An underground diaphragm wall structure and construction method at the inner corner of an underground excavation project

Abstract

The present invention discloses a diaphragm wall structure and a construction method at the inner corner of an underground excavation project, which includes a transverse diaphragm wall implemented in the tunnel of the underground excavation project and a longitudinal diaphragm wall with the same depth as it, and the two diaphragm walls are connected at the corner to form an L-shaped diaphragm wall structure at the corner; a vertical through groove is arranged at the end side of the transverse diaphragm wall corresponding to the position of the longitudinal diaphragm wall, and a tenon joint is arranged at the end of the longitudinal diaphragm wall and inserted into the notch of the groove and then integrally connected after pouring concrete. The tenon joint is provided with shoulders extending to both sides and integrally connected with the side surface of the transverse diaphragm wall. The corner joint of the present invention has a simple structure, high precision, reliable connection, good water stop effect, convenient construction, and effectively shortens the construction period.

Description

Technical Field

[0001] The invention belongs to the technical field of underground continuous wall construction at a corner in a tunnel, and in particular to an underground continuous wall structure at a corner in a dark excavation project and a construction method. Background Art

[0002] At present, in urban built-up areas with good geological conditions, shallow buried dark excavation is often used for the construction of large-scale underground municipal projects such as subway stations. Shallow buried dark excavation construction must require a waterless environment. In the past, it was mainly constructed by precipitation method, and the pumped groundwater was discharged into the municipal pipe network, which was a waste of groundwater resources and municipal drainage facilities. Underground continuous wall is a commonly used water-stopping form in foundation pit projects. It has the characteristics of mature technology and reliable quality. Combining it with shallow buried dark excavation projects can achieve non-precipitation construction, which is very beneficial to the protection of groundwater. However, due to the narrow working space in the tunnel and the poor flexibility of underground continuous wall construction in the tunnel, only straight-line walls can be constructed at present. The underground deep groove of the underground continuous wall is too large to cause collapse, which has high safety hazards. For the corner connection of the underground continuous wall, the existing joint forms (I-beam, lock pipe, lock box, etc.) cannot well achieve reliable connection of two vertical underground continuous walls. The connection accuracy is low, the leakage phenomenon is serious, and the water flow erosion at the corner of the wall is serious. This has become a difficulty restricting the application of underground continuous wall technology in tunnels and needs to be solved urgently. Summary of the invention

[0003] The invention provides an underground continuous wall structure and construction method at a corner in a dark excavation project, which aims to solve the problems of collapse caused by large excavation deep trenches of existing underground continuous walls, unreliable corner connection joints of underground continuous walls, serious leakage and low connection accuracy.

[0004] The present invention adopts the following technical solutions:

[0005] An underground continuous wall structure at a corner in a dark excavation project, comprising a horizontal underground continuous wall implemented in a dark excavation tunnel and a longitudinal underground continuous wall of the same depth, wherein the two underground continuous walls are connected at a corner to form an L-shaped underground continuous wall structure at a corner; a vertical through groove is arranged on the side surface of the end of the horizontal underground continuous wall corresponding to the position of the longitudinal underground continuous wall, a mortise and tenon joint is arranged on the end of the longitudinal underground continuous wall, and the mortise and tenon joint is inserted into the notch of the groove and poured with concrete to be integrally connected thereto, and the mortise and tenon joint is provided with bosses extending to both sides to be integrally connected to the side surface of the horizontal underground continuous wall.

[0006] A transverse steel cage is arranged in the transverse underground continuous wall, and a longitudinal steel cage is arranged in the longitudinal underground continuous wall; welded trapezoidal channel steel is embedded in the transverse steel cage, and the welded trapezoidal channel steel is formed by welding side plates and web plates. After the transverse steel cage is poured with concrete, the welded trapezoidal channel steel forms the vertically penetrating groove.

[0007] The horizontal steel reinforcement cage includes horizontal steel bars, horizontal additional steel bars, vertical main steel bars and the welded trapezoidal steel channels; the horizontal steel bars are horizontally bent inward along both sides of the welded trapezoidal steel channels along the side plates, and are welded at the intersections with the same number of the horizontal additional steel bars inside the horizontal steel reinforcement cage; the outer sides of the side plates of the welded trapezoidal steel channels are welded to the horizontal steel bars, and the outer sides of the webs of the welded trapezoidal steel channels are welded to the horizontal additional steel bars.

[0008] The horizontal steel reinforcement cage is assembled in vertical sections, and the section height is 3m to 5m. The vertical main steel bars are connected and lengthened through steel bar mechanical connection sleeves, and the welded trapezoidal steel channels are connected and lengthened by welding or bolt connection with connecting steel plates on the inner side of the webs.

[0009] Anti-flow-around iron sheets are arranged at the end parts of the side walls of the welded trapezoidal steel channels and extend to both sides. The anti-flow-around iron sheets are vertically equal in height to the welded trapezoidal steel channels and are fixed to the inner surfaces of the end parts of the side plates of the welded trapezoidal steel channels by bolts.

[0010] The horizontal steel bars at the upper end of the longitudinal steel reinforcement cage gradually converge inward at the positions corresponding to the grooves, forming the tenon joints corresponding to the grooves, and after being embedded in the grooves, concrete is poured for integral connection.

[0011] A construction method for the diaphragm wall structure at the inner corner of an underground excavation project includes the following construction steps.

[0012] Step 1: Fabricate the horizontal steel reinforcement cage. At the corner connection, horizontally bend the horizontal steel bars inward, and weld and fix them at the intersections with the same number of horizontal additional steel bars inside the horizontal steel reinforcement cage to form a vertically through trapezoidal-section vertical steel bar groove. Embed the welded trapezoidal steel channels into the vertical steel bar groove, and weld and fix the welded trapezoidal steel channels to the horizontal steel bars and horizontal additional steel bars in the vertical steel bar groove respectively; anti-flow-around iron sheets are arranged at the end parts of the side walls of the welded trapezoidal steel channels and extend to both sides, and the anti-flow-around iron sheets are fixed to the inner surfaces of the end parts of the side plates of the welded trapezoidal steel channels by bolts.

[0013] Step 2: Implement a horizontal diaphragm wall trench in the underground excavation tunnel, and lower multiple horizontal steel reinforcement cages into the trench in sections. The section height is 3m to 5m. When the top of each section of the horizontal steel reinforcement cage is lowered to the trench opening position, the connection with the next section of the steel reinforcement cage is to connect and lengthen the vertical main steel bars through steel bar mechanical connection sleeves, and connect and lengthen the welded trapezoidal steel channels by welding or bolt connection with connecting steel plates on the inner side of the webs until it is flush with the horizontal diaphragm wall trench opening.

[0014] Step 3: Pour concrete into the horizontal diaphragm wall trench and the horizontal steel reinforcement cage to form a horizontal diaphragm wall with a vertically through groove.

[0015] Step 4: fabricate the longitudinal steel reinforcement cage; the transverse steel bars at the upper end of the longitudinal steel reinforcement cage gradually converge inward at the corresponding grooves to form the tenon joints corresponding to the grooves.

[0016] Step 5: Implement a longitudinal diaphragm wall groove in the tunnel of the undercut project with the same depth as the transverse diaphragm wall. Lower the longitudinal steel reinforcement cage into the groove in sections until it is flush with the opening of the longitudinal undercut deep groove; the section height is 3m - 5m. After the top of each section of the longitudinal steel reinforcement cage is lowered to the groove opening position, the connection with the next section of the steel reinforcement cage is to connect and extend the vertical main steel bars through a steel bar mechanical connection sleeve; the tenon joints are embedded into the grooves.

[0017] Step 6: Pour concrete into the longitudinal diaphragm wall groove and the longitudinal steel reinforcement cage to form the longitudinal diaphragm wall, so that the transverse diaphragm wall and the longitudinal diaphragm wall are connected to form the diaphragm wall at the inner corner of the undercut project.

[0018] In Step 5, when lowering the longitudinal steel reinforcement cage, a grouting pipe is reserved along the inner side wall of the groove. Grouting holes are reserved on the side wall of the grouting pipe, and the grouting pipe is extended by a screw thread sleeve; in Step 6, after the longitudinal diaphragm wall is poured, the gaps after pouring are grouted and filled through the grouting pipe.

[0019] The advantages of the present invention are as follows:

[0020] In the present invention, after the deep groove of the diaphragm wall is excavated in sections, the diaphragm wall is constructed in time to fill the excavation area, which can avoid the phenomenon of concrete flowing around during pouring, and there will be no collapse caused by large-area excavation, with high safety. The corner joint structure of the present invention can realize the reliable connection of two diaphragm walls at the tunnel corner. An L-shaped steel reinforcement cage is formed by the transverse diaphragm wall steel reinforcement cage and the longitudinal diaphragm wall steel reinforcement cage and is connected by reserved welded trapezoidal steel channels. The joint connection form is simple, with high precision, convenient construction, effectively shortening the construction period. The use of welded trapezoidal steel channel joints and anti-flow-around iron sheets increases the water-stop path, with good water-stop effect, effectively preventing leakage and water flow erosion at the corner. Description of the Drawings

[0021] Figure 1 It is a schematic cross-sectional structure diagram of the diaphragm wall of the present invention.

[0022] Figure 2 It is a schematic diagram of the composition of the steel reinforcement cage of the present invention.

[0023] Figure 3 It is a schematic diagram of the welded trapezoidal steel channel structure of the present invention.

[0024] Figure 4 It is a schematic diagram of the first vertical extension of the steel channel of the present invention.

[0025] Figure 5 This is the second vertical lengthening schematic diagram of the channel steel of the present invention.

[0026] Reference numerals:

[0027] 1 - Transverse diaphragm wall, 2 - Longitudinal diaphragm wall, 3 - Groove, 4 - Mortise joint, 5 - Transverse steel cage, 5.1 - Horizontal steel bar, 5.2 - Horizontal additional steel bar, 5.3 - Vertical main steel bar, 6 - Longitudinal steel cage, 7 - Welded trapezoidal channel steel, 7.1 - Side plate, 7.2 - Web, 8 - Connecting steel plate, 9 - Anti - flow - around iron sheet, 10 - Grouting pipe Detailed implementation manners

[0028] The following further describes the detailed implementation manners of the present invention with reference to the accompanying drawings.

[0029] As shown in Figure 1 , 2 , 3, 4, and 5, a diaphragm wall structure at the inner corner of an underground excavation project includes a transverse diaphragm wall 1 implemented in the tunnel of the underground excavation project and a longitudinal diaphragm wall 2 with the same depth as it, and the two diaphragm walls are connected at the corner to form an L - shaped diaphragm wall structure at the corner; a vertical through - groove 3 is provided at the corresponding position of the end side of the transverse diaphragm wall 1 facing the longitudinal diaphragm wall 2, and a mortise joint 4 is provided at the end of the longitudinal diaphragm wall 2 and inserted into the notch of the groove 3. After pouring concrete, they are integrally connected. The mortise joint 4 is provided with shoulders extending to both sides and integrally connected to the side of the transverse diaphragm wall 1.

[0030] A transverse steel cage 5 is arranged in the transverse diaphragm wall 1, and a longitudinal steel cage 6 is arranged in the longitudinal diaphragm wall 2; a welded trapezoidal channel steel 7 is embedded on the transverse steel cage 5, and the welded trapezoidal channel steel 7 is composed of a side plate 7.1 and a web 7.2 welded together. After the transverse steel cage 5 is poured with concrete, the welded trapezoidal channel steel 7 forms the vertically through - groove 3, see attached Figure 2 .

[0031] The transverse steel cage 5 includes a horizontal steel bar 5.1, a horizontal additional steel bar 5.2, a vertical main steel bar 5.3, and the welded trapezoidal channel steel 7; the horizontal steel bar 5.1 is horizontally bent inward along both sides of the side plate 7.1 of the welded trapezoidal channel steel 7 and welded to the same number of horizontal additional steel bars 5.2 at the intersection points; the outer side of the side plate 7.1 of the welded trapezoidal channel steel 7 is welded to the horizontal steel bar 5.1, and the outer side of the web 7.2 of the welded trapezoidal channel steel 7 is welded to the horizontal additional steel bar 5.2, see attached Figure 2 .

[0032] The horizontal steel reinforcement cage 5 is assembled vertically in sections, with the section height being 3 m to 5 m. The vertical main reinforcement bars 5.3 are lengthened by connecting with steel bar mechanical connection sleeves. The welded trapezoidal steel channels 7 are lengthened by welding or bolt connection with connecting steel plates 8 on the inner side of the webs 7.2. See Attachments Figure 2 、 3 、4, and 5.

[0033] Anti-flow-around iron sheets 9 are arranged at the end parts of the side walls of the welded trapezoidal steel channels 7 and extend to both sides. The anti-flow-around iron sheets 9 are vertically equal in height to the welded trapezoidal steel channels 7 and are fixed to the inner surfaces of the end parts of the side plates 7.1 of the welded trapezoidal steel channels 7 by bolts. See Attachments Figure 2 。

[0034] At the upper end of the longitudinal steel reinforcement cage 6, the horizontal steel bars at the positions corresponding to the grooves 3 gradually converge inward to form the tenon joints 4 corresponding to the grooves 3, and after being embedded in the grooves 3, concrete is poured for integral connection. See Attachments Figure 2 。

[0035] As Figure 1 、 2 、3, 4, and 5 show, a construction method for a diaphragm wall structure at the inner corner of an underground excavation project includes the following construction steps

[0036] Step 1: Fabricate the horizontal steel reinforcement cage 5. At the corner connection, bend the horizontal steel bars 5.1 horizontally inward and weld and fix them at the intersection points with the same number of horizontal additional steel bars 5.2 inside the horizontal steel reinforcement cage 5 to form a vertically through trapezoidal-section vertical steel bar groove. Embed the welded trapezoidal steel channels 7 into the vertical steel bar groove, and weld and fix the welded trapezoidal steel channels 7 with the horizontal steel bars 5.1 and horizontal additional steel bars 5.2 in the vertical steel bar groove respectively; anti-flow-around iron sheets 9 are arranged at the end parts of the side walls of the welded trapezoidal steel channels 7 and extend to both sides. The anti-flow-around iron sheets 9 are fixed to the inner surfaces of the end parts of the side plates 7.1 of the welded trapezoidal steel channels 7 by bolts. See Attachments Figure 2 ;

[0037] Step 2: Implement a horizontal diaphragm wall trench in the underground excavation tunnel. Lower multiple sections of the horizontal steel reinforcement cages 5 into the trench in sections, with the section height being 3 m to 5 m. When the top of each section of the horizontal steel reinforcement cage 5 is lowered to the trench opening position, the connection with the next section of the steel reinforcement cage is to lengthen the vertical main reinforcement bars 5.3 by connecting with steel bar mechanical connection sleeves, and lengthen the welded trapezoidal steel channels 7 by welding or bolt connection with connecting steel plates 8 on the inner side of the webs 7.2 until it is flush with the opening of the horizontal diaphragm wall trench. See Attachments Figure 2 、 3 、4, and 5;

[0038] Step 3: Pour concrete into the transverse diaphragm wall trench and the transverse steel reinforcement cage 5 to form a transverse diaphragm wall 1 with a vertically through groove. See Appendix Figure 1 ;

[0039] Step 4: Fabricate a longitudinal steel reinforcement cage; the transverse steel bars at the upper end of the longitudinal steel reinforcement cage 6 gradually converge inward at the groove 3 corresponding thereto to form the tenon joint 4 corresponding to the groove 3. See Appendix Figure 2 ;

[0040] Step 5: Implement a longitudinal diaphragm wall trench with the same depth as the transverse diaphragm wall 1 in the tunnel of the underground excavation project. Lower the longitudinal steel reinforcement cage 6 into the trench in sections until it is flush with the longitudinal underground excavation deep trench opening; the section height is 3 m to 5 m. After the top of each section of the longitudinal steel reinforcement cage 6 is lowered to the trench opening position, the connection with the next section of the steel reinforcement cage is to extend the vertical main steel bars 5.3 through a steel bar mechanical connection sleeve; the tenon joint 4 is embedded into the groove 3. See Appendix Figure 2 ;

[0041] Step 6: Pour concrete into the longitudinal diaphragm wall trench and the longitudinal steel reinforcement cage 6 to form the longitudinal diaphragm wall 2, so that the transverse diaphragm wall 1 and the longitudinal diaphragm wall 2 are connected to form an underground diaphragm wall at the inner corner of the underground excavation project. See Appendix Figure 1 .

[0042] In Step 5, when lowering the longitudinal steel reinforcement cage 6, reserve a grouting pipe 10 along the inner side wall of the groove 3. The side wall of the grouting pipe 10 is reserved with grouting holes, and the grouting pipe 10 is extended by a screw sleeve; in Step 6, after the longitudinal diaphragm wall 2 is poured, grout is injected through the grouting pipe 10 to fill the gaps after pouring. See Appendix Figure 1 .

Claims

1. An underground diaphragm wall structure at the inner corner of an underground excavation project, characterized in that: It includes a horizontal diaphragm wall (1) implemented in the tunnel of the mined - out engineering and a longitudinal diaphragm wall (2) with the same depth as it, and the two diaphragm walls are connected at the corner to form an L - shaped underground continuous wall structure at the corner; a vertical through - groove (3) is arranged on the end side of the horizontal diaphragm wall (1) corresponding to the position of the longitudinal diaphragm wall (2), and a tenon joint (4) is provided at the end of the longitudinal diaphragm wall (2). After inserting it into the notch of the groove (3) and pouring concrete, they are integrally connected. The tenon joint (4) is provided with shoulders extending to both sides and is integrally connected with the side surface of the horizontal diaphragm wall (1). A horizontal steel reinforcement cage (5) is arranged in the horizontal diaphragm wall (1), and a longitudinal steel reinforcement cage (6) is arranged in the longitudinal diaphragm wall (2); a trapezoidal steel channel (7) is embedded and welded on the horizontal steel reinforcement cage (5). The welded trapezoidal steel channel (7) is composed of a side plate (7.1) and a web (7.2) welded together. After the horizontal steel reinforcement cage (5) is poured with concrete, the vertical through - groove (3) is formed by the welded trapezoidal steel channel (7). A flow - prevention iron sheet (9) is arranged at the end of the side wall of the welded trapezoidal steel channel (7) and extends to both sides. The flow - prevention iron sheet (9) is vertically equal in height to the welded trapezoidal steel channel (7) and is fixed to the inner surface of the end of the side plate (7.1) of the welded trapezoidal steel channel (7) by bolts. The horizontal steel reinforcement cage (5) includes horizontal steel bars (5.1), horizontal additional steel bars (5.2), vertical main steel bars (5.3) and the welded trapezoidal steel channel (7); the horizontal steel bars (5.1) are horizontally bent inward along both sides of the side plate (7.1) of the welded trapezoidal steel channel (7) and are welded to the same number of horizontal additional steel bars (5.2) at the intersection points; the outer side of the side plate (7.1) of the welded trapezoidal steel channel (7) is welded to the horizontal steel bars (5.1), and the outer side of the web (7.2) of the welded trapezoidal steel channel (7) is welded to the horizontal additional steel bars (5.2).

2. The diaphragm wall structure at the internal corner of an underground excavation project as described in claim 1, wherein: The horizontal steel reinforcement cage (5) is assembled in vertical sections, and the section height is 3m - 5m. The vertical main steel bars (5.3) are connected and lengthened through steel bar mechanical connection sleeves, and the welded trapezoidal steel channel (7) is connected and lengthened by welding or bolt connection with a connecting steel plate (8) on the inner side of the web (7.2).

3. The diaphragm wall structure at the inner corner of a mined - out engineering project according to claim 1, characterized in that: The horizontal steel bars at the upper end of the longitudinal steel reinforcement cage (6) gradually converge at the position corresponding to the groove (3) to form the tenon joint (4) corresponding to the groove (3), and after being embedded in the groove (3), they are integrally connected by pouring concrete.

4. The construction method of the underground continuous wall structure at the inner corner in the mined - out engineering according to any one of claims 1 to 3 Characterized in that, including the following construction steps Step 1: Fabricate the horizontal steel reinforcement cage (5). At the corner connection, bend the horizontal steel bars (5.1) horizontally inward, and weld and fix them at the intersection points with the same number of horizontal additional steel bars (5.2) inside the horizontal steel reinforcement cage (5) to form a vertically penetrating trapezoidal cross-section vertical steel bar groove. Embed the welded trapezoidal steel channel (7) into this vertical steel bar groove, and weld and fix the welded trapezoidal steel channel (7) to the horizontal steel bars (5.1) and horizontal additional steel bars (5.2) inside the vertical steel bar groove respectively. At the end of the side wall of the welded trapezoidal steel channel (7), set anti-flow-around iron sheets (9) that extend to both sides, and fix the anti-flow-around iron sheets (9) by bolts on the inner surface of the end of the side plate (7.1) of the welded trapezoidal steel channel (7). Step 2: Implement a horizontal diaphragm wall trench in the tunnel of the underground excavation project. Lower multiple horizontal steel reinforcement cages (5) into the trench in sections, with the section height being 3m - 5m. After the top of each section of the horizontal steel reinforcement cage (5) is lowered to the trench opening position, the connection with the next section of the steel reinforcement cage is to connect and extend the vertical main steel bars (5.3) through a steel bar mechanical connection sleeve, and connect and extend the welded trapezoidal steel channel (7) by welding or bolting with a connecting steel plate (8) inside the web (7.2) until it is flush with the opening of the horizontal diaphragm wall trench. Step 3: Pour concrete into the horizontal diaphragm wall trench and the horizontal steel reinforcement cage (5) to form a horizontal diaphragm wall (1) with a vertically penetrating groove (3). Step 4: Fabricate the longitudinal steel reinforcement cage. The horizontal steel bars at the upper end of the longitudinal steel reinforcement cage (6) gradually converge inward at the corresponding groove (3) to form the tenon joint (4) corresponding to the groove (3). Step 5: Implement a longitudinal diaphragm wall trench with the same depth as the horizontal diaphragm wall (1) in the tunnel of the underground excavation project. Lower the longitudinal steel reinforcement cage (6) into the trench in sections until it is flush with the opening of the longitudinal underground excavation deep trench. The section height is 3m - 5m. After the top of each section of the longitudinal steel reinforcement cage (6) is lowered to the trench opening position, the connection with the next section of the steel reinforcement cage is to connect and extend the vertical main steel bars (5.3) through a steel bar mechanical connection sleeve. Embed the tenon joint (4) into the groove (3). Step 6: Pour concrete into the longitudinal diaphragm wall trench and the longitudinal steel reinforcement cage (6) to form the longitudinal diaphragm wall (2), so that the horizontal diaphragm wall (1) is connected to the longitudinal diaphragm wall (2) to form a diaphragm wall at the inner corner of the underground excavation project.

5. The construction method of the diaphragm wall structure at the inner corner of the mined - out area as claimed in claim 4, characterized in that, In Step 5, when lowering the longitudinal steel reinforcement cage (6), reserve a grouting pipe (10) along the inner side wall of the groove (3). The side wall of the grouting pipe (10) is reserved with grouting holes, and the grouting pipe (10) is extended by a screw sleeve. In Step 6, after the longitudinal diaphragm wall (2) is poured, grout is injected through the grouting pipe (10) to fill the gaps after pouring.

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