how to get valus in dynamic added textbox

Question

i create run time control like this
 Protected Sub RadioButtonList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles RadioButtonList1.SelectedIndexChanged

        Dim index As Integer
        For index = 1 To RadioButtonList1.SelectedValue
          Dim name_tb As New TextBox()
            'validator
            Dim name_req As New RequiredFieldValidator
        
            name_tb.ID = "name_tb" & index
            name_req.ID = "name_req" & index
            name_tb.TextMode = TextBoxMode.SingleLine
tabelcell.Controls.Add(name_tb)
'tabelcell add in trow
'trow then added in htmltable
div.Controls.Add(htmltable)
 Me.PlaceHolder1.Controls.Add(div)
next
I need to get textbox text when i click on submitt button on form.
Thanks