Repair holes in the concrete floor - underneath there is rubble and sand

Hello, we have now bought an old building and questions keep coming: for example this one: We have a concrete floor with a large hole in it. Below is a cavity of about 5-10cm and then rubble and sand. I would like to fill this hole with mortar, but does that work with the sandy substrate? Can I simply apply mortar generously after it has dried, or will I have the same problems again in spring as we have with our streets? I look forward to answers.... Greeeeeeeetings. Thomas

Pictures say more than a thousand words...

Year of construction?
How big is the hole? and where has the reinforcement gone?

...I like to upload images. My phone photos are still too large despite resizing. Thanks in advance for the reply!

Send me your mobile phone pictures to [E-Mail]Info@schenk-Bauberatung.de[/E-Mail]. I will be happy to upload them for you.

Rhineland greetings

Done

Rhenish greetings

Do I understand correctly that this is not a floor inside the house but outdoors?