Upper retaining wall construction method and system suitable for complex geology

Abstract

The invention relates to the technical field of building construction, in particular to an upper retaining wall construction method and system suitable for complex geology. The method comprises the steps that soil retaining pile pouring is carried out according to physical and mechanical property parameters of a construction soil layer, stress simulation analysis is carried out on the soil retaining pile, and configuration optimization is carried out on main reinforcements on the soil retaining pile according to an analysis result; waist beam axial force is calculated based on anchor cable tension, and reinforcing steel plates are installed in the channel steel according to the waist beam axial force; a soil retaining plate is installed between every two adjacent soil retaining piles, and the stress-strain states of the soil retaining plates under different soil pressure distributions are calculated through finite element analysis; the optimal distance of the expansion joint is calculated according to a temperature-deformation coupling model; the main reinforcements of the soil retaining pile are configured and optimized, the influence of soil pressure and pile body friction force on external stress of the main reinforcements is comprehensively considered through stress simulation analysis, the number and distance of the main reinforcements can be accurately adjusted, and steel bar materials can be saved and the cost can be reduced on the premise that the structure safety is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to an upper retaining wall construction method and system suitable for complex geology. Background Art

[0002] With the acceleration of urbanization, land resources are becoming increasingly scarce, and engineering construction is constantly expanding into underground space. Foundation pit engineering occupies an increasingly important position in the field of modern construction. Traditional foundation pit support methods, such as slope reduction and soil nail wall support, have exposed obvious limitations when faced with complex geological conditions and tight land space. Slope reduction support requires a larger site space to achieve natural slope reduction of the soil, which is often difficult to meet in urban areas with tight land use. Soil nail wall support has certain adaptability requirements for geological conditions. In the case of poor soil quality, soft soil layers or abundant groundwater, its support effect is difficult to guarantee, and safety problems such as soil nail pullout and soil collapse are prone to occur.

[0003] At present, the permanent support system formed by bored piles and anchor cables has solved some problems to a certain extent, but there are still many shortcomings. On the one hand, during the construction process, complex geological conditions often lead to low construction efficiency and extended construction period. For example, when encountering hard rocks or complex strata during the drilling process, traditional mechanical drilling equipment may face problems such as drilling difficulties and drilling deviation. It is necessary to frequently replace the drill bit or adopt special drilling technology, which not only increases the construction time, but also increases the construction cost. On the other hand, traditional construction technology has great challenges in cost control. The temporary support structure needs to be dismantled after the foundation pit project is completed. This process involves additional manpower, material resources and time investment, which increases the overall cost of the project. At this stage, a method and system for the construction of an upper retaining wall suitable for complex geology is needed. Summary of the invention

[0004] In order to solve the problems of low support stability and cumbersome and complicated support process in traditional foundation pit support, the present invention provides an upper retaining wall construction method and system suitable for complex geology.

[0005] In the first aspect, the present invention provides an upper retaining wall construction method suitable for complex geology, which adopts the following technical solution: An upper retaining wall construction method suitable for complex geology, comprising: S1. Cast retaining piles according to the physical and mechanical property parameters of the construction soil layer, perform force simulation analysis on the retaining piles, and optimize the configuration of the main reinforcement on the retaining piles according to the analysis results; S2. Use retaining piles as support to install the waist beam, including welding the anchor cable to the middle of the channel steel, and calculate the minimum welding size according to the anchor cable tension value; S3. Calculate the axial force of the waist beam based on the tension of the anchor cable, and install a reinforcement steel plate inside the channel steel according to the axial force of the waist beam; S4. Install retaining plates between adjacent retaining piles and calculate the stress-strain state of the retaining plates under different soil pressure distributions through finite element analysis; S5, constructing a temperature-deformation coupling model according to the temperature and displacement data of the overall retaining structure, and calculating the optimal spacing of the expansion joints according to the temperature-deformation coupling model; S6. Obtain the temperature and humidity data of the construction environment, and combine the concrete performance parameters to cast and maintain the overall concrete.

[0006] Furthermore, the retaining piles are cast according to the physical and mechanical property parameters of the construction soil layer, including obtaining the soil weight, active earth pressure coefficient and pile side friction resistance of each soil layer, using the total load calculation formula to obtain the load component of the single pile in the soil layer, summing the load components of each soil layer to obtain the total load, and determining the pile diameter and spacing of the retaining piles according to the total load. The total load calculation formula is: , in, It is expressed as the weight of soil, H is expressed as the depth of foundation pit, Expressed as the active earth pressure coefficient, It is expressed as the pile side friction of the i-th layer of soil, Expressed as the pile length of the i-th soil layer.

[0007] Furthermore, the configuration of the main reinforcement on the retaining pile is optimized according to the analysis results, including a force simulation analysis of the retaining pile, calculating the external force of the main reinforcement at different positions under the action of soil pressure and pile body friction, calculating the bending moment of the pile body according to the main reinforcement parameters, and adjusting the number and spacing of the main reinforcement based on the pile body bending moment and the external force.

[0008] Furthermore, the calculation of the minimum welding size according to the anchor cable tension value includes calculating the active earth pressure resultant of each layer of soil according to the active earth pressure coefficient, obtaining the total lateral force in combination with the force distribution of the anchor cable, and finally introducing the safety factor to obtain the anchor cable tension value. The minimum welding size is calculated according to the anchor cable tension value. The formula for the minimum welding size is: , in, is the weld shear stress, is the effective solder leg size, Calculate the length for the weld, is the weld shear strength value, is the anchor cable tension value.

[0009] Furthermore, the reinforcing steel plate is installed inside the channel steel according to the axial force of the waist beam, including obtaining the angle between the anchor cable and the waist beam and calculating the axial force of the waist beam in combination with the tension value of the anchor cable, respectively calculating the bending moment and shear force of the waist beam according to the axial force of the waist beam, presetting the distance of the waist beam span by the spacing between the retaining piles, and selecting the point with the largest bending moment and shear force within the preset waist beam span to install the reinforcing steel plate.

[0010] Furthermore, the stress-strain state of the retaining plate under different earth pressure distributions is calculated by finite element analysis, including constructing a finite element model according to the geometric shape and size of the retaining plate, using Rankine's earth pressure theory to obtain the load application force of the retaining plate, and obtaining the maximum bending moment and maximum deflection of the retaining plate under different earth pressure distributions by numerical calculation methods, and adjusting the spacing of the retaining plate steel bars based on the maximum bending moment and maximum deflection.

[0011] Furthermore, the temperature-deformation coupling model is constructed based on the temperature and displacement data of the entire retaining structure, including calculating the deformation caused by temperature and external force respectively according to the expansion coefficient, calculating the total expansion and contraction using the deformation caused by temperature and external force, and inputting the total expansion and contraction formula into the finite element analysis software to solve the deformation variables at different positions to obtain the temperature-deformation coupling model of the entire retaining structure.

[0012] Furthermore, the method of calculating the optimal spacing of expansion joints according to the temperature-deformation coupling model includes calculating the expansion and contraction of each section in the retaining structure using the temperature-deformation coupling model, determining the allowable expansion and contraction range of the retaining structure based on material properties, adjusting sections whose expansion and contraction are greater than the expansion and contraction range by setting expansion joints, splitting the original long sections into shorter sections, calculating the expansion and contraction of the entire retaining structure in sections again, and determining the optimal spacing through multiple rounds of optimization.

[0013] Furthermore, the overall concrete pouring and curing are carried out in combination with the concrete performance parameters, including setting a correction coefficient affected by the environment according to the temperature and humidity of the current construction environment, and presetting the water spraying interval based on the correction coefficient and the concrete performance parameters. The water spraying interval calculation formula is: , in, is the standard value of concrete strength, is the correction factor for environmental impact, is the measured strength of concrete at curing time t, It is the best maintenance time.

[0014] In the second aspect, an upper retaining wall construction system suitable for complex geology comprises: Retaining piles, waist beams, anchor cables and retaining boards; The retaining plate is composed of a panel and tie bars, a double-layer bidirectional steel mesh is arranged inside the panel, one end of the tie bar is connected to the steel mesh inside the panel, and the other end of the tie bar is connected to the adjacent retaining pile, and the longitudinal steel bars, stirrups, top and side of the retaining pile are respectively installed with strain gauges and displacement sensors; The inner surface of the retaining plate is provided with an earth pressure sensor, which is installed in a matrix arrangement and is used to measure the size and distribution of the earth pressure on the retaining plate. Strain gauges are attached to the double-layer bidirectional steel mesh inside the retaining plate and the key stress points on the concrete surface of the panel to measure the strain of the retaining plate during the stress process. The waist beam is composed of an upper channel steel and a lower channel steel, a reinforcing steel plate is arranged between the upper channel steel and the lower channel steel, strain gauges are pasted on the flanges, webs and reinforcing steel plates of the upper channel steel and the lower channel steel of the waist beam, and displacement sensors are installed at both ends and the middle of the waist beam. The strain gauges are used to measure the strain of the waist beam when it is subjected to force, and the displacement sensors are used to monitor the displacement of the waist beam in the horizontal and vertical directions; The end of the anchor cable is connected to a fixed steel plate, one end of the fixed steel plate is welded to the upper channel steel, and the other end of the fixed steel plate is connected to the lower channel steel through an iron wedge.

[0015] In summary, the present invention has the following beneficial technical effects: 1. The present invention optimizes the configuration of the main reinforcement of the retaining pile. Through force simulation analysis, the external force influence of the soil pressure and the friction force of the pile body on the main reinforcement, as well as the bending moment of the pile body are comprehensively considered. The number and spacing of the main reinforcement can be accurately adjusted, and the steel bar material can be saved and the cost can be reduced while ensuring the safety of the structure.

[0016] 2. The present invention calculates the axial force of the waist beam according to the tension of the anchor cable, and further calculates the bending moment and shear force of the waist beam, and reasonably installs the reinforcing steel plate inside the channel steel. By installing the reinforcing steel plate at the point where the bending moment and shear force are the largest, the bending and shearing resistance of the waist beam can be improved in a targeted manner, so that the waist beam can effectively transfer and bear the load under complex stress conditions, thereby enhancing the integrity of the entire retaining wall structure.

[0017] 3. The present invention utilizes finite element analysis combined with Rankine's earth pressure theory to perform stress-strain analysis on the retaining board, which can accurately simulate the mechanical behavior of the retaining board under different earth pressure distributions, and adjust the spacing of the retaining board reinforcement by calculating the maximum bending moment and maximum deflection, so that the retaining board can better resist the earth pressure, reduce the possibility of deformation and cracking, and improve the structural performance and service life of the retaining board.

[0018] 4. The present invention constructs a temperature-deformation coupling model based on the temperature and displacement data of the overall retaining structure, which can comprehensively consider the influence of temperature and external force on the retaining structure. Through multiple rounds of optimization calculation of the optimal spacing of expansion joints, the expansion and contraction problem of the retaining structure caused by temperature changes and external forces can be effectively solved, the structural damage caused by expansion and contraction deformation can be avoided, and the adaptability of the retaining wall structure under different environmental conditions is improved.

[0019] 5. During the installation of the waist beam, the present invention calculates the minimum welding size according to the tension value of the anchor cable to ensure that the strength of the welding connection meets the force requirements. This can prevent the failure of the connection between the anchor cable and the channel steel due to insufficient welding strength, thereby ensuring the reliability of the connection between the waist beam and the anchor cable, and thus improving the stability of the entire retaining wall system.

[0020] 6. The present invention configures a double-layer bidirectional steel mesh inside the panel of the retaining board, so that the panel has higher bending and shear strength and can effectively resist soil pressure. The steel mesh is evenly distributed in the panel and works in coordination with the concrete. When soil pressure acts on the panel, the steel bars can withstand tension and the concrete withstands pressure, thereby avoiding cracks or breakages in the panel.

[0021] 7. The present invention adopts a method of connecting the end of the anchor cable to the fixed steel plate. One end of the fixed steel plate is welded to the upper channel steel, and the other end is connected to the lower channel steel through an iron wedge. This connection method can reliably transmit the tension of the anchor cable to the waist beam, ensuring that there will be no relative displacement between the fixed steel plate and the upper channel steel when bearing the tension of the anchor cable. The use of the iron wedge further ensures the tightness of the connection between the fixed steel plate and the lower channel steel to prevent loosening during the force-bearing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall process of an upper retaining wall construction method suitable for complex geology according to Example 1 of the present invention.

[0023] Figure 2 This is a diagram of the anchor cable connection structure in an upper retaining wall construction method suitable for complex geology according to Example 2 of the present invention.

[0024] Figure 3 This is a diagram of the surface structure of retaining piles in an upper retaining wall construction method suitable for complex geology according to Example 2 of the present invention.

[0025] Among them, 1. Upper channel steel; 2. Fixed steel plate; 3. Clip; 4. Iron wedge; 5. Lower channel steel; 6. Anchor cable; 7. Steel mesh; 8. Retaining piles; 9. Tie bars. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0027] Example 1 Reference Figure 1 , an upper retaining wall construction method suitable for complex geology, comprising: Cast retaining piles according to the physical and mechanical properties of the construction soil layer, conduct force simulation analysis on the retaining piles, and optimize the configuration of the main reinforcement on the retaining piles based on the analysis results; Use retaining piles as support to install the waist beam, including welding the anchor cable to the middle of the channel steel, and calculate the minimum welding size according to the anchor cable tension value; The axial force of the waist beam is calculated based on the tension of the anchor cable, and the reinforcing steel plate is installed inside the channel steel according to the axial force of the waist beam; Install retaining plates between adjacent retaining piles, and calculate the stress-strain state of the retaining plates under different soil pressure distributions through finite element analysis; A temperature-deformation coupling model is constructed based on the temperature and displacement data of the overall retaining structure, and the optimal spacing of expansion joints is calculated based on the temperature-deformation coupling model; Acquire the temperature and humidity data of the construction environment, and combine it with the concrete performance parameters for overall concrete pouring and maintenance.

[0028] Specifically, a method for constructing an upper retaining wall suitable for complex geology includes the following steps: like Figure 1 As shown, S1, the retaining piles are cast according to the physical and mechanical property parameters of the construction soil layer, and the force simulation analysis of the retaining piles is performed, and the configuration of the main reinforcement on the retaining piles is optimized according to the analysis results; First, the soil weight, active earth pressure coefficient and pile side friction resistance of each soil layer are obtained. The soil weight is an important parameter reflecting the relationship between soil mass and volume. The construction land is sampled according to the construction environment to calculate the soil weight. For example, in sand, the soil weight is generally between 16-20kN / m³, while the soil weight of clay is around 18-22kN / m³. Different soil weights will cause retaining piles to bear different amounts of earth pressure. The active earth pressure coefficient is closely related to the internal friction angle of the soil layer. The internal friction angle is an important indicator of the shear strength of the soil. It can be measured by indoor triaxial tests or on-site in-situ shear tests. After obtaining the internal friction angle, the active earth pressure coefficient is calculated according to the Coulomb earth pressure theory. Then the pile side friction resistance is obtained. The acquisition method is not fixed. For example, the change of the pile axial force during the loading process is used to calculate the pile side friction resistance through the axial force difference. Finally, the total load is calculated. The total load calculation formula is: , in, It is expressed as the weight of soil, H is expressed as the depth of foundation pit, Expressed as the active earth pressure coefficient, It is expressed as the pile side friction of the i-th layer of soil, Expressed as the pile length of the i-th soil layer.

[0029] The pile diameter and spacing of retaining piles are determined according to the total load. The greater the total load, the larger the pile diameter should be and the smaller the pile spacing should be, so as to ensure that the retaining piles can effectively bear the soil pressure and maintain the stability of the foundation pit.

[0030] The finite element analysis software is used to establish a three-dimensional model of the retaining pile. In the model, the geometric dimensions and material properties of the retaining pile are accurately input (the elastic modulus of concrete is approximately , Poisson's ratio is about 0.2), soil pressure is applied to the outside of the retaining pile in the form of surface load, and its size is calculated based on the active earth pressure coefficient and soil weight. The friction of the pile body is reflected by setting up contact units to simulate the interaction between piles and soil. After simulation, the stress distribution of the retaining pile at different depths can be obtained, and then the external force of the main reinforcement at different parts under the action of soil pressure and pile friction can be calculated. For example, in the middle of the pile body, the main reinforcement may be subjected to large tensile stress due to the large bending moment generated by the soil pressure; near the pile end, the combined effect of the pile body friction and soil pressure makes the stress of the main reinforcement more complicated, and there may be both tension and pressure.

[0031] The bending moment of the pile body is calculated according to the main reinforcement parameters, and the bending moment calculation formula in structural mechanics is used: , in, Expressed as pile diameter, It is expressed as the main reinforcement stress. The bending moment is calculated through the simulated main reinforcement stress. The number and spacing of the main reinforcement are adjusted based on the bending moment of the pile body and the external force. If the bending moment of a certain part is large and the main reinforcement force is close to its yield strength, the number of main reinforcements is increased or the main reinforcement spacing is reduced. After adjustment, the force simulation analysis is performed again to verify the rationality of the main reinforcement configuration. After multiple rounds of optimization, the final number and spacing of main reinforcements are determined, so that the retaining piles can meet the force requirements while achieving an economically reasonable design goal, ensuring structural safety and reducing material costs.

[0032] S2. Use retaining piles as support to install the waist beam, including welding the anchor cable to the middle of the channel steel, and calculate the minimum welding size according to the anchor cable tension value; Two 25a channel steels are used as the waist beam material. First, the overall stress condition of the foundation pit support system is deeply analyzed. Taking into account the transmission path of the anchor cable tension and the distribution law of the soil pressure in the structure, the stress and strain of different types of channel steels when subjected to the expected anchor cable tension are analyzed through mechanical calculations. Combined with the material mechanics theory, the bending and shearing capacity of the channel steel are calculated. For example, based on the section modulus, moment of inertia and other parameters of the material, the bending normal stress formula is used: ,in, is the normal stress, M is the bending moment, W is the section modulus, and the shear stress formula ,in, is shear stress, Q is shear force, A is cross-sectional area, and the stress level of 25a channel steel under various possible working conditions is evaluated whether it is within the allowable range of the material.

[0033] At the same time, the finite element simulation analysis software is used to construct an overall model including the waist beam, anchor cables, retaining piles and soil. In the model, the material properties, such as the elastic modulus and Poisson's ratio of the channel steel, and the mechanical parameters of the soil, such as the elastic modulus, internal friction angle, cohesion, etc., are accurately set. The stress changes of the waist beam during different construction stages are simulated, such as the gradual application of soil pressure and the gradual tensioning of anchor cables during the excavation of the foundation pit. Through the simulation results, the deformation mode and stress concentration area of ​​the 25a channel steel are intuitively observed to verify its stability and reliability when bearing the tension of the anchor cables and transmitting the soil pressure. After a large number of calculations and simulation comparisons, it is determined that the 25a channel steel can meet the bearing requirements under the complex geological conditions of this project and provide solid lateral support for the entire support structure.

[0034] The anchor cable is set in the middle of the channel steel. From the perspective of force transmission, when the anchor cable is subjected to tension, the force is evenly transmitted to the channel steel to avoid eccentric force, thereby reducing additional bending moment and local stress concentration. If the anchor cable deviates from the center position, it will cause one side of the channel steel to be subjected to excessive force and the other side to be subjected to too little force, causing uneven deformation of the channel steel and reducing its bearing capacity and service life. For example, according to the translation theorem of force, eccentric force will produce an additional bending moment ,in, is the anchor cable tension, Due to the eccentricity, this additional bending moment will be superimposed on the original bending moment, making the stress state of the channel steel complicated and dangerous.

[0035] The end of the anchor cable is anchored on a 30X30cm steel plate. This connection method can effectively transfer the tension of the anchor cable to the channel steel, and further transfer it to the entire support structure through the channel steel. In the welding process, the calculation of the weld strength is a crucial link. According to the "Steel Structure Design Code", considering that the weld is subjected to both shear stress and tensile stress when bearing the tension of the anchor cable, the calculation formula under the composite stress state is used for calculation. For shear stress, the formula is used: , in, is the weld shear stress, is the effective solder leg size, Calculate the length for the weld, is the weld shear strength value, is the anchor cable tension value. The minimum value of the effective weld leg size is calculated by the known anchor cable tension value and the weld shear strength value to ensure that the weld will not be damaged under the shear stress. For the tensile stress, use the formula: ,in, is the tensile stress, It is the stress-bearing area of ​​the weld, which is compared with the design value of the weld tensile strength to ensure that the weld can meet the strength requirements under tensile stress.

[0036] S3. Calculate the axial force of the waist beam based on the tension of the anchor cable, and install a reinforcement steel plate inside the channel steel according to the axial force of the waist beam; The method of installing a reinforcing steel plate inside the channel steel according to the axial force of the waist beam comprises obtaining the angle between the anchor cable and the waist beam and calculating the axial force of the waist beam in combination with the tension value of the anchor cable, respectively calculating the bending moment and shear force of the waist beam according to the axial force of the waist beam, presetting the distance of the waist beam span by the spacing between the retaining piles, and selecting the point with the largest bending moment and shear force within the preset distance of the waist beam span to install the reinforcing steel plate.

[0037] The waist beam is regarded as a continuous beam model, and the retaining piles are used as supports. The distance of the waist beam span is preset according to the spacing L between the retaining piles. The load distribution on the waist beam is considered, which mainly includes the uniformly distributed load q (which can be calculated based on the soil pressure and the area of ​​the retaining board) transmitted to the waist beam by the soil pressure through the retaining board and the concentrated load generated by the anchor cable tension. , using the calculation formulas for bending moment and shear force in structural mechanics, for the bending moment under uniformly distributed load , shear force , for the bending moment under concentrated load , where a is the concentrated load Distance to support, shear force , and then get the total bending moment and total shear force. Within the preset span of the waist beam, through the analysis of the bending moment and shear force distribution, select the points with the largest bending moment and shear force to install the reinforcement steel plate. Generally speaking, the bending moment and shear force are often large near the concentrated load (such as near the anchor point). For example, after calculation, it is found that the bending moment reaches the maximum value at 1.2m away from the support, and the shear force is large at 0.8m away from the support, so the reinforcement steel plate is installed at these locations.

[0038] The reinforced steel plate can effectively improve the bearing capacity of the waist beam in areas with larger bending moments and shear forces. During installation, the reinforced steel plate is welded to the channel steel. Through the reinforcement of the reinforced steel plate, the waist beam can better resist deformation and damage under complex stress conditions, thereby ensuring the stability of the entire retaining wall structure.

[0039] S4. Install retaining plates between adjacent retaining piles and calculate the stress-strain state of the retaining plates under different soil pressure distributions through finite element analysis; First, the finite element model of the retaining wall was constructed using ANSYS software. According to the actual geometric shape and size of the retaining wall, a three-dimensional solid model was created. The panel thickness was set to 250 mm, and the double-layer bidirectional C10@200 steel mesh and the C10@400X1000 plum blossom-shaped tie bars were accurately simulated. Considering the bonding relationship between the steel bar and the concrete, the unit type was used to simulate the concrete and the steel bar respectively, such as the concrete using the solid unit and the steel bar using the rod unit. In the model, according to the material properties of C30 concrete, its elastic modulus was set to 30GPa, Poisson's ratio and other parameters, and the corresponding elastic modulus, yield strength and other material properties were given to the steel bar. These parameters are all derived from the standard specifications and test data of the material.

[0040] For the simulation of earth pressure, the distribution of earth pressure at different depths is determined according to the geological survey report and the principles of engineering mechanics. In the model, the earth pressure is applied to the outer surface of the retaining plate in the form of surface load, and different working conditions such as active earth pressure, static earth pressure and passive earth pressure are considered. The active earth pressure is calculated according to the Rankine earth pressure theory, that is, ,in, is the soil weight, is the thickness of the soil layer above the calculation point, is the active earth pressure coefficient, In order to calculate the cohesion, the soil pressure values ​​at different depths are applied to the corresponding positions of the model. At the same time, considering the interaction between the retaining board, the retaining piles and the surrounding soil, reasonable contact units are set at the connection between the retaining board and the retaining piles to simulate the force transmission and displacement coordination relationship between the two. In the setting of the boundary conditions of the retaining board, according to the actual constraints, its displacement in certain directions is restricted. For example, the bottom boundary can constrain its vertical displacement, and the boundaries on both sides can constrain the corresponding horizontal displacement according to the actual support conditions, so as to simulate the force environment of the retaining board in actual engineering.

[0041] After completing the model construction, parameter setting and load application, ANSYS software is used for solution calculation. The software uses numerical calculation methods to solve the stress-strain state of the retaining plate under different soil pressure distributions. In the result analysis, the focus is on the stress-strain state, that is, the maximum bending moment of the retaining plate. and maximum deflection The maximum bending moment can be found by viewing the stress distribution results in the model to find the cross-sectional location and value of the maximum bending moment. This value will be used to calculate the maximum stress of the retaining plate in the subsequent calculation. ,in The section resistance moment is calculated based on the cross-sectional dimensions of the retaining plate. For the maximum deflection, the displacement data of the retaining plate at different positions can be directly obtained from the software calculation results. The value at the maximum displacement is the maximum deflection. , where q is the uniformly distributed load considering earth pressure and additional load, L is the span of the retaining plate determined according to the spacing of retaining piles, and E is the elastic modulus of concrete. The moment of inertia of the retaining plate section is obtained by a detailed analysis of these results, which can provide a comprehensive understanding of the stress performance of the retaining plate under different earth pressure conditions, thereby providing a basis for optimizing the steel bar layout, increasing the number of steel bars or adjusting the steel bar spacing in areas with larger bending moments, to ensure that the retaining plate has sufficient safety and stability when subjected to earth pressure, and effectively protect the stability and safety of the foundation pit.

[0042] S5, constructing a temperature-deformation coupling model according to the temperature and displacement data of the overall retaining structure, and calculating the optimal spacing of the expansion joints according to the temperature-deformation coupling model; The retaining structure is represented as an integrated structure consisting of retaining piles, retaining plates and waist beams. The linear expansion coefficient of the retaining structure material is determined. For concrete structures, the linear expansion coefficient is generally about By arranging temperature sensors at different parts of the retaining structure, real-time temperature data T and the initial temperature of the structure are obtained. , according to the formula ,in, , L is the length of the structure, calculate the expansion and contraction caused by temperature change, analyze the external forces on the retaining structure, including soil pressure, structure self-weight, etc. The soil pressure can be determined according to Rankine's earth pressure theory or other earth pressure calculation methods, and the structure self-weight is calculated according to the material density and volume. Then, using the material mechanics formula, , where F is external force, L is structure length, E is elastic modulus, and A is cross-sectional area) to calculate the deformation caused by external force, and the deformation caused by temperature and external force is combined to obtain the total expansion and contraction. The total expansion and contraction formula is input into the finite element analysis software, and the geometric model of the retaining structure is constructed in the software. The material properties (including linear expansion coefficient, elastic modulus, Poisson's ratio, etc.) are set, and boundary conditions (such as soil pressure, structural deadweight, etc.) are applied according to the actual force conditions. The deformation at different positions is obtained through software solution, thereby constructing the temperature-deformation coupling model of the entire retaining structure. This model can reflect the deformation law of the retaining structure under the combined action of temperature and external force, and provide a basis for the subsequent calculation of the expansion joint spacing.

[0043] The constructed temperature-deformation coupling model is used to calculate the expansion and contraction of the retaining structure in sections. The retaining structure is divided into several sections according to its overall layout, functional characteristics and construction convenience. For example, the retaining piles and retaining boards are divided into several sections within a certain length range. The length of each section can be initially set between 15 and 20 meters. The expansion and contraction of each section under the action of temperature and external force is calculated to determine which sections have a large expansion and contraction that may exceed the allowable range.

[0044] According to the structural design specifications and material properties, the allowable expansion range of the retaining structure is determined. For example, for concrete retaining structures, the allowable expansion may be between a few millimeters and more than ten millimeters according to its strength grade, durability requirements and engineering experience. Compare the expansion of each section with the allowable value. If the expansion of a section is less than the allowable value, it means that the deformation of the section is within the controllable range under the current temperature and external force, and no special treatment is required for the time being. For the section with excessive expansion, there are two ways to adjust it. One is to reduce the length of the section, re-divide the section boundary, split the longer section into shorter sections, and then calculate the expansion of the new section again to see if it meets the requirements. The second is to set expansion joints at appropriate locations. The location of the expansion joints should be selected based on factors such as structural stress and construction convenience. Generally speaking, it should be set at a location where the structural stress is relatively small and the deformation is relatively uniform, such as setting expansion joints at the connection between two retaining boards or at a location where the spacing between retaining piles is relatively large and the stress is relatively balanced. After setting the expansion joints, it is equivalent to disconnecting the original continuous structure, reducing the overall deformation incoordination caused by temperature and external force.

[0045] After the above adjustments, the expansion and contraction amount of the entire retaining structure is calculated again in sections, and the deformation of each section is evaluated. The process of adjusting the sections, setting expansion joints, and calculating the expansion and contraction amount is repeated continuously. In each round, the integrity of the structure, construction cost, and maintenance convenience are comprehensively considered. Although setting too many expansion joints may better control deformation, it will increase construction costs and the difficulty of later maintenance, and may affect the integrity of the structure; while setting too few expansion joints may not effectively control deformation, resulting in problems such as cracks in the structure. Through multiple rounds of calculation and optimization, a balance point is found, that is, the optimal spacing of expansion joints is determined.

[0046] S6. Obtain the temperature and humidity data of the construction environment, and combine the concrete performance parameters to cast and maintain the overall concrete.

[0047] Finally, the whole concrete is poured and fixed, and the whole concrete is poured and cured in combination with the concrete performance parameters. The correction coefficient affected by the environment is set according to the temperature and humidity of the current construction environment. The water spraying interval is preset based on the correction coefficient and the concrete performance parameters. The water spraying interval calculation formula is: , in, is the standard value of concrete strength, It is the correction factor for environmental impact, which is determined according to the environmental temperature and humidity factors, and the value range is 0.8-1.2. is the measured strength of concrete at curing time t, The best maintenance time is when the ambient temperature is low and the humidity is high. The smaller the value, the longer the curing time will be; conversely, when the environmental conditions are good, the curing time will be appropriately shortened. This method of determining the curing time based on real-time monitoring data and concrete performance model can ensure that the retaining slab concrete is fully hydrated within the appropriate curing period, meet the design strength requirements, and improve the overall quality and durability of the retaining structure.

[0048] Example 2 The difference between this embodiment and embodiment 1 is that this embodiment provides an upper retaining wall construction system suitable for complex geology, including: Retaining piles, waist beams, anchor cables and retaining boards. The retaining boards are composed of panels and tie bars. A double-layer bidirectional steel mesh is arranged inside the panel. One end of the tie bar is connected to the steel mesh inside the panel, and the other end of the tie bar is connected to the adjacent retaining piles. The waist beam is composed of an upper channel steel 1 and a lower channel steel 5. A reinforcing steel plate is provided between the upper channel steel 1 and the lower channel steel 5. The end of the anchor cable is connected to a fixed steel plate 2. One end of the fixed steel plate 2 is welded to the upper channel steel 1, and the other end of the fixed steel plate 2 is connected to the lower channel steel 5 through an iron wedge 4.

[0049] Specifically, First, prepare the retaining plate. The panel is cast with concrete and equipped with a double-layer bidirectional steel mesh inside. One end of the tie bar is fixedly connected to the steel mesh inside the panel by welding or mechanical connection to ensure a firm connection. Then the other end of the tie bar is connected to the adjacent retaining pile. The connection point should ensure that the tie bar can effectively transmit force, such as using embedded connectors or drilling holes in the retaining piles, inserting the tie bar and pouring concrete to fix it. Install soil pressure sensors on the inner surface of the retaining plate. Install soil pressure sensors at the midpoints of its long and short sides, four corners and the center in a matrix arrangement. The spacing between adjacent soil pressure sensors is controlled at 1-3m. Use fixing bolts to fix the sensor on the surface of the retaining plate to ensure that the sensor is in close contact with the retaining plate and the force is evenly distributed.

[0050] Strain gauges are pasted on the double-layer bidirectional steel mesh inside the retaining board along the length direction of the steel bars, with a pasting interval of 0.5-1.5m, especially on the edge of the retaining board, the middle of the span and the connection with the connecting bars. Then the retaining piles and waist beams are installed. Bored cast-in-place piles are used and strain gauges are pasted on the longitudinal steel bars of the retaining piles at the top, middle, bottom and every 2-5m. A vertical displacement sensor is installed at the center of each pile top of the retaining pile. The base is pre-buried on the pile top and fixed to the base to ensure that the sensor is vertical and stable. On the side of the pile body, strain gauges are pasted at intervals of 2-3m starting from the pile top. A horizontal displacement sensor is installed, and the horizontal displacement sensor is fixed on the side of the pile body by a clamp-type mounting bracket to ensure that the sensor can accurately measure the lateral displacement of the retaining pile. Then, the upper channel steel and the lower channel steel are placed in parallel, and a reinforcing steel plate is installed between the two channel steels, which are connected by welding. Strain gauges are pasted on the flanges, webs and reinforcing steel plates of the upper channel steel and the lower channel steel of the waist beam, and are mainly arranged at the connection parts between the channel steel and the retaining pile, the connection parts between the channel steel and the anchor cable, and the mid-span position of the reinforcing steel plate. The pasting spacing of the strain gauges is 0.5-1m to ensure that the strain gauges are firmly pasted and can accurately measure the strain. Displacement sensors are installed at both ends and the middle of the waist beam, and the displacement sensors are fixed on the waist beam by drilling holes or welding mounting brackets on the channel steel to monitor the displacement of the waist beam in the horizontal and vertical directions. Finally, the data collected by the strain gauges, displacement sensors and pressure sensors are uploaded to the computer for data processing in Example 1.

[0051] When the soil exerts lateral earth pressure on the retaining wall, the earth pressure first acts on the retaining plate panel. Due to the synergistic effect of the double-layer bidirectional steel mesh 7 and the concrete inside the panel, the panel can effectively resist the bending moment and shear force generated by the earth pressure to prevent itself from being damaged. At the same time, the earth pressure on the panel is transmitted to the adjacent retaining piles through the tie bars 9, so that the retaining plate and the retaining piles 8 are jointly stressed, realizing the initial transmission and distribution of force in the retaining wall system, and ensuring the local stability of the retaining wall under the action of earth pressure.

[0052] like Figure 3As shown, the surface of the retaining pile 8 is then cleaned to enhance the bonding force between the subsequent construction materials and the pile body. C6@200 steel mesh 7 is laid on the surface of the retaining pile after cleaning. The retaining pile 8 transfers part of the soil pressure to the waist beam. At the same time, the tension of the anchor cable also acts on the waist beam. The upper channel steel 1 and the lower channel steel 5 of the waist beam can withstand and reasonably distribute these loads under the synergistic effect of the reinforcement steel plate. The upper and lower channel steels resist bending moment and shear force through their own strength and rigidity, and the reinforcement steel plate further enhances the load-bearing capacity of the waist beam at key positions. The waist beam has the ability to make a stable load-bearing component. Then, a concrete sprayer is used to spray C20 fine-grained concrete onto the surface of the retaining pile, covering the steel mesh 7 and the tie bars 9. The waist beam integrates and transmits the force from the retaining plate and the anchor cable 6. A part of the force is transmitted back to the retaining pile through the connection between the waist beam and the retaining pile 8, and further diffused into the soil. The other part of the force is balanced and adjusted inside the waist beam, ensuring the horizontal force balance and stability of the entire retaining wall system, and effectively preventing the retaining wall from becoming unstable due to excessive lateral deformation.

[0053] like Figure 2 As shown, one end of the anchor cable 6 is connected to the fixed steel plate 2 through the clip 3. During the installation process, ensure that the clip tightly clamps the anchor cable, and the anchor section of the anchor cable penetrates into the stable soil and is tightly combined with the soil. The anchoring force of the soil is used to balance the partial earth pressure on the retaining wall. When the retaining wall tends to deform outward, the anchor cable 6 is pulled to generate tension, which is transmitted to the waist beam through the end connection device. The welding of the fixed steel plate 2 and the upper channel steel 1 and the connection method of the iron wedge 4 with the lower channel steel 5 ensure that the tension of the anchor cable 6 can be reliably transmitted to the waist beam structure, and this connection method can adapt to different stress states and effectively prevent the loosening and damage of the connection parts. The anchoring effect of the anchor cable provides a strong reverse pulling force for the retaining wall, greatly improving the anti-overturning and anti-slip capabilities of the retaining wall, and ensuring the overall stability of the entire retaining wall system under complex geological conditions.

[0054] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for constructing an upper retaining wall suitable for complex geology, characterized in that: include: Cast retaining piles according to the physical and mechanical properties of the construction soil layer, conduct force simulation analysis on the retaining piles, and optimize the configuration of the main reinforcement on the retaining piles based on the analysis results; Use retaining piles as support to install the waist beam, including welding the anchor cable to the middle of the channel steel, and calculate the minimum welding size according to the anchor cable tension value; The axial force of the waist beam is calculated based on the tension of the anchor cable, and the reinforcing steel plate is installed inside the channel steel according to the axial force of the waist beam; Install retaining plates between adjacent retaining piles, and calculate the stress-strain state of the retaining plates under different soil pressure distributions through finite element analysis; A temperature-deformation coupling model is constructed based on the temperature and displacement data of the overall retaining structure, and the optimal spacing of expansion joints is calculated based on the temperature-deformation coupling model; Acquire the temperature and humidity data of the construction environment, and combine it with the concrete performance parameters for overall concrete pouring and maintenance.

2. The upper retaining wall construction method applicable to complex geology according to claim 1 is characterized in that: The retaining pile casting according to the physical and mechanical property parameters of the construction soil layer includes obtaining the soil weight, active earth pressure coefficient and pile side friction resistance of each soil layer, using the total load calculation formula to obtain the load component of a single pile in the soil layer, summing the load components of each soil layer to obtain the total load, and determining the pile diameter and spacing of the retaining pile casting according to the total load. The total load calculation formula is: ， in, It is expressed as the weight of soil, H is expressed as the depth of foundation pit, Expressed as the active earth pressure coefficient, It is expressed as the pile side friction of the i-th layer of soil, Expressed as the pile length of the i-th soil layer.

3. The upper retaining wall construction method applicable to complex geology according to claim 1 is characterized in that: The configuration of the main reinforcement on the retaining pile is optimized according to the analysis results, including a force simulation analysis of the retaining pile, calculating the external force of the main reinforcement at different positions under the action of soil pressure and pile body friction, calculating the bending moment of the pile body according to the main reinforcement parameters, and adjusting the number and spacing of the main reinforcement based on the pile body bending moment and the external force.

4. The upper retaining wall construction method applicable to complex geology according to claim 1 is characterized in that: The calculation of the minimum welding size according to the anchor cable tension value includes calculating the active earth pressure resultant of each layer of soil according to the active earth pressure coefficient, obtaining the total lateral force in combination with the force distribution of the anchor cable, and finally introducing the safety factor to obtain the anchor cable tension value. The minimum welding size is calculated according to the anchor cable tension value. The formula for the minimum welding size is: ， in, is the weld shear stress, is the effective solder leg size, Calculate the length for the weld, is the weld shear strength value, is the anchor cable tension value.

5. The upper retaining wall construction method applicable to complex geology according to claim 1, characterized in that: The method of installing a reinforcing steel plate inside the channel steel according to the axial force of the waist beam comprises obtaining the angle between the anchor cable and the waist beam and calculating the axial force of the waist beam in combination with the tension value of the anchor cable, respectively calculating the bending moment and shear force of the waist beam according to the axial force of the waist beam, presetting the distance of the waist beam span by the spacing between the retaining piles, and selecting the point with the largest bending moment and shear force within the preset distance of the waist beam span to install the reinforcing steel plate.

6. The upper retaining wall construction method applicable to complex geology according to claim 1, characterized in that: The finite element analysis is used to calculate the stress-strain state of the retaining plate under different soil pressure distributions, including constructing a finite element model according to the geometric shape and size of the retaining plate, using the Rankine earth pressure theory to obtain the load application force of the retaining plate, and using a numerical calculation method to obtain the maximum bending moment and maximum deflection of the retaining plate under different soil pressure distributions, and adjusting the spacing of the retaining plate steel bars based on the maximum bending moment and maximum deflection.

7. The upper retaining wall construction method applicable to complex geology according to claim 1, characterized in that: The temperature-deformation coupling model is constructed according to the temperature and displacement data of the entire retaining structure, including calculating the deformation caused by temperature and external force according to the expansion coefficient, calculating the total expansion and contraction using the deformation caused by temperature and external force, and inputting the total expansion and contraction formula into the finite element analysis software to solve the deformation at different positions to obtain the temperature-deformation coupling model of the entire retaining structure.

8. The upper retaining wall construction method applicable to complex geology according to claim 1, characterized in that: The method of calculating the optimal spacing of expansion joints according to the temperature-deformation coupling model includes calculating the expansion amount of each section in the retaining structure using the temperature-deformation coupling model, determining the allowable expansion amount range of the retaining structure based on material properties, adjusting the sections whose expansion amount is greater than the expansion amount range by setting expansion joints, splitting the original long sections into shorter sections, calculating the expansion amount of the entire retaining structure in sections again, and determining the optimal spacing through multiple rounds of optimization.

9. The upper retaining wall construction method applicable to complex geology according to claim 1, characterized in that: The overall concrete pouring and curing is carried out in combination with the concrete performance parameters, including setting the correction coefficient affected by the environment according to the temperature and humidity of the current construction environment, and presetting the water spraying interval based on the correction coefficient and the concrete performance parameters. The water spraying interval calculation formula is: ， in, is the standard value of concrete strength, is the correction factor for environmental impact, is the measured strength of concrete at curing time t, It is the best maintenance time.

10. An upper retaining wall construction system suitable for complex geology, characterized in that: The upper retaining wall construction system suitable for complex geology is used to implement the upper retaining wall construction method suitable for complex geology as claimed in claim 1, comprising: Retaining piles, waist beams, anchor cables and retaining boards; The retaining plate is composed of a panel and tie bars, a double-layer bidirectional steel mesh is arranged inside the panel, one end of the tie bar is connected to the steel mesh inside the panel, and the other end of the tie bar is connected to the adjacent retaining pile, and the longitudinal steel bars, stirrups, top and side of the retaining pile are respectively installed with strain gauges and displacement sensors; The inner surface of the retaining plate is provided with a pressure sensor, which is installed in a matrix arrangement. Strain gauges are pasted on the double-layer bidirectional steel mesh inside the retaining plate and on key stress points on the concrete surface of the panel; The strain gauge, displacement sensor and pressure sensor are respectively connected to the computer for communication, and the collected data are uploaded to the computer for data processing; The waist beam is composed of an upper channel steel and a lower channel steel, a reinforcing steel plate is arranged between the upper channel steel and the lower channel steel, strain gauges are pasted on the flanges, webs and reinforcing steel plates of the upper channel steel and the lower channel steel of the waist beam, and displacement sensors are installed at both ends and the middle of the waist beam; The end of the anchor cable is connected to a fixed steel plate, one end of the fixed steel plate is welded to the upper channel steel, and the other end of the fixed steel plate is connected to the lower channel steel through an iron wedge.

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