Facebook Ads API - how to add multiple rules to custom audience api call in PHP

I am trying to add 2 rules to api call like below:

$parameters     =       "name=TEST-Registered-CA&";
$parameters     .=      "subtype=WEBSITE&";
$parameters     .=      "retention_days=180&";
$parameters     .=      'rule={"and":[{"url":{"i_contains":"thankyou.asp"}},{"url":{"i_contains":"HotelVenueState=CA"}}]}';

http://ift.tt/1CidIm1;

When i try to run above on Facebook Graph Explorer, it gives following error "(#2654) Invalid JSON for rule: Supplied string for rule is not valid JSON" Rerence url (enter link description here

Can any one tell me what i am doing wrong with json ?