US 12,241,876 B1
Borehole wall spin-shearing device and testing method for in-situ borehole shear test
Wenkai Feng, Chengdu (CN); Xiaoyu Yi, Chengdu (CN); Xuyong Liu, Zhuhai (CN); Yihe Li, Chengdu (CN); Qian Li, Chengdu (CN); and Ke Wan, Chengdu (CN)
Assigned to Chengdu University Of Technology, Chengdu (CN); and Guangdong Eagler Geological Equipement Technology CO., LTD., Zhuhai (CN)
Filed by Chengdu University Of Technology, Chengdu (CN); and Guangdong Eagler Geological Equipment Technology CO., LTD., Zhuhai (CN)
Filed on Aug. 5, 2024, as Appl. No. 18/793,978.
Claims priority of application No. 202311474432.1 (CN), filed on Nov. 8, 2023.
Int. Cl. G01N 3/24 (2006.01); E21B 49/00 (2006.01); G01N 33/24 (2006.01)
CPC G01N 3/24 (2013.01) [E21B 49/006 (2013.01); G01N 33/24 (2013.01); G01N 2203/0025 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A borehole wall spin-shearing device for an in-situ borehole shear test, comprising a load applying assembly, a soil shearing assembly, and a data acquisition assembly, wherein
the load applying assembly is configured to apply a vertical load and an axial rotational load to the soil shearing assembly;
the soil shearing assembly comprises a plurality of shear plates; and the plurality of shear plates are configured to penetrate into undisturbed soil after being ejected due to the vertical load and then shear the undisturbed soil due to the axial rotational load; and
the data acquisition assembly is configured to acquire torque values of the plurality of shear plates during a process of shearing the undisturbed soil; the load applying assembly comprises a drilling rig; and the drilling rig comprises a drill rod and a servo motor located at a top of the drill rod;
the soil shearing assembly is connected to a bottom of the drill rod through a drill rod joint; and an output end of the servo motor is connected to the top of the drill rod;
the drill rod and the servo motor are respectively configured to apply the vertical load and the axial rotational load to the soil shearing assembly; the soil shearing assembly further comprises a shear cylinder in a hollow cylindrical structure; a spinning shaft is provided in the shear cylinder and is vertically movable; an upper half of the spinning shaft forms a cylindrical structure; and a top on the upper half of the spinning shaft is provided with the drill rod joint;
a lower half of the spinning shaft forms a conical structure with a tip facing downwards;
the spinning shaft is slidably connected to the shear cylinder;
a bottom circumferential outer wall of the shear cylinder is provided with a circular receiving groove; four shear plates centered on an axis of the shear cylinder are circumferentially evenly spaced in the circular receiving groove; each of the shear plates is in a curved plate structure; a length direction of the shear plates is identical to a length direction of the shear cylinder; the four shear plates enclose a cylindrical structure; and an axis of the cylindrical structure coincides with the central axis of the shear cylinder;
an inner curved surface of each shear plate facing the central axis of the shear cylinder protrudes to form a connecting piece; the connecting piece forms a trapezoid-like structure with a small upper end and a large lower end; an inner side of the connecting piece is provided with a fitting groove with a T-shaped cross-section along a length direction of the connecting piece; and a gradient of the inner side of the connecting piece is equal to a generatrix inclination of the lower half of the spinning shaft;
four notches are arranged at a bottom of the circular receiving groove for partial passage of the four connecting pieces; and the inner side of the connecting piece passes through the notch to be located inside the shear cylinder;
a conical surface on the lower half of the spinning shaft is provided with four guide rail strips, wherein the four guide rail strips are circularly spaced around an axis of the spinning shaft; and a length direction of each of the guide rail strips is oriented from a major-diameter end on the lower half of the spinning shaft towards a minor-diameter end on the lower half of the spinning shaft; and
each of the guide rail strips is provided with a T-shaped cross-section and matched with one connecting piece; and the guide rail strip is slidably provided in the fitting groove.