Dynamic real-time optimization construction method for ultra-large deep foundation pit in asymmetric excavation zero-distance close connection with existing underground structure

Abstract

The invention relates to a dynamic real-time optimization construction method for an ultra-large deep foundation pit of an asymmetric excavation zero-distance close existing underground structure. The dynamic real-time optimization construction method comprises the following steps that S10, the foundation pit is divided into a central area and a peripheral area on the two sides of the existing underground structure; s20, foundation pit construction is conducted according to the first construction scheme, and meanwhile stress deformation of the existing underground structure is monitored in real time; s30, constructing a numerical model, and performing numerical simulation inversion analysis on the first construction scheme to verify the accuracy of the model; s40, multiple groups of second construction schemes are constructed; s50, a foundation pit vertical construction scheme is determined; s60, multiple groups of third construction schemes are constructed; s70, a foundation pit transverse construction scheme is determined; and S80, according to the vertical construction scheme and the transverse construction scheme of the foundation pit, the three-dimensional warehouse dividing sequence is determined, and the two center area warehouse blocks and the six peripheral area warehouse blocks are constructed in an asymmetric staggered joint warehouse jumping mode. According to the method, the technical blank of zero-distance proximity construction under the working condition that the depths of the two sides are different can be filled up, and design parameters and construction method selections are provided for similar projects.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geotechnical engineering and underground engineering construction technology, in particular to the construction of super-large deep foundation pit close excavation in urban dense area, and specifically relates to a dynamic real-time optimization construction method for super-large deep foundation pit close excavation to existing underground structure. BACKGROUND

[0002] With the rapid economic development and continuous urbanization process, comprehensive transportation hubs have become the core facilities for first-tier cities to improve their functional carrying capacity. Such hubs integrate rail transit, ground public transportation and other transportation modes, and simultaneously integrate office, residential, commercial and other multi-format, forming an efficient "traffic + urban function" complex that not only meets the travel needs of citizens, but also promotes the intensive use of urban space. However, this cannot avoid construction near existing buildings. How to solve the influence of close foundation pit on existing operating stations is crucial to the construction of urban rail transit. In the development process of the Lize terminal building comprehensive transportation hub, the construction of the foundation pit on both sides of the Lize Business District Station of the existing Line 16 is involved. During the construction process, the excavation of foundation pit soil will cause soil unloading and uneven disturbance to the surrounding soil, thereby breaking the original ground stress balance. This destruction of balance will cause stress redistribution in the soil layer, which may lead to a chain reaction of enclosure structure deformation, pit soil settlement, and even cause the Lize Business District Station of the existing Line 16 to rise and deform, affecting its stability and safety. During the construction of the Lize Business District comprehensive transportation hub, the existing Line 16 needs to maintain normal operation, and according to the specification requirements, the deformation range needs to be strictly controlled within the interval of ±2mm to-3mm. This stringent standard not only requires real-time capture of structural responses through dynamic monitoring to avoid risks, but also requires optimization of construction steps in combination with engineering characteristics, precise control of excavation rhythm, support erection timing and other key links to ensure the safety of the operating line and the coordination of construction advancement.

[0003] At present, the research on foundation pit construction near existing buildings defines the "close" concept within a distance range of 3-5m, and the related research results are mainly focused on this interval. However, for the extreme condition of "zero distance" close between foundation pit and existing buildings, existing research has not been involved, and there is still a gap in related construction technology and theoretical support.

[0004] In addition, current research on foundation pit construction near existing buildings mainly focuses on the single condition of single-side close, and the related technical path and theoretical analysis are relatively mature. However, for the complex scenario of double-side close to existing buildings and the construction response when the excavation depth of the two foundation pits is different, the existing research coverage is low, and the stress mechanism and deformation control method still lack systematic discussion, and the depth and breadth of research need to be expanded.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] In view of the deficiencies of the prior art, the main purpose of the present application is to propose a dynamic real-time optimization construction method for a super-large deep foundation pit with asymmetric excavation and zero-distance proximity to existing underground structures, in order to solve the excavation construction problem of zero-distance proximity to existing underground structures with different excavation depths on both sides of the current super-large deep foundation pit.

[0007] The technical solution of the present application is as follows:

[0008] A dynamic real-time optimization construction method for a super-large deep foundation pit with asymmetric excavation and zero-distance proximity to existing underground structures, comprising the following steps:

[0009] S10, according to the characteristics of the super-large deep foundation pit with asymmetric excavation and zero-distance proximity to existing underground structures, the foundation pit is divided into a central area and a peripheral area on both sides of the existing underground structure;

[0010] S20, according to the first construction scheme, the foundation pit is constructed, and the first construction scheme is vertical symmetric layered construction, and the stress deformation of the existing underground structure is monitored in real time;

[0011] S30, a numerical model is constructed, numerical simulation inversion analysis is performed on the first construction scheme, and the accuracy of the model is verified according to the deformation simulation result and the monitoring result of the existing underground structure;

[0012] S40, based on the first construction scheme and combined with the stratum characteristics and engineering experience, a plurality of second construction schemes are constructed, and the plurality of second construction schemes are synchronous layered excavation of a plurality of predetermined step distances in the central area of the foundation pit and the peripheral area;

[0013] S50, numerical simulation is performed on the plurality of second construction schemes, and a vertical construction scheme of the foundation pit is determined, and the vertical construction scheme is synchronous layered excavation of a predetermined step distance in the central area of the foundation pit and the peripheral area;

[0014] S60, based on the second construction scheme and combined with the stratum characteristics and engineering experience, a plurality of third construction schemes are constructed, and the plurality of third construction schemes are block construction in the central area of the foundation pit and the peripheral area;

[0015] S70, numerical simulation is performed on the plurality of third construction schemes, and a horizontal construction scheme of the foundation pit is determined, and the horizontal construction scheme is block construction in the central area of the foundation pit and the peripheral area, and the foundation pit is divided into two central area blocks and six peripheral area blocks in the plane;

[0016] S80, according to the determined vertical construction scheme and horizontal construction scheme, a three-dimensional stereoscopic block sequence is determined, and the two central area blocks and the six peripheral area blocks are constructed in an asymmetric staggered seam jump block mode.

[0017] Preferably, in S20, the first construction scheme is an initial design construction scheme or a preliminary construction scheme determined according to engineering experience.

[0018] Preferably, in S40, the multiple sets of the second construction scheme include:

[0019] Synchronous layer-by-layer excavation of the center area and the peripheral area, with each excavation being 1m;

[0020] Synchronous layer-by-layer excavation of the center area and the peripheral area, with each excavation being 2m;

[0021] Synchronous layer-by-layer excavation of the center area and the peripheral area, with each excavation being 3m.

[0022] Preferably, in S50, the vertical construction scheme is synchronous layer-by-layer excavation of the center area and the peripheral area, with each excavation being 2m.

[0023] Preferably, in S60, the multiple sets of the third construction scheme include:

[0024] (1) Using a partitioned asynchronous excavation process, two center area blocks are constructed first, and then six peripheral area blocks are constructed;

[0025] (2) Using a partitioned asynchronous excavation process, six peripheral area blocks are constructed first, and then two center area blocks are constructed;

[0026] (3) Using a partitioned asynchronous excavation process, a "block jumping" sequence is used, two center area blocks are started first, and then six peripheral area blocks are excavated using an "interval excavation" jumping sequence: P1, P3, and P5 blocks are excavated first, and then P2, P4, and P6 blocks are excavated;

[0027] (4) Using a partitioned asynchronous excavation process, a "block jumping" sequence is used, two center area blocks are started first, and then six peripheral area blocks are excavated using an "interval excavation" jumping sequence: P2, P4, and P6 blocks are excavated first, and then P1, P3, and P5 blocks are excavated.

[0028] Preferably, in S80, a three-dimensional stereoscopic partitioned sequence is determined, and an asymmetric staggered jumping sequence mode is used for construction of the two center area blocks and the six peripheral area blocks, including:

[0029] The six peripheral area blocks are divided into a first group of peripheral area blocks for initial excavation and a second group of peripheral area blocks for subsequent excavation according to a "jumping sequence mode";

[0030] The first group of peripheral area blocks and the second group of peripheral area blocks are designed with a "1 / 3 block length stagger" in the plane;

[0031] The construction joint of the peripheral zone block and the central zone block is in vertical staggered position.

[0032] Preferably, in S80, each of the central zone blocks is divided into independent three-dimensional sub-blocks of a "floor sub-block", a "side wall sub-block" and a "floor sub-block" according to the vertical member stiffness difference.

[0033] Each of the peripheral zone blocks is divided into independent three-dimensional sub-blocks of a "floor sub-block", a "side wall sub-block" and a "floor sub-block" according to the vertical member stiffness difference, realizing vertical coordination of "excavation-supporting-structure construction".

[0034] Preferably, the central zone blocks are constructed "from bottom to top", the floor sub-blocks are excavated and the foundations are poured first, then the side wall sub-blocks are excavated layer by layer and the horizontal supports are simultaneously constructed, and finally the floor sub-blocks are constructed.

[0035] The peripheral zone blocks are constructed "from top to bottom", and after excavation to the bottom of the pit, the floor sub-blocks, the side wall sub-blocks and the floor sub-blocks are constructed "from top to bottom".

[0036] Preferably, after the floor sub-blocks of the central zone blocks are poured, a plurality of stress release joints are reserved on the surface thereof and the joint width is monitored, and after the joint width is stable, the side wall sub-blocks are poured layer by layer.

[0037] Preferably, after the construction of all sub-blocks is completed, the connecting parts of the sub-blocks are poured again to enhance the interface stiffness of the floor sub-blocks, the side wall sub-blocks and the floor sub-blocks, and form a closed three-dimensional overall structure.

[0038] The beneficial effects of the present application relative to the prior art are that the present application proposes a dynamic real-time optimization construction method for a super large deep foundation pit with asymmetric excavation and zero distance proximity to an existing underground structure, which can be better understood from one or more of the following aspects:

[0039] (1) The present application provides an effective construction method for the special case of a super large deep foundation pit with asymmetric excavation and zero distance proximity to an existing underground structure, which has no relevant engineering case reference, and through dynamic real-time optimization during construction, ensures that the construction scheme meets the control requirements of the stress and deformation of the underground structure, and ensures the safety of the existing underground structure during the zero distance proximity excavation on both sides.

[0040] (2) The present application first preliminarily formulates a first construction scheme and constructs the first construction scheme, further adopts a combination of numerical simulation and field monitoring to verify the accuracy of the numerical model, to ensure that the subsequent numerical simulation conforms to the actual construction.

[0041] (3) The application continues to construct multiple sets of second construction schemes based on the first construction scheme, and multiple sets of third construction schemes based on the second construction scheme, as comparative construction schemes, and carries out numerical simulation on the multiple sets of comparative construction schemes to determine the vertical construction scheme and the horizontal construction scheme according to the simulation results. The comparative construction schemes constructed based on the first construction scheme of the actual construction are more real, closer to the actual engineering, and more beneficial to the optimization of the actual construction scheme.

[0042] (4) The application optimizes the first construction scheme of the actual construction, on the one hand, the foundation pit is excavated in the vertical direction by using a symmetrical layered excavation process, both sides of the underground structure are simultaneously excavated, on the other hand, the foundation pit is divided into a center area block and a peripheral area block in the plane, and the blocks are constructed in coordination, so as to optimize the stress state; on this basis, the center area block is constructed by using the three-dimensional block division sequence combined with the top-down method, and the peripheral area block is constructed by using the three-dimensional block division sequence combined with the top-down method, the center top-down method improves the construction efficiency, quickly forms the core support, and the peripheral top-down method controls the structure deformation and reduces the environmental disturbance.

[0043] (5) The application uses a three-dimensional block division sequence, and the center area block and the peripheral area block are constructed by using an asymmetric staggered seam jump block mode, to realize the whole-process coordination of three-dimensional block division, staggered seam jump block and top-down combined construction.

[0044] (6) The research results of the application can perfect the database of non-symmetrical excavation zero-distance close construction, fill the technical gap of zero-distance close construction under the condition of two-side depth difference, and provide design parameters and construction method selection for similar projects (such as the scene of two-side foundation pit depth ratio>1).

[0045] It should be understood that the content described in the summary section is not intended to limit the key or important features of the embodiments of the application, nor is it intended to limit the scope of the application. Other features of the application will become apparent through the following description. In addition, the implementation of any embodiment of the application does not mean that multiple or all of the above beneficial effects are simultaneously or achieved. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other implementation drawings according to the provided drawings without creative labor.

[0047] The structures, proportions, sizes, etc. shown in the specification are merely used to cooperate with the content disclosed in the specification for understanding and reading by those skilled in the art, and do not define the limiting conditions for implementing the application, so they do not have technical substantive significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the application, should still fall within the scope of the technical content disclosed by the application.

[0048] Figure 1 The whole flowchart of the dynamic real-time optimization construction method of the embodiment of the application is shown in the figure.

[0049] Figure 2 The planning plane schematic diagram of the foundation pit engineering of the embodiment of the application is shown in the figure.

[0050] Figure 3 The existing underground structure elevation schematic diagram of the foundation pit engineering of the embodiment of the application is shown in the figure.

[0051] Figure 4 The excavation design elevation schematic diagram of the foundation pit engineering of the embodiment of the application is shown in the figure.

[0052] Figure 5 The dynamic real-time optimization construction content schematic diagram of the embodiment of the application is shown in the figure.

[0053] Figure 6 The zoning schematic diagram of the foundation pit on the plane of the embodiment of the application is shown in the figure.

[0054] Figure 7 The structure deformation monitoring and numerical simulation schematic diagram of the embodiment of the application is shown in the figure.

[0055] Figure 8 The second construction scheme deformation simulation schematic diagram of the embodiment of the application is shown in the figure.

[0056] Figure 9 The block excavation schematic diagram of the foundation pit on the plane of the embodiment of the application is shown in the figure.

[0057] Figure 10 The reserved 1 / 3 bin length stagger schematic diagram of the embodiment of the application is shown in the figure.

[0058] Figure 11 The next step construction schematic diagram of 1 / 3 bin length of the embodiment of the application is shown in the figure.

[0059] Figure 12 The foundation pit optimization construction scheme deformation schematic diagram of the embodiment of the application is shown in the figure. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear and understandable, the embodiments of the present application are further described in detail below in conjunction with the embodiments and drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but are not as limitations to the present application.

[0061] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and other terms should be understood in a broad sense, for example, can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0062] It should be understood that the terms "including / containing", "consisting of" or any other variants are intended to cover non-exclusive inclusion, so that the product, device, process or method including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes the elements inherent to such product, device, process or method. Without more limitation, the elements defined by the statement "including / containing", "consisting of" do not exclude the presence of other identical elements in the product, device, process or method including the elements.

[0063] It should also be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices, components or structures referred to must have a particular orientation, be constructed or operated in a particular orientation, and cannot be understood as a limitation to the present application.

[0064] In order to achieve the purpose of the present application, the research on non-symmetrical excavation in different zero-distance close construction is insufficient, mainly involving the following aspects of research:

[0065] 1. Study the particularity of the scene

[0066] Under the condition of zero-distance close construction, non-symmetrical excavation, i.e. the difference in excavation depth of two side foundation pits, will cause asymmetric unloading, and induce additional bending moment and shear deformation of the existing building foundation. The research on such complex stress scenarios is currently in the exploratory stage, and the related mechanical mechanism and control method has not yet formed a system.

[0067] 2. Key research dimensions

[0068] Influence of depth difference (different excavation depths on the east and west sides of the foundation pit) on construction disturbance: analyze the asymmetry of stress redistribution of the soil body when different depth foundation pits are excavated synchronously and its influence on the load transfer path of the existing building foundation; explore the tensile and compressive effects of the deformation difference of the enclosure structure caused by the depth difference on the existing building walls; quantify the effect difference of different excavation sequences (deep first, shallow second / shallow first, deep second) on disturbance control.

[0069] 3. Data output and technical objectives

[0070] Through field monitoring and numerical simulation, key data under the condition of depth difference are obtained: including the settlement curve of the existing building, the change of the axial force of the foundation pit enclosure structure, the lateral displacement distribution of the soil body, etc. A quantitative relationship model of "depth difference-stress asymmetry-building response" is established to determine the depth difference limit value and the collaborative excavation parameters for safe construction.

[0071] 4. Application expansion of the research

[0072] The research results can improve the database of zero-distance close construction, fill the technical gap of zero-distance close construction under the condition of depth difference, and provide design parameters and construction method selection for similar projects (such as scenarios where the depth ratio of the two sides of the foundation pit is >1).

[0073] The implementation of the present application will be described in detail in combination with preferred embodiments.

[0074] Firstly refer to Figure 1As shown in the flow chart, a dynamic real-time optimization construction method of an asymmetrically excavated zero-distance adjacent super-large deep foundation pit to an existing underground structure includes the following steps: S10, according to the characteristics of the asymmetrically excavated zero-distance adjacent super-large deep foundation pit to the existing underground structure, the foundation pit is divided into a central area and a peripheral area on both sides of the existing underground structure; S20, the foundation pit is constructed according to a first construction scheme, the first construction scheme is vertical symmetric layered construction of the foundation pit, and the stress deformation of the existing underground structure is monitored in real time; S30, a numerical model is constructed, numerical simulation inversion analysis is performed on the first construction scheme, and the accuracy of the model is verified according to the simulation results and the monitoring results of the deformation of the existing underground structure; S40, a plurality of second construction schemes are constructed based on the first construction scheme and combined with the stratum characteristics and engineering experience, the plurality of second construction schemes are synchronous layered excavation of a plurality of predetermined step distances of the central area of the foundation pit and the peripheral area in forward construction and reverse construction; S50, numerical simulation is performed on the plurality of second construction schemes, a vertical construction scheme of the foundation pit is determined, and the vertical construction scheme is synchronous layered excavation of a predetermined step distance of the central area of the foundation pit and the peripheral area in forward construction and reverse construction; S60, a plurality of third construction schemes are constructed based on the second construction scheme and combined with the stratum characteristics and engineering experience, the plurality of third construction schemes are block construction of the central area of the foundation pit and the peripheral area in forward construction and reverse construction; S70, numerical simulation is performed on the plurality of third construction schemes, a horizontal construction scheme of the foundation pit is determined, and the horizontal construction scheme is block construction of the central area of the foundation pit and the peripheral area in forward construction and reverse construction, the foundation pit is divided into two central area blocks and six peripheral area blocks in the plane; S80, according to the determined vertical construction scheme and horizontal construction scheme, a three-dimensional stereoscopic block sequence is determined, and the two central area blocks and the six peripheral area blocks are constructed in an asymmetrically staggered seam jumping block mode.

[0075] The present application changes different construction sequences, adopts a combination of numerical simulation and field monitoring, quantifies the displacement field (settlement, inclination) and stress field (foundation reaction, wall strain) change law of the existing underground structure under different construction sequences, compares and analyzes the disturbance control effect of multiple schemes, identifies the optimal construction sequence, that is, obtains the construction method with the smallest influence on the deformation and stress of the existing underground structure, so as to ensure the safety and normal operation of the station structure.

[0076] Next, taking the terminal building project of the Beijing Lize Business District Comprehensive Transportation Hub as an example, systematic analysis is carried out on the complex water and soil environment, foundation pit support system, combination of forward and reverse construction, and other characteristics, and the implementation of each link is described in detail.

[0077] As Figure 2As shown in the drawings, the Lize CBD station (Line 14, Line 16, airport line, Line 11, Lijing line and terminal) project is located in two plots of 64# and 65# and the surrounding road, the aboveground building scale is not more than 270,000 square meters, the underground building area is about 302,500 square meters, the design size of the foundation pit is 427m*154m*38m, at present, Line 14 and Line 16 have been built and opened to traffic, the station of the Daxing airport line is under construction, and the stations of Line 11 and Lijing line are reserved in the main structure of the station.

[0078] As shown in the drawings, Figure 3 , Figure 4 As shown in the drawings, the Lize city terminal comprehensive transportation hub needs to excavate the existing Line 16 foundation pit on both sides and construct the underground structure during the development process. The present application mainly optimizes the construction step sequence of the foundation pit on both sides of the existing Line 16 structure to reduce the influence on the deformation of the existing Line 16.

[0079] The Lize CBD site mainly exists in the pebble stratum, the pebble stratum particle grading curve presents continuous distribution characteristics, belongs to the excellent grading category, which makes the intergranular embedding effect strong, forms a small pore ratio and a dense natural framework structure. From the mechanical properties, it shows low compressibility; has high bearing capacity advantage, provides favorable natural supporting layer conditions for foundation engineering. However, the stratum has strong water permeability at the same time, is easy to cause seepage deformation such as piping and soil flow under the action of underground water, and puts forward strict requirements for the design of the waterproof curtain of the foundation pit excavation. In addition, the high strength and non-uniformity of the pebble layer will cause problems such as drilling difficulty and hole inclination exceeding the standard in pile foundation construction, and the dense structure may cause particle skeleton loosening under the vibration load, and induce additional settlement.

[0080] Based on the above composite characteristics of the pebble stratum, a plurality of comparison schemes need to be constructed for the construction step sequence, the structure stress, stratum deformation and other indexes under different schemes are quantified through numerical simulation, and the optimal construction scheme which can balance the safety risk and engineering benefit is finally determined through comprehensive comparison and selection combining the technical feasibility and economic rationality, as shown in the drawings. Figure 5

[0081] S10, according to the characteristics of the super-large deep foundation pit close to the existing underground structure by non-symmetrical excavation, the foundation pit is divided into a central area and a peripheral area on both sides of the existing underground structure;

[0082] As shown in the drawings, Figure 6 The existing Line 16 structure crosses the design area of the foundation pit, according to the characteristics of the foundation pit, the foundation pit is divided into a central area and a peripheral area on both sides of the existing underground structure, and each side of the existing underground structure is divided into a central area and a peripheral area enclosed on three sides of the central area, and the other side of the central area is the existing underground structure close to it at zero distance, that is, the existing Line 16 structure.

[0083] ​S20, performing foundation pit construction according to the first construction scheme, the first construction scheme being vertical symmetrical layered construction of the foundation pit, and real-time monitoring of stress deformation of the existing underground structure;

[0084] In this embodiment, the first construction scheme can be initially selected as an initial design construction scheme, or a preliminary construction scheme is determined according to engineering experience and site environment for actual construction.

[0085] In this embodiment, the stress deformation analysis of the existing underground structure includes:

[0086] (1) Steel pipe column stress and deformation analysis

[0087] The steel pipe column is the core vertical bearing component of the entire subway station, bearing the upper structure load, soil pressure, water pressure and train dynamic load, etc. Its stress is mainly axial compression, and it also needs to resist the bending moment and shear force caused by horizontal force. The steel pipe and the core concrete work together, the restraint effect of the steel pipe on the concrete can improve the bearing capacity and ductility of the component, and the core concrete can enhance the buckling resistance of the steel pipe. Therefore, when the subway station is constructed in close proximity, the stress and deformation of the steel pipe column should be focused on. The stress and deformation of the steel pipe column in the following key stages are mainly analyzed: different soil excavation methods are used in the two side foundation pits, and the stress conversion caused by soil unloading has a great influence on the stress and deformation of the steel pipe column; the east foundation pit horizontal support construction stage, after the completion of the horizontal support construction, the support gradually bears the horizontal load, which leads to the redistribution of stress, which has a great influence on the stress and deformation of the steel pipe column of the subway station; the terminal building construction completion stage, after the completion of the terminal building construction, the overall stress tends to be stable, and the stress and deformation of the steel pipe column tend to be stable, as shown in FIG. 8. Figure 7

[0088] (2) Side pile deformation analysis

[0089] The side pile is the core enclosure component of the entire subway station, resisting the lateral soil pressure, water pressure and construction load during the foundation pit excavation stage, maintaining the stability of the soil; controlling the lateral deformation of the station, forming a closed stress structure, and bearing the lateral load during the operation stage of the station. Therefore, when the subway station is constructed in close proximity, the lateral deformation of the side pile should be focused on. The lateral deformation of the side pile in the following key stages is mainly analyzed: different soil excavation methods are used in the two side foundation pits, and the stress conversion caused by soil unloading has a great influence on the lateral deformation of the side pile; the east foundation pit horizontal support construction stage, after the completion of the horizontal support construction, the support gradually bears the horizontal load, which leads to the redistribution of stress, which has a great influence on the lateral deformation of the side pile of the subway station; the terminal building construction completion stage, after the completion of the terminal building construction, the overall stress tends to be stable, and the lateral deformation of the side pile tends to be stable.

[0090] (3) Roof, middle plate and bottom plate deformation analysis

[0091] ​The station roof, middle plate and bottom plate are the core stress components of the subway station and jointly form a vertical bearing system: the roof directly bears the self-weight of the upper soil, ground overload and construction load and transmits the vertical force through stiffness diffusion; the middle plate is a horizontal separation structure and bears the reaction force of the interval shield construction and lateral constraint load and coordinates the stress of the upper and lower structures; and the bottom plate is directly seated on the ground bearing layer and resists the base reaction force and groundwater buoyancy and controls the overall settlement of the structure. Therefore, when the subway station is constructed in close proximity, the vertical deformation and planar displacement of the plate body need to be monitored. The deformation characteristics of the plate body in the following key stages are mainly analyzed: when the differential excavation process is used for the two side foundation pits, the vertical stress gradient caused by the difference in soil unloading rate and range will cause uneven settlement of the roof, middle plate and bottom plate; during the construction of the east side foundation pit lateral support, the horizontal constraint load is transmitted to the plate body through the enclosure structure as the support axial force is gradually applied, which causes internal force redistribution of the structure and may cause local flexural deformation of the plate body; after the completion of the terminal building construction, the overall stiffness of the structure system is formed, the deformation of the roof, middle plate and bottom plate is controlled by the combined action of the upper dead load and live load, the deformation rate tends to be flat and finally stabilizes.

[0092] Through the above deformation monitoring, the deformation law of the existing underground structure is analyzed according to the monitoring data.

[0093] S30, a numerical model is constructed, numerical simulation and inversion analysis are performed on the first construction scheme, and the accuracy of the model is verified according to the simulation results and the monitoring results of the existing underground structure deformation;

[0094] As shown in Figure 7 , it can be seen that the numerical model constructed by the present application is suitable and can be used for subsequent simulation of comparison of construction schemes.

[0095] It should be noted that the numerical model constructed here and the inversion analysis method are not the focus of the present application and will not be described in detail, as long as the simulation can be performed and the results are reasonable.

[0096] S40, a plurality of second construction schemes are constructed based on the first construction scheme and combined with the stratum characteristics and engineering experience, and the plurality of second construction schemes are synchronous layered excavation of a plurality of predetermined step distances in the center area of the foundation pit and the surrounding area by forward construction and reverse construction;

[0097] In this embodiment, according to the stratum characteristics of the foundation pit and combined with engineering experience, the center area of the east and west foundation pits of the existing station is excavated by forward construction and the surrounding area is excavated by reverse construction, and the excavation step distance is set to 1m, 2m and 3m each time. Specifically as follows:

[0098] (1) the east and west foundation pits and the surrounding foundation pits of the existing No. 16 line station are symmetrically constructed in layers, 1m each time;

[0099] Please refer to Figure 4, both sides and the surrounding reverse excavation foundation pit synchronous implementation of earthwork excavation operation, the single excavation depth is strictly controlled to 1m, through the step unloading to reduce the disturbance to the enclosure structure and the surrounding environment. The specific construction process is as follows: when the right side of the foundation pit is excavated to B4M (the middle layer of the underground four layers), the first transverse support is immediately constructed to form the initial force balance system; then the two horizontal supports corresponding to the B3 layer bottom plate and top plate are constructed in turn by using the reverse construction method, and after the completion of the support system construction, the stiffness acceptance is carried out to ensure that the design stiffness requirements are met. After the three support systems are accepted and meet the strength conditions, the excavation is continued to the B4 layer bottom plate elevation, and the fourth support is simultaneously constructed, and finally the excavation of the foundation pit to the bottom is completed under the collaborative stress of the four supports. In the main structure construction stage, the terminal building bottom plate and the steel pipe column are first poured, and then the terminal building main structure is constructed layer by layer upwards in the reverse construction mode, the completed structure layer is used as a temporary support system to realize the integration of "structure construction and load bearing", and the structural deformation and foundation pit stability in the construction process are effectively controlled.

[0100] (2) The existing 16th line station east and west sides and the surrounding foundation pit are symmetrically constructed in layers, each time 2m;

[0101] The existing 16th line station foundation pit project adopts symmetrically layered excavation technology, and the east and west sides and the surrounding reverse foundation pit synchronous implementation of earthwork excavation operation, the single excavation depth is strictly controlled to 2m, through the step unloading to reduce the disturbance to the enclosure structure and the surrounding environment. The specific construction process is as follows: when the right side of the foundation pit is excavated to B4M high, the first transverse support is immediately constructed to form the initial force balance system; then the two horizontal supports corresponding to the B3 layer bottom plate and top plate are constructed in turn by using the reverse construction method, and after the completion of the support system construction, the stiffness acceptance is carried out to ensure that the design stiffness requirements are met. After the three support systems are accepted and meet the strength conditions, the excavation is continued to the B4 layer bottom plate elevation, and the fourth support is simultaneously constructed, and finally the excavation of the foundation pit to the bottom is completed under the collaborative stress of the four supports. In the main structure construction stage, the terminal building bottom plate and the steel pipe column are first poured, and then the terminal building main structure is constructed layer by layer upwards in the reverse construction mode, the completed structure layer is used as a temporary support system to realize the integration of "structure construction and load bearing", and the structural deformation and foundation pit stability in the construction process are effectively controlled.

[0102] (3) The existing 16th line station east and west sides and the surrounding foundation pit are symmetrically constructed in layers, each time 3m;

[0103] The existing Lize Business District Station of Line 16 adopts a symmetric layered excavation process, and the soil excavation work is simultaneously implemented in the east and west side and the surrounding reverse construction foundation pit. The single excavation depth is strictly controlled to be 3m, and the disturbance to the enclosure structure and the surrounding environment is reduced by step unloading. The specific construction process is as follows: when the right side foundation pit is excavated to the B4M elevation, the first transverse support is immediately constructed to form the initial force balance system; then the two horizontal supports corresponding to the B3 layer bottom plate and top plate are sequentially constructed by using the reverse construction method, and the support system is constructed. After the completion of the construction, the stiffness acceptance is carried out to ensure that the design stiffness requirement is met. After the three support systems are accepted and meet the strength conditions, the excavation is continued to the B4 layer bottom plate elevation, and the fourth support is simultaneously constructed, and finally the excavation of the foundation pit to the bottom is completed under the cooperative stress of the four supports. During the main structure construction stage, the bottom plate of the terminal building and the steel pipe column are first poured, and then the main structure of the terminal building is constructed layer by layer upwards in a reverse construction manner, the completed structure layer is used as a temporary support system, and the integration of “structure construction and load bearing” is realized, so as to effectively control the structural deformation and the stability of the foundation pit in the construction process.

[0104] The deformation values simulated by the above three groups of excavation step distances 1m, 2m and 3m are shown in Figure 8

[0105] S50, numerical simulation is performed on multiple second construction schemes to determine a vertical construction scheme of the foundation pit, and the synchronous layered excavation step distance is predetermined for the center area of the foundation pit and the reverse construction of the surrounding area;

[0106] In this embodiment, combined with the “economicity-safety” two-dimensional weight evaluation factor, according to the deformation curve and economicity comparison shown in Figure 8 , it is determined that scheme (2) is constructed, that is, the existing Lize Business District Station of Line 16 adopts a symmetric layered excavation process, and the soil excavation work is simultaneously implemented in the east and west side and the surrounding reverse construction foundation pit. The single excavation depth is strictly controlled to be 2m, and the disturbance to the enclosure structure and the surrounding environment is reduced by step unloading.

[0107] S60, based on the second construction scheme and combined with the stratum characteristics and engineering experience, multiple third construction schemes are constructed, and the multiple third construction schemes are block construction of the center area and the surrounding area of the foundation pit.

[0108] In this embodiment, based on the characteristics of the foundation pit and the symmetric layered construction with a single excavation of 2m, the foundation pit is divided into two center area blocks and six surrounding area blocks on the plane, and the multiple third construction schemes include:

[0109] (1) adopt a partition asynchronous excavation process, first construct two center area blocks in sequence, and then construct six surrounding area blocks in reverse;

[0110] ​The existing Lize Business District Station of Line 16 adopts the partition asynchronous excavation technology, and the construction sequence is "first two central blocks in sequence, then six peripheral blocks in reverse sequence". The specific construction steps are as follows: firstly, the construction of two central blocks is started, and the soil is excavated in layers, with the single excavation depth strictly controlled to 2m. The horizontal support is constructed synchronously with the excavation process to ensure the force balance of the enclosure structure. After the support system is accepted, the structure in this area is constructed by the sequence construction method, i.e. the foundation, wall, floor and other components are poured in sequence from bottom to top, which provides internal stable support for the construction of the peripheral area. After the structure construction of the two central blocks is completed and reaches the design strength, the soil excavation of the six peripheral blocks is carried out synchronously, with the single excavation depth also strictly controlled to 2m. The whole process follows the principle of "layered excavation and time-limited support", which maximizes the shortening of the time of the unsupported excavation of the foundation pit and reduces the risk of deformation. After the soil excavation of the six peripheral blocks reaches the design elevation of the pit bottom, reverse construction is immediately started. The floor, wall and vertical components are poured layer by layer from top to bottom, and the central structure and the temporary support system of the peripheral area are used to form a bearing frame to further stabilize the overall shape of the foundation pit. Finally, the overall closure of the whole foundation pit and structure is realized, and through the construction sequence of inside first and outside later, the anti-deformation effect of the central structure is fully utilized to ensure the safety of the project and the surrounding environment.

[0111] (2) The partition asynchronous excavation technology is adopted, and the construction sequence is "first six peripheral blocks in reverse sequence, then two central blocks in sequence";

[0112] The existing Lize Business District Station of Line 16 adopts the partition asynchronous excavation technology, and the construction sequence is "first six peripheral blocks in reverse sequence, then two central blocks in sequence";

[0113] (3) Adopting the partition asynchronous excavation technology, using the "block jump warehouse" order, first start two center area warehouse block construction, then use the "interval excavation" jump warehouse order to excavate six peripheral area warehouse blocks: excavate P1, P3, P5 warehouse blocks first, then excavate P2, P4, P6 warehouse blocks;

[0114] The existing No. 16 line Lize Business District Station foundation pit project adopts the partition asynchronous excavation technology, and is implemented in the order of "block jump warehouse". The specific construction steps are as follows: first, start the construction of two center area warehouse blocks, carry out soil layering excavation, strictly control the single excavation depth to 2m, and simultaneously construct horizontal supports to ensure the force balance of the enclosure structure. After the support system is accepted, the structure in this area is constructed by using the sequential construction method, that is, the foundation, wall, floor and other components are poured in sequence according to the "from bottom to top" order, providing internal stable support for the construction of the surrounding area. After the structure construction of the two center area warehouse blocks is completed and reaches the design strength, the peripheral area is divided into six independent warehouse blocks (numbered P1-P6), and the "interval excavation" jump warehouse order is used to carry out the work: excavate P1, P3, P5 warehouse blocks first, follow the principle of "layering excavation, time limit for support", immediately construct temporary support after single excavation of 2m, excavate to the design elevation of the pit bottom, then transfer to top-down construction, pour floor, wall and vertical components layer by layer, and form a local stable system using the center structure and the already constructed structure in this warehouse block. Excavate P2, P4, P6 warehouse blocks after 10 days or more, simultaneously implement support and top-down construction, accurately connect the construction joints with the center area and adjacent warehouse blocks, and after the top-down construction of all peripheral warehouse blocks is completed, the connecting parts of each warehouse block are poured again to form a closed structure system.

[0115] (4) Adopting the partition asynchronous excavation technology, using the "block jump warehouse" order, first start two center area warehouse block construction, then use the "interval excavation" jump warehouse order to excavate six peripheral area warehouse blocks: excavate P2, P4, P6 warehouse blocks first, then excavate P1, P3, P5 warehouse blocks.

[0116] The existing No. 16 line Lize Business District Station foundation pit project adopts a partitioned asynchronous excavation process, and a sequential implementation of "block jumping". The specific construction steps are as follows: first, start the construction of two central block warehouses, first perform soil layering excavation, strictly control the single excavation depth to be 2m, and simultaneously construct horizontal supports to ensure the force balance of the enclosure structure. After the support system is accepted, the structure in this area is constructed by using the sequential construction method, that is, the components such as foundation, wall and floor are poured in sequence according to the "from bottom to top" order, which provides internal stable support for the surrounding area construction. After the structure construction of the two central block warehouses is completed and reaches the design strength, the surrounding area is divided into six independent block warehouses (P1-P6), and the "interval excavation" jump sequence is used to carry out the work: the first batch of P2, P4 and P6 block warehouses are excavated, which follows the principle of "layered excavation, time-limited support", and after single excavation of 2m, temporary support is immediately constructed, and after excavation to the design elevation of the pit bottom, reverse construction is started, and the floor, wall and vertical components are poured layer by layer from top to bottom, and a local stable system is formed by using the central structure and the already constructed structure of the block warehouse. After 10 days or more, P1, P3 and P5 block warehouses are excavated, and support and reverse construction are simultaneously implemented, the construction joints are accurately connected with the central area and the adjacent block warehouses, and after the reverse construction of all the surrounding block warehouses is completed, the connecting parts of each block warehouse are poured again to form a closed structure system.

[0117] S70, numerical simulation is performed on multiple groups of third construction schemes to determine a lateral construction scheme of the foundation pit, and the lateral construction scheme is block construction of the central area by sequential construction and the surrounding area by reverse construction, the foundation pit is divided into two central block warehouses and six surrounding block warehouses in the plane;

[0118] In this embodiment, combined with the three-dimensional quantitative decision factors of "geology-structure-environment", according to the characteristics of the asymmetric excavation of the super-large deep foundation pit close to the existing underground structure, the central area is divided into two central block warehouses on both sides of the existing underground structure, and the surrounding area is divided into six surrounding block warehouses around the central area, as shown in Figure 9 , the surrounding block warehouses are P1-P6.

[0119] As can be easily understood, the central block warehouse is the central area of the foundation pit, and in this application, due to the existence of the existing underground structure, the existing underground structure separates the foundation pit, and excavates different depths on both sides, so the central area is divided into two central block warehouses to construct on both sides respectively, and the surrounding area is divided into six surrounding block warehouses.

[0120] The central block warehouse is constructed by using the sequential construction method "from bottom to top" according to the three-dimensional block division sequence, and the surrounding block warehouse is constructed by using the reverse construction method "from top to bottom" according to the three-dimensional block division sequence, that is, Figure 9 , reverse P1, reverse P2, reverse P3, reverse P4, reverse P5 and reverse P6. The sequential construction of the central area improves the construction efficiency, quickly forms the core support, the reverse construction of the surrounding area controls the structure deformation, and reduces the environmental disturbance.

[0121] S80, according to the determined vertical construction scheme and horizontal construction scheme of the foundation pit, determine the three-dimensional stereoscopic warehouse sequence, and adopt the asymmetric staggered joint warehouse mode for construction of the two central area warehouse blocks and the six peripheral area warehouse blocks.

[0122] In this embodiment, continuing to refer to Figure 9 , according to the “warehouse jumping mode”, the peripheral area warehouse blocks are divided into a group of P1, P3, P5 warehouse blocks and a group of P2, P4, P6 warehouse blocks, the P1, P3, P5 warehouse blocks are excavated first, and the P2, P4, P6 warehouse blocks are excavated subsequently (the excavation sequence can be interchanged);

[0123] And, the P1, P3, P5 warehouse blocks and the P2, P4, P6 warehouse blocks are designed to be staggered by 1 / 3 warehouse length in the plane, as shown in Figure 10 , Figure 11 , the P1 is full-length constructed, the P3 is reserved for 1 / 3 seam length for next step construction, the P5 is full-length constructed, the P2 is full-length constructed, the P4 is reserved for 1 / 3 seam length for next step construction, and the P6 is full-length constructed;

[0124] At the same time, the construction joints of the peripheral area warehouse blocks and the central area warehouse blocks are vertically staggered to avoid forming a through stress transmission path.

[0125] Further, according to the vertical member stiffness difference of the underground structure to be constructed, each central area warehouse block is divided into independent three-dimensional sub-warehouse blocks of “bottom plate sub-warehouse block”, “side wall sub-warehouse block” and “floor sub-warehouse block”; the bottom plate is separately divided into a bottom core warehouse due to its large thickness and high equivalent stiffness; the side wall and the floor are divided into side wall warehouse and floor warehouse due to the stiffness difference.

[0126] Similarly, each peripheral area warehouse block is divided into independent three-dimensional sub-warehouse blocks of “bottom plate sub-warehouse block”, “side wall sub-warehouse block” and “floor sub-warehouse block” according to the vertical member stiffness difference, so as to ensure that the layered excavation and support match the stiffness requirements of the corresponding vertical warehouse blocks and realize the vertical coordination of “excavation-support-structure construction”.

[0127] Further, the central area warehouse block is constructed “from bottom to top”, the bottom plate sub-warehouse block is excavated first and the foundation is poured, then the side wall sub-warehouse block is excavated layer by layer and the horizontal support is simultaneously constructed, and finally the floor sub-warehouse block is constructed; a “bottom plate warehouse advanced pouring combined with vertical member construction in stages” scheme is adopted, after the bottom plate is poured, 3 stress release joints with a width of 20 mm are reserved on the surface thereof, the joint width is monitored after 7 days, and after the joint width is stable, the side wall warehouse and the floor warehouse are poured layer by layer, the traditional sequential construction method is optimized to release the vertical shrinkage stress and avoid stress concentration between different stiffness members.

[0128] The peripheral zone bin block is constructed from top to bottom, and after excavation to the bottom design elevation, the floor sub-bin block, the side wall sub-bin block and the bottom plate sub-bin block are constructed from top to bottom, and in the construction process, the local stable system is formed by relying on the center stiffness core and the already constructed structure of the bin block.

[0129] After the construction of all sub-bin blocks is completed, the secondary pouring is performed on the connecting parts of each sub-bin block to enhance the bin block interface stiffness of the bottom plate sub-bin block, the side wall sub-bin block and the floor sub-bin block, and finally a closed three-dimensional overall structure is formed to realize the whole-process cooperation of "three-dimensional sub-warehouse", "staggered and jumping bin" and "combination construction of forward and reverse construction".

[0130] In summary, the present application aims to fill the theoretical gap by targeted research due to the lack of mature theoretical support and data reference for the design of construction schemes in such scenarios caused by the extreme working conditions, the great difficulty in risk control, and the lack of practical engineering cases and systematic research of the ultra-large deep foundation pit with asymmetric excavation and zero-distance proximity to existing underground structures. The present application focuses on analyzing the disturbance mechanism of key steps in different construction schemes on the existing building, and the differential settlement characteristics of the existing building foundation caused by the superimposed upper load during the construction phase of the terminal building structure.

[0131] In terms of research methods and technical paths, the present application adopts a combination of numerical simulation and field monitoring to quantify the displacement field (settlement, inclination) change law of the existing building under different construction steps, as shown in Figure 7 The numerical simulation results are consistent with the field test results; the disturbance control effects of multiple schemes are compared and analyzed to optimize the optimal construction process, as shown in Figure 12 The deformation value of the existing underground structure in the optimal scheme construction is greatly reduced.

[0132] The research results of the present application can form the disturbance control technical guidelines for asymmetric excavation and zero-distance proximity construction, and clearly define the safety threshold (such as the settlement rate of the existing building ≤0.5mm / d) and dynamic adjustment strategy of each construction step, providing replicable construction experience and technical support for similar projects.

[0133] As a person skilled in the art would readily understand that the above-mentioned preferred schemes can be freely combined and superimposed without conflict.

[0134] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A dynamic real-time optimization construction method for ultra-large deep foundation pits with asymmetric excavation and zero-distance proximity to existing underground structures, characterized in that, Includes the following steps: S10. Based on the characteristics of the ultra-large deep foundation pit with zero distance proximity to the existing underground structure during asymmetric excavation, the foundation pit is divided into a central area and a peripheral area on both sides of the existing underground structure. S20. Carry out the foundation pit construction according to the first construction plan. The first construction plan is to construct the foundation pit vertically in symmetrical layers, while monitoring the stress and deformation of the existing underground structure in real time. S30. Construct a numerical model and perform numerical simulation and inversion analysis on the first construction scheme. Verify the accuracy of the model based on the existing underground structure deformation simulation results and monitoring results. S40. Based on the first construction scheme and combined with the geological characteristics and engineering experience, construct multiple sets of second construction schemes. The multiple sets of second construction schemes are to simultaneously excavate multiple predetermined steps in the central area of ​​the foundation pit in the forward direction and the surrounding area in the reverse direction. S50. Numerical simulation is performed on multiple sets of the second construction scheme to determine the vertical construction scheme of the foundation pit. The vertical construction scheme is to excavate the central area of ​​the foundation pit in the forward direction and the surrounding area in the reverse direction simultaneously at predetermined step distances. S60. Based on the second construction scheme and combined with the geological characteristics and engineering experience, construct multiple sets of third construction schemes. The multiple sets of third construction schemes are block construction of the central area of ​​the foundation pit in the forward direction and the surrounding area in the reverse direction. S70. Numerical simulation is performed on multiple sets of the third construction scheme to determine the transverse construction scheme of the foundation pit. The transverse construction scheme is to construct the foundation pit in blocks by working forward in the central area and backward in the peripheral area. The foundation pit is divided into two central area blocks and six peripheral area blocks in the plane. S80. Based on the determined vertical and horizontal construction plans for the foundation pit, determine the three-dimensional compartmentalization sequence, and carry out construction of the two central compartments and six peripheral compartments using an asymmetrical staggered compartmentalization mode.

2. The construction method according to claim 1, characterized in that, In S20, the first construction plan is the initial design construction plan or the preliminary construction plan determined based on engineering experience.

3. The construction method according to claim 1, characterized in that, In S40, multiple sets of the second construction schemes include: The central area of ​​the foundation pit is excavated in a forward direction while the surrounding area is excavated in a reverse direction, with each excavation being 1m in length. The central area of ​​the foundation pit is excavated in a forward direction while the surrounding area is excavated in a reverse direction, with each excavation being 2m in length. The central area of ​​the foundation pit is excavated in a forward direction while the surrounding area is excavated in a reverse direction, with each excavation being 3 meters deep.

4. The construction method according to claim 3, characterized in that, In S50, the vertical construction scheme is to excavate the central area of ​​the foundation pit in a forward direction and the surrounding area in a reverse direction simultaneously in layers, with each excavation being 2m.

5. The construction method according to claim 1, characterized in that, In S60, the multiple sets of the third construction schemes include: (1) The asynchronous excavation process is adopted, with the two central blocks constructed in sequence first, and the six peripheral blocks constructed in reverse. (2) The asynchronous excavation process is adopted, with the six peripheral blocks constructed in reverse and the two central blocks constructed in sequence. (3) The asynchronous excavation process is adopted, and the "segmented excavation" sequence is adopted. First, the construction of two central area blocks is started, and then the six peripheral area blocks are excavated in the "interval excavation" sequence: the first batch of blocks P1, P3 and P5 are excavated, and then blocks P2, P4 and P6 are excavated. (4) The asynchronous excavation process is adopted, and the "segmented excavation" sequence is adopted. First, the construction of two central area blocks is started, and then the six peripheral area blocks are excavated in the "interval excavation" sequence: the first batch of blocks P2, P4 and P6 are excavated, and then blocks P1, P3 and P5 are excavated.

6. The construction method according to claim 5, characterized in that, In S80, the three-dimensional compartmentalization sequence is determined, and an asymmetrical staggered compartmentalization pattern is used for the construction of the two central compartments and six peripheral compartments, including: The six surrounding area blocks were divided into the first group of surrounding area blocks to be excavated in the first batch and the second group of surrounding area blocks to be excavated in the subsequent batch, according to the "skip-block mode". The first group of surrounding warehouse blocks and the second group of surrounding warehouse blocks are designed with "1 / 3 warehouse length offset" in the plane; The construction joints between the surrounding storage area and the central storage area are vertically staggered.

7. The construction method according to claim 6, characterized in that, In S80, each of the central area blocks is divided into independent three-dimensional sub-blocks, namely "bottom plate sub-block", "side wall sub-block", and "floor slab sub-block", according to the difference in the stiffness of the vertical components; Each of the surrounding blocks is divided into independent three-dimensional sub-blocks, namely "bottom slab sub-blocks", "side wall sub-blocks" and "floor slab sub-blocks", according to the difference in the stiffness of the vertical components, so as to achieve vertical coordination of "excavation-support-structural construction".

8. The construction method according to claim 7, characterized in that, The central area storage blocks are constructed "from bottom to top". First, the bottom slab storage blocks are excavated and the foundation is poured. Then, the side wall storage blocks are excavated layer by layer and the horizontal supports are constructed simultaneously. Finally, the floor slab storage blocks are constructed. The surrounding area storage blocks are constructed "from top to bottom". After excavating to the design elevation of the pit bottom, the floor slab storage blocks, side wall storage blocks, and bottom slab storage blocks are constructed "from top to bottom".

9. The construction method according to claim 8, characterized in that, After the bottom slab of the central area slab is poured, multiple stress relief joints are reserved on its surface and the joint width is monitored. After the joint width stabilizes, the side wall slabs are poured in layers.

10. The construction method according to claim 9, characterized in that, After all sub-blocks are constructed, secondary pouring is carried out at the connection points of each sub-block to enhance the rigidity of the block interfaces of the bottom slab sub-blocks, side wall sub-blocks, and floor slab sub-blocks, forming a closed three-dimensional integral structure.

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