Long and short combined steel sheet pile foundation pit supporting structure

Abstract

The application relates to a long-short combined steel sheet pile foundation pit supporting structure and relates to the technical field of foundation pit supporting in civil engineering, which comprises a combined steel sheet assembly, a surrounding purlin assembly and an inner support assembly. The application adopts 2-long-2-short alternate arrangement of a first long steel sheet pile, a second long steel sheet pile, a first short steel sheet pile and a second short steel sheet pile, reduces the rock depth and quantity of the steel sheet pile body, reduces the difficulty and material cost of driving, ensures the overall tightness of the combined steel sheet assembly through the design of the first long slot and the first short slot, avoids water and soil loss caused by the connection gap of the traditional pile body, improves the overall support, the surrounding purlin assembly connects the steel surrounding purlin and the combined steel sheet assembly through short positioning bolts and long positioning bolts, cooperates with gaskets to enhance the connection stability, avoids vibration loosening, the inner support assembly realizes detachable layered installation through steel pipe inner support columns, connecting plates and connecting bolts, conforms to the principle of supporting first and digging later, and is more easily operated than the traditional inner support.

Description

Technical Field

[0001] This application relates to the field of foundation pit support technology in civil engineering, and in particular to a long and short combined steel sheet pile foundation pit support structure. Background Technology

[0002] In pipeline construction in urban areas, the excavation depth of trenches and foundation pits is usually shallow, but due to factors such as dense underground pipelines and restrictions imposed by surrounding buildings, the working area is often quite narrow.

[0003] Traditional support methods mainly involve vertical excavation combined with steel pipe pile support. However, when encountering hard rock formations, it is difficult to directly drive steel sheet piles. Currently, the industry generally adopts a process of drilling holes with rotary drilling rigs, backfilling with miscellaneous fill, and then driving steel sheet piles with vibratory hammers. However, this process has problems such as complex procedures, extended construction period, and high cost.

[0004] Existing technologies suffer from low construction efficiency due to difficulties in driving sheet piles into hard rock formations, and the traditional pre-hole backfilling process is complex and time-consuming. With the acceleration of urbanization, the demand for pipeline construction under such geological conditions is increasing, and there is an urgent need for an efficient and economical support technology to solve the above problems. Utility Model Content

[0005] The purpose of this application is to provide a long and short combined steel sheet pile foundation pit support structure that can significantly improve construction efficiency while reducing construction costs, thus solving the problems mentioned in the background art.

[0006] This application provides a long and short combined steel sheet pile foundation pit support structure with the following technical solution: A long and short combined steel sheet pile foundation pit support structure includes a combined steel sheet assembly, a waler assembly, and an internal bracing assembly. The combined steel sheet assembly includes a first long steel sheet pile, a second long steel sheet pile, a first short steel sheet pile, and a second short steel sheet pile arranged alternately in sequence. A first long slot is provided between the first long steel sheet pile and the second long steel sheet pile, and a first short slot is provided between the first short steel sheet pile and the second short steel sheet pile. The waler assembly includes four steel walers. The first long steel sheet pile and the first short steel sheet pile are both internally threaded with short positioning bolts. The second long steel sheet pile and the second short steel sheet pile are both internally threaded with long positioning bolts. The steel walers are connected to the first long steel sheet pile and the first short steel sheet pile through the short positioning bolts. The steel walers are also connected to the second long steel sheet pile and the second short steel sheet pile through the long positioning bolts. The internal support assembly includes multiple steel pipe internal support columns, which are respectively installed between the four steel walers.

[0007] By adopting the above technical solution, the combined steel sheet assembly uses a 2-long-2-short arrangement of first long steel sheet piles, second long steel sheet piles, first short steel sheet piles, and second short steel sheet piles, which fits the support design for hard rock strata. The long steel sheet piles can be inserted into the hard rock strata to a sufficient depth to ensure bearing capacity, while the short steel sheet piles reduce the depth and number of penetrations to reduce construction difficulty. The waler assembly connects the steel waler to the combined steel sheet assembly through short and long positioning bolts. Together with the steel pipe internal support columns of the internal support assembly, a dual collaborative support system is formed. It follows the principle of supporting before excavation and layered excavation, which effectively improves the overall stability of the foundation pit. At the same time, it eliminates the backfilling process after traditional pre-drilling, simplifies the construction process, and improves construction efficiency.

[0008] Preferably, the first long slot is formed on both sides of the first long sheet pile, and the first short slot is formed on both sides of the first short sheet pile. The first long sheet pile, the second long sheet pile, the first short sheet pile, and the second short sheet pile are interlocked with each other through the first long slot and the first short slot, and the opening directions of the first long slot and the first short slot are consistent.

[0009] By adopting the above technical solution, the first long slot and the first short slot enable the first long steel sheet pile, the second long steel sheet pile, the first short steel sheet pile, and the second short steel sheet pile to interlock with each other, and the opening direction is consistent, which meets the requirements for tight installation of the combined steel sheet assembly, can effectively transmit lateral force, avoid water and soil loss or displacement caused by gaps between the piles, and at the same time ensure the integrity of the alternating arrangement of 2 long and 2 short, which facilitates the control of the verticality of the combined steel sheet assembly during construction and meets the requirement of tight interlocking of the slots.

[0010] Preferably, each of the short and long positioning bolts is fitted with a gasket at its end, and the gaskets are located between the steel waler and the combined steel plate assembly.

[0011] By adopting the above technical solution, the gasket is placed between the steel waler and the combined steel plate assembly, which can buffer the tightening force of the short and long positioning bolts, enhance the sealing and stability of the connection, prevent the positioning bolts from loosening due to vibration during construction, ensure the continuous and reliable restraint effect of the steel waler on the combined steel plate assembly, and realize the reinforcement installation of the steel waler.

[0012] Preferably, each of the steel pipe internal support columns has two connecting pieces fixedly connected to both ends, and each connecting piece has a connecting bolt installed inside.

[0013] By adopting the above technical solution, the connecting plates and connecting bolts at both ends of the steel pipe internal support column provide a detachable connection structure for the internal support. This facilitates the layered installation and removal of the steel waler and steel pipe internal support column, which are required to be installed every 2m of excavation. The operation is flexible and the connection is firm, which can effectively transmit the lateral pressure of the foundation pit and avoid support deformation caused by the failure of the connection between the internal support component and the waler component, thus ensuring construction safety.

[0014] Preferably, the two ends of the steel pipe inner support column are respectively installed on the inner wall of the corresponding steel waler through connecting plates and connecting bolts.

[0015] By adopting the above technical solution, the steel pipe inner support column is connected to the inner wall of the steel waler through connecting plates and connecting bolts, so that the internal support force can be evenly transmitted to the steel waler and the combined steel plate assembly. This can effectively resist the lateral thrust of the soil during trench excavation, prevent the combined steel plate assembly from tilting due to uneven force, and ensure the stability of the foundation pit excavation process.

[0016] Preferably, the lengths of the first long sheet pile and the second long sheet pile are the same, the lengths of the first short sheet pile and the second short sheet pile are the same, and the lengths of the first long sheet pile and the second long sheet pile are greater than the lengths of the first short sheet pile and the second short sheet pile.

[0017] By adopting the above technical solution, the lengths of the first and second longest sheet piles are greater than the lengths of the first and second shortest sheet piles, thus achieving a combination design of sheet piles of two lengths. The longer sheet piles meet the depth requirements for insertion into hard rock layers to ensure support strength, while the shorter sheet piles reduce material usage and rock penetration work, lower rental costs and construction difficulty, and at the same time facilitate flexible adjustment according to geological conditions, adapting to trench construction scenarios containing hard rock layers.

[0018] Preferably, the short positioning bolts and long positioning bolts are distributed at intervals along the length direction of the steel waler, and the spacing between the short positioning bolts and long positioning bolts is adapted to the arrangement spacing of the first long steel sheet pile, the second long steel sheet pile, the first short steel sheet pile, and the second short steel sheet pile.

[0019] By adopting the above technical solution, the spacing of the short and long positioning bolts is matched with the spacing of the sheet piles inside the combined steel plate assembly, ensuring that the steel waler can evenly distribute the lateral force transmitted by the sheet piles, avoiding local stress concentration caused by misalignment of connection points, and facilitating rapid positioning and installation during construction, reducing measurement and adjustment time, and improving the accuracy of the connection between the waler assembly and the combined steel plate assembly.

[0020] Preferably, the combined steel sheet assembly uses a first long steel sheet pile, a second long steel sheet pile, a first short steel sheet pile, and a second short steel sheet pile as basic units, arranged cyclically along the length of the foundation pit.

[0021] By adopting the above technical solution, the combined steel plate components are arranged in a cyclical manner along the length of the foundation pit, with 2 long and 2 short units as the basic units. This is suitable for pipeline trenches with a length of more than 50m, which can ensure the continuity and consistency of long-distance trench support, facilitate construction organization and quality control, and the unitized arrangement can be flexibly adjusted according to the trench length to avoid material waste. Combined with the pre-hole technology in the construction method, it can realize efficient support construction of long-distance hard rock strata.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] This novel long and short combined sheet pile foundation pit support structure employs an alternating arrangement of two long and two short sheet piles (first long, second long, first short, and second short) compared to traditional support methods. This reduces the depth and number of sheet piles driven into the rock, lowering the difficulty of installation and material costs. The design of the first long slot and the first short slot ensures the overall tightness of the combined sheet pile components, preventing soil erosion caused by gaps in traditional pile connections and improving the overall support integrity. The waler components are connected to the combined sheet pile components via short and long positioning bolts, with gaskets enhancing connection stability and preventing vibration-induced loosening. The internal support components utilize steel pipe internal support columns, connecting plates, and connecting bolts for detachable, layered installation, adhering to the principle of supporting before excavation. This is easier to operate than traditional internal supports, and the overall structure eliminates the backfilling process after traditional pre-drilling. Combined with the unitized cyclic arrangement of the combined sheet pile components, it is suitable for long-distance trenches, significantly improving construction efficiency, reducing costs, and ensuring foundation pit stability. This solves the problems of complex procedures, low efficiency, and high costs associated with existing technologies. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall front view structure of this application;

[0025] Figure 2 This is a schematic diagram of the overall side view of the structure of this application;

[0026] Figure 3 For this application Figure 2 Enlarged schematic diagram of the structure at point A in the middle;

[0027] Figure 4 This is a schematic diagram of the overall frontal planar structure of this application;

[0028] Figure 5 This is a schematic diagram of the overall top view of the structure of this application;

[0029] Figure 6 For this application Figure 5 Enlarged schematic diagram of the structure at point B.

[0030] In the picture:

[0031] 1. Combined steel sheet assembly; 101. First long steel sheet pile; 102. Second long steel sheet pile; 103. First long slot; 104. First short steel sheet pile; 105. Second short steel sheet pile; 106. First short slot; 2. Waler assembly; 201. Steel waler; 202. Short positioning bolt; 203. Long positioning bolt; 204. Gasket; 3. Internal support assembly; 301. Steel pipe internal support column; 302. Connecting piece; 303. Connecting bolt. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1 -Appendix Figure 6 This application will be described in further detail below.

[0033] Example 1: A long and short combined steel sheet pile foundation pit support structure, referring to... Figure 1 , Figure 4 and Figure 6 The system includes a combined steel plate assembly 1, a waler assembly 2, and an internal bracing assembly 3. The combined steel plate assembly 1 includes a first long steel sheet pile 101, a second long steel sheet pile 102, a first short steel sheet pile 104, and a second short steel sheet pile 105 arranged alternately in sequence. A first long slot 103 is provided between the first long steel sheet pile 101 and the second long steel sheet pile 102, and a first short slot 106 is provided between the first short steel sheet pile 104 and the second short steel sheet pile 105. The first long slot 103 is located on both sides of the first long steel sheet pile 101, and the first short slot 106 is located on both sides of the first short steel sheet pile 104. The first long steel sheet pile 101, the second long steel sheet pile 102, the first short steel sheet pile 104, and the second short steel sheet pile 105 are arranged alternately in sequence. Sheet piles 105 are interlocked by a first long slot 103 and a first short slot 106, with the opening directions of the first long slot 103 and the first short slot 106 being consistent. The first long slot 103 and the first short slot 106 enable the first long steel sheet pile 101, the second long steel sheet pile 102, the first short steel sheet pile 104, and the second short steel sheet pile 105 to interlock with each other, and the opening directions are consistent. This meets the requirements for tight installation of the combined steel plate assembly 1, effectively transmits lateral forces, avoids water and soil loss or displacement caused by gaps between the piles, and ensures the integrity of the alternating arrangement of 2 long and 2 short piles. This facilitates the control of the verticality of the combined steel plate assembly 1 during construction and meets the requirement for tight interlocking of the tooth grooves.

[0034] Reference Figure 2 , Figure 4 and Figure 6The first long sheet pile 101 and the second long sheet pile 102 have the same length, as do the first short sheet pile 104 and the second short sheet pile 105. The lengths of the first long sheet pile 101 and the second long sheet pile 102 are greater than the lengths of the first short sheet pile 104 and the second short sheet pile 105. The lengths of the first long sheet pile 101 and the second long sheet pile 102 are greater than the lengths of the first short sheet pile 104 and the second short sheet pile 105. This design combines two lengths of sheet piles. The longer sheet piles meet the depth requirements for insertion into hard rock layers to ensure support strength, while the shorter sheet piles reduce material usage and rock-penetration work, lowering rental costs and construction difficulty. Simultaneously, they allow for flexible adjustments based on geological conditions, adapting to trench construction scenarios involving hard rock layers. The sheet pile assembly 1 uses the first long sheet pile 101, the second long sheet pile 102, the first short sheet pile 104, and the second short sheet pile 105 as basic units, arranged cyclically along the length of the foundation pit. The combined sheet pile assembly 1 uses 2 long and 2 short sheets as basic units, arranged cyclically along the length of the foundation pit. It is suitable for pipeline trenches with a length of more than 50m, which can ensure the continuity and consistency of long-distance trench support, facilitate construction organization and quality control, and the unitized arrangement can be flexibly adjusted according to the trench length to avoid material waste. Combined with the pre-drilling technology in the construction method, it can realize efficient support construction of long-distance hard rock strata. The length of the first long sheet pile 101 and the second long sheet pile 102 is preferably 9m, and the length of the first short sheet pile 104 and the second short sheet pile 105 is preferably 6m.

[0035] Reference Figure 4 , Figure 5 and Figure 6The waler assembly 2 includes four steel walers 201. The first long sheet pile 101 and the first short sheet pile 104 are internally threaded with short positioning bolts 202. The second long sheet pile 102 and the second short sheet pile 105 are internally threaded with long positioning bolts 203. The steel walers 201 are connected to the first long sheet pile 101 and the first short sheet pile 104 via the short positioning bolts 202, and the steel walers 201 are connected to the first long sheet pile 101 and the first short sheet pile 104 via the long positioning bolts 203. 3. Connected to the second long sheet pile 102 and the second short sheet pile 105, each short positioning bolt 202 and long positioning bolt 203 has a gasket 204 fitted at its end. Multiple gaskets 204 are located between the steel waler 201 and the combined steel plate assembly 1. The gaskets 204, positioned between the steel waler 201 and the combined steel plate assembly 1, can buffer the tightening force of the short positioning bolts 202 and long positioning bolts 203, enhancing the sealing and stability of the connection. To prevent the positioning bolts from loosening due to vibration during construction and to ensure the continuous and reliable constraint effect of the steel waler 201 on the combined steel plate assembly 1, the short positioning bolts 202 and long positioning bolts 203 are distributed at intervals along the length of the steel waler 201. The spacing between the short positioning bolts 202 and long positioning bolts 203 is adapted to the arrangement spacing of the first long steel sheet pile 101, the second long steel sheet pile 102, the first short steel sheet pile 104, and the second short steel sheet pile 105. The spacing between the short positioning bolts 202 and long positioning bolts 203 is adapted to the arrangement spacing of each steel sheet pile inside the combined steel plate assembly 1. This ensures that the steel waler 201 can evenly distribute the lateral force transmitted by the steel sheet piles, avoid local stress concentration caused by misalignment of connection points, and facilitate rapid positioning and installation during construction, reducing measurement and adjustment time and improving the accuracy of the connection between the waler assembly 2 and the combined steel plate assembly 1.

[0036] Example 2: A long and short combined steel sheet pile foundation pit support structure, referring to... Figure 2 , Figure 3 and Figure 5Based on the same concept as Embodiment 1 above, this embodiment proposes an internal support component 3 comprising multiple steel pipe internal support columns 301. These steel pipe internal support columns 301 are respectively installed between four steel walers 201. Each steel pipe internal support column 301 has two connecting pieces 302 fixedly connected to both ends. Each connecting piece 302 has a connecting bolt 303 installed inside. The connecting pieces 302 and connecting bolts 303 at both ends of the steel pipe internal support column 301 provide a detachable connection structure for the internal support. This facilitates the layered installation and removal of the steel walers 201 and steel pipe internal support columns 301, requiring installation every 2 meters of excavation. The operation is flexible and the connection is seamless. It is sturdy and can effectively transmit the lateral pressure of the foundation pit, avoid the support deformation caused by the failure of the connection between the inner support component 3 and the waler component 2, and ensure construction safety. The two ends of the steel pipe inner support column 301 are installed on the inner wall of the corresponding steel waler 201 through the connecting piece 302 and the connecting bolt 303, respectively. The steel pipe inner support column 301 is connected to the inner wall of the steel waler 201 through the connecting piece 302 and the connecting bolt 303, so that the internal support force can be evenly transmitted to the steel waler 201 and the combined steel plate component 1. It can effectively resist the lateral thrust of the soil during the trench excavation process, prevent the combined steel plate component 1 from tilting due to uneven force, and ensure the stability of the foundation pit excavation process.

[0037] It should be noted that the general construction method for this support structure is as follows: Surveyors use a total station to lay out the control lines for the pilot holes according to the construction drawings and mark them with lime lines. After determining the location of the pilot hole for the first long steel sheet pile, the center point of each pilot hole is measured one by one using a steel ruler, and bamboo sticks or steel bar segments are inserted as markers. Before the pilot drilling rig is in place, the area below should be leveled and compacted to ensure that the bottom of the drilling rig is stable and will not tilt or move during drilling. Before the drilling rig starts working, a plumb bob should be used to check the verticality of the drill rod in both the front and side directions, and the angle of the drill rod should be adjusted in time. The drill bit tip should be aligned with the center point of the pilot hole. After the drilling rig is debugged, the first pilot hole is drilled using a 150mm diameter drill bit. After reaching the design depth, drilling is stopped and the drill rod is pulled out. During the pilot hole drilling process, operators should continuously monitor the verticality of the drill rod, promptly adjusting any deviations to ensure the verticality of the completed hole. The drilling depth can be verified based on the number of drill rod sections and the length of the last section. After the initial pilot hole is completed, a 400mm diameter drill bit is used for the second pilot hole drilling, following the same trajectory. Upon encountering hard rock layers, drilling should be slow and at a constant speed to avoid damaging the drill bit; mud can be injected for lubrication if necessary. Once the designed depth is reached, the drill rod is removed, and any soil brought to the surface during drilling is cleaned to facilitate the transfer of the drilling rig to the next pilot hole location. Sheet pile driving should commence immediately after pilot hole construction, with minimal intervals to ensure stability of the pilot hole location. The first sheet pile (length 101) is driven first, with strict control over its verticality to serve as a guide. Measurements should be taken every 1 meter of driving to ensure correct positioning and vertical penetration. Simultaneously, it should be ensured that the sheet piles reach the designed depth, achieving stability through the compression of the surrounding soil and rock. After driving the first long sheet pile 101 and the second long sheet pile 102 consecutively, the first short sheet pile 104 should be driven into the non-pivot position. During the process, the inclination should be measured and monitored at all times, and controlled to not exceed 2%. If the inclination is too large, it is strictly forbidden to straighten or adjust it; the entire sheet pile should be pulled out and re-driven. After driving the first short sheet pile 104 and the second short sheet pile 105 consecutively, the above construction should be repeated, alternating until all sheet piles in this section are driven.

[0038] The implementation principle of this application embodiment is as follows: the combined steel plate assembly 1 serves as the core support structure, with two long and two short units consisting of a first long steel sheet pile 101, a second long steel sheet pile 102, a first short steel sheet pile 104, and a second short steel sheet pile 105 arranged cyclically along the length of the foundation pit. The lengths of the first long steel sheet pile 101 and the second long steel sheet pile 102 are greater than the lengths of the first short steel sheet pile 104 and the second short steel sheet pile 105, allowing them to be inserted to a sufficient depth into the hard underground rock layer to provide vertical anchoring force and overall bearing capacity. The lengths of the first short steel sheet pile 104 and the second short steel sheet pile 105 are... The shorter length of the two short sheet piles 105 reduces the depth and number of piles driven into the rock, thus lowering the difficulty of driving. Simultaneously, the first long slot 103 and the first short slot 106 interlock, forming a continuous whole with all sheet piles, effectively transmitting lateral earth pressure and preventing deformation due to excessive stress on a single pile. At the locations of the first long sheet pile 101 and the second long sheet pile 102, the drilling rig first uses a small drill bit to loosen the soil and break up hard rock, then uses a large drill bit to enlarge the hole to complete the pilot hole construction. No backfilling of miscellaneous fill is required, allowing direct driving operations and simplifying the construction process. (Wall assemblies...) In component 2, the steel waler 201 connects the long and short sheet piles respectively through short positioning bolts 202 and long positioning bolts 203, evenly distributing the lateral force borne by the combined steel sheet assembly 1. The gasket 204 buffers the fastening force between the steel waler 201 and the combined steel sheet assembly 1, preventing loosening of the connection due to vibration and ensuring the continuous and reliable restraint effect of the waler on the sheet piles. The internal support component 3 serves as a lateral support system, with the steel pipe internal support column 301 installed between multiple steel walers 201 through connecting plates 302 and connecting bolts 303, following the principle of supporting before excavation. The layered installation, with each layer gradually installed as the trench is excavated, transfers lateral forces to the support structures on both sides, balancing the soil thrust and preventing tilting of the combined steel sheet assembly 1 and waler assembly 2 due to uneven stress. In addition, the first and second longest steel sheet piles 101 are driven directly after pre-drilling at their corresponding positions, eliminating the need for backfilling with miscellaneous fill. Combined with the arrangement of 2 long and 2 short piles, the construction process is simplified while ensuring support strength. This allows the overall structure to adapt to hard rock geological conditions and achieve stability and safety of the foundation pit through the synergistic effect of each component.

[0039] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A long and short combined steel sheet pile foundation pit support structure, comprising a combined steel sheet assembly (1), a waler assembly (2), and an internal bracing assembly (3), characterized in that: The combined steel sheet assembly (1) includes a first long steel sheet pile (101), a second long steel sheet pile (102), a first short steel sheet pile (104), and a second short steel sheet pile (105) arranged alternately in sequence. A first long slot (103) is provided between the first long steel sheet pile (101) and the second long steel sheet pile (102), and a first short slot (106) is provided between the first short steel sheet pile (104) and the second short steel sheet pile (105). The waler assembly (2) includes four steel walers (201). The first long steel sheet pile (101) and the first short steel sheet pile (104) are all internally threaded with short fixed sections. Positioning bolts (202), the second long sheet pile (102) and the second short sheet pile (105) are both threaded with long positioning bolts (203), the steel waler (201) is connected to the first long sheet pile (101) and the first short sheet pile (104) through short positioning bolts (202), the steel waler (201) is connected to the second long sheet pile (102) and the second short sheet pile (105) through long positioning bolts (203), the internal support assembly (3) includes multiple steel pipe internal support columns (301), and the multiple steel pipe internal support columns (301) are respectively installed between the four steel walers (201).

2. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: The first long slot (103) is opened on both sides of the first long sheet pile (101), and the first short slot (106) is opened on both sides of the first short sheet pile (104). The first long sheet pile (101), the second long sheet pile (102), the first short sheet pile (104) and the second short sheet pile (105) are interlocked with each other through the first long slot (103) and the first short slot (106), and the opening direction of the first long slot (103) and the first short slot (106) is consistent.

3. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: Each of the short positioning bolts (202) and long positioning bolts (203) is provided with a gasket (204) at its end, and the plurality of gaskets (204) are located between the steel waler (201) and the combined steel plate assembly (1).

4. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: Two connecting pieces (302) are fixedly connected to both ends of each of the steel pipe internal support columns (301), and a connecting bolt (303) is installed inside each of the connecting pieces (302).

5. The long and short combined steel sheet pile foundation pit support structure according to claim 4, characterized in that: The two ends of the steel pipe inner support column (301) are respectively installed on the inner wall of the corresponding steel waler (201) through connecting pieces (302) and connecting bolts (303).

6. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: The lengths of the first long sheet pile (101) and the second long sheet pile (102) are the same, the lengths of the first short sheet pile (104) and the second short sheet pile (105) are the same, and the lengths of the first long sheet pile (101) and the second long sheet pile (102) are greater than the lengths of the first short sheet pile (104) and the second short sheet pile (105).

7. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: The short positioning bolts (202) and long positioning bolts (203) are distributed at intervals along the length direction of the steel waler (201), and the spacing between the short positioning bolts (202) and long positioning bolts (203) is adapted to the arrangement spacing of the first long steel sheet pile (101), the second long steel sheet pile (102), the first short steel sheet pile (104) and the second short steel sheet pile (105).

8. The long and short combined steel sheet pile foundation pit support structure according to claim 1, characterized in that: The combined steel sheet assembly (1) uses the first long steel sheet pile (101), the second long steel sheet pile (102), the first short steel sheet pile (104), and the second short steel sheet pile (105) as basic units, and is arranged cyclically along the length of the foundation pit.

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