concrete plate requires underground suppor

huangyhg

concrete plate requires underground support
my problem is a pretty hefty one. i have a plate of concrete that is sinking towards the house (i'll try drawing it in ascii):
(house)
¯¯¯|
   |
   | /&macr;&macr;&macr;&macr;  <--(plate sinking towards the foundation)
&macr;&macr;&macr; /
the / represents the direction of the plate (mind you it isn't 45 degrees either, but it has dropped a good 5 inches over a period of time), and is not part of the plate itself. i came up with three ideas in order to put a stop to the sinking:
1) to screw l shaped rods (4) into the foundation and use the longer part to stick out of the foundation to serve as a base for the plate to sit on to avoid the plate from dropping.
2) to dig a large hole from the surface of the plate and dig through the soft, shifting material until i find solid ground, then pour mortar to create a pillar that stands on solid ground.
3) to drill at a near-45 degree angle into the plate and further into the foundation and allow the wall to sit on a |/ (straight-backed v) shaped rod to support the weight.
for the most part, the plate has very soft materials that shift around and sink, and some parts are hollow. anyone have suggestions as to what to do? i just want the plate to stop moving downwards.
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excuse me, the diagram for the house didn't work out:
(house)
&macr;&macr;&macr;|
     |
     |  /&macr;&macr;&macr;&macr;  <--(plate sinking towards the foundation)
&macr;&macr;&macr; /
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