Intelligent pre-optimization construction method of variable depth foundation pit support-water stop collaborative parameters

Abstract

The application discloses an intelligent pre-optimization construction method for variable-depth foundation pit support-water stop collaborative parameters, which comprises the following steps: acquiring the depth, longitudinal slope, geological pressure, soil layer distribution and water level information of a target variable-depth foundation pit, and constructing a foundation pit characteristic data set; analyzing the data set by using an intelligent pre-optimization model, and outputting support-water stop collaborative parameters; performing pile pouring and jet grouting pile construction based on the collaborative parameters; excavating the foundation pit and exposing the pile body of the pile, hanging a reinforcement mesh and performing surface layer support construction by spraying concrete, and adjusting the spraying pressure according to the change of the depth of the foundation pit during spraying; and through intelligent pre-optimization and closed-loop feedback, the application realizes accurate matching and dynamic regulation and control of the variable-depth foundation pit support-water stop parameters, reduces material loss and leakage risk, and improves construction efficiency and safety.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, and in particular to an intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping. Background Technology

[0002] With the increasing intensity of urban underground space development, the application of variable depth foundation pits (depth range of 4.33m to 14.75m, longitudinal slope of -3.99% to +3.98%) in projects such as underpasses and subway stations is becoming more and more widespread, and the coordinated construction of their support and water-stopping systems faces severe challenges.

[0003] Existing technologies generally suffer from the following problems: On the one hand, the adaptation of support parameters is significantly lagging. Traditional methods use fixed support parameters (such as a uniform pile diameter of Φ1000mm and a jet grouting pile spacing of 1200mm) to deal with foundation pits of varying depths, without considering the dynamic coupling relationship between foundation pit depth, longitudinal slope, and geological pressure. This results in over-support in shallow foundation pit sections and insufficient water-stopping in deep foundation pit sections, leading to both material waste and leakage risks. On the other hand, the support-water-stopping sequence is disconnected. The construction interval between cast-in-place piles and jet grouting piles is relatively long (usually more than 30 minutes), and a real-time pressure feedback mechanism has not been established, resulting in insufficient overlap length of the water-stopping curtain (usually only 180~200mm) and poor water-stopping continuity. In addition, intelligent pre-optimization technology is lacking. Existing research still uses empirical formulas to calculate support parameters and has not built an intelligent pre-optimization model based on machine learning, making it impossible to achieve accurate matching of support parameters with geological conditions and foundation pit depth. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an intelligent pre-optimization construction method for the coordinated parameters of support and water-stopping in variable-depth foundation pits. By constructing a foundation pit feature dataset, establishing an intelligent pre-optimization model, implementing pile-curtain time-sequence coordinated control, and dynamically adjusting the spraying pressure with depth, the method achieves precise matching and dynamic control of the parameters of the support structure and the water-stopping system, reduces material consumption, minimizes leakage risk, and improves construction efficiency and safety.

[0005] To achieve the above objectives, the technical solution adopted in this invention is an intelligent pre-optimization construction method for synergistic parameters of variable depth foundation pit support and water-stopping, comprising the following steps: Step 1: Obtain information on the depth, longitudinal slope, geological pressure, soil layer distribution, and groundwater level of the target variable-depth foundation pit, and construct the corresponding foundation pit feature dataset; Step 2: Analyze the foundation pit feature dataset based on the pre-established intelligent pre-optimization model, and output the support-water-stopping synergistic parameters corresponding to the target variable depth foundation pit; Step 3: Construct cast-in-place piles and jet grouting piles based on the aforementioned support-water-stopping synergistic parameters; Step 4: Excavate the foundation pit and expose the pile body of the cast-in-place piles. Hang steel mesh on the pile body and spray concrete to realize the surface support construction. When spraying concrete, adjust the spraying pressure according to the changes in the depth of the foundation pit.

[0006] The further improvement of the intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergistic parameters of the present invention is that the intelligent pre-optimization model is a machine learning model trained based on historical engineering data.

[0007] The intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergy parameters of the present invention is further improved in that the support-water-stopping synergy parameters include the diameter of the cast-in-place pile, the embedment length of the cast-in-place pile, the spacing of the jet grouting pile, and the pile depth of the jet grouting pile.

[0008] The intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergistic parameters of the present invention is further improved in that, when performing step 3 above, the cast-in-place piles are constructed first, and jet grouting pile construction is started within 20 minutes after the cast-in-place piles are formed.

[0009] The intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergistic parameters of the present invention is further improved in that, when performing step 3 above, a pressure sensing component is simultaneously embedded during the hole-forming process of the cast-in-place pile, so as to monitor the stress state of the cast-in-place pile in real time through the pressure sensing component, and dynamically adjust the jet grouting pressure according to the stress state of the cast-in-place pile during the construction of the jet grouting pile, so that the stress of the cast-in-place pile is kept within the preset safe range.

[0010] The further improvement of the intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergistic parameters of the present invention is that, when performing step 4 above, the concrete spraying pressure increases with the foundation pit depth in a gradient of 0.05 MPa / m, wherein the spraying pressure for shallow foundation pit section is 0.4 MPa and the spraying pressure for deep foundation pit section is 0.8 MPa.

[0011] Compared with the prior art, the advantages of the present invention are: 1. By using an intelligent pre-optimization model to analyze the characteristic dataset of the foundation pit and output the support-water-stopping coordination parameters corresponding to the target variable depth foundation pit, the accurate matching of the diameter of the cast-in-place pile, the spacing of the jet grouting pile and the pile depth is achieved. This solves the problem of parameter adaptation lag in the traditional empirical formula method, effectively reduces material loss in shallow foundation pit sections and reduces the risk of leakage in deep foundation pit sections. Compared with the traditional method, it reduces material loss.

[0012] 2. By adopting a timing control strategy of "starting jet grouting construction within 20 minutes after the bored pile is formed", and simultaneously embedding pressure sensing components during the bored pile process to monitor the stress state of the bored pile in real time, the jet grouting pressure is dynamically adjusted according to the stress state of the bored pile to keep the stress of the bored pile within the preset safe range. This not only solves the problem of insufficient pile-curtain overlap caused by insufficient pressure, but also avoids the risk of excessive pressure squeezing the bored pile. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0015] Figure 2 This is a schematic diagram illustrating the construction process of cast-in-place piles and jet grouting piles according to the present invention. Detailed Implementation

[0016] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0017] The intelligent pre-optimization construction method for variable depth foundation pit support-water-stopping synergistic parameters of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Please see Figures 1-2 As shown, the intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping includes the following steps: Step 1: Obtain information on the depth, longitudinal slope, geological pressure, soil layer distribution, and groundwater level of the target variable-depth foundation pit, and construct the corresponding foundation pit feature dataset; Step 2: Analyze the feature dataset of the foundation pit based on the pre-established intelligent pre-optimization model, and output the support-water-stopping synergistic parameters corresponding to the target variable depth foundation pit; Step 3: Based on the support-water-stopping synergy parameters, carry out the construction of cast-in-place piles and jet grouting piles; Step 4: Excavate the foundation pit and expose the pile body of the cast-in-place piles. Hang steel mesh on the pile body and spray concrete to realize the surface support construction. When spraying concrete, adjust the spraying pressure according to the changes in the depth of the foundation pit.

[0019] By combining the above steps, precise matching and dynamic control of the support and water-stopping parameters for variable-depth foundation pits are achieved, significantly reducing material loss and leakage risks, and effectively improving construction efficiency and safety.

[0020] Specifically, before the surface support construction, a local finite element model of capping beam-steel mesh-shotcrete is established for the boundary between shallow and deep foundation pits (the section with the largest depth gradient). The stress distribution characteristics of this section under earth pressure are analyzed. The optimal stress transfer path for this section is determined with the goal of minimizing the maximum principal stress of the structure. The prestress value of the steel mesh in each section is determined according to depth along the longitudinal direction of the foundation pit. Based on the analysis results, at the boundary between shallow and deep foundation pits and in each depth section, the corresponding prestress is applied to the steel mesh by reserving adjustable connectors (pre-adjustment accuracy ±5kN), so that the steel mesh is in a taut state before the shotcrete construction, ensuring that the capping beam, steel mesh and shotcrete form a collaborative working system when under stress.

[0021] The optimal stress transfer path at the boundary between shallow and deep foundation pits was determined by finite element analysis. Differential prestress was applied to the steel mesh along the longitudinal direction of the foundation pit according to depth, so that the steel mesh of both shallow and deep foundation pit sections could be in a tensioned state that met the stress requirements of the section before shotcreting. This avoided stress concentration or structural cracks caused by sudden changes in stress at the boundary between shallow and deep foundation pits, and ensured that the cap beam, steel mesh and shotcreting formed a collaborative working system throughout the entire depth range.

[0022] Preferably, the intelligent pre-optimization model is a machine learning model trained based on historical engineering data.

[0023] Specifically, the historical engineering data includes the parameters of the support structure and the water-stop curtain under different depth conditions, as well as the corresponding stress-seepage monitoring results. By performing feature normalization and correlation training on the historical engineering data, the intelligent pre-optimization model is obtained.

[0024] By using historical engineering data covering different depth conditions for normalization and correlation training, the model is made capable of generalization across depths, ensuring that each segment of the variable depth foundation pit obtains a collaborative parameter matching scheme that is adapted to the depth conditions of that segment.

[0025] Specifically, the intelligent pre-optimization model includes a pre-optimization module, a construction monitoring module, and a dynamic feedback module. The pre-optimization module is used to output support-water-stopping synergistic parameters based on the foundation pit feature dataset. The construction monitoring module is used to collect real-time monitoring data of support structure stress and water-stopping during construction. The dynamic feedback module is used to compare the monitoring data with preset thresholds, and when the deviation exceeds the preset range, it generates a parameter correction scheme to guide subsequent construction parameter adjustments.

[0026] Through the coordinated operation of the pre-optimization module, construction monitoring module, and dynamic feedback module, a complete closed loop of "pre-optimization-construction monitoring-dynamic feedback" is formed, realizing the continuous optimization of the support-water-stopping coordination parameters and ensuring the timeliness and accuracy of parameter adjustments in subsequent unconstructed sections.

[0027] Preferably, the support-water-stopping coordination parameters include the diameter of the cast-in-place pile, the embedment length of the cast-in-place pile, the spacing of the jet grouting piles, and the pile depth of the jet grouting piles.

[0028] By outputting differentiated combinations of cast-in-place pile diameter, embedment length, jet grouting pile spacing, and pile depth, each depth segment can obtain a parameter matching scheme adapted to the geological conditions of that segment, avoiding the contradiction of excessive support in shallow foundation pits and insufficient support in deep foundation pits, and achieving a balance between material conservation and enhanced safety.

[0029] Preferably, when performing step 3 above, the cast-in-place pile is constructed first, and the jet grouting pile construction is started within 20 minutes after the cast-in-place pile is formed.

[0030] By limiting the start time of jet grouting pile construction to within 20 minutes after the pile hole is formed, the jet grouting slurry can effectively overlap with the pile body before the mud skin on the pile hole wall hardens. This avoids the pile-curtain bond strength being weakened due to the hardening of the mud skin on the hole wall caused by excessive intervals, and improves the continuity of water stoppage.

[0031] Preferably, when performing step 3 above, a pressure sensing component is simultaneously installed during the drilling process of the cast-in-place pile to monitor the stress state of the cast-in-place pile in real time through the pressure sensing component. During the construction of the jet grouting pile, the jet grouting pressure is dynamically adjusted according to the stress state of the cast-in-place pile so that the stress of the cast-in-place pile is kept within a preset safe range.

[0032] By synchronously embedding pressure sensing components to monitor the stress state of the cast-in-place piles in real time, and dynamically adjusting the jet grouting pressure accordingly during jet grouting construction, the stress on the cast-in-place piles is always kept within the preset safe range. This ensures sufficient overlap between the pile and the curtain when the jet grouting pressure is insufficient, and avoids damage or displacement of the pile body due to squeezing when the jet grouting pressure is too high. This solves the contradiction between "insufficient overlap" and "squeezing damage", ensuring the overlap length of the water-stop curtain and the quality of the pile formation.

[0033] Specifically, the pressure sensing component includes a strain gauge (accuracy ±0.1με) and an earth pressure cell (accuracy ±0.5kPa), with a monitoring frequency of not less than once per minute.

[0034] Specifically, the preset safe range is that the pile strain does not exceed 500με and the soil pressure does not exceed 200kPa. If the pressure sensor data exceeds this threshold, the rotation speed of the jet grouting pile drill bit (20~30rpm) and the grout flow rate (30~50L / min) will be automatically adjusted to bring the stress on the cast-in-place pile back to the safe range.

[0035] Preferably, when performing step 4 above, the concrete spraying pressure increases gradually with the depth of the foundation pit by a gradient of 0.05 MPa / m, wherein the spraying pressure for shallow foundation pit sections is 0.4 MPa and the spraying pressure for deep foundation pit sections is 0.8 MPa.

[0036] Specifically, the foundation pit adopts a layered excavation method, excavating and supporting layer by layer. After each layer is excavated, the loose soil on the surface of the cast-in-place piles and the soil surface between the piles is removed, and a steel mesh is laid. Then, shotcrete construction is carried out. The shotcrete pressure increases with the depth of the foundation pit in a gradient of 0.05MPa / m. The shotcrete pressure is 0.4MPa for shallow foundation pit sections (depth ≤ 6m) and 0.8MPa for deep foundation pit sections (depth ≥ 12m). The intermediate depth is linearly interpolated.

[0037] By gradually increasing the spraying pressure with depth gradient, the spraying pressure at each depth section is matched with the actual soil pressure, avoiding excessive pressure in shallow foundation pits that causes rebound waste and insufficient pressure in deep foundation pits that leads to incomplete spraying, and ensuring that the compaction of sprayed concrete is not less than 95% across the entire depth range.

[0038] It should be noted that the structures, proportions, sizes, etc., illustrated in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding and reading. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A smart pre-optimization construction method for synergistic parameters of variable depth foundation pit support-waterstopping, characterized in that, Including the following steps: Step 1: Obtain information on the depth, longitudinal slope, geological pressure, soil layer distribution, and groundwater level of the target variable-depth foundation pit, and construct the corresponding foundation pit feature dataset; Step 2: Analyze the foundation pit feature dataset based on the pre-established intelligent pre-optimization model, and output the support-water-stopping synergistic parameters corresponding to the target variable depth foundation pit; Step 3: Construct cast-in-place piles and jet grouting piles based on the aforementioned support-water-stopping synergistic parameters; Step 4: Excavate the foundation pit and expose the pile body of the cast-in-place piles. Hang steel mesh on the pile body and spray concrete to realize the surface support construction. When spraying concrete, adjust the spraying pressure according to the changes in the depth of the foundation pit.

2. The intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping as described in claim 1, characterized in that, The intelligent pre-optimization model is a machine learning model trained based on historical engineering data.

3. The intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping as described in claim 1, characterized in that, The support-water-stopping coordination parameters include the diameter of the cast-in-place pile, the embedment length of the cast-in-place pile, the spacing of the jet grouting piles, and the pile depth of the jet grouting piles.

4. The intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping as described in claim 1, characterized in that, When performing step 3 above, the cast-in-place piles are constructed first, and the jet grouting pile construction is started within 20 minutes after the cast-in-place piles are formed.

5. The intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping as described in claim 4, characterized in that, When performing step 3 above, a pressure sensing component is simultaneously installed during the drilling process of the cast-in-place pile to monitor the stress state of the cast-in-place pile in real time. During the construction of the jet grouting pile, the jet grouting pressure is dynamically adjusted according to the stress state of the cast-in-place pile to keep the stress of the cast-in-place pile within a preset safe range.

6. The intelligent pre-optimization construction method for the synergistic parameters of variable depth foundation pit support and water-stopping as described in claim 1, characterized in that, When performing step 4 above, the concrete spraying pressure increases gradually with the depth of the foundation pit by 0.05 MPa / m, with the spraying pressure for shallow foundation pits being 0.4 MPa and the spraying pressure for deep foundation pits being 0.8 MPa.

Images