Blockchain.info send may transactions API v2
As of January 2016 Blockchain.info made changes to the wallet API service that now requires you to run a local nodeJS service to handle the calls. This will require you to have root access to your webserver so you will need to use a VPS instead of a basic shared web host. 

Also I don't recommend hand-coding the JSON yourself when using sendmany. Instead create an array and then use the json_encode function.

$array = array(
    "1someAddress" =&gt; 20000,
    "1someAddress2" =&gt; 150000,
    "1someAddress3" =&gt; 314159
); 
$addresses = json_encode($array);


You're not the only one that has hard time with the new version of their API. If you still need some help check out these resources. 

https://www.youtube.com/watch?v=X8jsaf4sEgs
http://btcthreads.com/how-to-setup-blockchain-wallet-service/ 

I started a PHP library for communicating with the nodeJS service, (still needs work, some functions are missing) https://github.com/coinables/blockchain-wallet-APIv2-PHP-Library