How to create JSON object with array of nested arrays for multipletimes and multiple times?

How to create JSON object with array of nested arrays for multipletimes
and multiple times?

$data=array
(
"Maths" : [
{
"Name" : "ramesh", // First element
"Marks" : 67,
"age" : 23
}, {
"Name" : "mayur", // Second element
"Marks" : 65,
"age" : 21
}
],
"Science" : [
{
"Name" : "ram", // First Element
"Marks" : 56,
"age" : 27
},
{
"Name" : "Santosh", // Second Element
"Marks" : 78,
"age" : 41
}
]
);