Can I purchase the train ticket on my arrival date at Tianjin?

Of course, you can purchase the tickets on your arrival date, but it is not sure whether the tickets have been sold out as train tickets are always under great demand in China. Thus, you would better book the tickets online around 10 days in advance. And the issued tickets would be delivered to your appointed hotel address in China. It takes only around 1hr by high-speed train from Tianjin to Jinan.