mount unknown filesystem type 'lvm2_member'

Not to detract from the accepted answer, but wanted to offer a more complete solution that hasn't failed me yet.

udisksctl unlock -b /dev/sdb5
sudo mkdir /mnt/data
sudo mount /dev/dm-1 /mnt/data

run into mount: unknown filesystem type 'LVM2_member' do the commands below

sudo bash
vgdisplay
vgrename <VG UUID> new_name
modprobe dm-mod
vgchange -ay
lvscan
mount /dev/new_name/root /mnt/data/

I just recently installed Ubuntu 16.04 using LVM. I have just done this once, so I won't claim to be an authority on this. My quick take, you are using incorrect syntax. Below is a copy of my "fstab" file. Note the syntax for mounting a logical volume.

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>                    <type>        <options>            <dump>  <pass>
/dev/mapper/ubuntu--vg-root /                     ext4         errors=remount-ro       0       1

# Logical volume for home
/dev/mapper/ubuntu--vg-newhome /home        ext4         errors=remount-ro       0       2


# /boot was on /dev/sda1 during installation
# Boot volume (partition) Not part of Logical Volume Management (LVM)
UUID=ed575497-3e49-43ae-aaf6-2f482b516a2b /boot   ext2         defaults                0       2

# Swap volume (partition)  Uses Logical Volume Management (LVM)
/dev/mapper/ubuntu--vg-swap_1 none                 swap        sw                      0       0

#Mount Western Digital Passport Drive On Router  - Not part of Logical Volume Management (LVM)
//rt-n56u/sda1 /media/My_Passport cifs file_mode=0777,dir_mode=0777,rw,guest,sec=ntlm,uid=1000,forceuid,gid=34,forcegid,nofail 0      0

I would also suggest obtaining "Logical Volume Management" from the Ubuntu Software Center" and studying the graphical image display. Use that image to ascertain your mount points with VLM. You can also see your disk drive layout under LVM by using the command below:

sudo lvdisplay

I also wrote a short tutorial (based on my one and only experience), which may be of some use: Create Logical "Home" Volume When Using Logical Volume Management (VLM)

PS: If you do a clean install of Ubuntu, there is a checkbox for using LVM (in my case), so there is no need to actually install LVM should you see that checkbox and check it.

You used the exact same name (ubuntu-vg) for your new volume group as the old volume group. You must give them unique names. You can rename one of the groups using vgrename and its UUID.

Find the UUID with vgdisplay and then rename the volume group:

vgrename <VG UUID> new_name