Replace you success block with :
success: function (data) {
$("#GridView1").empty();
var data1 = data.d;
//incase you want some headers
$("#GridView1").append("<tr><th>Id</th><th>Col1</th><th>Col2</th><th>Col3</th></tr>")
for (var i = 0; i < data1.length; i++) {
$("#GridView1").append("<tr><td>" + data1[i].Id + "</td><td>" + data1[i].col1 + "</td><td>" + data1[i].col2 + "</td><td>" + data1[i].col3 + "</td></tr>");
}
}
Hope this helps!!