One way to capture the SQL blocks and deadlocks is to run Profiler on the SQL Data Server.
In SharePoint 2013 there are two jobs that you can activate in the jobs definition section to monitor the blocks caused by SQL Databases. The jobs are :
1 – Diagnostic data provider: SQL blocking reports
2 – Diagnostic data provider: SQL deadlocks
SQL blocking reports captures the text of any queries that cause the blocking and SQL deadlocks captures the call graphs of the deadlocks in SQL.
The default schedule for the above jobs is 1 minute, and you can monitor the running jobs and failed jobs in the Monitoring Section of Central Administration of SharePoint 2013.
Microsoft reference article: http://technet.microsoft.com/en-us/library/cc678870(v=office.15).aspx#DefaultJobs