tray A, a landslide meter B, a gradient observation duct C, a sinking observation spot D, and a crevice meter E. While the monitor devices mentioned above can monitor the slope land conditions, they are very expensive. To install those equipment on the slope land retaining structure also is costly and time-consuming.