Narrow site foundation pit support parameter dynamic regulation and control method and system

Abstract

This invention discloses a method and system for dynamic control of support parameters for foundation pits in confined spaces, relating to the field of foundation pit construction monitoring. The technical solution includes: S1, acquiring multi-source monitoring data of the foundation pit retaining structure, surrounding soil, and external environment; S2, inverting the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions based on the multi-source monitoring data; S3, constructing a spatiotemporal non-uniform stiffness gradient model based on the equivalent earth pressure distribution field, soil stiffness degradation field, and the spatial constraint boundary of the foundation pit; S4, determining the corresponding support parameter correction amount for each region based on the spatiotemporal non-uniform stiffness gradient model; S5, performing dynamic control of the support parameters based on the correction amount; and S6, iteratively updating the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data after control. The beneficial effects of this invention are: it enables regional dynamic control of support parameters, enhancing the coordinated control capability of the retaining structure, surrounding soil, and external environment.

Description

Technical Field

[0001] This invention relates to the field of foundation pit construction monitoring, and in particular to a method and system for dynamic control of foundation pit support parameters in confined spaces. Background Technology

[0002] With the increasing intensity of urban underground space development, deep foundation pit engineering is widely used in projects such as subway ancillary works, underground parking garages, integrated utility tunnels, and basements of high-rise buildings. Especially in urban built-up areas, foundation pit projects are often located near existing buildings, roads, underground pipelines, underground structures, or adjacent engineering structures. The construction site is narrow, the surrounding environment is sensitive, and the requirements for deformation control are high, forming typical construction conditions in confined spaces.

[0003] Existing foundation pit projects typically employ retaining structures such as diaphragm walls, pile banks, cast-in-place piles, and steel-cement-soil mixing walls, combined with steel supports, concrete supports, anchor cables, or a combination of these support methods. During construction, the condition of the foundation pit is usually assessed using monitoring data such as retaining structure displacement, support axial force, deep horizontal displacement of the soil, surface settlement, and deformation of surrounding buildings and structures. When monitoring values ​​approach or exceed warning thresholds, adjustments are made based on experience to the prestressing of supports, anchor cable tension, local reinforcement measures, or construction schedule.

[0004] However, existing technologies primarily rely on direct interpretation of monitoring values ​​or threshold-triggered control, mainly focusing on identifying surface response phenomena. They struggle to further identify the true interaction between the retaining structure and the surrounding soil, as well as the changes in soil stiffness. This leads to problems such as delayed, insufficient, or excessive regulation. Furthermore, the constraints around foundation pits in confined spaces often exhibit significant asymmetry, with varying support requirements at different depths and construction stages in different areas. Existing technologies often employ uniform parameters or control strategies, making it difficult to achieve refined, zoned, and phased regulation. Moreover, existing analysis methods are largely based on static parameters from the design phase, failing to reflect the dynamic changes in earth pressure distribution, soil stiffness, and support stress during construction. They also struggle to utilize new monitoring data after regulation to continuously refine the model and form a closed-loop control system.

[0005] Therefore, it is necessary to provide a dynamic control method and system for support parameters under the construction conditions of foundation pits in confined spaces, so as to improve the matching degree between support parameters and actual working conditions and enhance the coordinated control capability of the retaining structure, surrounding soil and external environment. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method and system for dynamic control of foundation pit support parameters in confined spaces.

[0007] The technical solution includes the following steps: S1. Obtain multi-source monitoring data on the foundation pit retaining structure, surrounding soil and external environment; S2. Based on the multi-source monitoring data, the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions are obtained by inversion. S3. Based on the equivalent earth pressure distribution field, soil stiffness degradation field and spatial constraint boundary of the foundation pit, construct a spatiotemporal non-uniform stiffness gradient model. S4. Determine the correction amount of the support parameters for each region based on the spatiotemporal non-uniform stiffness gradient model. S5. Perform dynamic adjustment of support parameters according to the correction amount of the support parameters; S6. Iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data after adjustment.

[0008] Preferably, the multi-source monitoring data in step S1 includes at least the displacement data of the retaining structure, the stress data of the support components, the deep horizontal displacement data of the surrounding soil, the surface settlement data outside the pit, and the deformation data of the environment outside the pit. The displacement data of the retaining structure is used to characterize the deformation state of the retaining structure at different depths, the stress data of the support components is used to characterize the stress state of the support system under the current working conditions, the deep horizontal displacement data of the surrounding soil is used to characterize the displacement response of the surrounding soil at different depths, and the surface settlement data and environmental deformation data outside the pit are used to characterize the impact of the foundation pit construction on the surrounding surface and sensitive protected objects.

[0009] Preferably, in step S2, a basic analysis model matching the current construction conditions is established based on the displacement data of the retaining structure, the stress data of the support components, and the deep horizontal displacement data of the surrounding soil. The parameters related to the lateral action of the soil are adjusted according to the deviation between the model's calculated response and the measured response, so as to invert the equivalent earth pressure distribution field under the current conditions.

[0010] Preferably, in step S2, based on the deep horizontal displacement data of the surrounding soil, the displacement data of the retaining structure, and the deformation data of the environment outside the pit, and according to the difference between the displacement changes of each monitoring point under the current working condition and the response under the initial working condition or the design reference state, the change state of the soil stiffness in the corresponding area is determined to form the soil stiffness degradation field under the current working condition.

[0011] Preferably, in step S3, the space of the foundation pit is divided into regions according to the planar outline of the foundation pit, the layout range of the retaining structure, the distribution of the support layers and the distribution of the surrounding environment, forming multiple analysis units with spatial location attributes and depth attributes. The equivalent earth pressure distribution field, the soil stiffness degradation field and the spatial constraint boundary of the foundation pit are mapped to each analysis unit to determine the target stiffness requirement of each analysis unit under the current working condition, and the spatiotemporal non-uniform stiffness gradient model is constructed.

[0012] Preferably, in step S4, based on the target stiffness requirement results corresponding to each analysis unit and the actual parameter state of the current support system in the corresponding area, a correspondence between the target stiffness requirement and the adjustable support parameters is established, and the stiffness requirement difference of each analysis unit is converted into the parameter correction direction and parameter correction magnitude of the support prestress, support axial force, anchor cable tension force or local reinforcement degree according to the correspondence.

[0013] Preferably, in step S4, when determining the correction amount of the support parameters corresponding to each region, the correction amount of the support parameters is checked or corrected in combination with the key control area, the parameter transition relationship between adjacent areas, the synergistic matching relationship between support parameters, the bearing capacity and adjustment margin of support components, as well as the construction space limitations and work accessibility.

[0014] Preferably, in step S5, the foundation pit support system is dynamically adjusted by adopting a zoned implementation method based on the correction amount of the support parameters corresponding to each region; wherein, for the correction amount of the support parameters with a large adjustment range, the adjustment is carried out by phased implementation, phased loading, phased unloading or gradual release, and the key control area and its adjacent areas are coordinated.

[0015] Preferably, in step S6, when the working conditions change or the preset update cycle is reached, real-time monitoring data after adjustment is obtained, and the target stiffness requirements of each analysis unit, the transition relationship between adjacent analysis units, and the temporal characteristics under the construction stage are re-identified and corrected based on the real-time monitoring data, so as to iteratively update the spatiotemporal non-uniform stiffness gradient model.

[0016] A dynamic control system for foundation pit support parameters in confined spaces, characterized in that it comprises: The monitoring data acquisition and processing module is used to acquire multi-source monitoring data of the foundation pit retaining structure, surrounding soil and external environment according to a preset acquisition strategy, and to preprocess the multi-source monitoring data. Based on the spatial constraint characteristics of different areas of the foundation pit, the module establishes the correspondence between monitoring data and spatial areas to form a structured monitoring dataset with spatial identification. The data inversion module is used to invert the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions based on the structured monitoring dataset. The stiffness gradient model construction module is used to construct a spatiotemporal non-uniform stiffness gradient model based on the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit. The control decision module is used to determine the corresponding support parameter correction amount for each region based on the spatiotemporal non-uniform stiffness gradient model, and to verify or correct the support parameter correction amount. The control and execution module is used to dynamically control the pit support system by implementing zoned control based on the correction amount of the support parameters, and to record the control process. The model iteration update module is used to acquire real-time monitoring data after regulation and to iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data.

[0017] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: 1. This invention acquires multi-source monitoring data of the retaining structure, surrounding soil and external environment, and inverts the equivalent earth pressure distribution field and soil stiffness degradation field based on the multi-source monitoring data. It can further identify the actual stress state and actual stiffness state of the foundation pit from the surface response, overcoming the problem that the existing technology mainly relies on direct interpretation of monitoring values ​​and is difficult to reflect the real interaction relationship.

[0018] 2. The present invention constructs a spatiotemporal non-uniform stiffness gradient model based on the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit. It can characterize the differences in support stiffness requirements under different regions, different depths, and different construction stages, and overcome the shortcomings of existing technologies that use uniform parameter control under narrow site conditions and are difficult to adapt to the problem of non-uniform spatial constraints.

[0019] 3. This invention determines the correction amount of support parameters corresponding to each region based on the spatiotemporal non-uniform stiffness gradient model, and establishes the correspondence between the target stiffness requirement and the support preload, support axial force, anchor cable tension or local reinforcement degree. It can directly convert the support requirements into executable parameter adjustment results, and improve the pertinence and accuracy of support parameter control.

[0020] 4. When determining the correction amount of support parameters, this invention combines the key control area, the parameter transition relationship between adjacent areas, the synergistic matching relationship of support parameters, the bearing capacity of components, and the conditions for feasible construction to check or correct the correction amount. This can avoid problems such as sudden changes in local stiffness, abnormal transfer of force, and difficulty in implementing control measures, thereby improving the engineering feasibility and safety of the control scheme.

[0021] 5. The present invention adopts a dynamic control method of zoned implementation for the foundation pit support system based on the correction amount of the support parameters corresponding to each region, and adjusts the parameters with large adjustment range by phased implementation, phased loading, phased unloading or gradual release, which can reduce the risk of sudden changes in the response of the retaining structure and soil caused by excessive adjustment at one time in the prior art.

[0022] 6. The present invention acquires real-time monitoring data after regulation and iteratively updates the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data, enabling the model to continuously reflect the actual state changes of the foundation pit during construction, forming a closed-loop control process of monitoring, inversion, modeling, regulation and updating, overcoming the shortcomings of existing technology models that are static and difficult to continuously correct.

[0023] 7. This invention is applicable to foundation pit engineering in narrow sites adjacent to existing buildings, roads, underground pipelines or other sensitive protected objects. It can control the deformation of the retaining structure while taking into account the response of the surrounding soil and the disturbance of the external environment, thereby improving the safety of foundation pit construction, environmental protection effect and construction organization adaptability. Attached Figure Description

[0024] Figure 1 The flowchart shows a method for dynamically adjusting the support parameters of a foundation pit in a confined space, as provided in the first embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] Example 1 This embodiment uses the foundation pit construction process under confined space conditions as an application scenario to illustrate the dynamic control method of foundation pit support parameters in confined space. The confined space refers to a construction site where existing buildings, roads, underground pipelines, underground structures, or adjacent engineering structures exist around the foundation pit, and where the construction site is limited, the support layout space is limited, and the requirements for foundation pit deformation control are high. Under such site conditions, the foundation pit retaining structure is significantly affected by the surrounding space constraints. The stress state, deformation response, and support requirements of the support system in different areas usually vary considerably. If uniform parameters are still used for support control, it is easy to lead to insufficient support capacity or redundant support configuration in some areas, thereby affecting the safety of foundation pit construction and the stability of the surrounding environment.

[0030] In this embodiment, the foundation pit can adopt an internal bracing support system, an anchor cable support system, or a combination of internal bracing and anchor cables. The retaining structure can be a diaphragm wall, pile wall, cast-in-place pile, steel-cement-soil mixing wall, or other commonly used foundation pit retaining structures. The foundation pit construction adopts a layered, segmented, or zoned excavation method. During the excavation process, the support parameters are dynamically analyzed, corrected, and controlled based on real-time on-site monitoring data to improve the matching degree between the support parameters and the actual working conditions.

[0031] To implement the method of this invention, a multi-source monitoring unit, a data processing platform, and a support parameter adjustment execution unit are set up at the foundation pit site. The multi-source monitoring unit is used to acquire multi-source monitoring data of the foundation pit retaining structure, surrounding soil, and external environment. The multi-source monitoring data may include one or more of the following: retaining structure displacement data, deep horizontal displacement data of surrounding soil, stress data of support components, surface settlement data outside the pit, and deformation data of the external environment. The deformation data of the external environment may include settlement data, tilt data, and deformation data of adjacent buildings (structures), underground pipelines, etc. Accordingly, the multi-source monitoring unit may be implemented using one or more of the following: displacement monitoring device, deep displacement monitoring device, support component stress monitoring device, settlement monitoring device, and tilt or strain monitoring device.

[0032] The data processing platform is communicatively connected to the multi-source monitoring unit and is used to receive multi-source monitoring data collected on-site, and to organize, analyze, and calculate the multi-source monitoring data. The data processing platform can be deployed in a construction site control terminal, an engineering monitoring server, or other computing devices with data processing capabilities. It is used to complete processes such as equivalent earth pressure distribution field inversion, soil stiffness degradation field inversion, spatiotemporal non-uniform stiffness gradient model construction, and determination of support parameter corrections. The support parameter adjustment execution unit is connected to the data processing platform and is used to dynamically control the foundation pit support system based on the support parameter corrections output by the data processing platform. The support parameter adjustment execution unit may include a support prestressing adjustment device, an anchor cable tensioning device, a local reinforcement construction device, or other execution devices used to adjust the support stress state and local support capacity.

[0033] S1. Obtain multi-source monitoring data on the foundation pit retaining structure, surrounding soil, and external environment.

[0034] It should be noted that the purpose of this step is to acquire multi-source monitoring data that comprehensively reflects the response of the retaining structure, the surrounding soil, and the external environment, based on the current construction conditions of the foundation pit. The acquired data are not isolated monitoring values, but rather a collection of monitoring information characterizing the working status of the foundation pit support system under the current conditions.

[0035] In practical implementation, the multi-source monitoring unit can collect data from various monitoring objects under the control of a central control system or data processing platform, according to a preset acquisition strategy. The acquisition strategy includes at least two components: acquisition frequency and acquisition time point. The acquisition frequency determines the data acquisition interval for different construction stages, while the acquisition time point ensures that various monitoring data of the retaining structure, surrounding soil, and external environment have a clear temporal correspondence under the same construction conditions. Preferably, various monitoring data are collected synchronously or correspondingly according to a unified time benchmark.

[0036] Furthermore, the multi-source monitoring data acquired in this step includes at least the following: retaining structure displacement data, support component stress data, deep horizontal displacement data of the surrounding soil, surface settlement data outside the pit, and environmental deformation data outside the pit. Retaining structure displacement data reflects the deformation of the retaining structure at different depths; preferably, horizontal displacement data of the top, middle, and bottom of the retaining structure is acquired, and vertical displacement data can also be acquired if necessary. Support component stress data reflects the stress state of supports, anchors, or other support components under the current working conditions. Deep horizontal displacement data of the surrounding soil characterizes the horizontal displacement response of the surrounding soil at different depths. Surface settlement data outside the pit reflects the range and degree of impact of pit excavation and support adjustments on the surrounding surface. Environmental deformation data outside the pit reflects the deformation response of existing buildings, underground pipelines, and other sensitive protected objects during construction.

[0037] It should also be noted that the aforementioned multi-source monitoring data can be obtained using commonly used monitoring equipment in this field. This invention does not limit the use of a specific model or type of monitoring equipment; any equipment capable of acquiring data from the corresponding monitoring object and meeting the engineering monitoring accuracy requirements can be used to implement this step.

[0038] Furthermore, to ensure that the acquired data accurately corresponds to the current construction conditions, the data collection frequency can be dynamically adjusted according to the construction stage and site conditions. During relatively stable construction phases, periodic data collection can be conducted at the conventional frequency. When the excavation depth changes, support components are loaded or unloaded, local reinforcement is implemented, the bottom construction is switched, or monitoring data shows a significant trend, the data collection frequency can be increased to enhance the ability to capture sudden changes in the current working conditions.

[0039] After completing the collection of various data, the acquired data should be aggregated and processed. Specifically, the displacement data of the retaining structure, the stress data of the support components, the deep horizontal displacement data of the surrounding soil, the surface settlement data outside the pit, and the deformation data of the environment outside the pit should be organized according to a unified data format. A correspondence between the measuring point number, the collection time, the monitoring type, and the monitoring value should be established so that monitoring data from different sources and of different types can be managed uniformly under the same data structure.

[0040] Furthermore, after the multi-source monitoring data is collected, preprocessing should be performed to improve the usability and reliability of the data. Preprocessing may include anomaly identification and removal, missing data completion, and data smoothing. Anomalies can be identified based on the continuity of changes in the same measuring point over time periods, the consistency of responses between adjacent measuring points, and the matching relationship between construction conditions and monitoring changes. For missing data caused by monitoring interruptions, communication anomalies, or equipment failures, it can be completed by combining valid data from previous and subsequent time periods, data from neighboring measuring points, or historical data from similar conditions. For high-frequency fluctuating data caused by sensor noise or environmental interference, smoothing methods can be used to reduce random interference.

[0041] It should also be noted that, in order to ensure the reliability of the data source itself, the status of the monitoring equipment can be checked simultaneously during the data acquisition process. In practice, the status of the monitoring equipment can be determined based on information such as whether the equipment output is continuous, whether the numerical changes are reasonable, and whether the responses between adjacent measuring points are basically consistent. When an abnormal failure or obvious distortion of the output of a certain measuring point is found, the data of that measuring point can be marked, temporarily blocked, or manual review can be initiated.

[0042] Furthermore, in the scenario of constructing a foundation pit in a confined space, where the surrounding constraints are often significantly uneven, it is preferable to establish a correspondence between multi-source monitoring data and the spatial areas of the foundation pit. Specifically, each monitoring point can be zoned and labeled according to the spatial relationship between different sides of the foundation pit and existing buildings, roads, underground pipelines, or open areas, so that the acquired data not only has temporal continuity but also spatial distinguishability.

[0043] It should be noted that the result of this step is a structured multi-source monitoring dataset corresponding to the current construction conditions. This multi-source monitoring dataset includes at least the displacement information of the retaining structure, the stress information of the support components, the deep horizontal displacement information of the surrounding soil, and the deformation information of the external environment. Furthermore, a unified temporal and spatial correspondence has been established between the above information.

[0044] S2. Based on the multi-source monitoring data, the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions are obtained by inversion.

[0045] It should be noted that the purpose of this step is to further transform the surface response information from multi-source monitoring data, which directly reflects the displacement of the retaining structure, the stress on the support components, the deformation of the surrounding soil, and changes in the external environment, into state results that can characterize the actual interaction between the retaining structure and the surrounding soil under the current construction conditions. Specifically, the equivalent earth pressure distribution field formed in this step is used to characterize the actual lateral action of the soil outside the retaining structure on the retaining structure, and the soil stiffness degradation field is used to characterize the actual deformation capacity change of the surrounding soil under the current conditions.

[0046] Furthermore, in this step, the structured multi-source monitoring dataset is first retrieved, and the monitoring data corresponding to the current construction condition is extracted from it. The current construction condition here refers to the range of on-site conditions corresponding to a specific excavation stage, a specific support loading stage, a specific local reinforcement stage, or a specific construction disturbance stage. To avoid mixing of monitoring data between different construction stages, in practice, the monitoring data should be correlated with construction records, excavation depth, support installation status, and on-site work nodes.

[0047] It should be noted that the equivalent earth pressure distribution field is not a direct application of the theoretical earth pressure results, but rather an inversion of the actual lateral load distribution results based on the displacement response of the retaining structure, the stress response of the support components, and the deformation response of the surrounding soil under the current working conditions. Due to the combined effects of multiple factors during the construction of foundation pits in confined spaces, such as uneven spatial constraints, differences in the stiffness of the support system, the propagation of excavation disturbances, and the influence of surrounding sensitive targets, the actual action state of the soil outside the retaining structure on the retaining structure usually differs from the theoretical earth pressure distribution used in the conventional design stage. Therefore, it is necessary to infer and identify this action state based on field monitoring data.

[0048] Furthermore, when performing the equivalent earth pressure distribution field inversion, a coupling analysis relationship between the retaining structure and the surrounding soil that matches the current foundation pit working condition should be established first. Specifically, a basic analysis model under the current working condition can be established based on the foundation pit's geometric dimensions, retaining structure type, support layout, excavation depth, soil strata distribution, and the spatial location of monitoring points. This basic analysis model describes the interaction between the retaining structure, support system, and surrounding soil, and uses the retaining structure displacement data, support component stress data, and deep horizontal displacement data of the surrounding soil as correction criteria. During the inversion process, by continuously adjusting the parameters related to the lateral action of the soil in the model, the calculated responses of the retaining structure and support components gradually approach the measured responses, thereby deriving the equivalent earth pressure distribution state corresponding to the current working condition.

[0049] It should also be noted that the soil stiffness degradation field is used to characterize the degree of stiffness reduction of the surrounding soil relative to its initial state under the current construction conditions and its spatial distribution. During the excavation of the foundation pit, the soil will experience changes in its deformation capacity due to factors such as unloading, stress path changes, adjustment of support forces, groundwater disturbance, and changes in surrounding additional loads. This change usually manifests as a weakening of the soil's resistance to deformation in some areas, which in turn affects the deformation mode of the retaining structure and the stress state of the support system.

[0050] Furthermore, when performing soil stiffness degradation field inversion, the deep horizontal displacement data of the surrounding soil, the displacement data of the retaining structure, and the deformation data of the external environment can be used as the main analytical basis. In practice, the displacement changes of each monitoring point under the current working condition can be compared with the response under the initial working condition or design reference condition. Combined with the coupling relationship between the retaining structure and the surrounding soil, areas with significant deformation increases, high displacement concentration, and expanded influence transmission range can be identified. For the above-mentioned areas, it can be further determined whether the deformation constraint capacity of the soil under the current working condition has weakened compared with the initial state, and the soil stiffness change results in different regions and depth ranges can be formed accordingly.

[0051] Furthermore, to improve the inversion accuracy of the equivalent earth pressure distribution field and soil stiffness degradation field, this step preferably adopts an iterative correction method for joint inversion. Specifically, an initial inversion result can be generated based on the current monitoring data. This initial inversion result is then substituted into the aforementioned basic analysis model to obtain the retaining structure displacement response, support component stress response, and surrounding soil displacement response corresponding to the current parameter state. This calculated response is then compared with the measured monitoring data. If a significant deviation still exists between the two, the parameters related to the lateral action state and soil stiffness state are adjusted, and the calculation and comparison are repeated until the model-calculated response and the actual monitoring response meet the predetermined matching requirements.

[0052] It should also be noted that, to enhance the utilization of multi-source monitoring data in inversion analysis, the role of different monitoring data in result identification can be comprehensively considered during the inversion process. Specifically, the retaining structure displacement data is mainly used to correct the overall deformation trend of the retaining structure; the support component stress data is mainly used to correct the constraint state of the support system on the deformation of the retaining structure and soil; the deep horizontal displacement data of the surrounding soil is mainly used to correct the response characteristics of the soil in the depth direction; and the deformation data of the external environment is mainly used to assist in identifying the impact range of the foundation pit construction on the surrounding sensitive areas.

[0053] Furthermore, in the scenario of foundation pit construction in confined spaces, since different sides of the foundation pit often correspond to different spatial constraints and different surrounding sensitive targets, this step preferably performs inversion processing by region. In specific implementation, the multi-source monitoring data can be divided into regions based on the spatial relationship between different sides of the foundation pit and existing buildings, roads, underground pipelines, underground structures, or open areas, and the equivalent earth pressure characteristics and soil stiffness change characteristics of each region under the current working conditions can be identified separately.

[0054] Furthermore, in this step, the intermediate parameter results obtained from the inversion should be further mapped into continuous state field results. In specific implementation, the lateral action state of the soil in each region obtained from the inversion can be organized according to the depth distribution and regional distribution of the retaining structure to form an equivalent earth pressure distribution field; at the same time, the soil stiffness variation state in each region obtained from the inversion can be organized according to the soil layer distribution, depth range and spatial region to form a soil stiffness degradation field.

[0055] It should also be noted that after the inversion results are generated, it is preferable to perform a rationality check on the equivalent earth pressure distribution field and the soil stiffness degradation field. In specific implementation, the generated equivalent earth pressure distribution field and soil stiffness degradation field can be re-substituted into the foundation analysis model to calculate the response results of the retaining structure displacement, the stress on the support components, and the displacement of the surrounding soil, and then compared with the actual monitoring data. When the deviation between the calculated results and the measured results is within the allowable range, the current inversion results can be considered to effectively represent the actual state under the current construction conditions; when the deviation exceeds the allowable range, the area division method, parameter correction method, or data matching relationship can be further adjusted before re-inverting.

[0056] It should be noted that this step produces two results: the equivalent earth pressure distribution field and the soil stiffness degradation field under the current working conditions. This step generates the actual stress state field and the actual stiffness state field that match the current working conditions.

[0057] S3. Based on the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit, construct a spatiotemporal non-uniform stiffness gradient model.

[0058] It should be noted that the purpose of this step is to uniformly couple the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit, forming a spatiotemporal non-uniform stiffness gradient model that can characterize the differences in support stiffness requirements under different regions, depths, and construction conditions of the foundation pit. This spatiotemporal non-uniform stiffness gradient model is not a simple superposition of various input information, but rather a model result that comprehensively considers the actual lateral forces currently acting on the retaining structure, the current deformation capacity of the surrounding soil, and the differences in external constraint conditions in different regions, thus providing a unified expression of the support stiffness requirements.

[0059] It should be noted that the spatial constraint boundary in this step is used to characterize the external constraints and corresponding deformation control requirements of different areas of the foundation pit in a confined space. The spatial constraint boundary includes not only the geometric and construction conditions such as the foundation pit's own plan shape, corner positions, retaining structure outline, support component layout, excavation depth range, and construction access location, but also the constraints formed by external environmental conditions such as surrounding existing buildings, roads, underground pipelines, underground structures, adjacent engineering structures, and open areas.

[0060] Furthermore, in practical implementation, the foundation pit space is first divided into regions based on the foundation pit's planar outline, the layout of the retaining structure, the distribution of support layers, and the distribution of the surrounding environment. This regional division can be carried out along the perimeter of the foundation pit or by layering along the depth direction, thus forming analysis units with spatial location and depth attributes. For corner locations, areas near existing buildings, roads, underground pipelines, and locations with significantly limited construction space, the analysis unit division can be appropriately refined; for areas with relatively uniform spatial conditions and relatively low sensitivity to the surrounding environment, larger analysis units can be appropriately used.

[0061] Furthermore, after dividing the analysis units, the equivalent earth pressure distribution field is mapped to the corresponding retaining structure area and depth segment, and the soil stiffness degradation field is mapped to the corresponding soil area and depth range. These two fields are then correlated with the spatial constraint boundaries corresponding to each analysis unit. The equivalent earth pressure distribution field reflects the magnitude and distribution characteristics of the actual lateral soil forces acting on the retaining structure in the area where each analysis unit is located. The soil stiffness degradation field reflects the degree of deformation capacity attenuation in the soil in the area where each analysis unit is located. The spatial constraint boundaries reflect the allowable deformation level and feasible support layout conditions in the area where each analysis unit is located. By unifying and correlating these three types of information, the required support stiffness level and its differences for different analysis units under the current construction conditions can be identified.

[0062] It should also be noted that the spatiotemporal nonuniform stiffness gradient model in this step is not equivalent to a single set of stiffness values, but rather is used to characterize the continuous spatial variation of support stiffness requirements and their dynamic variation during the construction process. The spatial nonuniformity characterizes the differences in stiffness requirements between different areas around the foundation pit, different sections at different depths, and locally sensitive areas. The temporal variation characterizes how the stiffness requirements of different analysis units adjust as the excavation depth changes, support components are gradually installed or adjusted, local reinforcement is implemented, and monitoring responses are updated.

[0063] Furthermore, when constructing a spatiotemporally non-uniform stiffness gradient model, the stiffness requirement expression results for each analysis unit can be generated first. The stiffness requirement of each analysis unit is determined by at least the following aspects: first, the lateral action level of the actual soil outside the retaining structure, characterized by the equivalent earth pressure distribution location; second, the degree of soil deformation capacity attenuation, characterized by the soil stiffness degradation location; third, the sensitivity of the surrounding environment and the allowable deformation level, characterized by the spatial constraint boundary; and fourth, the layout conditions of the support components and the conditions for construction feasibility. By comprehensively considering the above factors, the target stiffness requirement results for each analysis unit under the current working conditions can be generated.

[0064] Furthermore, to ensure the model accurately reflects the transitional relationships between different analysis units, the stiffness requirement variations between adjacent analysis units should be coordinated when generating the stiffness requirement expression results. In practice, the magnitude and direction of stiffness requirement variations should be continuously transitioned based on the response correlation between adjacent areas, thereby forming a gradually changing stiffness gradient along the circumference and depth of the foundation pit, avoiding sudden changes in local stiffness, stress imbalance, or abnormally concentrated deformation.

[0065] It should also be noted that, in confined spaces, due to the often significant asymmetry of surrounding boundary constraints, it is preferable to establish differentiated stiffness gradient expressions for areas near existing buildings, roads, underground pipelines, underground structures, and relatively open areas. For areas near sensitive targets such as existing buildings, roads, or underground pipelines, higher stiffness control requirements can be assigned; for more open areas with lower sensitivity to the external environment, local stiffness control requirements can be appropriately reduced while meeting overall stability requirements.

[0066] Furthermore, to enable the model to be updated synchronously with construction conditions, construction stage factors should be incorporated into the model when constructing the spatiotemporal non-uniform stiffness gradient model. These construction stage factors include at least the current excavation layer, the number of installed support layers, the current stress state of the support components, the implementation status of local reinforcement, and the monitoring of response change trends. As construction progresses, the equivalent earth pressure distribution field and the soil stiffness degradation field will change, and the stiffness requirements corresponding to different analysis units will also change accordingly.

[0067] Furthermore, in practical implementation, the target stiffness requirements of each analysis unit can be uniformly organized based on the stiffness requirement results of each analysis unit, the transition relationship between adjacent units, and the feasible range defined by the spatial constraint boundary, forming a spatiotemporal non-uniform stiffness gradient model under the current working condition. The output of this model can be expressed as the target stiffness requirement value, target stiffness requirement level, relative stiffness distribution order, or other results that can characterize the differences in stiffness requirements for each analysis unit.

[0068] Furthermore, to ensure the rationality of the constructed model, a consistency check can be performed after the model is formed. Specifically, the stiffness requirement distribution of each analysis unit represented by the model can be compared with the equivalent earth pressure distribution field, the soil stiffness degradation field, and the current monitoring response trend. This helps determine whether areas with higher stiffness requirements correspond to locations with greater actual stress, more significant soil stiffness degradation, or more sensitive surrounding environments, and whether areas with lower stiffness requirements correspond to locations with relatively open spaces or relatively gentle responses. When the model output matches the actual response pattern under the current working condition, the model can be considered to effectively describe the support stiffness requirement distribution under the current working condition. When there is a significant mismatch, the method of dividing the analysis units, the spatial constraint boundary association method, or the transition relationship between adjacent areas can be adjusted, and the model can be reconstructed.

[0069] It should be noted that this step produces a spatiotemporal non-uniform stiffness gradient model under the current working conditions. This step allows for the generation of a support stiffness requirement distribution that is adapted to the conditions of confined spaces.

[0070] S4. Based on the spatiotemporal non-uniform stiffness gradient model, determine the correction amount of the support parameters corresponding to each region.

[0071] It should be noted that the purpose of this step is to determine the specific support parameter adjustment results corresponding to the target stiffness requirements of each area. The support parameter correction amount refers to the increment, reduction, or maintenance amount required relative to the current support state. Using the expression of correction amount allows the adjustment results to directly correspond to the existing support state on site, facilitating adjustments during actual construction.

[0072] Furthermore, the adjustment amount of the support parameters can be expressed as an adjustment of the support prestress, support axial force, anchor cable tension, local reinforcement degree, or other parameter changes that can alter the support constraint capacity of the corresponding area, depending on the support system type and on-site adjustable conditions. In cases where the support capacity of a local area is insufficient, soil stiffness degrades significantly, or spatial constraint requirements are high, the adjustment amount of the support parameters can also be reflected as an adjustment of local reinforcement measures to improve the support effect in the corresponding area.

[0073] Furthermore, in practical implementation, the target stiffness requirement results corresponding to each analysis unit can be read first, and combined with the actual parameter status of the current support system in the corresponding area, the difference in support capacity of each area can be identified. The actual parameter status can be determined by combining the current stress state of the support components, the deformation state of the retaining structure, the arrangement state of the support components, and the current construction stage, and is used to characterize the support constraint capacity actually provided in the corresponding area. By comparing the target stiffness requirement with the current support capacity, the direction and magnitude of parameter correction for each area can be determined.

[0074] Furthermore, when determining the correction amounts for support parameters in each area, a correspondence should be established between the target stiffness requirement and the adjustable support parameters. In practice, this correspondence can be established based on the structure of the support system, the characteristics of the effects of various support components on the overall support stiffness, and the influence of different parameter changes on the deformation of the retaining structure and the environmental response. Through this correspondence, the stiffness requirement difference of each analysis unit can be converted into specific parameter correction directions and magnitudes.

[0075] It should also be noted that different types of support parameters have different adjustment characteristics and applicable ranges. Therefore, when determining the correction amount of support parameters, it is not advisable to use a single parameter to uniformly address the stiffness requirements of all areas. For support systems that mainly bear lateral restraint, the stiffness requirements of the corresponding areas can be met primarily by adjusting the support preload or support axial force. For anchoring systems that mainly bear deep restraint, the stiffness requirements of the corresponding areas can be met primarily by adjusting the anchor cable tension or graded loading. For areas with significant stiffness degradation, deformation concentration, or insufficient local support capacity, the support effect of the corresponding areas can be improved through local reinforcement.

[0076] Furthermore, in the scenario of foundation pit construction in confined spaces, the spatial constraints and sensitivity of the surrounding environment often vary across different areas. Therefore, when determining the correction amount for support parameters, key control areas can be prioritized. These key control areas can be understood as areas with high target stiffness requirements, significant deviations in current support capacity, a high concentration of surrounding sensitive targets, significant local stiffness degradation, or prominent construction space constraints. For these areas, higher correction priority and stricter correction control requirements can be assigned.

[0077] Furthermore, when determining the correction amount of support parameters for each area, it should not be simply determined proportionally based on the target stiffness requirement. Instead, it should comprehensively consider the current construction stage, current stress state, local environmental sensitivity, and on-site feasibility. For areas with high deformation control requirements and many surrounding sensitive targets, when the corresponding stiffness requirement exceeds the current support capacity, the correction amount of support parameters for that area should be increased first. For areas with relatively open spaces, low environmental sensitivity, and relatively abundant current support capacity, the correction amount of support parameters for the corresponding area can be appropriately reduced.

[0078] It should also be noted that when determining the correction amount for support parameters, the parameter changes between adjacent areas should be coordinated. In specific implementation, for analysis units adjacent to areas with high stiffness requirements, an appropriate transition correction amount can be set to ensure that the changes in support parameters between adjacent areas remain continuous, thereby reducing the risk of abnormal local stress transfer and deformation concentration.

[0079] Furthermore, in this step, the adjustment amount of the support parameters can be determined using a tiered control method. For areas with small differences in stiffness requirements and relatively gentle response changes, a small-amplitude parameter fine-tuning method can be used; for areas with stiffness requirements significantly higher than the current support capacity and more obvious local responses, a larger-amplitude parameter adjustment method can be used; for areas with obvious adverse trends, insufficient support capacity, and high environmental sensitivity, reinforcement correction can be carried out in combination with local strengthening methods based on parameter adjustments.

[0080] Furthermore, in determining the correction amount of support parameters, the synergistic matching relationship between different support parameters should also be considered. When a certain area needs to improve its overall support capacity, it may not be possible to meet the requirements by adjusting a single parameter alone, but rather by combining the support system, anchoring system, and local reinforcement measures for synergistic correction. Therefore, when determining the parameter correction amount, the characteristics of the effects of different parameters on the deformation of the retaining structure, soil response, and environmental impact should be considered to avoid conflicts or mutual cancellations between different control measures.

[0081] Furthermore, when determining the correction amount for support parameters, the load-bearing capacity of on-site components, adjustment margin, and feasibility of construction should be comprehensively considered. Each support component has a corresponding load-bearing range and adjustment range, and the determined parameter correction amount should not exceed the safe adjustment capacity of the existing components. For parameters that directly affect the stress state of components, such as support prestressing force and anchor cable tension, the correction amount should be determined in conjunction with the current stress level of the components and the remaining adjustment capacity. For parameters of local reinforcement, the correction amount should be determined in conjunction with the on-site working space, equipment accessibility, and construction schedule. For correction amounts that are difficult to implement immediately under current conditions, they can be adjusted to phased implementation or other feasible methods can be used as alternatives.

[0082] It should also be noted that in confined spaces, the limitations of construction space and operational accessibility directly affect the determination of parameter correction amounts. For areas with limited operating space, difficult equipment access, or insufficient conditions for adjusting existing components, priority should be given to adjustment methods that do not require large-scale component replacement or new structures, such as prioritizing stress adjustment of existing support components, graded loading, or local reinforcement. For areas with operational conditions, a more comprehensive approach to adjusting support parameters can be adopted based on the target stiffness requirements.

[0083] Furthermore, in this step, it is preferable to organize the determined support parameter corrections into a structured result. The structured result should at least clearly define the corresponding control area, control parameter type, parameter correction direction, parameter correction magnitude, and corresponding construction condition information. If necessary, it may also include auxiliary information such as control priority order or control implementation conditions.

[0084] It should also be noted that, to ensure the rationality of the determined results, it is preferable to verify the adjustment amount of the support parameters. In practice, the trends of displacement changes in the retaining structure, stress changes in the support components, and environmental response changes after the implementation of the proposed parameter adjustments can be predicted, and it can be determined whether they meet the support capacity adjustment requirements for the corresponding area. When the prediction results match the target requirements, the determined support parameter adjustments can be considered reasonable and effective; when the prediction results show significant deviations or may cause new adverse responses, the parameter adjustments can be further adjusted and re-verified.

[0085] It should be noted that this step produces the corrected support parameters for each area under the current construction conditions. This step allows for the generation of support parameter adjustments that match the current working conditions.

[0086] S5. Perform dynamic adjustment of support parameters according to the correction amount of the support parameters.

[0087] It should be noted that the purpose of this step is to adjust the parameters of the foundation pit support system according to the determined correction amount of the support parameters, so that the actual stress state, constraint state and local support capacity of the support system change towards the target requirements. The dynamic control of the support parameters is not a one-time, static parameter setting, but a process of adjusting the corresponding support parameters in real time, by region and as needed, based on the current construction conditions, the on-site support status and the differences in the control area.

[0088] Furthermore, the control targets implemented in this step can be determined based on the support system type and on-site adjustable conditions. When the foundation pit adopts an internal support system, the dynamic control of support parameters can mainly be reflected in the adjustment of support preload, support axial force, or local support constraint capacity. When the foundation pit adopts an anchor cable support system, the dynamic control of support parameters can mainly be reflected in the adjustment of anchor cable tension, anchor cable graded loading, or local anchoring capacity. When the foundation pit adopts a combined support system, the dynamic control of support parameters can also be reflected in the coordinated adjustment between different support components. For situations where there is significant stiffness degradation, obvious deformation concentration, or where conventional parameter adjustments are insufficient to meet requirements in local areas, local reinforcement control can also be implemented.

[0089] Furthermore, in specific implementation, the parameter type, correction direction, and correction magnitude corresponding to each control area can be identified first based on the correction amount of the support parameters, and then the implementation can be organized separately for each area. For areas that need to improve support capacity, the corresponding support parameters can be positively adjusted; for areas with relatively abundant support capacity and allowing for a moderate release of deformation coordination capacity, the corresponding support parameters can be negatively adjusted; for areas where the current support capacity is basically consistent with the target requirements, the original parameter state can be maintained without significant adjustment.

[0090] It should be noted that when adjusting the relevant parameters of the support system, the preload or axial force of the support can be applied in stages, unloaded in stages, or maintained quantitatively according to the correction requirements of the corresponding area. In specific implementation, existing loading devices, adjustment devices, or other adjustable support components can be used to apply corresponding adjustments to the support components, so that the support reaches the required parameter state without exceeding the safe bearing range and adjustment range of the components. For situations where the support stiffness requirement in a local area increases and the adjustment range of the existing support components is insufficient, local reinforcement measures can be implemented according to the site conditions.

[0091] Furthermore, when adjusting the relevant parameters of the anchoring system, the anchor cable tension can be adjusted according to the correction requirements of the corresponding area. The anchor cable tension can be adjusted in a single step or in stages to avoid abrupt changes in the response of the retaining structure and surrounding soil due to excessively rapid local adjustments. For areas with high requirements for deep displacement control or significant soil stiffness degradation, the deep constraint capacity can be enhanced primarily through adjustments to the anchoring system parameters. For areas with insufficient anchoring capacity or significant stress deviations, local anchoring reinforcement can be used for adjustment.

[0092] It should also be noted that when implementing local reinforcement and control, local reinforcement or local support enhancement can be implemented in local areas according to the reinforcement requirements corresponding to the correction amount of support parameters. In specific implementation, in areas with concentrated deformation, areas with obvious soil stiffness degradation, or areas where the adjustment of support parameters is difficult to directly meet the requirements, local reinforcement measures can be used to improve the soil constraint capacity or the overall support capacity of the support system in the corresponding areas.

[0093] Furthermore, when implementing dynamic adjustment of support parameters, a zoned implementation approach should be adopted. Due to significant differences in spatial constraints, environmental sensitivity, and support requirements across different areas of a confined site, it is not advisable to uniformly adjust parameters across the entire pit at the same amplitude and pace. Instead, differentiated adjustments should be implemented based on the corresponding correction amounts for each area. For key control areas, priority should be given to implementing corresponding control actions; for areas adjacent to key control areas, coordinated adjustments can be implemented synchronously according to transitional correction requirements; for general areas, parameter adjustments can be implemented in batches based on current working conditions and site conditions.

[0094] Furthermore, when implementing dynamic adjustment of support parameters, the continuity and gradualness of the adjustment process should be controlled. Support parameter adjustments should not be made drastically in a single, localized area. In practice, for adjustments with large magnitudes, phased implementation, multiple loadings, or gradual releases can be used. For situations where multiple areas require adjustment simultaneously, the implementation sequence should be rationally arranged according to the importance of the areas, environmental sensitivity, and on-site operating conditions.

[0095] It should also be noted that when dynamically adjusting support parameters, the coordination relationship between adjacent areas should be considered simultaneously. Specifically, when adjusting a region to increase its support capacity, attention should be paid to whether adjacent areas show insufficient restraint or an increased local response due to force transmission; similarly, when adjusting a region to decrease its support capacity, its impact on the deformation coordination state of adjacent areas should be assessed. For areas with obvious linkages, parameter adjustments can be implemented synchronously in a coordinated manner.

[0096] Furthermore, when implementing this step, on-site construction conditions and operational safety requirements should also be taken into account. Dynamic adjustment of support parameters should be carried out within the safe bearing capacity of the support components, on-site operational capabilities, and permitted construction organization limits. For adjustments requiring immediate implementation, they can be executed promptly in conjunction with the current operational status; for adjustments restricted by construction access, equipment accessibility, overlapping operations, or work periods, implementation can be arranged provided that safety and construction organization requirements are met. For adjustments that cannot be directly completed under current conditions, they can be handled through phased implementation, partial substitution, or delayed implementation.

[0097] Furthermore, in this step, it is preferable to manage the dynamic adjustment process of support parameters in a recordable manner. This recordable manner should at least include the adjustment area, the adjustment object, the parameter correction direction, the parameter correction magnitude, the implementation time, and the implementation status. By recording the execution process, the implementation status of support parameter adjustment in each area can be clearly reflected.

[0098] It should be noted that after this step is completed, the actual parameter state of the support system will change accordingly, and the support constraint capacity, local support strength, and overall support state in different areas will also be adjusted accordingly. By implementing this step, dynamic adjustment results of support parameters adapted to the current working conditions can be generated.

[0099] S6. Iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data after adjustment.

[0100] It should be noted that the purpose of this step is to dynamically correct the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring response after the implementation of dynamic adjustment of support parameters. This ensures that the model continuously reflects the actual stress state, actual stiffness state, and changes in support requirements of the foundation pit under the current construction conditions. The iterative update is not a simple repetition of the original model, but rather a re-identification and correction of the stiffness requirement expression of each region, the transition relationship between regions, and the spatiotemporal distribution characteristics in the model based on new field monitoring results.

[0101] Furthermore, in specific implementation, real-time monitoring data after the adjustment of support parameters should be obtained first. This real-time monitoring data remains multi-source monitoring data of the foundation pit retaining structure, surrounding soil, and external environment, preferably including retaining structure displacement data, support component stress data, deep horizontal displacement data of surrounding soil, surface settlement data outside the pit, and deformation data of the external environment. The adjusted real-time monitoring data can reflect the actual changes in the response of the retaining structure, soil, and environment after the adjustment of support parameters.

[0102] Furthermore, the model update in this step can be triggered by changes in working conditions or by a preset cycle. The model update process can be initiated when the excavation layer changes, support components are installed or adjusted, local reinforcement is completed, the monitoring response shows a significant changing trend, or the preset update cycle is reached. By combining working condition-triggered and cycle-triggered methods, the model can be promptly corrected when critical conditions change, while maintaining an appropriate update rhythm during relatively stable working conditions.

[0103] It should also be noted that before updating the model, the real-time monitoring data after the control measures should be reorganized and verified. In practice, newly added monitoring data can be collected according to a unified time benchmark and spatial identifier to ensure consistent temporal and spatial correspondence with existing monitoring data. For instantaneous fluctuations that occur shortly after the control measures are implemented, they should be identified by considering the timing of the control action, construction disturbances, and response characteristics of adjacent monitoring points to distinguish between transient changes caused by the control measures and valid data reflecting true changes in the operating conditions. If necessary, newly added monitoring data can be merged with historical monitoring data to form continuous monitoring data results covering the process before and after the control measures.

[0104] Furthermore, in this step, the iterative updates not only include the target stiffness requirement results for each analysis unit, but also the related regional distribution characteristics, the transition relationship between adjacent regions, and the temporal variation characteristics during the construction phase. When the adjusted monitoring data shows that the displacement of the retaining structure in a certain area has significantly decreased, the stress on the support components has become more reasonable, and the disturbance of the surrounding environment has been suppressed, it can be considered that the original stiffness requirement expression for that area is relatively reasonable; when the adjusted monitoring data still shows that the deformation in a certain area continues to develop, the stress deviation intensifies, or the disturbance range expands, it indicates that the original stiffness requirement expression for that area still has deviations and needs further correction.

[0105] Furthermore, during the iterative update process, the equivalent stress characteristics and stiffness change characteristics of each analysis unit can be reassessed. In specific implementation, based on the adjusted changes in the displacement of the retaining structure, the stress changes of the support components, the displacement changes of the deep soil, and the deformation changes of the external environment, the current stiffness requirements of each analysis unit can be reassessed to determine whether they are too high, too low, or basically matched, and the stiffness requirement expression results of the corresponding region in the model can be corrected accordingly.

[0106] It should also be noted that when updating the model, priority should be given to areas where significant changes in response have occurred after the implementation of control measures. Specifically, areas with large adjustments to support parameters, areas where the response has improved significantly after control measures, areas where abnormal trends still exist after control measures, and areas where adjacent areas are significantly affected by the linkage should be prioritized for updating. By prioritizing model correction in key areas, the relevance and efficiency of model updates can be improved.

[0107] Furthermore, during iterative updates, the transition relationships between analysis units should be synchronously corrected. It should be noted that when the stiffness requirement state of a certain region changes after regulation is implemented, it often affects the force transmission and deformation coordination relationships of its adjacent regions. Therefore, when updating the model, it is not advisable to only perform isolated corrections on a single region, but rather to synchronously adjust the continuity of the stiffness gradient between regions in conjunction with the response changes of adjacent regions. In specific implementation, the stiffness requirement difference and transition amplitude between regions can be appropriately adjusted based on the degree of coordination of the monitored response changes before and after regulation of adjacent analysis units, so that the updated model still maintains a continuous, smooth gradient distribution characteristic that conforms to the engineering response law.

[0108] Furthermore, in confined spaces, due to the significant asymmetry of surrounding environmental constraints, this step should also dynamically modify the stiffness requirement expression under the influence of spatial constraint boundaries, taking into account the environmental response results after adjustment. When areas near existing buildings, roads, underground pipelines, or other sensitive protected objects still exhibit strong environmental response sensitivity after adjustment, the stiffness control requirement for these areas in the model can be increased; when the environmental response of certain areas significantly weakens and deformation control tends to stabilize after adjustment, the stiffness requirement expression for the corresponding areas can be appropriately reduced to avoid excessive local constraints.

[0109] Furthermore, during model updates, the model should be temporally corrected to reflect changes in the construction phases. Excavation pit construction typically involves layered, segmented, and phased advancements. Changes in the response after adjusting support parameters are not only related to the adjustment action itself but also closely tied to the current construction phase. Therefore, during iterative model updates, the stiffness requirement expression at different time points in the model should be readjusted, taking into account the current excavation level, the installation status of support components, the state of local reinforcement, and changes in construction disturbances.

[0110] It should also be noted that in this step, the changing trends during the model update process can be recorded and analyzed. In practice, the current update results can be compared with the previous round of model results to identify the direction, magnitude, and stability of stiffness demand changes in different regions. Regions with large changes, strong persistence of changes, or abnormal changing trends can be marked as key areas of focus.

[0111] Furthermore, in this step, iterative updates can be implemented using a cyclical correction approach. Specifically, after each round of control is completed and new real-time monitoring data is acquired, the model can be updated. After the update, subsequent monitoring results are used for the next round of verification and correction. For areas where monitoring response changes are gradual and the model matches the field conditions well, the update frequency can be appropriately reduced; for areas where monitoring response changes significantly, support requirements change rapidly, or environmental sensitivity is high, the update frequency can be appropriately increased.

[0112] Furthermore, after the model update is completed, it is preferable to perform a consistency check on the update results. Specifically, the updated stiffness demand distribution can be compared with the monitored response state after adjustment. This determines whether regions with high stiffness demand in the model correspond to locations where the actual response is still active, the stress is still concentrated, or the environment is still sensitive. Conversely, it determines whether regions with relatively flat stiffness demand correspond to locations where the response has significantly improved and the deformation coordination is good. When the updated model distribution matches the actual response pattern after adjustment, the iterative update result can be considered reasonable and effective. When significant deviations still exist, the method of dividing the analysis unit, the regional transition relationship, or the expression of stiffness demand can be further revised.

[0113] It should be noted that the model formed after this step is a spatiotemporal non-uniform stiffness gradient model corrected by real-time monitoring data after adjustment. This model can reflect the changing state of support stiffness requirements in different areas, depths, and stages of the foundation pit under the current construction conditions, and maintains dynamic consistency with the actual on-site response results. Through this step, the spatiotemporal non-uniform stiffness gradient model can be continuously updated and corrected throughout the entire construction process.

[0114] Example 2 is an embodiment of the present invention, which provides an experiment on dynamic control of foundation pit support parameters in a confined space.

[0115] To verify the applicability and effectiveness of the proposed dynamic control method for foundation pit support parameters in confined spaces under complex urban built-up area conditions, a set of field comparative tests was designed, combining on-site monitoring, state inversion, zonal modeling, parameter correction, and iterative updates.

[0116] The test scenario was a deep foundation pit project in the core area of ​​a city. The foundation pit has a plan dimension of approximately 58.4 meters × 34.7 meters and a designed excavation depth of 15.8 meters. The retaining structure uses an 800 mm underground continuous wall, and the support system adopts a combination of three steel supports and local prestressed anchor cables.

[0117] The nearest point of the foundation pit to a seven-story office building on the west side is approximately 6.2 meters, and the nearest point to an existing municipal utility tunnel on the south side is approximately 3.9 meters. A secondary urban road lies to the east. The construction site is surrounded by a high concentration of sensitive environmental targets, representing a typical foundation pit construction scenario in a confined space. In this scenario, the retaining structure is significantly affected by the differences in surrounding constraints. If a uniform parameter control method is used, insufficient support capacity may easily occur in locally sensitive areas, while redundant support may form in relatively open areas. Therefore, this site is suitable for verifying the dynamic control effect of the present invention under non-uniform spatial constraints.

[0118] To ensure the comparability of the test process, a continuous construction period from the second support down to the completion of the third support within the same engineering section was selected as the verification window. During this stage, the lateral displacement of the retaining wall, the redistribution of the support axial force, the horizontal displacement of the deep soil, and the settlement outside the pit were significantly different, which can fully demonstrate the advantages and disadvantages of the support parameter control strategy.

[0119] Thirty-two displacement monitoring points were set up along the retaining wall, 18 stress monitoring points were set up on the steel supports and local anchor cables, 12 deep horizontal displacement monitoring points were set up in the surrounding soil, and 18 settlement and environmental deformation monitoring points were set up on the surface outside the pit and in the area adjacent to buildings and pipelines. Sampling was carried out every 2 hours under stable working conditions, and every 10 minutes under excavation conversion, support loading, local reinforcement and abnormal fluctuation conditions.

[0120] The collected multi-source monitoring data, after outlier removal, missing value completion, and short-period fluctuation smoothing, were spatially labeled according to the sensitive areas of adjacent buildings to the west, pipelines to the south, roads to the east, and relatively open areas to the north, forming a structured monitoring dataset. Subsequently, based on the displacement of the retaining structure, the stress of the support components, the deep horizontal displacement of the surrounding soil, the surface settlement outside the pit, and the deformation of the environment outside the pit, the equivalent earth pressure distribution field and the soil stiffness degradation field under the current working conditions were inverted. Then, combined with the pit's planar boundary, the support layout range, and the surrounding environmental constraints, a spatiotemporal non-uniform stiffness gradient model was constructed.

[0121] Based on this, the correction amounts for the prestressing force, axial force, local anchor cable tension, and local reinforcement degree in each region were determined, and dynamic adjustments were performed using a zoned, phased, and gradual control method. To highlight the advantages of this invention, seven sets of comparative objects were set up in the experiment: single-point threshold control, unified prestressing force control, axial force feedback control only, displacement feedback control only, single-round inversion control, zoned dynamic control, and the complete scheme of this invention.

[0122] Each group was compared under the same working boundary, the same excavation rhythm, and the same monitoring conditions to ensure that the test results were comparable and convincing.

[0123] Table 1 Experimental Data

[0124] As can be seen from the table, the complete solution of this invention, namely the "partitioning + iterative update" solution of Experiment G, is superior to the traditional control method and intermediate improvement scheme in terms of retaining structure deformation control, external environment protection, support stress coordination and construction organization efficiency.

[0125] Taking the maximum horizontal displacement at the top of the wall as an example, the maximum horizontal displacement under the single-point threshold control in control A was 18.6 mm, while in experiment G it decreased to 8.2 mm, a reduction of approximately 55.9%; the maximum horizontal displacement of the deep soil decreased from 24.3 mm to 11.7 mm, a reduction of approximately 51.9%; the maximum settlement of the ground surface outside the pit decreased from 17.2 mm to 7.8 mm, a reduction of approximately 54.7%; and the maximum differential settlement of adjacent buildings decreased from 9.6 mm to 3.9 mm, a reduction of approximately 59.4%. These results demonstrate that this invention does not merely passively control the surface displacement of the retaining structure, but rather identifies the coupled response between the retaining structure, surrounding soil, and the environment outside the pit through multi-source monitoring data, and then implements targeted adjustments to the support parameters, thereby effectively reducing disturbance to adjacent buildings and the surface environment while suppressing the deformation of the retaining structure.

[0126] Further comparison of Control C ("axial force feedback control only") and Control D ("displacement feedback control only") reveals that while the single feedback control strategy is superior to traditional single-point threshold and uniform preload control, its improvement is localized. Control C performs better in terms of the axial force deviation rate of the support, at 13.5%, which is better than Control D's 14.0%, indicating that axial force feedback alone can effectively correct uneven stress distribution within the support system. However, in terms of maximum horizontal displacement at the top of the wall, settlement outside the pit, and differential settlement of adjacent buildings, Control D's values ​​are 14.8 mm, 14.0 mm, and 7.5 mm, respectively, all slightly better than Control C's 15.9 mm, 14.9 mm, and 8.2 mm, indicating that displacement feedback alone provides more direct control over the external deformation response.

[0127] This result precisely reveals a typical shortcoming of existing technologies: single-index control often only corrects local phenomena and cannot simultaneously take into account the support stress state, soil deformation state, and external environmental response. This invention solves the problem that single feedback control cannot cover multiple objective constraints by inverting the equivalent earth pressure distribution field and soil stiffness degradation field in step S2, constructing a spatiotemporal non-uniform stiffness gradient model in step S3, and then converting the target stiffness requirement into multiple types of support parameter corrections in step S4.

[0128] The comparison between Experiments E, F, and G better reflects the hierarchical innovation of the present invention. In Experiment E, after a single-round inversion control, the maximum horizontal displacement at the top of the wall decreased to 11.9 mm, and the displacement recovery rate increased to 33.1% after a single-cycle control. This indicates that simply inverting the multi-source monitoring results into the actual stress and stiffness states is significantly superior to traditional empirical control. In Experiment F, after further introducing zonal dynamic control, the maximum horizontal displacement at the top of the wall decreased to 9.7 mm, the deep soil displacement decreased to 13.9 mm, and the maximum surface settlement outside the pit decreased to 9.2 mm. This demonstrates that incorporating spatial constraint boundaries and regional differences into the stiffness gradient model can avoid stiffness mismatch caused by uniform parameter control across the entire pit.

[0129] After adding step S6 to the iterative update of Experiment F, Experiment G further improved various indicators. The displacement at the top of the wall, the displacement of deep soil, the settlement outside the pit, and the differential settlement of the building were reduced by approximately 15.5%, 15.8%, 15.2%, and 17.0% respectively compared to Experiment F. The axial force deviation rate of the support was further reduced from 7.7% to 6.2%, and the response time lag for parameter adjustment was shortened from 2.6 hours to 1.8 hours. Therefore, the key advantage of this invention lies not only in the "initial adjustment" but also in its ability to continuously update the model based on real-time monitoring data after adjustment, ensuring that the target stiffness requirements and support parameter corrections always closely reflect the actual working conditions on site.

[0130] In terms of construction organization and economy, this invention also demonstrates substantial advantages. The cumulative duration of unsupported exposure in Experiment G was 18.9 hours, which was about 43.8% less than the 33.6 hours in Control A. This indicates that zonal control and iterative updates can identify risks in sensitive areas earlier and optimize the timing of support adjustments, reducing the cumulative exposure caused by waiting and rework.

[0131] The consumption of local reinforcement materials decreased from 18.4 cubic meters to 13.2 cubic meters, a reduction of approximately 28.3%. This indicates that the invention does not rely on simply increasing reinforcement materials to achieve a safety margin, but rather achieves more effective resource allocation by more accurately identifying key areas and target parameters. Simultaneously, the average daily progress during the construction phase increased from 1.62 meters / day to 1.98 meters / day, and the comprehensive risk index decreased from 0.79 to 0.28. This demonstrates that while improving safety and environmental control capabilities, the invention did not sacrifice construction efficiency. Instead, it improved overall construction progress efficiency by reducing response time lag, minimizing erroneous adjustments, and reducing the frequency of early warning events.

[0132] In particular, regarding the number of over-warning events, the complete solution only occurred once, while the control and intermediate solutions occurred 5, 4, 4, 3, 2, and 2 times respectively. This distribution indicates that the present invention does not rely on an idealized zero-warning result to demonstrate its advantages, but rather significantly reduces the frequency of high-risk events under real and complex working conditions, which is more in line with the real characteristics of engineering practice. In summary, the data in the table fully demonstrates that the present invention, through a complete technical chain consisting of multi-source monitoring, state inversion, stiffness gradient modeling, parameter correction, zonal control, and iterative updates, can effectively overcome the shortcomings of single-index control, unified parameter control, and static model control in existing technologies, and has significant innovation, novelty, and engineering application value.

[0133] Example 3 provides a dynamic control system for foundation pit support parameters in confined spaces, as described in any one of claims 1-9, characterized in that it comprises: The monitoring data acquisition and processing module is used to acquire multi-source monitoring data of the foundation pit retaining structure, surrounding soil and external environment according to a preset acquisition strategy, and to preprocess the multi-source monitoring data. Based on the spatial constraint characteristics of different areas of the foundation pit, the module establishes the correspondence between monitoring data and spatial areas to form a structured monitoring dataset with spatial identification. The data inversion module is used to invert the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions based on the structured monitoring dataset. The stiffness gradient model construction module is used to construct a spatiotemporal non-uniform stiffness gradient model based on the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit. The control decision module is used to determine the corresponding support parameter correction amount for each region based on the spatiotemporal non-uniform stiffness gradient model, and to verify or correct the support parameter correction amount. The control and execution module is used to dynamically control the pit support system by implementing zoned control based on the correction amount of the support parameters, and to record the control process. The model iteration update module is used to acquire real-time monitoring data after regulation and to iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data.

[0134] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for dynamic regulation and control of parameters of foundation pit support in a narrow site, characterized in that, Includes the following steps: S1. Obtain multi-source monitoring data on the foundation pit retaining structure, surrounding soil and external environment; S2. Based on the multi-source monitoring data, the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions are obtained by inversion. S3. Based on the equivalent earth pressure distribution field, soil stiffness degradation field and spatial constraint boundary of the foundation pit, construct a spatiotemporal non-uniform stiffness gradient model. S4. Determine the correction amount of the support parameters for each region based on the spatiotemporal non-uniform stiffness gradient model. S5. Perform dynamic adjustment of support parameters according to the correction amount of the support parameters; S6. Iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data after adjustment.

2. The method according to claim 1, wherein, The multi-source monitoring data mentioned in step S1 includes at least the displacement data of the retaining structure, the stress data of the support components, the deep horizontal displacement data of the surrounding soil, the surface settlement data outside the pit, and the deformation data of the environment outside the pit. The displacement data of the retaining structure is used to characterize the deformation state of the retaining structure at different depths, the stress data of the support components is used to characterize the stress state of the support system under the current working conditions, the deep horizontal displacement data of the surrounding soil is used to characterize the displacement response of the surrounding soil at different depths, and the surface settlement data and environmental deformation data outside the pit are used to characterize the impact of the foundation pit construction on the surrounding surface and sensitive protected objects.

3. The method according to claim 2, wherein, In step S2, based on the displacement data of the retaining structure, the stress data of the support components, and the deep horizontal displacement data of the surrounding soil, a basic analysis model matching the current construction conditions is established. Based on the deviation between the model-calculated response and the measured response, the parameters related to the lateral action of the soil are adjusted to invert the equivalent earth pressure distribution field under the current conditions.

4. The method according to claim 3, wherein, In step S2, based on the deep horizontal displacement data of the surrounding soil, the displacement data of the retaining structure, and the deformation data of the environment outside the pit, and according to the difference between the displacement changes of each monitoring point under the current working condition and the response under the initial working condition or the design reference condition, the change state of soil stiffness in the corresponding area is determined to form the soil stiffness degradation field under the current working condition.

5. The method according to claim 4, wherein, In step S3, the space of the foundation pit is divided into regions based on the planar outline of the foundation pit, the layout range of the retaining structure, the distribution of the support layers and the distribution of the surrounding environment, forming multiple analysis units with spatial location attributes and depth attributes. The equivalent earth pressure distribution field, the soil stiffness degradation field and the spatial constraint boundary of the foundation pit are mapped to each analysis unit to determine the target stiffness requirement of each analysis unit under the current working condition, and the spatiotemporal non-uniform stiffness gradient model is constructed.

6. The method according to claim 5, wherein, In step S4, based on the target stiffness requirement results corresponding to each analysis unit and the actual parameter state of the current support system in the corresponding area, a correspondence between the target stiffness requirement and the adjustable support parameters is established. Based on the correspondence, the stiffness requirement difference of each analysis unit is converted into the parameter correction direction and parameter correction magnitude of the support prestress, support axial force, anchor cable tension, or local reinforcement degree.

7. The method according to claim 6, wherein, In step S4, when determining the correction amount of the support parameters corresponding to each region, the correction amount of the support parameters is checked or corrected in combination with the key control area, the parameter transition relationship between adjacent areas, the synergistic matching relationship between support parameters, the bearing capacity and adjustment margin of support components, as well as the construction space limitations and work accessibility.

8. The method according to claim 7, wherein, In step S5, the foundation pit support system is dynamically adjusted according to the corresponding support parameter correction amount for each area using a zoned implementation method. For support parameter correction amounts with large adjustment ranges, adjustments are made in stages, loading in stages, unloading in stages, or releasing gradually. Coordinated implementation is carried out in key control areas and their adjacent areas.

9. The method according to claim 8, wherein, In step S6, when the working conditions change or the preset update cycle is reached, real-time monitoring data after adjustment is obtained, and the target stiffness requirements of each analysis unit, the transition relationship between adjacent analysis units, and the temporal characteristics under the construction stage are re-identified and corrected based on the real-time monitoring data, so as to iteratively update the spatiotemporal non-uniform stiffness gradient model.

10. A system for implementing the dynamic regulation of the parameters of the support of a foundation pit in a confined space according to any one of claims 1-9, characterized in that, include: The monitoring data acquisition and processing module is used to acquire multi-source monitoring data of the foundation pit retaining structure, surrounding soil and external environment according to a preset acquisition strategy, and to preprocess the multi-source monitoring data. Based on the spatial constraint characteristics of different areas of the foundation pit, the module establishes the correspondence between monitoring data and spatial areas to form a structured monitoring dataset with spatial identification. The data inversion module is used to invert the equivalent earth pressure distribution field and soil stiffness degradation field under the current working conditions based on the structured monitoring dataset. The stiffness gradient model construction module is used to construct a spatiotemporal non-uniform stiffness gradient model based on the equivalent earth pressure distribution field, the soil stiffness degradation field, and the spatial constraint boundary of the foundation pit. The control decision module is used to determine the corresponding support parameter correction amount for each region based on the spatiotemporal non-uniform stiffness gradient model, and to verify or correct the support parameter correction amount. The control and execution module is used to dynamically control the pit support system by implementing zoned control based on the correction amount of the support parameters, and to record the control process. The model iteration update module is used to acquire real-time monitoring data after regulation and to iteratively update the spatiotemporal non-uniform stiffness gradient model based on the real-time monitoring data.

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