One kind is provided with the underground structure side wall template single side stable reinforcing method of no fat groove

Abstract

The application discloses a kind of no fat tank underground structure side wall formwork single-side stabilizing reinforcement methods, belong to underground building formwork construction technical field.The reinforcement system mainly includes pre-buried anchoring base, adjustable combined inclined strut, vertical prestressed tensioning mechanism and vertical limiting anti-floating component;When construction, pre-buried anchoring base and pre-buried anchor point are pre-buried in foundation bottom plate, assemble inverted L-shaped combined formwork and main and secondary back lath, layering lays adjustable combined inclined strut, utilizes vertical prestressed tensioning mechanism to make discrete support unit to cooperate with stress, and the vertical limiting anti-floating component is used to constrain formwork displacement upward;When concrete pouring, real-time monitoring formwork displacement, dynamically adjusts its pre-tightening force to compensate deformation.The application cancels through-wall pull screw rod, eliminates screw rod water seepage channel, adapts no fat tank narrow working condition, solves the uneven stress of traditional single-side formwork, formwork expansion and floating problem, wall body shaping and construction safety are high, applicable to subway, underground garage close containment underground side wall construction.

Description

Technical Field

[0001] This invention relates to the field of underground building formwork construction technology, and in particular to a method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs. Background Technology

[0002] In the construction of urban underground parking garages and subway-attached underground structures, due to land use and foundation pit boundary restrictions, some underground sidewalls are arranged closely with the foundation pit retaining structure. The traditional wide trench is eliminated, and there is no working space on the outside. Only the inner single-sided formwork construction process can be adopted.

[0003] Currently, single-sided formwork in non-grooved concrete trench conditions mostly relies on pre-embedded anchors in the base plate combined with a diagonal bracing system to resist the lateral pressure of concrete. However, existing single-sided formwork technology still has many practical engineering defects: First, most existing reinforcement systems only consider resisting the horizontal lateral pressure of concrete, lacking a limiting structure specifically for the buoyancy force during pouring. During concrete pouring, the formwork is prone to upward movement, causing quality defects such as misalignment and gaps at the bottom of the wall. Second, the multiple sets of diagonal bracing arranged on site are mostly independent of each other, lacking an integral tie structure that can connect the various sets of supports and back braces into a whole. The cooperative force-bearing capacity between supports is poor, and there is a risk of overload and instability of a single set of supports when the local stress is too large. Third, most processes only conduct a static inspection after all the tooling is installed; there is a lack of real-time monitoring and dynamic force compensation and control methods during concrete pouring. After the formwork deforms, it can only be dealt with afterward, and it is impossible to actively control it during the process. Fourth, some construction schemes still rely on through-wall tie rods for formwork reinforcement. These tie rods penetrate the wall and waterproofing layer, and the locations where they are sealed can easily become seepage channels, posing a significant risk of waterproofing leakage, especially for underground structures with high water levels. Fifth, most conventional diagonal braces are rigid, with limited angle adjustment range, making them prone to stress concentration and lacking versatility for sidewalls of different heights.

[0004] Therefore, there is an urgent need to develop a construction method for unilateral stabilization and reinforcement of sidewall formwork that is suitable for non-grooving conditions, has the advantages of lateral pressure resistance, anti-floating, good overall integrity, dynamic process control, and avoids the hidden danger of water seepage from through-wall bolts. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for unilateral stabilization and reinforcement of sidewall formwork in underground structures without geotextile grooves. This method solves the technical problems of easy formwork expansion and floating under the condition of close-fitting enclosure structures without geotextile grooves, as well as the cumbersome nature of traditional tooling and the water seepage risks caused by through-wall bolts. It enables modular and rapid installation and dismantling, ensures the forming accuracy of concrete walls, and reduces the risk of leakage in underground structures.

[0006] This invention solves the above-mentioned technical problems by providing a method for unilateral stabilization and reinforcement of sidewall formwork in underground structures without troughs, comprising the following construction steps: S1. Foundation Slab Embedded Anchor Bases: Before pouring the foundation slab of the underground structure, multiple sets of anchor bases are pre-embedded according to the calculated spacing. The anchor base includes an embedded anchor plate and a connecting lug. The anchor plate is embedded inside the concrete of the foundation slab, and the connecting lug protrudes upwards from the upper surface of the foundation slab, serving as the bottom force support point of the diagonal bracing assembly. The horizontal and vertical spacing of the anchor bases is determined based on the side wall height and the lateral pressure of the concrete.

[0007] S2. Side wall reinforcement and base surface pretreatment: Complete the binding of underground side wall reinforcement; the foundation pit retaining structure serves as the outer support interface of the side wall. The inner base surface of the retaining structure is leveled, and a waterproof layer is laid between the inner side of the retaining structure and the side wall. There is no trench operation working surface on the outer side of the side wall.

[0008] S3. Assembly and positioning of formwork and back ribs: Hoist and assemble the inverted L-shaped combined formwork, which consists of vertically arranged formwork panels and horizontally arranged top sealing formwork; the formwork panels and vertical secondary back ribs are fixed to each other with conventional fasteners in the field to achieve load transfer; the vertical secondary back ribs and the horizontal main back ribs are arranged perpendicularly to each other and fixed to each other with conventional fasteners in the field to achieve load transfer; the bottom of the formwork abuts against the positioning stop of the foundation plate to complete the initial positioning of the formwork.

[0009] S4. Assembly of single-sided reinforced tooling: 1) Hinge the lower end of the adjustable combined diagonal brace (hereinafter referred to as diagonal brace) to the connecting lug of the pre-embedded anchor base on the base plate; the diagonal brace includes a full-length hollow sleeve, two reverse threaded adjusting screws, and a locking buckle, which can freely adjust the support length and tilt angle; 2) The upper end of the diagonal brace is hinged and pressed against the transverse main back rib. The diagonal brace group is arranged in layers along the height of the side wall, and the lower diagonal brace bears the main concrete lateral pressure. 3) Install a vertical prestressing tensioning mechanism. This mechanism is arranged vertically along the entire length, with tensioning bolts running through the height of the wall. Only the top and bottom two horizontal main back ribs are locked and tensioned, and vertical prestress is applied to connect the discrete single-span support system along the wall length into a whole. The horizontal main back ribs in the middle position are left open, retaining a small amount of adaptive deformation allowance to avoid rigid stress concentration. 4) Install a vertical limiting anti-floating component at the top of the template. One end of the vertical limiting anti-floating component is pressed against the upper edge of the template, and the other end is pulled down to the pre-embedded anchor point of the foundation slab of the underground structure to restrain the template from moving upward during the concrete pouring process.

[0010] S5. Template Deformation Pre-detection: After all tooling is assembled, apply pre-jacking force uniformly by adjusting the lead screw; collect initial verticality data of the template using tilt and displacement detection accessories, verify the pre-tightening force of the diagonal brace, and eliminate tooling gaps.

[0011] S6. Sidewall Concrete Pouring and Dynamic Control: Layered pouring and vibration of underground sidewall impermeable concrete through grouting holes in the top sealing formwork; real-time monitoring data of lateral displacement and upward floating of the formwork during the pouring process; when the displacement exceeds the warning threshold, the extension of the diagonal bracing rod is finely adjusted on site to dynamically compensate for the lateral pressure of the concrete and control the deformation of the formwork.

[0012] S7. Concrete curing and tooling removal: After the concrete reaches the specified demolding strength, remove the vertical limiting anti-floating components, vertical prestressing tensioning mechanism, and adjustable combined diagonal bracing in sequence, and then remove the main and secondary back ribs and formwork; after cleaning, derusting and oiling, all kinds of reinforcement tooling components can be reused.

[0013] Furthermore, the adjustable combined diagonal brace adopts a full-length hollow sleeve and an upper and lower double reverse-threaded adjusting screw structure, with synchronous extension and retraction at both ends, resulting in high adjustment accuracy and a wide range. Both the upper and lower ends are equipped with hinged ear plates, which can freely adjust the support tilt angle, eliminate hard contact stress concentration, and have strong overall bending rigidity, making it less prone to deformation under pressure.

[0014] Furthermore, the vertical prestressing tensioning mechanism includes a tensioning screw, a locking nut, and a pressure sensing pad. The tensioning screw is arranged vertically, locking only the uppermost and lowermost two transverse main back ribs, while the middle transverse main back rib is left unattended. The pressure sensing pad is fitted onto the tensioning screw and clamped between the locking nut and the main back ribs, converting the axial prestress of the screw into a readable signal. This allows construction personnel to obtain real-time prestress values, accurately control the tensioning prestress, and achieve uniform stress distribution across multiple supports.

[0015] Furthermore, the vertical limiting anti-floating component adopts a combination structure of flexible tie rod and rigid pressure head. The rigid pressure head is locked and fixed to the top surface of the top sealing template, which can simultaneously constrain the overall floating of the top sealing template and the side template. The flexible tie rod is connected downward to the pre-embedded anchor point of the foundation plate to offset the floating load superimposed by the buoyancy of concrete pouring and the lifting component of the inclined brace.

[0016] Furthermore, in step S6, the thickness of the layered pouring is controlled to be no more than 500mm to reduce instantaneous lateral pressure, and the warning threshold for monitoring lateral displacement is set to 3mm.

[0017] Furthermore, in S1, the anchor bases and pre-embedded anchor points are arranged according to the calculation results of the side wall concrete lateral pressure. The anchor bases are arranged with a horizontal spacing of 1.2 to 1.8 m and a longitudinal spacing of 1.5 to 2.0 m. The pre-embedded anchor points correspond to the installation positions of the vertical limiting components at the top of the template and are simultaneously pre-embedded and fixed inside the foundation slab.

[0018] Furthermore, the tilt and displacement detection accessories used in step S5 are tilt sensors and displacement sensors, which are arranged at different heights of the transverse main back rib to collect data on template verticality and initial gap; and the pre-jacking force of each diagonal brace is adjusted evenly based on the pressure sensor pad readings.

[0019] Furthermore, in step S4, the adjustable combined diagonal bracing is arranged in at least three layers along the height of the side wall: upper, middle, and lower. The lower layer of diagonal bracing bears most of the lateral pressure of the concrete, while the upper layer of diagonal bracing assists in restraining the deformation of the top of the formwork.

[0020] Furthermore, in S7, the concrete demolding strength must meet the design requirements, and the concrete strength of the side wall must be no less than 75% of the design strength before tooling and formwork removal operations can be carried out; after removal, the adjustable combined diagonal braces, tension bolts, rigid pressure heads and other metal components shall be derusted and oiled for maintenance, and used for reuse in subsequent construction sections. Beneficial effects

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. This method is fully compatible with the construction of underground sidewalls without drainage channels. The outer side relies on the retaining structure, eliminating the need for personnel to work on the outside. It does not require through-wall tie rods, thus eliminating weak points for underground water seepage caused by tie rod holes. At the same time, it avoids the tie rods puncturing and damaging the waterproof layer between the retaining structure and the wall, thereby improving the reliability of waterproofing of underground sidewalls.

[0022] 2. This invention employs a combination of pre-embedded anchor bases in the base plate, layered adjustable diagonal braces, vertical prestressing tension, and vertical anti-floating limiters. This not only reliably resists the lateral expansion force of the concrete formwork but also specifically suppresses the formwork floating problem during the pouring stage, solving the two major common problems of uneven stress and formwork floating in traditional single-sided formwork in one go. The hinged adjustable diagonal braces can adapt to different wall heights and support angles, making the structure more versatile and adaptable. Combined with the split inverted L-shaped top sealing formwork, it completely eliminates the problem of grout leakage at the top, significantly improving the quality of wall forming.

[0023] 3. The diagonal brace of this invention adopts a continuous hollow sleeve and a bidirectional adjustable structure with upper and lower double reverse thread adjusting screws. Unlike the existing single-end adjustable and rigid clamping diagonal braces, it has higher adjustment accuracy, stronger rigidity, and wider adaptability. The fully hinged structure at both ends can adapt to different wall heights and inclination angles, and the force is uniform without stress concentration.

[0024] 4. The top sealing template has reserved grouting holes to enable concrete pouring and vibration in a sealed state, which not only ensures the top is sealed to prevent grout leakage, but also ensures the compactness of the pouring; the whole set of tools is modular and easy to assemble and disassemble, can be reused multiple times, and has high construction efficiency and good economy.

[0025] 5. The pouring process is equipped with real-time deformation monitoring and dynamic pre-tightening force compensation, making the entire process controllable and adjustable. The verticality and flatness of the wall are significantly improved, making it suitable for high-standard underground engineering construction such as subways and underground parking garages. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the overall structure of the single-sided stabilization and reinforcement system for the sidewall formwork of the underground structure without a fertilizer trench, as shown in the embodiment. Figure 2 This is a vertical cross-sectional schematic diagram of the single-sided stabilization and reinforcement system for the sidewall formwork of the underground structure without a fertilizer tank, as illustrated in this embodiment. Figure 3 for Figure 2 Enlarged view at point A in the middle; Figure 4 This is a schematic diagram of the anchoring base component in an embodiment; Figure 5 This is a schematic diagram of an adjustable combined diagonal brace component as shown in the embodiment. Figure 6 This is a schematic diagram of the vertical prestressing tensioning mechanism in an embodiment; Figure 7 This is a schematic diagram illustrating the connection status between the vertical limiting and anti-floating component and the template in an embodiment. In the diagram: 1. Foundation pit retaining structure; 2. Waterproof layer; 3. Underground sidewall to be poured; 4. Formwork panel; 5. Vertical secondary back rib; 6. Horizontal main back rib; 7. Foundation base plate; 8. Anchor base; 81. Embedded anchor plate; 82. Connecting lug; 9. Adjustable combined diagonal brace; 91. Continuous hollow sleeve; 92. Reverse thread adjusting screw; 93. Locking buckle; 10. Vertical prestressing tensioning mechanism; 101. Tensioning screw; 102. Locking nut; 103. Pressure sensing gasket; 11. Vertical limiting anti-floating component; 111. Rigid pressure head; 112. Flexible tie rod; 113. Fixing bolt; 12. Embedded anchor point; 13. Top sealing formwork; 14. Grouting hole; 15. Countersunk bolt. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0028] Example 1, please refer to Figures 1 to 7 This embodiment is applied to an underground side wall project attached to a subway. The foundation slab is 1200mm thick and the side wall is 5.4m high. It adopts a continuous underground wall without trenching and there is no working surface on the outside. The reinforcement method of this invention is used for construction.

[0029] S1. Foundation Slab Embedded Anchor Bases: Before pouring the foundation slab 7, based on the calculation results of the concrete lateral pressure at a wall height of 5.4m, anchor bases 8 are pre-embedded at a horizontal spacing of 1.5m and a longitudinal spacing of 1.8m; at the same time, special pre-embedded anchor points 12 are pre-embedded at the top limit position of the corresponding template of the foundation slab 7; the pre-embedded anchor plates 81 of the anchor bases 8 are embedded in the concrete of the foundation slab, and the connecting lugs 82 are exposed on the upper surface of the foundation slab, serving as dedicated force support points for the diagonal bracing.

[0030] S2. Side wall reinforcement and base surface pretreatment: Complete the binding of side wall reinforcement; grind and level the base surface inside the underground continuous wall, i.e. the foundation pit retaining structure 1; lay the waterproof membrane layer 2 between the inside of the foundation pit retaining structure 1 and the underground side wall 3 to be poured; there is no trench operation surface on the outside of the side wall.

[0031] S3. Assembly and Positioning of Template and Back Ribs: The inverted L-shaped combined template is hoisted and assembled. The template consists of a vertical template panel 4 and a horizontal top sealing template 13. The template panel 4 and the top sealing template 13 are fastened together as an integral rigid structure by multiple sets of countersunk bolts 15, which are subjected to force synchronously and without relative displacement. Multiple grouting holes 14 are evenly opened on the surface of the top sealing template 13 for concrete pouring and vibration operations, and can also expel air from the pouring cavity to reduce honeycomb and pitting defects in the wall. Vertical secondary back ribs 5 and horizontal main back ribs 6 are arranged on the back of the template panel 4. The template panel 4 and the vertical secondary back ribs 5, and the vertical secondary back ribs 5 and the horizontal main back ribs 6 are all fixed with conventional fasteners in this field to achieve complete force transmission. The bottom of the template as a whole is positioned against the foundation plate 7 to complete the precise initial positioning.

[0032] S4. Single-sided reinforcement fixture assembly: The adjustable combined diagonal brace 9 is arranged diagonally, with its lower end hinged to the connecting lug 82 of the anchor base 8, and its upper end hinged to the support to tighten against the transverse main back rib 6; the adjustable combined diagonal brace 9 consists of a full-length hollow sleeve 91, two reverse-thread adjusting screws 92, and two sets of locking buckles 93; during assembly, the two sets of locking buckles 93 are first pre-fitted onto the upper and lower reverse-thread adjusting screws 92, and the two screws are respectively reverse-threaded from the upper and lower ends of the full-length hollow sleeve 91. Screw it into the thread; rotating the central hollow sleeve 91 drives the upper and lower screw rods to extend outward or retract inward simultaneously, achieving precise bidirectional adjustment of the total length of the diagonal brace; after adjusting to the target length and angle, tighten the upper and lower sets of locking buckles 93 respectively. The buckles are tightly attached to the end faces of both ends of the sleeve to lock the extension of the screw rod, preventing the screw rod from retracting, slipping, or loosening under the vibration of the pouring process; both ends of the diagonal brace adopt a hinged ear plate structure, which can freely adapt to the angle and disperse stress, avoiding stress concentration from rigid contact. The axial thrust of the adjustable combined diagonal brace 9 is decomposed into a horizontal component perpendicular to the wall and a vertical component pointing upward. The horizontal component offsets the lateral expansion force of the concrete, while the vertical component will be superimposed on the buoyancy of the concrete, causing the formwork to float. Multiple sets of adjustable combined diagonal braces 9 are discretely arranged along the length of the wall to form independent support points.

[0033] The vertical prestressing tensioning mechanism 10 is assembled, with tensioning screws arranged vertically along the entire length of the wall. Only the top and bottom two horizontal main back braces 6 are locked, tensioned, and subjected to vertical prestressing force, connecting multiple sets of diagonal bracing units dispersed along the wall length to achieve overall coordinated force distribution. The middle horizontal main back brace is left unsecured and unrestrained, retaining a small amount of adaptive deformation allowance to accommodate dynamic deformation during casting and avoid stress concentration. Pressure sensing pads 103 are clamped between the locking nut 102 and the upper and lower main back braces to monitor the prestressing force value in real time, ensuring balanced and uniform prestressing force across all supports. The forces of the adjustable combined diagonal brace 9 and the vertical prestressing tensioning mechanism 10 are transmitted through the horizontal main back braces, with no direct contact between them.

[0034] A vertical limiting anti-floating component 11 is installed, comprising a rigid pressure head 111 and a flexible tie rod 112. The rigid pressure head 111 presses against the upper surface of the top sealing template 13 and is locked to the top sealing template 13 by two fixing bolts 113. While the rigid pressure head 111 presses against the top sealing template 13, it simultaneously constrains the template panel 4 below, which is fixed together by countersunk bolts 15, thus achieving overall limiting of the entire inverted L-shaped template system. The upper end of the flexible tie rod 112 is connected to the rigid pressure head 111, passes through the gap between two adjacent vertical secondary back ribs, passes through the gap between the horizontal main back rib and the template panel, and the lower end is vertically pulled downward to the pre-embedded anchor point 12 of the foundation slab 7, forming a stable downward restraint force to offset the superimposed floating load of the concrete pouring buoyancy and the upward lifting force of the inclined brace. The vertical limiting anti-floating component 11 is arranged discretely along the length of the wall and can be staggered with the vertical secondary back ribs 5, resulting in uniform force distribution and stable limiting effect.

[0035] S5. Template Deformation Pre-detection: After all tooling is assembled, rotate the adjustable combined diagonal brace 9 and apply a pre-jacking force uniformly using the reverse thread adjustment screw 92; place the tilt sensor and displacement sensor on the transverse main back rib 6 at different heights to collect the initial verticality and flatness data of the template, and combine the pre-tightening force value fed back by the pressure sensing pad 103 to adjust the pre-jacking force of each group of adjustable combined diagonal braces 9 evenly, so as to completely eliminate the tooling assembly gap.

[0036] S6. Side wall concrete pouring and dynamic control: Impermeable concrete is poured in layers through the grouting holes 14 of the top sealing formwork 13, with the thickness of each layer controlled at 450mm, and each layer is vibrated and compacted. The lateral displacement and floating amount of the formwork are monitored in real time throughout the pouring process. The lateral displacement warning threshold is set at 3mm. Once the monitoring data exceeds the threshold, the extension of the screw of the adjustable combined diagonal brace 9 is adjusted immediately to dynamically compensate for the lateral pressure and control the deformation of the formwork in real time.

[0037] S7. Concrete curing and tooling removal: After the concrete strength of the side wall reaches 75% of the design strength, remove the vertical limiting anti-floating component 11, the vertical prestressing tensioning mechanism 10, and the adjustable combined diagonal brace 9 in sequence. Then remove the horizontal main back rib 6, the vertical secondary back rib 5, and the formwork panel 4. Remove rust and apply oil to the removed metal components such as the adjustable combined diagonal brace 9, tensioning screw 101, and rigid pressure head 111, and reuse them in the next construction section.

[0038] After the construction of this embodiment is completed, the underground side wall 3 to be poured has no obvious misalignment, and the verticality and flatness meet the acceptance requirements of the underground side wall. There are no defects such as bulging or floating, and the waterproof layer 2 is not punctured.

[0039] The above embodiments and accompanying drawings are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. The present invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the present invention do not depart from the spirit of the present invention and should also fall within the protection scope of the claims of the present invention. Other related technical structures not disclosed in detail in the present invention are existing technologies in the art.

Claims

1. A method for unilateral stabilization and reinforcement of sidewall formwork in a trenchless underground structure, characterized in that, Includes the following steps: S1. Foundation slab pre-embedded anchor base: Before pouring the foundation slab of the underground structure, multiple sets of anchor bases are pre-embedded according to the calculated spacing. The pre-embedded anchor plate of the anchor base is embedded in the concrete of the foundation slab, and the connecting ear seat is exposed on the surface of the foundation slab, serving as the bottom force support point of the adjustable combined diagonal brace. S2. Side wall reinforcement and base surface pretreatment: Complete the binding of side wall reinforcement, use the foundation pit retaining structure as the outer support interface of the side wall, level the base surface inside the retaining structure, lay a waterproof layer between the inner side of the retaining structure and the side wall, and there is no trench operation working surface outside the side wall. S3. Assemble and position the template and back ribs: Assemble the inner template panel, arrange the vertical secondary back ribs and the horizontal main back ribs on the back of the template, and complete the initial positioning by abutting the bottom of the template against the positioning stop of the foundation plate. S4. Single-sided reinforcement fixture assembly: The lower end of the adjustable combined diagonal brace is hinged to the connecting lug of the anchor base, and the upper end of the adjustable combined diagonal brace is hinged to the support to tighten the transverse main back rib. The adjustable combined diagonal brace group is arranged in layers along the height of the side wall; the vertical prestressing tensioning mechanism is assembled to tie the main back rib and apply prestressing force; the vertical limiting anti-floating component is installed, one end of which is pressed against the upper edge of the template, and the other end is pulled downward to the pre-embedded anchor point of the foundation plate of the underground structure to constrain the upward displacement of the template; S5. Template Deformation Pre-detection: Adjust the adjustable combined diagonal bracing screw to apply pre-jacking force, collect the initial verticality data of the template, and verify the pre-tightening force of the tooling. S6. Side wall concrete pouring and dynamic control: pour side wall concrete in layers, monitor the lateral displacement and upward floating of the formwork in real time, and fine-tune the extension of the adjustable combined diagonal bracing when the displacement exceeds the threshold. S7. Concrete curing and tooling removal: After the concrete reaches the demolding strength, remove the vertical limiting anti-floating components, vertical prestressing tensioning mechanism, and adjustable combined diagonal bracing in sequence, and then remove the back ribs and formwork. The tooling components are cleaned and reused.

2. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: The adjustable combined diagonal brace includes a full-length hollow sleeve, two reverse-threaded adjusting screws, and two sets of locking buckles. The two reverse-threaded adjusting screws are threaded onto the upper and lower ends of the full-length hollow sleeve, allowing for simultaneous bidirectional adjustment of the total length. The locking buckles are fitted onto the connection between the screws and the sleeve. The adjustable combined diagonal brace has hinged lugs at both the upper and lower ends. The lower end is hinged to a special anchor base for the base plate, and the upper end is hinged to a transverse main back brace, allowing for free adjustment of the support tilt angle to adapt to construction at different side wall heights.

3. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: The vertical prestressing tensioning mechanism includes a tensioning screw, a locking nut, and a pressure sensing pad. The tensioning screw is arranged vertically, locking only the top and bottom two horizontal main back ribs, while the middle horizontal main back rib is left unattended. The pressure sensing pad is fitted onto the tensioning screw and clamped between the locking nut and the main back ribs, and can output a readable prestressing force signal, making it convenient for construction personnel to obtain real-time prestressing force values.

4. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: The vertical limiting anti-buoyancy component includes a rigid pressure head and a flexible tie rod. The rigid pressure head presses against the upper edge of the template, and the flexible tie rod connects downward to the pre-embedded anchor point of the foundation plate of the underground structure to counteract the buoyancy force of the template generated by concrete pouring.

5. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: In step S6, the thickness of each concrete layer should not exceed 500mm, and the lateral displacement warning threshold for the formwork panel should be set to 3mm.

6. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without fertilizer trenches according to claim 1, characterized in that: In S1, the anchor base and the pre-embedded anchor points are arranged according to the calculation results of the side wall concrete lateral pressure. The anchor base is arranged horizontally at a spacing of 1.2 to 1.8 m and longitudinally at a spacing of 1.5 to 2.0 m. The pre-embedded anchor points correspond to the installation positions of the vertical limiting components at the top of the formwork and are simultaneously pre-embedded and fixed inside the foundation slab.

7. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: The tilt and displacement detection accessories used in step S5 are tilt sensors and displacement sensors, which are placed at different heights of the transverse main back rib to collect template verticality and initial gap data; based on the pre-tightening force value read by the pressure sensor pad, the pre-jacking force of each adjustable combined diagonal brace is balanced.

8. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without fertilizer trenches according to claim 1, characterized in that: In step S4, the adjustable combined diagonal bracing is arranged in at least three layers along the height of the side wall: upper, middle, and lower. The lower layer of adjustable combined diagonal bracing bears most of the lateral pressure of the concrete, while the upper layer of adjustable combined diagonal bracing assists in restraining the deformation of the top of the formwork.

9. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: In S7, the concrete demolding strength must meet the design requirements, and the concrete strength of the side wall must not be less than 75% of the design strength before tooling and formwork removal can be carried out. Adjustable combined diagonal braces, tension bolts, rigid pressure heads and other metal components after removal should be derusted and oiled for maintenance, and used for reuse in subsequent construction sections.

10. The method for unilateral stabilization and reinforcement of sidewall formwork for underground structures without troughs according to claim 1, characterized in that: The template adopts a split inverted L-shaped combination structure, including a vertically set template panel and a horizontally set top sealing template. The template panel and the top sealing template are fastened together by multiple sets of countersunk bolts. The top sealing template has several grouting holes for concrete pouring and vibration venting. The rigid pressure head of the vertical limiting anti-floating component is locked and fixed to the upper surface of the top sealing template by fixing bolts, which simultaneously restrains the overall upward displacement of the top sealing template and the template panel.

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