public DataTable GetAllSiteCollections(string url)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("URL");
        dt.Columns.Add("Name");
        SPSecurity.RunWithElevatedPrivileges(delegate()
        {
            SPWebApplication webApplication = SPWebApplication.Lookup(new Uri(url));
            foreach (SPSite site in webApplication.Sites)
            {
                dt.Rows.Add(new object[] { site.Url, site.Url });
            }
        });

        return dt;
    }