Soil shear strength in-situ testing device and testing method thereof

The invention discloses a soil shear strength in-situ testing device and a testing method thereof. The soil shear strength in-situ testing device comprises a hollow large-diameter spiral drill rod, a small-diameter spiral drill rod and a drill rod pulling-out device, the large-diameter spiral drill rod and the small-diameter spiral drill rod are coaxially arranged in the vertical direction, the small-diameter spiral drill rod is installed in a hollow space of the large-diameter spiral drill rod, and the drill rod pulling-out device comprises a supporting frame, a hand-drive block installed on the supporting frame and a crane scale connected with the hand-drive block. The device has the advantages that the device is light, easy and convenient to operate, high in flexibility and convenient to move; the device is suitable for remolded soil sample testing, and is especially suitable for on-site construction undisturbed soil body testing. The two spiral drill rods are arranged to rotate in the same direction, the