I don't know if you have them in your location, but that sounds like voles. They especially like cutting off bean & pea vines... don't know why they do that, rather than just eat the plant, as gophers do.

Thank you Zeedman. Yes, it appears that it is voles. My cat catches a lot of them but he has fallen behind.

I use lava rock in my trenches when I plant beans and it decreases the damage a lot, I had very few bean vines nipped off this year.

I had mice in the garden for a couple years and they chewed off the bean stems. It's a real bummer when it's pole beans and can kill the whole vine. It helped a little to put a small fence of chicken wire around the pole beans. This year the mice disappeared.....which made me very happy!