A highway reconstruction and expansion new and old roadbed differential settlement collaborative control construction method

Abstract

The application relates to the field of road engineering, and particularly discloses a highway reconstruction and expansion new-old roadbed differential settlement cooperative control construction method, which comprises the following steps: dividing the reconstruction and expansion road section into several sections and performing differential settlement risk assessment to divide risk grades; respectively matching corresponding construction schemes according to different risk grades; laying monitoring points in the construction process to collect settlement data in real time and calculate differential settlement rates; comparing the differential settlement rates with preset threshold values, and dynamically adjusting construction parameters if the differential settlement rates exceed the threshold values; after the construction is completed, performing overall evaluation on the differential settlement of the whole line, identifying defect causes if the differential settlement of the whole line does not meet the design standard, and performing directional reinforcement treatment until the differential settlement of the whole line meets the design standard. Through the combination of zoned evaluation, graded treatment, real-time monitoring and dynamic adjustment and closed-loop reinforcement, the application realizes precise control of the whole process of the differential settlement.

Description

Technical Field

[0001] This invention belongs to the field of road engineering, specifically a construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion. Background Technology

[0002] Highway reconstruction and expansion projects are a crucial component of my country's transportation infrastructure construction. With rapid economic and social development and continuous traffic growth, many highways built in the early stages have entered the reconstruction and expansion phase. Unlike newly constructed highways, reconstruction and expansion projects involve the splicing and deformation coordination of old and new roadbeds. Existing roadbeds, after years of operation, have largely completed consolidation and settlement under their own weight and traffic loads, and the settlement tends to stabilize. However, newly widened roadbeds will experience additional settlement during the filling process. Significant differences exist between the old and new roadbeds in terms of material properties, degree of consolidation, and load history, leading to uneven settlement deformation after construction, known as differential settlement. Excessive differential settlement will result in excessive tensile and shear stresses on the pavement structure, causing longitudinal cracks, misalignment, and even roadbed instability, seriously threatening road structural safety and driving comfort. Therefore, effectively controlling differential settlement between the old and new roadbeds is a critical technical issue that urgently needs to be addressed in the design and construction of reconstruction and expansion projects.

[0003] Currently, there are various existing technologies for controlling differential settlement between new and old roadbeds. For example, interface reinforcement measures such as geogrid reinforcement and geocell installation are used to improve the integrity of the junction between new and old roadbeds; lightweight fillers (such as foamed lightweight soil) are used to fill the new roadbed to reduce the self-weight load of the embankment; and composite foundations such as cement mixing piles and prestressed pipe piles are used to reinforce weak foundations. These methods typically address single influencing factors or single construction stages with localized measures, and the control methods are independent of each other, lacking systematic coordination and linkage. When sudden situations such as abnormal differential settlement rates occur during construction, existing methods struggle to dynamically adjust subsequent construction parameters based on real-time monitoring data. They also lack a closed-loop mechanism to trace the root causes of defects back from the overall post-construction evaluation results and implement targeted reinforcement, resulting in insufficient timeliness and accuracy in differential settlement control. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a construction method for coordinated control of differential settlement between new and old roadbeds in highway reconstruction and expansion projects. This method solves the problem in existing technologies where the lack of a closed-loop control mechanism based on real-time monitoring data for dynamic parameter adjustment and post-construction evaluation feedback leads to insufficient timeliness and accuracy in differential settlement control.

[0005] This invention provides a construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion, comprising the following steps:

[0006] Step 1: Based on geological survey data and existing roadbed technical condition indicators, the road section to be reconstructed and expanded is divided into several sections along the route direction.

[0007] Step 2: Conduct differential settlement risk assessments for each section, and divide each section into high-risk, medium-risk, and low-risk sections based on the assessment results;

[0008] Step 3: For high-risk, medium-risk, and low-risk sections, match corresponding differential settlement control construction schemes respectively. The control construction schemes include at least a foundation treatment scheme and a roadbed filling scheme. The treatment intensity of the scheme matched for high-risk sections is higher than that for medium-risk sections, and the treatment intensity of the scheme matched for medium-risk sections is higher than that for low-risk sections.

[0009] Step four: During the construction of each section, settlement monitoring points are set up at key sections of the old and new roadbeds to collect settlement data in real time, and the differential settlement rate between the old and new roadbeds in each section is calculated based on the collected settlement data. ;

[0010] Step 5: Calculate the differential settlement rates for each section. With preset rate threshold Comparison: If If so, maintain the current construction parameters and continue construction; if If this occurs, the parameter adjustment process will be initiated, dynamically adjusting at least one construction parameter for that section until the differential settlement rate of that section recovers to normal. until;

[0011] Step Six: After the construction of each section is completed, an overall assessment of the differential settlement of the entire subgrade is conducted. If the overall differential settlement meets the design standards, the construction is completed. If the overall differential settlement does not meet the design standards, the root causes of the defects that cause the differential settlement to exceed the limit are identified in the substandard sections, and targeted reinforcement treatment is carried out on the corresponding sections according to the root causes of the defects. After the reinforcement treatment, the differential settlement is reassessed until the differential settlement of the entire line meets the design standards.

[0012] Preferably, in step two, the differential settlement risk assessment adopts a two-layer progressive assessment method:

[0013] In the first-level assessment, based on the geological survey data and fill height of each section, the estimated differential settlement was calculated using empirical formulas. , will satisfy The section was determined to be a low-risk section, which will meet the requirements. The section was identified as a high-risk section, among which To preset the first risk threshold, To preset a second risk threshold, and ;

[0014] For satisfying For ambiguous sections, the second level of assessment is conducted, using numerical simulation to perform refined differential settlement analysis on the section, and the risk level of the section is determined based on the refined analysis results.

[0015] Preferably, in step five, the parameter adjustment process includes:

[0016] Determine the construction parameters to be adjusted for the current section that exceeds the standard. The construction parameters include at least one of the following: number of compaction passes, moisture content of fill material, filling thickness, speed of compaction machinery, and spacing of foundation treatment piles.

[0017] The construction parameters are adjusted gradually with a preset adjustment step size. After each adjustment, settlement data is collected again and the differential settlement rate is calculated until... ;

[0018] If adjusting a single construction parameter within its physical constraints still fails to restore the differential settlement rate to its normal value... Then, multiple construction parameters will be adjusted simultaneously in a coordinated manner.

[0019] Preferably, when coordinating the adjustment of multiple construction parameters, the individual parameter constraint boundaries of each construction parameter and the associated constraint relationships between different construction parameters are pre-established; before each round of coordinating adjustment scheme is executed, it is checked whether the current coordinating adjustment scheme simultaneously satisfies all the individual parameter constraint boundaries and all the associated constraint relationships; if satisfied, the current coordinating adjustment scheme is executed; if any constraint is violated, the values ​​of each construction parameter in the current coordinating adjustment scheme are reduced back to the corresponding constraint boundary range, and the adjustment is executed with the reduced scheme.

[0020] Preferably, in step four, the settlement monitoring points are arranged as follows:

[0021] Monitoring sections are set up at the splicing point of the new and old roadbeds, the centerline of the new roadbed, and the shoulder of the old roadbed. At least three monitoring points are set up on the new roadbed side and the old roadbed side of each monitoring section. The monitoring points are distributed at equal intervals along the transverse direction of the roadbed, and the monitoring points on both sides of the splicing point of the new and old roadbeds are arranged symmetrically with respect to the splicing joint.

[0022] Preferably, in step six, the directional reinforcement process includes the following sub-steps:

[0023] Sub-step one: For the substandard section, trace the root cause of the defect, check the contribution of candidate defect causes to the current differential settlement defect in turn, and determine the candidate defect cause with the highest contribution as the root cause of the defect; the candidate defect cause includes at least one of the following: insufficient foundation treatment depth, excessive pile spacing, substandard compaction of fill material, inadequate drainage measures, and excessively fast filling rate;

[0024] Sub-step two: Select corresponding reinforcement measures according to the root cause of the defect. The reinforcement measures include at least one of grouting, adding geogrid, supplementing compaction and adding drainage facilities, and apply the reinforcement measures only to the specific construction link or location where the root cause of the defect is located.

[0025] Step three: After performing the reinforcement treatment, re-collect differential settlement data for this section to verify the reinforcement effect.

[0026] Preferred options also include:

[0027] Throughout the entire construction cycle, geological condition data, construction parameter data, settlement monitoring data, reinforcement treatment data, and corresponding treatment effect data for each section are entered into the settlement control database, and the settlement control database is dynamically maintained.

[0028] When conducting risk assessments and designing plans for subsequent construction sections or projects, historical data similar to the current working conditions are retrieved from the settlement control database as a reference.

[0029] Preferably, in step three, a transition zone is set between different risk level zones:

[0030] A first transition zone is set between the high-risk zone and the medium-risk zone. Within the first transition zone, the intensity of construction treatment decreases gradually from the high-risk zone side to the medium-risk zone side.

[0031] A second transition zone is set up between the medium-risk zone and the low-risk zone. Within the second transition zone, the intensity of construction treatment gradually decreases from the medium-risk zone side to the low-risk zone side.

[0032] Preferably, in step four, after collecting settlement data and before calculating differential settlement rate, a data confidence assessment step is also included:

[0033] Based on the current operating status parameters of the monitoring equipment and the current environmental conditions, assess the confidence score of the currently collected settlement data. and the confidence score Compared with the preset confidence threshold Compare;

[0034] like Then the current settlement data will be used to calculate the differential settlement rate;

[0035] like If the current settlement data is not used, manual retesting or equipment calibration will be triggered for that monitoring point. Data will be collected again after the retesting or calibration until the confidence level is met. .

[0036] Preferably, in step three, standard construction procedures are implemented for sections identified as low-risk sections, and the actual differential settlement response of the section is continuously monitored during the construction process.

[0037] If the actual differential settlement response characteristics monitored during construction exceed the expected response range of the low-risk section, the risk level of that section will be upgraded from low risk to medium risk, and the construction treatment plan will be switched to the construction treatment plan corresponding to the medium-risk section to continue construction.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] By differentiating risk levels in the reconstruction and expansion sections according to geological conditions and roadbed conditions, and by employing a two-layer progressive assessment strategy to conduct refined analysis of ambiguous sections, the risk level classification becomes more accurate, avoiding omissions and misjudgments caused by a single assessment method. Differentiated foundation treatment and roadbed filling schemes are matched for different risk levels, ensuring that the treatment intensity precisely corresponds to the actual risk level. This prevents overtreatment of low-risk sections and undertreatment of high-risk sections, achieving optimal allocation of limited construction resources.

[0040] During construction, settlement data is collected in real time by setting up monitoring sections and calculating differential settlement rate. Once the rate exceeds the standard, the parameter dynamic adjustment process is triggered, enabling the system to respond quickly to abnormal responses during construction and effectively curb the continued development of differential settlement. For sections that still do not meet the design standards after construction, the source of defects is accurately located through root cause tracing and targeted reinforcement is implemented, avoiding ineffective disturbance to completed qualified sections by generalized correction.

[0041] The introduction of a confidence assessment mechanism ensures the reliability of monitoring data, and the dynamic maintenance of the database guarantees the continuous effectiveness of the system in long-term operation. The entire control process forms a self-correcting closed-loop system, which significantly reduces the reliance on human experience, improves the reliability and construction efficiency of differential settlement control in renovation and expansion projects, and has good engineering adaptability. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the construction method in Embodiment 1 of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1: This example uses the reconstruction and expansion of a two-way four-lane expressway into a two-way eight-lane expressway as an example. The reconstruction and expansion section is approximately 12.6 km long. The original roadbed width was 26 m, and the expanded roadbed width is 42 m, with each side widened by 8 m. The geological conditions along the route are mainly silty clay and sand layers, with local soft soil interlayers of 2 m to 6 m thickness. The reconstruction and expansion project adopts a widening method by splicing the two sides, with the designed fill height at the splicing point between the old and new roadbeds being 2.5 m to 4.2 m. Figure 1 As shown, the specific construction method is as follows:

[0045] Step 1: Section Division

[0046] Based on geological survey data and the technical condition indicators of the existing roadbed, the road section to be reconstructed and expanded is divided into several sections along the route; the specific method for section division is as follows:

[0047] (1) Collect geological survey data along the route and extract the stratigraphic distribution and soil physical and mechanical parameters (including natural water content, void ratio, compression modulus, cohesion and internal friction angle, etc.) of each mileage section.

[0048] (2) Investigate the technical condition of the existing roadbed, including the existing roadbed filling materials, compaction degree, completed settlement and pavement damage;

[0049] (3) Calculate the embankment height for each mileage section;

[0050] (4) Divide continuous road sections with similar geological conditions, similar embankment heights and consistent existing roadbed conditions into the same section.

[0051] In this embodiment, the entire 12.6 km line is divided into 17 sections, which are numbered as follows: The length of each section varies from 400 m to 1200 m.

[0052] Step 2: Differential Settlement Risk Assessment

[0053] Differential settlement risk assessments were conducted for each section, and based on the assessment results, each section was divided into high-risk, medium-risk, and low-risk sections.

[0054] Differential settlement risk assessment adopts a two-tiered progressive assessment approach:

[0055] In the first-level assessment, based on the geological survey data and fill height of each section, the estimated differential settlement was calculated using empirical formulas. The empirical formula is:

[0056]

[0057] in, Estimated differential settlement (unit: mm). The height of the new roadbed embankment (unit: m). The compression modulus of the underlying layer of the existing roadbed (unit: MPa). The compression modulus of the underlying layer of the new roadbed (unit: MPa). This is a correction factor (ranging from 0.6 to 1.2, determined based on formation homogeneity). This is the load influence factor (range 0.8 to 1.5, determined based on the widening width).

[0058] Preset first risk threshold Preset a second risk threshold ; will satisfy The section has been preliminarily identified as a low-risk section; it will meet the requirements. The section has been preliminarily identified as a high-risk section.

[0059] In this embodiment, , , , , Five sections The area has been preliminarily identified as a low-risk zone. , , , Four sections It has been preliminarily identified as a high-risk area.

[0060] For satisfying The ambiguous segment (in this embodiment) , , , , , , , (A total of 8 sections), entering the second level of evaluation.

[0061] In the second-level evaluation, the FLAC3D finite difference numerical simulation software was used to establish a numerical simulation analysis model for the widened roadbed; the method for establishing the numerical model is as follows:

[0062] (1) Establish stratigraphic models based on geological survey data of each section, and adopt the Mohr-Coulomb elastoplastic constitutive model for each soil layer;

[0063] (2) Establish geometric models of the old and new roadbeds based on the design cross-sectional dimensions. The old roadbed uses the parameters of the already consolidated roadbed, and the new roadbed is simulated by layered filling.

[0064] (3) Apply boundary conditions: the bottom of the model is fixed, and the two sides are horizontally constrained;

[0065] (4) Simulate the layered filling process of the new roadbed according to the actual construction procedures, and calculate the differential settlement after construction;

[0066] (5) The differential settlement obtained by numerical simulation is used as the result of refined analysis.

[0067] The risk level of each ambiguous segment is determined based on the results of refined analysis; in this embodiment, the risk level is determined after the second-level evaluation: , , This is a high-risk area. , , , , This is a medium-risk area.

[0068] Ultimately, there were a total of 7 high-risk sections along the entire line. , , , , , , There are a total of 5 medium-risk zones. , , , , There are a total of 5 low-risk sections. , , , , ).

[0069] Step 3: Differentiated and Matching Construction Plans

[0070] For high-risk, medium-risk, and low-risk sections, corresponding differential settlement control construction schemes are matched respectively.

[0071] High-risk sections are reinforced with composite foundations. The composite foundation treatment scheme is as follows: prestressed high-strength concrete pipe piles (PHC piles) with a diameter of 400 mm and a pile spacing of 2.0 m to 2.5 m, arranged in a square pattern, with the pile tip penetrating the soft soil layer into the underlying bearing layer for no less than 2.0 m; a 0.5 m thick graded crushed stone cushion layer is laid on top of the piles, and two layers of bidirectional geogrid are laid inside the cushion layer, with the ultimate tensile strength of the geogrid not less than 80 kN / m; when filling the new roadbed, steps are excavated on the slope of the old roadbed, with a step width of not less than 1.5 m and the step surface inclined inward by 2% to 4%; the fill material is well-graded sand and gravel fill material, with a layered filling thickness of not more than 0.3 m and a compaction degree of not less than 96%.

[0072] Lightweight foundation treatment is adopted for medium-risk sections. The lightweight foundation treatment scheme is as follows: cement mixing pile composite foundation is adopted, with a pile diameter of 500 mm, a pile spacing of 1.5 m to 2.0 m, arranged in a triangle, and a pile length of 6 m to 10 m; a 0.3 m thick crushed stone cushion layer is laid on the pile top, and a layer of bidirectional geogrid is laid inside the cushion layer, with an ultimate tensile strength of not less than 50 kN / m; when filling the new roadbed, steps are excavated on the slope of the old roadbed, with a step width of not less than 1.2 m; the fill material is roadbed fill soil that meets the specifications, with a layered filling thickness of not more than 0.3 m and a compaction degree of not less than 95%.

[0073] Low-risk sections are treated with conventional filling. The conventional filling scheme is as follows: after removing the surface humus, the roadbed fill material is directly filled in layers with a layer thickness of no more than 0.3 m and a compaction degree of no less than 94%; steps are excavated on the slope of the old roadbed with a step width of no less than 1.0 m.

[0074] Step 4: Setting up the transition section

[0075] A transition zone is set between different risk level zones; the specific setting method is as follows:

[0076] A first transition zone with a length of 30 m to 50 m is set between the high-risk and medium-risk sections. Within the first transition zone, the intensity of construction treatment gradually decreases from the high-risk section side to the medium-risk section side. Taking the transition from composite foundation to cement mixing piles as an example: within the transition zone, the spacing between pipe piles gradually transitions from 2.0 m on the high-risk side to 2.5 m on the medium-risk side, and the pile length gradually transitions from penetrating the soft soil layer on the high-risk side to the designed pile length on the medium-risk side.

[0077] A second transition zone, 20 m to 30 m in length, is set up between the medium-risk and low-risk zones. Within the second transition zone, the intensity of construction treatment gradually decreases from the medium-risk zone side to the low-risk zone side.

[0078] In this embodiment, a total of 6 first transition sections and 4 second transition sections are set.

[0079] Step 5: Deployment of Settlement Monitoring Points

[0080] During the construction of each section, settlement monitoring points were set up at key sections of the new and old roadbeds.

[0081] The settlement monitoring points are set up as follows: monitoring sections are set up at the junction of the new and old roadbeds, the centerline of the new roadbed, and the shoulder of the old roadbed. At least three monitoring points are set up on both the new and old roadbed sides of each monitoring section. The monitoring points are evenly distributed along the transverse direction of the roadbed, and the monitoring points on both sides of the junction of the new and old roadbeds are symmetrically arranged with respect to the joint.

[0082] The specific deployment plan is as follows:

[0083] (1) Spacing of monitoring sections along the line: one monitoring section is set up every 40 m in high-risk sections, one monitoring section is set up every 60 m in medium-risk sections, and one monitoring section is set up every 80 m in low-risk sections.

[0084] (2) Six monitoring points are set up at each monitoring section: one at the shoulder of the old roadbed, one at the edge of the old roadbed carriageway, one 0.5 m away from the old roadbed at the splice joint, one 0.5 m away from the new roadbed at the splice joint, one at the edge of the new roadbed carriageway, and one at the shoulder of the new roadbed.

[0085] (3) The monitoring points are settling plates or settlement observation piles. The settlement plates are buried in the subgrade base, and the settlement observation piles are buried in the top surface of the subgrade.

[0086] In this embodiment, a total of approximately 180 monitoring sections and approximately 1080 monitoring points are set up along the entire line.

[0087] Step Six: Real-time Acquisition of Settlement Data and Calculation of Differential Settlement Rate

[0088] Settlement data is collected in real time, and the differential settlement rate between the old and new roadbeds in each section is calculated based on the collected settlement data. .

[0089] Settlement data were collected using a precision level with a measurement accuracy of no less than 0.1 mm. During the construction of the new roadbed, observations were made after each layer was filled. After the completion of the construction, observations were made weekly for the first month, bi-weekly for the second and third months, and monthly thereafter.

[0090] Differential Settlement Rate The calculation method is as follows:

[0091]

[0092] in, The cumulative settlement of the new roadbed monitoring points during the monitoring period (unit: mm). The cumulative settlement (unit: mm) of the old roadbed monitoring points at the corresponding locations within the same monitoring period. For monitoring periods (unit: days).

[0093] In this embodiment, the measured differential settlement rate of each monitoring section during the new roadbed filling period was 0.5 mm / d to 6.2 mm / d.

[0094] Step 7: Confidence Assessment of Settlement Data

[0095] After collecting settlement data and before calculating differential settlement rates, a data confidence assessment step is also included.

[0096] Based on the current operating status parameters of the monitoring equipment and the current environmental conditions, assess the confidence score of the currently collected settlement data. Confidence score The calculation method is as follows:

[0097]

[0098] in, The equipment operating status is scored (range 0-1), based on the calibration validity period of the level, the number of observations since the last calibration, and the current working status. Environmental conditions are scored (range 0-1), based on environmental factors such as temperature, wind speed, and visibility at the time of observation. A stability score for historical data (range 0-1) is assigned based on the degree of dispersion of historical observation data at the monitoring point. , , Let be the weighting coefficient, satisfying In this embodiment, the values ​​are 0.4, 0.3, and 0.3, respectively.

[0099] Preset reliability threshold .

[0100] like Then the current settlement data will be used to calculate the differential settlement rate;

[0101] like If the current settlement data is not used, manual retesting or equipment calibration will be triggered for that monitoring point. Data will be collected again after the retesting or calibration until the confidence level is met. .

[0102] In this embodiment, approximately 97.3% of the monitoring data had a confidence score greater than 0.85 and were directly used for calculation; approximately 2.7% of the data triggered a review process due to insufficient confidence.

[0103] Step 8: Dynamic Adjustment of Parameters

[0104] Differential settlement rates in each section With preset rate threshold Compare them.

[0105] Preset rate threshold The differential settlement rate threshold during the filling of the new subgrade is determined according to the "Technical Specification for Highway Subgrade Construction" (JTG / T 3610—2019) and design requirements. Post-construction differential settlement rate threshold after roadbed filling is completed. .

[0106] like If so, continue construction while maintaining the current construction parameters;

[0107] like If this occurs, the parameter adjustment process will be initiated, dynamically adjusting at least one construction parameter for that section until the differential settlement rate of that section recovers to normal. until.

[0108] The parameter adjustment process is as follows:

[0109] (1) Determine the construction parameters to be adjusted for the current section that exceeds the standard. The construction parameters include at least one of the following: number of compaction passes, moisture content of fill material, filling thickness, speed of compaction machinery and spacing of foundation treatment piles.

[0110] (2) The values ​​of the construction parameters are gradually adjusted using a preset adjustment step size. After each adjustment, settlement data is collected again and the differential settlement rate is calculated until the adjustment is completed. ;

[0111] (3) If adjusting a single construction parameter within its physical constraints still fails to restore the differential settlement rate to its normal value, Then, multiple construction parameters will be adjusted simultaneously in a coordinated manner.

[0112] In this embodiment, When the section reached the 5th layer of filling, the differential settlement rate Exceeding the threshold First, adjust the number of compaction passes, increasing it from the designed 6 passes to 8 passes. The density was reduced to 5.8 mm / d, but still did not meet the standard; the filling thickness was then adjusted, decreasing from 0.3 m to 0.25 m. It decreased to 4.3 mm / d, returning to within the threshold.

[0113] When coordinating the adjustment of multiple construction parameters, pre-establish individual parameter constraint boundaries for each construction parameter and the correlation constraint relationships between different construction parameters. The individual parameter constraint boundaries are determined according to design specifications and the performance of construction machinery. For example, the number of compaction passes should be no less than 4 and no more than 12, the moisture content of the fill material should be controlled within ±2% of the optimum moisture content, and the filling thickness should not exceed 0.4 m and not be less than 0.15 m. Correlation constraint relationships include, for example, increasing the number of compaction passes to ensure compaction when the filling thickness increases.

[0114] Before each round of collaborative adjustment scheme is executed, it is checked whether the current collaborative adjustment scheme simultaneously satisfies all single-parameter constraint boundaries and all related constraint relationships. If it does, the current collaborative adjustment scheme is executed. If any constraint is violated, the values ​​of each construction parameter in the current collaborative adjustment scheme are reduced back to the corresponding constraint boundary range, and the adjustment is executed with the reduced scheme.

[0115] In this embodiment, When the section reached the 7th layer of filling, adjusting a single parameter was insufficient to achieve the required differential settlement rate. Therefore, a coordinated adjustment was initiated: the number of compaction passes was increased from 6 to 10, while the filling thickness was reduced from 0.3 m to 0.2 m. Constraint verification showed that both parameters were within their respective constraint boundaries and satisfied the associated constraint that "the number of compaction passes should increase accordingly after the filling thickness is reduced." The adjustment was then executed. It decreased from 6.8 mm / d to 3.2 mm / d.

[0116] The parameter adjustment process also records the trend of differential settlement rate changes in the section during several rounds of adjustment in the past.

[0117] If historical trends show that the improvement in the settlement rate of the current adjustment direction is continuously narrowing (the improvement rate in each of the three consecutive adjustments is more than 30% less than the previous one), then it is judged that the current adjustment direction is approaching saturation, and the alternative adjustment direction should be switched in advance.

[0118] If historical trends show that the improvement in settlement rate is stable (the improvement rate fluctuates by no more than ±15% in three consecutive rounds of adjustments), then the current adjustment direction will be maintained and adjustments will continue.

[0119] In this embodiment, After four rounds of adjustments to increase the number of compaction passes, the improvement rate of the section decreased from 2.8 mm / d in the first round to 0.5 mm / d in the fourth round, with a narrowing rate of more than 30%. It was judged to be approaching saturation, so the alternative direction of reducing the filling thickness was switched. After two more rounds of adjustments, the standard was met.

[0120] Step Nine: Dynamic Risk Upgrade in Low-Risk Zones

[0121] For sections identified as low-risk areas, standard construction procedures are implemented, and the actual differential settlement response of the section is continuously monitored during construction.

[0122] If the actual differential settlement response characteristics monitored during construction exceed the expected response range of the low-risk section, the risk level of that section will be upgraded from low risk to medium risk, and the construction treatment plan will be switched to the construction treatment plan corresponding to the medium-risk section to continue construction.

[0123] The method for determining the expected response range is as follows: based on the method used in the first-level assessment. Based on calculated values ​​and historical engineering experience under similar geological conditions, an upper limit for the differential settlement rate at each construction stage in this section is set.

[0124] In this embodiment, The section was originally identified as a low-risk section, but differential settlement rates occurred when the fourth layer of filling was completed. Approaching the threshold Furthermore, the risk level showed a continuous upward trend, exceeding the expected response range. Therefore, the risk level of this section was upgraded from low to medium risk, and the construction plan was changed from conventional filling to a medium-risk treatment plan consisting of cement mixing piles, a crushed stone cushion layer, and a single-layer geogrid. Monitoring continued after the change. The flow rate was stabilized at 2.1 mm / d to 3.5 mm / d, meeting the control requirements.

[0125] Step 10: Prioritization during multi-segment parallel processing

[0126] When the differential settlement rate of multiple sections exceeds the preset threshold simultaneously, the comprehensive urgency score for each section is calculated based on the degree of exceedance of the differential settlement rate, the rate of change of the differential settlement rate, and the impact of that section on the overall construction period. .

[0127] Comprehensive handling urgency score The calculation method is as follows:

[0128]

[0129] in, For rate overscalar (unit: mm / d). The rate of change of differential settlement rate (unit: ), The impact on the construction period is scored (value range 0 to 1). , , Let be the weighting coefficient, satisfying In this embodiment, the values ​​are 0.4, 0.3, and 0.3, respectively.

[0130] Scoring based on the urgency of the overall processing The parameters are adjusted sequentially for each segment, from highest to lowest.

[0131] In this embodiment, week 8 also has ( ), ( ), ( Three sections exceeded the standard, according to The values ​​are sorted from highest to lowest as follows → → Process them sequentially.

[0132] Step 11: Overall Differential Settlement Assessment and Targeted Reinforcement along the Entire Line

[0133] After the construction of each section is completed, an overall assessment of the differential settlement of the entire roadbed will be conducted.

[0134] The overall evaluation indicators include:

[0135] (1) Post-construction settlement of new roadbed The length must not exceed 15 cm;

[0136] (2) Additional settlement of old roadbed The size must not exceed 3 cm;

[0137] (3) Differential settlement between old and new roadbeds The length must not exceed 5 cm;

[0138] (4) The increase in road camber caused by differential settlement shall not exceed 0.5%;

[0139] (5) The longitudinal slope change caused by differential settlement between adjacent road sections shall not exceed 0.4%.

[0140] If the overall differential settlement meets the above design standards, then construction is complete.

[0141] If the overall differential settlement does not meet the design standards, the root causes of the defects leading to the excessive differential settlement are identified in the substandard sections, and targeted reinforcement treatment is performed on the corresponding sections according to the root causes of the defects.

[0142] Targeted reinforcement treatment includes the following sub-steps:

[0143] Sub-step 1: Trace the root causes of defects in the substandard sections; check the contribution of candidate defect causes to the current differential settlement defects in turn; candidate defect causes include at least one of the following: insufficient foundation treatment depth, excessive pile spacing, substandard compaction of fill material, inadequate drainage measures, and excessively fast filling rate.

[0144] The method for judging the degree of contribution is as follows: compare the design parameters with the actual construction parameters one by one, calculate the deviation rate of each parameter and its sensitivity to differential settlement, and obtain the sensitivity through numerical simulation; and determine the candidate defect cause with the highest degree of contribution as the root cause of the defect.

[0145] Sub-step two: Select the corresponding reinforcement measures according to the root cause of the defect; the reinforcement measures include at least one of grouting, adding geogrid, supplementing compaction and adding drainage facilities; apply the reinforcement measures only to the specific construction link or location where the root cause of the defect is located.

[0146] For example: if the root cause is insufficient foundation treatment depth, then the section should be reinforced by supplementary grouting or the addition of deep mixing piles; if the root cause is excessive pile spacing, then the piles should be denser in the excessive area; if the root cause is substandard compaction of the fill material, then supplementary compaction should be carried out within a certain depth range below the top surface of the roadbed; if the root cause is inadequate drainage measures, then blind drains or drainage cushions should be added.

[0147] Sub-step 3: After performing the reinforcement treatment, re-collect differential settlement data for this section to verify the reinforcement effect.

[0148] In this embodiment, the overall evaluation of the entire line revealed... The differential settlement between the old and new roadbeds in this section was 6.2 cm, exceeding the design standard of 5 cm. After tracing the root cause, it was found that the length of the foundation treatment piles in this section was 1.5 m shorter than the design value, which was the root cause of the defect. To address this root cause, additional grouting was performed in this section, with grouting holes arranged in a 1.5 m × 1.5 m grid, and the grouting depth reaching 1 m below the design pile bottom elevation. After the additional grouting was completed, the differential settlement was re-observed, and the settlement was reduced to 4.1 cm, meeting the design standard.

[0149] After the reinforcement treatment is completed, if the reinforcement treatment only involves a local section of the entire line, then only the reinforced section and its adjacent affected sections will be reassessed for differential settlement. The results of the previous assessment will be used directly for the remaining unaffected sections. The scope of the affected section is defined as within 50 m on both sides of the reinforced section.

[0150] Step 12: Dynamic Maintenance of Settlement Control Database

[0151] Throughout the entire construction cycle, geological condition data, construction parameter data, settlement monitoring data, reinforcement treatment data, and corresponding treatment effect data for each section are entered into the settlement control database; the settlement control database is dynamically maintained.

[0152] The specific methods for database maintenance are as follows:

[0153] (1) Newly generated construction data and monitoring data are added to the database in real time;

[0154] (2) Mark or remove outdated or verified inaccurate historical data from the database;

[0155] (3) Regularly perform statistical analysis on the data in the database and update the typical value range and correlation coefficient of each parameter.

[0156] When conducting risk assessments and designing plans for subsequent construction sections or projects, historical data similar to the current working conditions are retrieved from the settlement control database as a reference.

[0157] During the construction process of this embodiment, a total of 17 sets of geological data, approximately 2,600 construction parameter records, approximately 15,000 settlement monitoring data, and 7 sets of reinforcement treatment records were entered. The establishment of the database provides reliable data support for the differential settlement risk assessment and construction scheme design of subsequent similar projects.

[0158] Example 2: The difference between this example and Example 1 is that a certain section of the entire line (mileage K3+200~K4+800) passes through a deep soft soil section with a soft soil thickness of 8 m to 12 m. The composite foundation treatment scheme for the high-risk section adopts cast-in-place foamed lightweight soil instead of conventional fill.

[0159] The specific plan is as follows: After the PHC pipe pile composite foundation treatment is completed, a 0.5 m thick crushed stone cushion layer is laid on top of the piles, and the layer above the cushion layer is filled with cast-in-place foamed lightweight soil; the wet density of the foamed lightweight soil is controlled at... The fluidity is controlled between 170 mm and 190 mm, and the 28-day compressive strength is not less than 1.0 MPa. The foamed lightweight soil is poured in sections, with each section not exceeding 15 m in length and 0.5 m in thickness. The next layer can only be poured after the strength of the lower layer reaches 70% of the design strength.

[0160] After using foamed lightweight soil for filling, the post-construction differential settlement calculated by numerical simulation for this section decreased from 7.8 cm for conventional filling schemes to 3.2 cm; the on-site measured post-construction differential settlement was 3.5 cm, which meets the design standard requirements; at the same time, the self-supporting properties of foamed lightweight soil avoid the lateral compression of the old roadbed by conventional filling, and the additional settlement of the old roadbed is only 0.8 cm, which is far less than the control standard of 3 cm.

[0161] Example 3: The difference between this example and Example 1 is that a high-risk section of the entire line (mileage K7+600~K8+400) is adjacent to a bridge, and the differential settlement coordination between the bridgehead roadbed and the bridge structure needs to be considered at the same time.

[0162] The foundation treatment plan for this section is as follows: CFG pile composite foundation is adopted within 30 m on both sides of the bridge abutment. The pile diameter is 400 mm, the pile spacing is 1.5 m, and the pile length penetrates the soft soil layer and enters the bearing layer by no less than 3 m. A 0.6 m thick crushed stone cushion layer + two layers of geogrid are laid on the pile top. The roadbed fill material of the bridge abutment transition section adopts graded crushed stone + cement stabilized material, with a compaction degree of no less than 97%.

[0163] Settlement monitoring is densely deployed at the bridgehead transition section: the spacing between monitoring sections is reduced to 20 m, and 5 monitoring points are set up on both the new and old roadbed sides of each section; settlement observation points are added at the bridge abutment to simultaneously monitor the settlement and tilt of the bridge abutment itself.

[0164] During construction, the differential settlement rate threshold of the bridge abutment transition section was tightened to... ;when Time-triggered parameter adjustment; in this embodiment, the bridgehead transition section is adjusted when the fill reaches the 6th layer. By coordinating adjustments such as increasing the number of compaction passes from 6 to 10 and reducing the fill thickness from 0.3 m to 0.2 m, It decreased to 2.1 mm / d.

[0165] In the overall post-construction assessment, the differential settlement between the old and new roadbeds at the bridgehead transition section was 3.2 cm, and the differential settlement between the bridge abutment and the adjacent embankment was 2.8 cm, which meets the requirement that the differential settlement between the bridge abutment and the adjacent embankment of the reconstructed and expanded highway should not exceed 5 cm.

[0166] Example 4: The difference between this example and Example 1 is that the entire low-risk section ( , , , , During the construction process, a condition-triggered standard process management is adopted.

[0167] The standard construction process for low-risk sections is pre-defined, including: 1.0 m wide step excavation, 0.3 m thick filling, 6 passes of compaction, and 94% compaction degree.

[0168] During construction, an intermediate monitoring data assessment is conducted after every three layers of filling are completed. The assessment includes whether the actual differential settlement rate exceeds 1.5 times the predicted value during the assessment of the first layer of that section.

[0169] If the risk level is not exceeded (4 out of 5 low-risk sections in this embodiment meet the requirements), then the standard construction process will continue.

[0170] If it exceeds (in this embodiment) When the section was filled to the 6th layer, the actual If the value exceeds the predicted value of 2.5 mm / d by more than 1.5 times, a dynamic risk escalation is triggered, upgrading the section from low risk to medium risk. The construction plan is then switched to the cement mixing pile + crushed stone cushion + single-layer geogrid scheme corresponding to the medium-risk section. Monitoring continues after the switch. The flow rate stabilized at 2.8 mm / d, meeting the control requirements.

[0171] Example 5: The difference between this example and Example 1 is that the overall evaluation revealed... The post-construction differential settlement of the section (high-risk section) was 5.8 cm, slightly exceeding the design standard of 5 cm. After multi-dimensional evaluation index analysis, it was found that the main defect dimension was that the post-construction settlement of the new roadbed was too large (16.2 cm, exceeding the standard of 15 cm), while the additional settlement of the old roadbed (1.2 cm) and the increase in the cross slope of the road camber (0.35%) both met the requirements.

[0172] The evaluation weights are dynamically adjusted based on the compliance gaps in each dimension: the compliance gap is largest in the post-construction settlement dimension of new roadbeds, so its weight is increased from the initial 0.25 to 0.45; the weights of other dimensions are reduced accordingly.

[0173] The root cause was traced back to the fact that the fine particle content in the new roadbed fill material of this section was too high (exceeding 12%, while the design requirement is not to exceed 8%), resulting in high compressibility despite meeting the compaction standard. To address this root cause, impact compaction was used to reinforce the area within 2 m below the top surface of the roadbed in this section. After 20 passes of impact compaction and 6 months of follow-up monitoring, the post-construction settlement of the new roadbed decreased from 16.2 cm to 14.5 cm, and the differential settlement decreased from 5.8 cm to 4.2 cm, meeting the design standards.

[0174] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made by those skilled in the art to the above embodiments within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A highway reconstruction and expansion new and old roadbed differential settlement collaborative control construction method, characterized in that, Includes the following steps: Step 1: Based on geological survey data and existing roadbed technical condition indicators, the road section to be reconstructed and expanded is divided into several sections along the route direction. Step 2: Conduct differential settlement risk assessments for each section, and divide each section into high-risk, medium-risk, and low-risk sections based on the assessment results; Step 3: For high-risk, medium-risk, and low-risk sections, match corresponding differential settlement control construction schemes respectively. The control construction schemes include at least a foundation treatment scheme and a roadbed filling scheme. The treatment intensity of the scheme matched for high-risk sections is higher than that for medium-risk sections, and the treatment intensity of the scheme matched for medium-risk sections is higher than that for low-risk sections. Step four: During the construction of each section, settlement monitoring points are set up at key sections of the old and new roadbeds to collect settlement data in real time, and the differential settlement rate between the old and new roadbeds in each section is calculated based on the collected settlement data. ; Step 5: Calculate the differential settlement rates for each section. With preset rate threshold Comparison: If If so, maintain the current construction parameters and continue construction; if If this occurs, the parameter adjustment process will be initiated, dynamically adjusting at least one construction parameter for that section until the differential settlement rate of that section recovers to normal. until; Step Six: After the construction of each section is completed, an overall assessment of the differential settlement of the entire subgrade is conducted. If the overall differential settlement meets the design standards, the construction is completed. If the overall differential settlement does not meet the design standards, the root causes of the defects that cause the differential settlement to exceed the limit are identified in the substandard sections, and targeted reinforcement treatment is carried out on the corresponding sections according to the root causes of the defects. After the reinforcement treatment, the differential settlement is reassessed until the differential settlement of the entire line meets the design standards.

2. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step two, the differential settlement risk assessment adopts a two-layer progressive assessment method: In the first-level assessment, based on the geological survey data and fill height of each section, the estimated differential settlement was calculated using empirical formulas. , will satisfy The section was determined to be a low-risk section, which will meet the requirements. The section was identified as a high-risk section, among which To preset the first risk threshold, To preset a second risk threshold, and ; For satisfying For ambiguous sections, the second level of assessment is conducted, using numerical simulation to perform refined differential settlement analysis on the section, and the risk level of the section is determined based on the refined analysis results.

3. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step five, the parameter adjustment process includes: Determine the construction parameters to be adjusted for the current section that exceeds the standard. The construction parameters include at least one of the following: number of compaction passes, moisture content of fill material, filling thickness, speed of compaction machinery, and spacing of foundation treatment piles. The construction parameters are adjusted gradually with a preset adjustment step size. After each adjustment, settlement data is collected again and the differential settlement rate is calculated until... ; If adjusting a single construction parameter within its physical constraints still fails to restore the differential settlement rate to its normal value... Then, multiple construction parameters will be adjusted simultaneously in a coordinated manner.

4. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 3, characterized in that, When coordinating the adjustment of multiple construction parameters, the individual parameter constraint boundaries of each construction parameter and the associated constraint relationships between different construction parameters are established in advance. Before each round of coordinating adjustment scheme is executed, it is checked whether the current coordinating adjustment scheme simultaneously satisfies all the individual parameter constraint boundaries and all the associated constraint relationships. If it does, the current coordinating adjustment scheme is executed. If any constraint is violated, the values ​​of each construction parameter in the current coordinating adjustment scheme are reduced back to the corresponding constraint boundary range, and the adjustment is executed with the reduced scheme.

5. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step four, the settlement monitoring points are deployed as follows: Monitoring sections are set up at the splicing point of the new and old roadbeds, the centerline of the new roadbed, and the shoulder of the old roadbed. At least three monitoring points are set up on the new roadbed side and the old roadbed side of each monitoring section. The monitoring points are distributed at equal intervals along the transverse direction of the roadbed, and the monitoring points on both sides of the splicing point of the new and old roadbeds are arranged symmetrically with respect to the splicing joint.

6. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step six, the directional reinforcement process includes the following sub-steps: Sub-step one: For the substandard section, trace the root cause of the defect, check the contribution of candidate defect causes to the current differential settlement defect in turn, and determine the candidate defect cause with the highest contribution as the root cause of the defect; the candidate defect cause includes at least one of the following: insufficient foundation treatment depth, excessive pile spacing, substandard compaction of fill material, inadequate drainage measures, and excessively fast filling rate; Sub-step two: Select corresponding reinforcement measures according to the root cause of the defect. The reinforcement measures include at least one of grouting, adding geogrid, supplementing compaction and adding drainage facilities, and apply the reinforcement measures only to the specific construction link or location where the root cause of the defect is located. Step three: After performing the reinforcement treatment, re-collect differential settlement data for this section to verify the reinforcement effect.

7. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, Also includes: Throughout the entire construction cycle, geological condition data, construction parameter data, settlement monitoring data, reinforcement treatment data, and corresponding treatment effect data for each section are entered into the settlement control database, and the settlement control database is dynamically maintained. When conducting risk assessments and designing plans for subsequent construction sections or projects, historical data similar to the current working conditions are retrieved from the settlement control database as a reference.

8. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step three, a transition zone is set between different risk level zones: A first transition zone is set between the high-risk zone and the medium-risk zone. Within the first transition zone, the intensity of construction treatment decreases gradually from the high-risk zone side to the medium-risk zone side. A second transition zone is set up between the medium-risk zone and the low-risk zone. Within the second transition zone, the intensity of construction treatment gradually decreases from the medium-risk zone side to the low-risk zone side.

9. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, Step four, after collecting settlement data and before calculating differential settlement rate, also includes a data confidence assessment step: Based on the current operating status parameters of the monitoring equipment and the current environmental conditions, assess the confidence score of the currently collected settlement data. and the confidence score Compared with the preset confidence threshold Compare; like Then the current settlement data will be used to calculate the differential settlement rate; like If the current settlement data is not used, manual retesting or equipment calibration will be triggered for that monitoring point. Data will be collected again after the retesting or calibration until the confidence level is met. .

10. The construction method for coordinated control of differential settlement between old and new roadbeds in highway reconstruction and expansion according to claim 1, characterized in that, In step three, standard construction procedures are implemented for sections identified as low-risk areas, and the actual differential settlement response of the section is continuously monitored during the construction process. If the actual differential settlement response characteristics monitored during construction exceed the expected response range of the low-risk section, the risk level of that section will be upgraded from low risk to medium risk, and the construction treatment plan will be switched to the construction treatment plan corresponding to the medium-risk section to continue construction.

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