End point closing wall forming device of extrusion type underground diaphragm wall and method for operating same

A method for closing end-of-wall for a press-fit underground continuous wall, comprising:

• Step 1:
• according to a design of depth and thickness of a diaphragm wall, selecting and assembling an appropriate base section (10) and an auxiliary section (10′), wherein a vertical total length, which is limited by a design elevation construction process conditions, is varied by using auxiliary sections (10′) of different lengths, wherein when the base section (10) and the auxiliary section (10′) are connected, joints (8) are aligned to prevent water seepage, and threaded holes (35″) arranged vertically on an outer wall (3) are also aligned, wherein bolts (35) are used to secure the joints, and a protective cover (44) is fastened with plastic rivets (22) at bottom ends of a separation rail (5) and a small external wall body (3′) to prevent muddy water from entering;
• Step 2:
• when a main body (1) is fixed, sliding a small dovetail track (21′) on the separation rail (5), from a top of the main body (1), into a small concave dovetail groove (17) so that a pawl (18) touches a protruding shoulder (6), thereby a lower bevel of the pawl (18) slides over an upper bevel of the protruding shoulder (6) in the small concave dovetail groove (17) on a short side (11′) of an inner cavity (2), forcing the pawl (18) to convert a vertical movement energy through bevel mechanics to urge a pawl shaft (23) to move a pawl back shoulder (23) to press a supporting spring (25) horizontally along a guide shaft (27) so that the pawl (18) is pushed to retract into a pawl chamber (24), such that the small dovetail track (21′) can pass over the protruding shoulder (6) to a predetermined position at a bottom of the base section (10);
• when a separation device is stuck with concrete and not moving, lifting the main body (1) up, thereby the upper bevel of the protruding shoulder (6) collides with the lower bevel of the pawl (18), and the pawl (18) is pushed to retract into the pawl chamber (24) such that the protruding shoulder (6) passes over the pawl (18), and the main body (1) can continue to ascend until it is pulled out of the ground;
• pushing the main body (1) and the separation device into ground, thereby a flat lower surface of the protruding shoulder (6) bumps against an upper flat surface of the pawl (18), wherein the small dovetail (21′) is limited to a vertical movement due to confine of the small concave dovetail groove (17), thereby the protruding shoulder (6) drives the pawl (18) to drive and, therefore, the separation device down until it arrives at a predetermined underground place;
• Step 3:
• pushing an end-of-wall-closing wall-forming device (45) into ground along an axis of an underground diaphragm wall, sliding the dovetail groove (7) on a first automatic wall-forming device (46) on a dovetail track (21) on the end-of-wall-closing wall-forming device (45) and pressing the first automatic wall-forming device (46) into the ground, filling it with concrete, and then using a static pile driver to insert a dovetail groove (7) on a second automatic wall-forming device (46′) onto a dovetail track (7′) on the first automatic wall-forming device (46) and pressing the second automatic wall-forming device (46′) into the ground, filling it with concrete and slowly raising the first automatic wall-forming device (46), wherein a double-flap valve (4) opens under action of gravity, thereby concrete in the inner cavity (2) flows out to fill a void left by raising the main body (1) to form a first segment of an underground wall unit, wherein the separation device does not follow the first automatic wall-forming device (46) out and remains attached to the end-of-wall-closing wall-forming device (45), and wherein the concrete flowing out of the first automatic wall-forming device (46) adheres to outside of the separation rail (5) and a wing (19), wherein when construction of underground continuous wall reaches an end for enclosure, inserting a dovetail track (7′) on a last automatic wall-forming device (46″) into a dovetail groove (7) on the end-of-wall-closing wall-forming device (45), and pressing the last automatic wall-forming device (46″) to a same depth underground to complete mechanical closure between the end-of-wall-closing wall-forming device (45) and the last automatic wall-forming device (46″), filling concrete into the end-of-wall-closing wall-forming device (45) and the last automatic wall-forming device (46″), starting an electric vibrator (32) or an air-powered vibrator (32′) and gradually raising the end-of-wall-closing wall-forming device (45), thereby the main body (1) of the end-of-wall-closing wall-forming device (45) is pulled out and the separation rail (5), the wing (19), and the protective cover (44) are left in newly formed concrete underground continuous wall;
• and lifting the last automatic wall-forming device (46″) while vibrating, thereby the last automatic wall forming device (46″) is pulled out because no concrete has solidified, while the separation rail (5), the wing (19), and an “z,21 ” flap (19′) are left in a concrete wall section to form an impermeable structure.