A method for embankment widening construction based on biological mineralization and reinforcement cooperation

Abstract

The present application relates to the technical field of embankment reinforcement and widening, and provides an embankment widening construction method based on biological mineralization and reinforcement cooperation. The present application combines the micro-cementation of enzyme-induced calcium carbonate precipitation in the inclusion body with the macro-constraint of geogrid to form a "friction-cement" composite interface, which greatly improves the shear and impermeability of the new and old roadbed combination surface. At the same time, the synergistically enhanced transition zone as a stiffness coordination layer can effectively homogenize the load and absorb the differential deformation, thereby inhibiting uneven settlement and preventing reflection cracks. The present application spatially couples and functionally cooperates the micro-cementation strengthening ability of enzyme-induced calcium carbonate precipitation with the macro-reinforcement constraint ability of geogrid, fundamentally improves the weak area of the widened embankment, and significantly improves the integrity and long-term stability of the widened embankment.

Description

Technical Field

[0001] This invention relates to the field of embankment reinforcement and widening technology, and in particular to an embankment widening construction method based on the synergy of biomineralization and reinforcement. Background Technology

[0002] An embankment is a fill roadbed whose top surface is higher than the original ground level. Currently, embankment widening projects generally adopt the construction method of excavating steps, laying geogrids, and filling in layers. Its effect mainly depends on the friction and interlocking effect between the reinforcement and the soil.

[0003] This traditional method faces three major challenges: First, the difference in physical and mechanical properties between the new and old fill materials results in a weak interface that is prone to shear slip and seepage channels; second, the compressive settlement of the new roadbed and the residual settlement of the old roadbed are difficult to coordinate, which can easily induce longitudinal reflective cracks at the interface; and third, the large amount of borrowed soil filling causes significant disturbance to the ecological environment.

[0004] Meanwhile, enzyme-induced calcium carbonate precipitation (EICP), as an emerging biomineralization reinforcement technology, has been proven to effectively cement soil particles and improve soil strength and stiffness. However, existing research has mostly focused on foundation treatment or shallow slope protection. Its application mode is mostly large-area uniform treatment or shallow infiltration. It has not yet been systematically and creatively applied to solve the core problem of interface bonding and settlement control in embankment widening.

[0005] Therefore, this invention aims to overcome the aforementioned limitations and provide a novel widening technology that can significantly improve the overall integrity of new and old embankments, precisely control differential settlement, and is environmentally friendly. Its core lies in solving how to spatially couple and functionally synergize the microscopic cementing and strengthening ability of enzyme-induced calcium carbonate precipitation with the macroscopic reinforcement and constraint ability of geotextiles, thereby fundamentally improving the weak areas of the widened embankment.

[0006] Therefore, it is necessary to propose a construction method for embankment widening based on the synergy of biomineralization and reinforcement to solve or at least alleviate the above-mentioned defects. Summary of the Invention

[0007] The main objective of this invention is to provide a road embankment widening construction method based on the synergy of biomineralization and reinforcement, in order to solve the technical problems in existing road embankment widening projects, which are prone to shear slip, differential settlement and reflective cracking due to the weak interface between the old and new roadbeds and the lack of an effective coordinated deformation mechanism.

[0008] To achieve the above objectives, this invention provides a method for embankment widening construction based on the synergy of biomineralization and reinforcement, comprising the following steps:

[0009] S1 involves excavating the slope of the old embankment to create multiple inward-sloping steps.

[0010] S2, in each step area, construction is carried out layer by layer from bottom to top to build a collaboratively enhanced transition zone; wherein, step S2 includes steps S21~S24:

[0011] S21, For the first layer: The geogrid is laid on the step surface, and the anchoring section is laid on the vertical surface of the step and fixed by anchors, the supporting section is laid on the horizontal tread of the step, and the wrapping section extends outward from the horizontal tread; the geogrid includes the anchoring section, the supporting section and the wrapping section connected in sequence.

[0012] For the subsequent nth layer: the geogrid is laid on the top surface of the composite layer formed by the (n-1)th layer, and the geogrid of the nth layer is connected to the geogrid of the (n-1)th layer. The supporting section of the nth layer is laid on the top surface of the composite layer of the (n-1)th layer, and the wrapping section of the nth layer extends outward from the top surface of the composite layer of the (n-1)th layer, n≥2;

[0013] S22, spread a layer of filler on the supporting section of the current construction layer, and then fold the wrapping section of the current construction layer back to cover and wrap the filler;

[0014] S23, the encapsulated filler is compacted, then enzyme-induced calcium carbonate precipitation is performed, and then static curing is carried out to form a cemented and reinforced composite layer.

[0015] S24. Repeat steps S21 to S23, and use the top surface of the composite layer formed each time as the construction base surface for the next cycle. Stack the composite layer layer by layer until the total thickness of the stacked composite layer reaches the design elevation of the synergistic reinforcement transition zone, thereby forming the synergistic reinforcement transition zone.

[0016] S3, a new embankment is constructed in layers outside the synergistic enhancement transition zone, and the new embankment and the synergistic enhancement transition zone are connected.

[0017] Preferably, the enzyme-induced calcium carbonate precipitation treatment in step S23 includes the following steps:

[0018] S231, Preparation of enzyme-induced calcium carbonate precipitation solution: Dissolve urea, calcium chloride and urease in water according to a predetermined ratio to prepare enzyme-induced calcium carbonate precipitation solution.

[0019] S232, the enzyme-induced calcium carbonate precipitation solution is injected or permeated into the compacted filler through a grouting device;

[0020] S233, maintain the encapsulated filler in a temperature and humidity environment suitable for calcium carbonate crystallization for a predetermined time;

[0021] S234, inside the encapsulated filler, the enzyme induces a reaction in the calcium carbonate precipitation solution, and the generated calcium carbonate crystals partially adhere to the surface of the geogrid ribs to form an encapsulation layer, and partially precipitate between the filler particles and at the interface between the filler particles and the ribs to form a bridging network; the encapsulation layer and the bridging network together constitute a calcium carbonate cement that microscopically interlocks the geogrid, the filler particles and the stepped surface of the old embankment.

[0022] Preferably, during the enzyme-induced calcium carbonate precipitation treatment in step S23, the following steps are performed simultaneously:

[0023] An array of resistivity monitoring electrodes is deployed within the encapsulated packing material in the processing area.

[0024] The initial resistivity distribution data of the encapsulated filler before processing is measured and obtained through the resistivity monitoring electrode array.

[0025] During the enzyme-induced calcium carbonate precipitation process or during post-treatment maintenance, real-time resistivity distribution data is acquired at preset time intervals using the resistivity monitoring electrode array.

[0026] The difference between the real-time resistivity distribution data and the initial resistivity distribution data is determined, and based on the difference, the measured value of the current cementitious content is calculated in reverse according to the calibration relationship between the resistivity change and the cementitious content established in advance through indoor experiments.

[0027] The measured value of the current cementitious content is compared with the preset target cementitious content value;

[0028] When the comparison result shows that the measured value of the current cementitious body content is lower than the target cementitious body content value, it is determined that the overall cementation of the monitoring area is insufficient. Based on the difference, a control command is generated, and at least one of the following control operations is performed: adjusting the concentration of the enzyme-induced calcium carbonate precipitation solution in subsequent grouting cycles, adjusting the grouting volume in subsequent grouting cycles, or starting supplementary grouting for continuous areas where the resistivity change is lower than the average change in the area.

[0029] Preferably, the control operation is as follows: when a continuous region with a resistivity change of less than 15% of the regional average change is identified based on the real-time resistivity distribution data, the continuous region is determined to be a weak cementation region, and supplementary grouting is initiated for the continuous region.

[0030] Preferably, the grouting volume for initiating supplementary grouting in the continuous area is obtained through the following steps:

[0031] Using formula The grouting volume is calculated; wherein, This refers to the average change in resistivity within the monitoring area that belongs to the same construction layer as the continuous region. This refers to the average resistivity change of the continuous region. The estimated volume of the continuous region. The reinforcement coefficient is the one pre-calibrated through indoor testing. This represents the volume of enzyme-induced calcium carbonate precipitation solution required to increase the unit resistivity change per unit volume of packing material.

[0032] Preferably, step S3 includes the following steps:

[0033] S31. During the construction of the new embankment, the settlement of the old embankment and the settlement of the new embankment fill are monitored simultaneously, and the absolute value of the difference in settlement between the new embankment fill and the old embankment is calculated.

[0034] S32, determine whether the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement early warning threshold;

[0035] S33, when the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement warning threshold, the construction parameter adjustment is triggered, and at least one of the following control operations is performed: reduce the paving and compaction rate of the current filling layer, reduce the layer thickness of the subsequent filling layer, or increase the laying density of geogrid in the subsequent filling layer.

[0036] S34, when the absolute value of the differential settlement difference is less than the preset differential settlement warning threshold, continue to fill the new embankment in layers outside the synergistic enhancement transition zone according to the current construction parameters, and connect the new embankment and the synergistic enhancement transition zone.

[0037] Preferably, in step S3, the filling of the new embankment and the construction of the synergistic reinforcement transition zones at each level are carried out in an interleaved manner, specifically including the following steps:

[0038] S301, after completing the construction of the synergistic enhancement transition zone in the lowest step area, the new embankment is then constructed in layers outside the synergistic enhancement transition zone.

[0039] S302, following the steps in a bottom-up order, for each upper step area currently under construction, execute the following sub-steps sequentially:

[0040] S3021, carry out the construction of the coordinated reinforcement transition zone in the upper step area;

[0041] S3022, When the top surface of the new embankment rises to be flush with the top surface of the completed upper-level synergistic reinforcement transition zone, the reinforcement layer of the new embankment is connected to the synergistic reinforcement transition zone.

[0042] S3023, continue to fill the new embankment in layers upwards;

[0043] Repeat step S302 until the construction of the collaborative enhancement transition zone for all step areas is completed and the new embankment is filled to the design elevation.

[0044] Preferably, the following steps are included before step S1:

[0045] S01 involves enzymatically induced calcium carbonate precipitation grouting reinforcement in the natural foundation and old embankment toe area beneath the widened area, forming a foundation reinforcement zone and a slope toe reinforcement zone.

[0046] The solution concentration and grouting pressure used in step S01 for enzyme-induced calcium carbonate precipitation grouting reinforcement are designed to be lower than the corresponding parameter levels used in step S23 for enzyme-induced calcium carbonate precipitation treatment.

[0047] Meanwhile, the target cementitious content in the construction control of step S01 is lower than the target cementitious content in step S23, so that the overall stiffness and permeability of the formed foundation reinforcement zone and the slope toe reinforcement zone are between the untreated natural foundation and the synergistic enhancement transition zone, thereby forming a mechanical and hydraulic gradient transition layer from the natural foundation to the interface between the old and new roadbeds in the vertical direction.

[0048] Preferably, the predetermined ratio in step S231 is: urea concentration 0.75-1.0 mol / L, calcium chloride concentration 0.5-0.75 mol / L, and urease activity not less than 3.0 U / mL.

[0049] Preferably, step S232, in which the enzyme-induced calcium carbonate precipitation solution is injected into the compacted filler using a grouting device, includes the following steps:

[0050] Use PVC pipes or seamless steel pipes with a diameter of 25-40mm as grouting pipes. Layout holes in a square or quincunx pattern with a spacing of 1.0-1.5 meters. Use a drilling rig to drill holes to the designed depth, insert the grouting pipes, and backfill the pipe area with coarse sand to form a filter layer.

[0051] A dual-liquid grouting pump is used to inject the prepared enzyme-induced calcium carbonate precipitation solution into the packing material through the grouting pipe; wherein, the grouting pressure is 0.2-0.5MPa, the grouting rate is 5-10L / min, and the grouting volume per hole is based on achieving the designed diffusion radius or grout overflowing from the hole opening;

[0052] For areas with a grouting depth greater than 2 meters, segmented retreat grouting is adopted. After a single grouting is completed, the area is left to stand for 36-48 hours to allow calcium carbonate to be initially formed.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] This invention provides a method for embankment widening construction based on the synergy of biomineralization and reinforcement. This application implements biomineralization treatment in the compacted fill layer wrapped by geogrid, so that the generated calcium carbonate crystals form a large number of micro-crystalline bridges between fill particles and at the contact points with the geogrid ribs, and form a mineral encapsulation layer on the surface of the ribs to form a "friction-cementation" composite mechanism. This greatly improves the interfacial shear strength and impermeability from the material essence, thereby transforming the traditional weak bonding surface into a high-strength, high-integrity composite material interface, fundamentally eliminating the risk of shear slip and seepage channels.

[0055] The synergistic enhancement transition zone constructed in this application is an integral functional layer composed of high-strength grid and enzyme-induced calcium carbonate precipitation solution cemented soil. Its stiffness is between that of the old embankment and the newly added fill, forming a smooth stiffness transition gradient. It can efficiently homogenize load transfer, alleviate stress concentration, and actively absorb and coordinate the differential deformation between the old and new roadbeds. Therefore, it can suppress uneven settlement at the joint and effectively prevent the generation of longitudinal reflective cracks in the road from the source.

[0056] This application achieves spatial coupling and functional synergy between the two through a cyclical process of laying, back-wrapping, compaction, and grouting curing. The geogrid provides macroscopic constraints to control lateral deformation; the cementation of the enzyme-induced calcium carbonate precipitation solution provides delayed microscopic solidification reinforcement, significantly improving overall stiffness and durability. The two complement each other in construction sequence and functional performance, jointly anchoring and bonding the new and old embankments into a cohesive composite material whole.

[0057] In addition, this application can make greater use of available soil and improved soil in the site or adjacent areas, reduce reliance on borrowed high-quality soil and long-distance transportation, thereby saving resources, reducing energy consumption, and mitigating the damage to the ecological environment of the borrow pit. Attached Figure Description

[0058] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0059] Figure 1 A schematic diagram of the cross-section of the embankment structure after applying the embankment widening construction method of this application;

[0060] Figure 2 This is a schematic flowchart of one embodiment of the present invention;

[0061] Figure 3 This is a flowchart illustrating the steps involved in the enzyme-induced calcium carbonate precipitation process in step S23 of one embodiment of the present invention.

[0062] Figure 4 This is a schematic diagram of the physical specimen after the preparation of the indoor test sample in one embodiment of the present invention;

[0063] Figure 5 This is a schematic diagram of a sample immersed in pure water in one embodiment of the present invention.

[0064] Figure 6 This is a schematic diagram of the actual product after 15 days of bonding treatment and curing, according to one embodiment of the present invention.

[0065] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings.

[0066] Explanation of icon numbers:

[0067] 10. Old embankment; 20. New embankment; 30. Original slope line of old embankment; 40. Synergistic enhancement transition zone; 50. Horizontal tread of the step; 60. Vertical surface of the step; 70. Top surface of the composite layer. Detailed Implementation

[0068] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0069] 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 a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0070] In this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Furthermore, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. If the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0071] Please refer to Figures 1 to 6 The present invention provides a method for embankment widening construction based on the synergy of biomineralization and reinforcement, comprising the following steps:

[0072] S1. Excavate the slope of the old embankment 10 to form multiple inwardly sloping steps; survey and set out, and clear the site. Excavate the slope of the old embankment 10 into inwardly sloping steps (2%-4%) according to the design slope (usually 1:0.5-1:1), with a step width of not less than 1.5 meters. For example... Figure 1 In the middle, the sloping dotted line is the original slope line 30 of the old embankment.

[0073] S2, in each step area, construction is carried out layer by layer from bottom to top to construct a collaboratively reinforced transition zone 40; wherein, step S2 includes steps S21 to S24:

[0074] S21, for the first layer: A geogrid is laid on the step surface, with the anchoring section laid on the vertical surface 60 of the step and fixed by anchors, the supporting section laid on the horizontal tread 50 of the step, and the wrapping section extending outward from the horizontal tread; the geogrid includes the anchoring section, supporting section, and wrapping section connected sequentially; preferably, a high-strength, high-modulus, low-creep biaxially oriented polypropylene or polyester geogrid is used, with an ultimate tensile strength of not less than 80 kN / m and a corresponding strain ≤10%. Specifically, a high-strength biaxial geogrid (ultimate tensile strength ≥80 kN / m) is laid on the first step. The geogrid is divided into three sections according to its function: the anchoring section (about 0.5 meters long) is close to the vertical surface of the step 60, and "L" shaped steel anchor rods (16 mm in diameter and 1.0 meter in length) are passed through the geogrid nodes and anchored into the old embankment 10 for fixation; the supporting section is laid flat on the horizontal tread of the step; and the wrapping section (the length is determined according to the design, usually ≥2.0 meters) extends freely to the widening side.

[0075] For the subsequent nth layer: the geogrid is laid on the top surface 70 of the composite layer formed by the (n-1)th layer, and the geogrid of the nth layer is connected to the geogrid of the (n-1)th layer. The supporting section of the nth layer is laid on the top surface 70 of the composite layer of the (n-1)th layer, and the wrapping section of the nth layer extends outward from the top surface 70 of the composite layer of the (n-1)th layer, where n≥2; the nth layer of geogrid is laid on the top surface 70 of the composite layer formed by the (n-1)th layer. Preferably, the supporting section of the nth layer geogrid is longitudinally connected to the (n-1)th layer geogrid using plastic connecting rods or wires, with the connection point spacing not exceeding 0.5 meters.

[0076] S22, spread a layer of fill material on the support section of the current construction layer, then fold back the wrapping section of the current construction layer to cover and wrap the fill material; spread another layer of fill material on the laid support section. The loose thickness is strictly controlled at 0.25-0.3 meters to ensure that the compacted thickness matches the vertical spacing of the geogrid. After spreading, immediately fold back the reserved wrapping section of the geogrid upwards to cover and wrap the fill material layer, forming a closed wrapping state with the lower support and the upper cover.

[0077] S23, the encapsulated filler is compacted, then subjected to enzyme-induced calcium carbonate precipitation treatment, and then allowed to stand for curing to form a cemented and reinforced composite layer; preferably, the encapsulated filler is vibrated and compacted to a compaction degree of not less than 95%, and after compaction, the construction layer is immediately subjected to enzyme-induced calcium carbonate precipitation treatment.

[0078] S24. Repeat steps S21-S23, using the top surface 70 of each composite layer as the construction base for the next cycle. Stack the composite layers layer by layer until the total thickness of the stacked composite layers reaches the design elevation of the synergistic reinforcement transition zone 40, thus forming the synergistic reinforcement transition zone 40. Repeat steps S21 to S23, using the hardened top surface 70 of the previous layer as the base for the next layer. Continue this upward construction layer by layer until the entire stepped area is filled to the design elevation, ultimately forming an integral synergistic reinforcement transition zone 40 that tightly interlocks with each stepped area of ​​the old embankment 10 and whose interior can be composed of "geogrid-cemented soil" cyclic units.

[0079] S3, a new embankment is constructed in layers outside the synergistic enhancement transition zone 40, and the new embankment 20 and the synergistic enhancement transition zone 40 are connected.

[0080] In this application, biomineralization treatment is carried out in the compacted fill layer wrapped by geogrid, so that the generated calcium carbonate crystals form a large number of micro-crystalline bridges between the fill particles and at the contact points with the geogrid ribs, and a mineral coating layer is formed on the surface of the ribs to form a "friction-cementation" composite mechanism. This greatly improves the interfacial shear strength and impermeability from the material essence, thereby transforming the traditional weak bonding surface into a high-strength, high-integrity composite material interface, fundamentally eliminating the risk of shear slip and seepage channels.

[0081] The synergistic enhancement transition zone 40 constructed in this application is an integral functional layer composed of high-strength grid and enzyme-induced calcium carbonate precipitation solution cemented soil. Its stiffness is between that of the old embankment 10 and the newly added fill, forming a smooth stiffness transition gradient. It can efficiently homogenize load transfer, alleviate stress concentration, and actively absorb and coordinate the differential deformation between the old and new roadbeds. Therefore, it can suppress uneven settlement at the joint and effectively prevent the generation of longitudinal reflective cracks in the road from the source.

[0082] This application achieves spatial coupling and functional synergy between the two through a cyclical process of laying, back-wrapping, compaction, and grouting curing. The geogrid provides macroscopic constraints to control lateral deformation; the cementation of the enzyme-induced calcium carbonate precipitation solution provides delayed microscopic solidification reinforcement, significantly improving overall stiffness and durability. The two complement each other in construction sequence and functional performance, jointly anchoring and bonding the new and old embankments into a cohesive composite material whole.

[0083] In addition, this application can make greater use of available soil and improved soil in the site or adjacent areas, reduce reliance on borrowed high-quality soil and long-distance transportation, thereby saving resources, reducing energy consumption, and mitigating the damage to the ecological environment of the borrow pit.

[0084] In a preferred embodiment, the enzyme-induced calcium carbonate precipitation treatment in step S23 includes the following steps:

[0085] S231, Preparation of enzyme-induced calcium carbonate precipitation solution: Dissolve urea, calcium chloride and urease in water according to a predetermined ratio to prepare enzyme-induced calcium carbonate precipitation solution.

[0086] As a preferred example, the predetermined ratio in step S231 is: urea concentration 0.75-1.0 mol / L, calcium chloride concentration 0.5-0.75 mol / L, and urease activity not less than 3.0 U / mL. Specifically, calculate the amount of each component based on the ratio of urea concentration 0.75-1.0 mol / L and calcium chloride concentration 0.5-0.75 mol / L. First, dissolve the calculated urea and calcium chloride in clean water and stir thoroughly until completely dissolved. After the solution temperature drops to room temperature (25±5℃), add sufficient urease powder or liquid and stir to mix evenly, ensuring that the urease activity in the final mixture is not less than 3.0 U / mL. The solution should be prepared and used immediately to avoid enzyme activity attenuation.

[0087] To verify the cementing and reinforcing effect of enzyme-induced calcium carbonate precipitation (EICP) technology on embankment fillers, the inventors conducted indoor experiments, the specific process of which is as follows:

[0088] Preparation of experimental materials: The enzyme-induced calcium carbonate precipitation solution was prepared by mixing a cementing solution and a urease solution at a volume ratio of 1:1. The cementing solution consisted of an equal volume mixture of 0.75 mol / L urea and 0.75 mol / L calcium chloride; the concentration of the urease solution was 1.2 g / L, and the urease (type II) activity used was 3.5 U / mg. The urease was derived from sword bean and provided in powder form. Throughout the experiment, the urease was tightly packaged and stored in a refrigerator at a constant temperature of 4°C.

[0089] Sample Preparation: Embankment fill soil intended for the project was selected, air-dried, crushed, and sieved to prepare standard cylindrical samples. To simulate weathering and breakage and increase the cementation contact area, the samples underwent a wet-dry cycle treatment: first, they were dried at 105℃ to constant weight, then immersed in pure water until saturated; this constituted one cycle, which was repeated three times. Afterward, the treated samples were axially crushed to form fragmented blocks with through-cracks, such as... Figure 4 As shown.

[0090] Cementing and curing: The fragmented specimens were secured with nylon cable ties to simulate their in-situ state, and then immersed in the prepared enzyme-induced calcium carbonate precipitation solution. After curing at room temperature (20±2℃) for 15 days, they were removed.

[0091] Test results: such as Figures 5 to 6 As shown, the cracks in the sample were effectively filled by the generated calcium carbonate crystals, successfully re-cementing into a whole. Even when lifted to a certain height, the sample remained intact, without any detachment or disintegration. This intuitive experimental result demonstrates that enzyme-induced calcium carbonate precipitation treatment can produce a significant cementing effect on fractured soil, preliminarily verifying its feasibility in reinforcing embankment interface fillers.

[0092] S232, the enzyme-induced calcium carbonate precipitation solution is injected or permeated into the compacted filler using grouting equipment; specifically, grouting holes are arranged in a square or staggered pattern, with a hole spacing of 1.0-1.5 meters. A grouting pipe (PVC or seamless steel pipe) with a diameter of 25-40 mm is inserted into the middle or lower part of the filler layer. A dual-liquid grouting pump is used to inject the prepared enzyme-induced calcium carbonate precipitation solution at a low pressure of 0.2-0.5 MPa and a rate of 5-10 L / min. The grouting volume per hole is controlled until the solution oozes from adjacent holes or the filler surface, ensuring that the enzyme-induced calcium carbonate precipitation solution permeates the entire predetermined treatment area, especially the interface area where the geogrid ribs contact the filler.

[0093] In another embodiment, before spreading the fill material in step S22, the enzyme-induced calcium carbonate precipitation solution prepared in S231 can be used as mixing water and mechanically mixed with the engineering fill material (preferably sand or gravel). The amount of solution added is about 8%-15% of the dry weight of the fill material, and the mixture is mixed until uniform. This premixed improved soil is then used for spreading and compaction.

[0094] S233, maintain the encapsulated filler in a temperature and humidity environment suitable for calcium carbonate crystallization for a predetermined time; immediately after grouting or paving, cover and cure the construction area (e.g., cover with geotextile or plastic film). During curing, maintain the ambient temperature between 20-35℃ and the relative humidity above 80%, with a curing time of 24-48 hours. Avoid rain or direct sunlight to prevent rapid evaporation of moisture.

[0095] S234, inside the encapsulated filler, the enzyme induces a reaction in the calcium carbonate precipitation solution, and the generated calcium carbonate crystals partially adhere to the surface of the geogrid ribs to form an encapsulation layer, and partially precipitate between the filler particles and at the interface between the filler particles and the ribs to form a bridging network; the encapsulation layer and the bridging network together constitute a calcium carbonate cement that microscopically interlocks the geogrid, the filler particles and the stepped surface of the old embankment 10.

[0096] Numerous calcium carbonate crystals grow, adhere, and accumulate on the surface of the ribs of geogrids (such as polypropylene or polyester materials), forming a microscale, hard calcium carbonate coating layer. At the same time, at the contact points and gaps between the ribs and the surrounding filler particles, calcium carbonate crystals grow from both sides (the surface of the ribs and the surface of the filler particles) and connect with each other, forming a large number of microscopic crystalline bridges, constituting a continuous bridging network.

[0097] In this embodiment, the wrapping layer and bridging network together constitute a three-dimensional calcium carbonate cement. This calcium carbonate cement achieves both physical interlocking (increasing mechanical interlocking force through wrapping and bridging) and chemical bonding (physicochemical adsorption between crystals and polymer ribs and filler particles) at the microscopic level. This tightly connects the geogrid ribs, new filler particles, and the 10-step surface of the old embankment and its attached soil into a composite material whole, realizing the coordinated work of the new and old roadbeds.

[0098] In a preferred embodiment, during the enzyme-induced calcium carbonate precipitation treatment in step S23, the following steps are performed simultaneously:

[0099] An array of resistivity monitoring electrodes is deployed within the encapsulated packing material in the processing area.

[0100] The initial resistivity distribution data of the encapsulated filler before processing is measured and obtained through the resistivity monitoring electrode array.

[0101] Specifically, immediately before the enzyme-induced calcium carbonate precipitation treatment in step S23, an electrode array of a four-electrode resistivity monitoring system can be deployed in the treatment area of ​​the construction layer according to a 1.0m × 1.0m grid. The electrodes are stainless steel probes, inserted to the middle of the filler layer. All electrodes are connected to a multi-channel resistivity meter via wires. After the system is powered on, based on Ohm's law, the apparent resistivity value of each measuring point is acquired and recorded by measuring the injected current and the resulting potential difference. Furthermore, a mature resistivity tomography inversion algorithm can be used to reconstruct the three-dimensional spatial distribution of the filler resistivity within the construction area, obtaining a three-dimensional resistivity inversion cloud map.

[0102] During the enzyme-induced calcium carbonate precipitation process or the post-treatment maintenance, real-time resistivity distribution data is acquired by the resistivity monitoring electrode array at preset time intervals; for example, the electrode array is activated at fixed time intervals (such as every 2 hours) to acquire real-time resistivity distribution data.

[0103] The difference between the real-time resistivity distribution data and the initial resistivity distribution data is determined, and based on the difference, the measured value of the current cementitious content is calculated in reverse according to the calibration relationship between the resistivity change and the cementitious content established in advance through indoor experiments.

[0104] Specifically, the calibration relationship can be obtained through the following steps:

[0105] Before construction, a reliable calibration relationship can be established through indoor tests: using the same filler and enzyme-induced calcium carbonate precipitation solution formulation as on-site, a series of standard samples with different degrees of cementation (achieved by controlling the amount of enzyme-induced calcium carbonate precipitation solution added) are prepared. The resistivity of each sample is measured using the same resistivity measurement system, and the actual calcium carbonate cement content is determined by destructive testing (such as unconfined compressive strength testing) or chemical titration. A scatter plot is drawn with the resistivity change as the x-axis and the cement content as the y-axis, and linear or nonlinear regression fitting is performed using the least squares method to obtain the calibration function. This calibration function serves as the mathematical model for the calibration relationship calculated on-site.

[0106] By substituting the resistivity change at each measuring point into the calibration relationship mathematical model, the current measured value of the cementitious content at the current location of that measuring point can be calculated. Furthermore, the average value of the measured cementitious content in the entire monitoring area can be taken as the current measured value of the cementitious content.

[0107] The measured value of the current cementitious content is compared with the preset target cementitious content value. The preset target cementitious content value can be set based on experience or retrieved from the calibration relationship mathematical model.

[0108] When the comparison result shows that the measured value of the current cementitious body content is lower than the target cementitious body content value, it is determined that the overall cementation of the monitoring area is insufficient. Based on the difference, a control command is generated, and at least one of the following control operations is performed: adjusting the concentration of the enzyme-induced calcium carbonate precipitation solution in subsequent grouting cycles, adjusting the grouting volume in subsequent grouting cycles, or starting supplementary grouting for continuous areas where the resistivity change is lower than the average change in the area.

[0109] For example, in subsequent grouting cycles, the urea concentration in the enzyme-induced calcium carbonate precipitation solution can be increased by 10%, or the total grouting flow rate can be increased by 15%. This enhances the overall reaction intensity, ensuring that the average cementitious content of the construction layer meets the standard, and resolving the issue of substandard overall reinforcement effect caused by batch-to-batch variations in environmental temperature and solution activity. Alternatively, even if the average cementitious content meets the standard, targeted grouting can be performed on continuous areas where the resistivity change is lower than the regional average change. This eliminates hidden quality defects caused by uneven grouting and local heterogeneity of the soil in traditional methods, significantly improving the uniformity of interface reinforcement.

[0110] Preferably, the control operation is as follows: when a continuous region with a resistivity change lower than 15% of the regional average change is identified based on the real-time resistivity distribution data, the continuous region is determined to be a weak cementation region, and supplementary grouting is initiated for the continuous region. Specifically, the measuring points with resistivity changes lower than 15% of the regional average change can be clustered using a connected component analysis algorithm. A set of measuring points that are interconnected in three-dimensional space and have a projected area of ​​not less than 0.5 square meters on the horizontal plane is determined to be a continuous region.

[0111] Furthermore, the amount of grout to be injected into the continuous area for supplementary grouting is obtained through the following steps:

[0112] Using formula The grouting volume is calculated; wherein, This refers to the average change in resistivity within the monitoring area that belongs to the same construction layer as the continuous region. This refers to the average resistivity change of the continuous region. The estimated volume of the continuous region can be calculated, for example, based on the three-dimensional resistivity inversion cloud map mentioned above, by determining the boundary of the continuous region in the three-dimensional resistivity inversion cloud map, and then combining the known thickness of the construction layer (e.g., 0.3 meters) with geometric volume formulas such as cubes or prisms. The reinforcement coefficient is the one pre-calibrated through indoor testing. This represents the volume of enzyme-induced calcium carbonate precipitation solution required to increase the unit resistivity change per unit volume of filler. For example, using the same filler as in the field, compacted to the same density, multiple cubic specimens of known volume are prepared. A precisely measured but different volume of enzyme-induced calcium carbonate precipitation solution is injected into each specimen. After curing under standard conditions, the resistivity change of each specimen is measured using the same resistivity testing method as in the field. For each specimen, the injection volume per unit volume is calculated. A scatter plot is drawn with the resistivity change on the x-axis and the injection volume per unit volume on the y-axis. A linear regression is then performed, and the resulting fitted curve is the reinforcement coefficient. .

[0113] As another preferred embodiment, the reinforcement coefficient k can be implemented using a dynamic correction scheme. Specifically, after completing the supplementary grouting of a certain continuous area and reaching the predetermined curing time, the resistivity change of the area is remeasured to obtain the actual increase value (i.e., the net increase in resistivity change of the area compared to that before the supplementary grouting). Based on the supplementary grouting volume performed this time, the estimated volume of the area, and the actual increase value, the actual reinforcement coefficient for this treatment is calculated.

[0114] The specific formula is as follows: ;in, The amount of grout to be injected to initiate supplementary grouting in the continuous area, This is the actual reinforcement coefficient. This represents the actual improvement value. To estimate the volume, the actual reinforcement coefficient is then weighted and fused with the historical values ​​of the previously used reinforcement coefficient. The updated value is used as the reinforcement coefficient for subsequent calculations. The dynamic correction process in this embodiment enables the system to adapt to complex changes in soil and environmental conditions on site and continuously optimize the control accuracy.

[0115] In a preferred embodiment, step S3 includes the following steps:

[0116] S31, during the construction of the new embankment 20, the settlement of the old embankment 10 and the settlement of the new embankment 20 fill body are monitored simultaneously, and the absolute value of the differential settlement difference between the new embankment 20 fill body and the old embankment 10 settlement is calculated. At the start of the new embankment 20 construction, a settlement monitoring system is established simultaneously to detect differential settlement in real time. Specifically, for the settlement monitoring of the old embankment 10, a settlement monitoring point is set up every 20 meters on the shoulder and slope of the old embankment 10 adjacent to the widening area. A hydrostatic level or a high-precision fully automatic total station is used for monitoring to obtain the elevation data of each monitoring point, which is used as the settlement data of the old embankment 10.

[0117] For settlement monitoring of the new embankment 20 fill, during the construction of the new embankment 20, after each layer is completed and compacted, settlement plates are immediately installed along the centerline of the top surface of that layer and near the outer edge of the widened section. This is a mature method in geotechnical engineering. The settlement plate consists of a base plate, a measuring rod, and a protective sleeve. The base plate is embedded on the compacted surface, and the measuring rod is extended vertically to a height that can be accessed later. The sleeve protects the measuring rod from damage by the fill material. The elevation change at the top of the measuring rod is recorded manually using a level or by an automatic settlement sensor. This change value represents the cumulative settlement of the new fill at that point since its installation.

[0118] Elevation data of monitoring points on the new and old embankments are collected simultaneously. For the same monitoring section, the difference between the settlement of the monitoring point of the new embankment 20 fill body and the settlement of the corresponding monitoring point of the old embankment 10 is calculated, and the absolute value is taken to obtain the real-time differential settlement value.

[0119] S32, determine whether the absolute value of the differential settlement difference is greater than or equal to a preset differential settlement warning threshold; the differential settlement warning threshold can be based on the material mechanical properties and deformation coordination requirements of the pavement structural layer, for example, the differential settlement warning threshold is set to 15mm. When the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement warning threshold, a dynamic adjustment mechanism for construction parameters is triggered, such as reducing the paving and compaction rate, reducing the layer thickness, or increasing the reinforcement density, in order to control the development of settlement.

[0120] S33, when the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement warning threshold, the construction parameter adjustment is triggered, and at least one of the following control operations is performed: reduce the paving and compaction rate of the current filling layer, reduce the layer thickness of the subsequent filling layer, or increase the laying density of geogrid in the subsequent filling layer.

[0121] S34, when the absolute value of the differential settlement difference is less than the preset differential settlement warning threshold, continue to fill the new embankment 20 in layers outside the synergistic enhancement transition zone 40 according to the current construction parameters, and connect the new embankment 20 and the synergistic enhancement transition zone 40.

[0122] In a preferred embodiment, step S3 involves the overlapping of the construction of the new embankment 20 and the construction of the synergistic reinforcement transition zones 40 at each level, specifically including the following steps:

[0123] S301, after completing the construction of the synergistic reinforcement transition zone 40 in the lowest step area, the new embankment 20 is immediately constructed in layers outside the synergistic reinforcement transition zone 40; firstly, following the cyclical process steps S21-S24 of step S2, the construction of the synergistic reinforcement transition zone 40 in the lowest step (i.e., the first step) area is completed. After the curing of the top composite layer in this area is completed, the new embankment 20 is immediately constructed in layers towards the widening side, using the outer vertical plane of the synergistic reinforcement transition zone 40 as a reference.

[0124] S302, following the steps in a bottom-up order, for each upper step area currently under construction, execute the following sub-steps sequentially:

[0125] S3021, carry out the construction of the collaborative enhancement transition zone 40 of the upper step area; for example, start the construction of the collaborative enhancement transition zone 40 of the second step.

[0126] S3022, when the top surface of the new embankment 20 rises to be flush with the top surface of the completed upper-level synergistic reinforcement transition zone 40, the reinforcement layer of the new embankment 20 is connected to the synergistic reinforcement transition zone 40; for example, while constructing the second-level step transition zone, the upward filling of the new embankment 20 continues. When the top surface elevation of the new embankment 20 is flush with the top surface elevation of the second-level step synergistic reinforcement transition zone 40, the geogrid of the new embankment 20 at this elevation is connected to the topmost geogrid of the second-level synergistic reinforcement transition zone 40.

[0127] Preferably, for the area that is in horizontal contact with the top of the synergistic reinforcement transition zone 40, the laid geogrid should overlap with the top layer of the synergistic reinforcement transition zone 40 in the horizontal direction, with an overlap length of not less than 1.0 meter. It can be fixed by perforation and binding using a special polymer connecting rod or a high-strength U-shaped clamp to ensure the continuity of the reinforcement effect from the synergistic reinforcement transition zone 40 to the new embankment 20 and avoid weak links in the structure.

[0128] Furthermore, for the area in contact with the facade of the synergistic enhancement transition zone 40, when the new embankment 20 is filled to the corresponding height, the geogrid layer is laid close to the facade of the synergistic enhancement transition zone 40, and the connection can be ensured by structural measures (such as using short anchors or connecting with the geogrid pre-embedded in the facade of the synergistic enhancement transition zone 40).

[0129] S3023, continue to fill the new embankment 20 layer by layer upwards; after completing the connection of S3022, continue to fill the next layer of the new embankment 20 layer by layer upwards, and then begin the construction of the third step's synergistic enhancement transition zone 40.

[0130] Repeat step S302, that is, repeat the cycle of construction of the first-level transition zone, filling to level, connecting, and continuing to fill, until the construction of the coordinated enhancement transition zone 40 of all step areas is completed and the new embankment 20 is filled to the design elevation.

[0131] In a preferred embodiment, the following steps are included before step S1:

[0132] S01, enzyme-induced calcium carbonate precipitation grouting reinforcement is carried out on the natural foundation and the slope toe area of ​​the old embankment under the widened area to form a foundation reinforcement area and a slope toe reinforcement area.

[0133] As described in the background section, traditional embankment widening methods are insufficient in treating the underlying soft soil foundation. The compressive settlement of the new roadbed and the residual settlement of the old roadbed are difficult to coordinate, which is one of the core causes of differential settlement at the junction. If the high-stiffness new and old roadbed structures are placed directly on the weak natural foundation, significant stress concentration will occur due to the abrupt change in stiffness, exacerbating uneven settlement after construction.

[0134] The foundation reinforcement zone is the natural foundation under the expanded roadbed projection range, with the treatment boundary extending at least 1.0 meter beyond the toe line of the new embankment at slope 20. The slope toe reinforcement zone extends 1.5 meters to both sides along the toe line of the old embankment at slope 10, forming shear keys. Subsequently, grouting holes are arranged in a square or quincunx pattern in the above two zones, with a hole spacing of 1.2 to 1.5 meters to cover the entire reinforcement volume.

[0135] The solution concentration and grouting pressure used in step S01 for enzyme-induced calcium carbonate precipitation grouting reinforcement are designed to be lower than the corresponding parameter levels used in step S23 for enzyme-induced calcium carbonate precipitation treatment. As a preferred example, an EICP solution with a urea concentration of 0.5-0.7 mol / L and a calcium chloride concentration of 0.3-0.5 mol / L is prepared, with a urease activity of not less than 2.0 U / mL. This concentration level is lower than the concentration of the enzyme-induced calcium carbonate precipitation solution used for interface strengthening described above.

[0136] Meanwhile, the target cementitious content in the construction control of step S01 is lower than the target cementitious content in step S23, so that the overall stiffness and permeability of the formed foundation reinforcement zone and the slope toe reinforcement zone are between the untreated natural foundation and the synergistic enhancement transition zone 40, thereby forming a mechanical and hydraulic gradient transition layer from the natural foundation to the interface between the old and new roadbeds in the vertical direction.

[0137] The objective of construction control in this stage is to achieve an average cementitious content of 1.5%-2.5% in the reinforced soil. The target cementitious content for construction control in step S01 is lower than the target cementitious content set in the interface transition zone (e.g., 3%-5%).

[0138] Through the aforementioned parameter differentiation design, a continuous and gentle stiffness gradient is formed in the vertical profile, from the natural foundation (low stiffness, high permeability), to the foundation / slope toe reinforcement zone (medium stiffness, medium permeability), and then to the synergistic reinforcement transition zone 40 (high stiffness, low permeability). Simultaneously, after the calcium carbonate crystals partially fill the pores, the permeability coefficient of the reinforcement zone is moderately reduced, falling between the undisturbed soft soil and the highly cemented interface layer, forming a hydraulic gradient. Furthermore, when the superstructure load is transferred through the new embankment 20, the stiffness gradient layer effectively diffuses and homogenizes stress, preventing stress concentration at the bottom of the rigid old and new subgrades, thereby reducing the additional stress impact on the underlying soft soil and lowering instantaneous settlement. During long-term post-construction settlement, the intermediate stiffness reinforcement layer, with its compressibility between the two, coordinates the consolidation settlement of the natural foundation and the deformation of the superstructure, greatly mitigating differential settlement. The moderate permeability variation helps control the seepage path of groundwater in the reinforcement area, playing a certain stabilizing role at the slope toe.

[0139] In a preferred embodiment, step S232, in which the enzyme-induced calcium carbonate precipitation solution is injected into the compacted filler through a grouting device, includes the following steps:

[0140] Use PVC pipes with perforated patterns or seamless steel pipes with a diameter of 25-40mm as grouting pipes. Layout the holes in a square or quincunx pattern with a spacing of 1.0-1.5 meters. Drill holes to the designed depth using a drilling rig, insert the grouting pipes, and backfill the area around the pipes with coarse sand to form a filter layer. Grouting holes should be laid out immediately after the current construction layer filler has been compacted and leveled. For example, use PVC perforated pipes with a diameter of 30mm as grouting pipes. Layout holes in a quincunx pattern in the construction area with a spacing of 1.2 meters. Use a light drilling rig to drill vertically, ensuring the hole depth penetrates the compacted layer and reaches approximately 0.1 meters below it to ensure the enzyme-induced calcium carbonate precipitation solution can treat the bottom interface of the layer. After drilling, insert the grouting pipes, and backfill the annular space between the grouting pipes and the hole wall with washed coarse sand (2-5mm particle size) and compact it to form a filter layer.

[0141] A dual-liquid grouting pump is used to inject the prepared enzyme-induced calcium carbonate precipitation solution into the filler through the grouting pipe. The grouting pressure is 0.2-0.5 MPa to avoid splitting the soil, and the grouting rate is 5-10 L / min. The grouting volume per hole is based on reaching the designed diffusion radius or grout seepage from the hole opening. That is, grouting in a hole is stopped when the injection volume reaches the design volume estimated based on the porosity (e.g., about 80-120 liters per hole), or when uniform seepage of solution is observed at adjacent grouting holes or on the surface of the treated area.

[0142] For areas with a grouting depth greater than 2 meters, segmented retreat grouting is adopted. After each grouting pass, static curing is performed for 36-48 hours to allow initial calcium carbonate formation. For example, when the treatment depth is 2.5 meters, the grouting pipe is first lowered to a depth of 2.5 meters, and 1 / 3 of the designed grout volume for that section is injected; then the grouting pipe is raised by 1.0 meter, and the second 1 / 3 is injected; finally, it is raised by another 1.0 meter, and the remaining grout volume is injected. After each grouting pass, static curing must be performed for no less than 36 hours. Calcium carbonate crystals require time, and the 36-48 hour static curing period provides a time window for the urease catalytic reaction and the nucleation and growth of calcium carbonate crystals. During this period, maintaining a humid environment allows the generated calcium carbonate crystals to precipitate more fully at the particle contact points and the surface of the ribs, forming a strong bridge and encapsulation, ensuring the quality of the reinforcement.

[0143] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for embankment widening construction based on the synergy of biomineralization and reinforcement, characterized in that, Includes the following steps: S1 involves excavating the slope of the old embankment to create multiple inward-sloping steps. S2, in each step area, construction is carried out layer by layer from bottom to top to build a collaboratively enhanced transition zone; wherein, step S2 includes steps S21~S24: S21, For the first layer: The geogrid is laid on the step surface, and the anchoring section is laid on the vertical surface of the step and fixed by anchors, the supporting section is laid on the horizontal tread of the step, and the wrapping section extends outward from the horizontal tread; the geogrid includes the anchoring section, the supporting section and the wrapping section connected in sequence. For the subsequent nth layer: the geogrid is laid on the top surface of the composite layer formed by the (n-1)th layer, and the geogrid of the nth layer is connected to the geogrid of the (n-1)th layer. The supporting section of the nth layer is laid on the top surface of the composite layer of the (n-1)th layer, and the wrapping section of the nth layer extends outward from the top surface of the composite layer of the (n-1)th layer, n≥2; S22, spread a layer of filler on the supporting section of the current construction layer, and then fold the wrapping section of the current construction layer back to cover and wrap the filler; S23, the encapsulated filler is compacted, then enzyme-induced calcium carbonate precipitation is performed, and then static curing is carried out to form a cemented and reinforced composite layer. S24. Repeat steps S21 to S23, and use the top surface of the composite layer formed each time as the construction base surface for the next cycle. Stack the composite layer layer by layer until the total thickness of the stacked composite layer reaches the design elevation of the synergistic reinforcement transition zone, thereby forming the synergistic reinforcement transition zone. S3, a new embankment is constructed in layers outside the synergistic enhancement transition zone, and the new embankment and the synergistic enhancement transition zone are connected.

2. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 1, characterized in that, The enzyme-induced calcium carbonate precipitation treatment in step S23 includes the following steps: S231, Preparation of enzyme-induced calcium carbonate precipitation solution: Dissolve urea, calcium chloride and urease in water according to a predetermined ratio to prepare enzyme-induced calcium carbonate precipitation solution. S232, the enzyme-induced calcium carbonate precipitation solution is injected or permeated into the compacted filler through a grouting device; S233, maintain the encapsulated filler in a temperature and humidity environment suitable for calcium carbonate crystallization for a predetermined time; S234, inside the encapsulated filler, the enzyme induces a reaction in the calcium carbonate precipitation solution, and the generated calcium carbonate crystals partially adhere to the surface of the geogrid ribs to form an encapsulation layer, and partially precipitate between the filler particles and at the interface between the filler particles and the ribs to form a bridging network; the encapsulation layer and the bridging network together constitute a calcium carbonate cement that microscopically interlocks the geogrid, the filler particles and the stepped surface of the old embankment.

3. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 2, characterized in that, During the enzyme-induced calcium carbonate precipitation treatment in step S23, the following steps are performed simultaneously: An array of resistivity monitoring electrodes is deployed within the encapsulated packing material in the processing area. The initial resistivity distribution data of the encapsulated filler before processing is measured and obtained through the resistivity monitoring electrode array. During the enzyme-induced calcium carbonate precipitation process or during post-treatment maintenance, real-time resistivity distribution data is acquired at preset time intervals using the resistivity monitoring electrode array. The difference between the real-time resistivity distribution data and the initial resistivity distribution data is determined, and based on the difference, the measured value of the current cementitious content is calculated in reverse according to the calibration relationship between the resistivity change and the cementitious content established in advance through indoor experiments. The measured value of the current cementitious content is compared with the preset target cementitious content value; When the comparison result shows that the measured value of the current cementitious body content is lower than the target cementitious body content value, it is determined that the overall cementation of the monitoring area is insufficient. Based on the difference, a control command is generated, and at least one of the following control operations is performed: adjusting the concentration of the enzyme-induced calcium carbonate precipitation solution in subsequent grouting cycles, adjusting the grouting volume in subsequent grouting cycles, or starting supplementary grouting for continuous areas where the resistivity change is lower than the average change in the area.

4. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 3, characterized in that, The control operation is as follows: when a continuous region with a resistivity change of less than 15% of the regional average change is identified based on the real-time resistivity distribution data, the continuous region is determined to be a weak cementation region, and supplementary grouting is initiated for the continuous region.

5. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 4, characterized in that, The amount of grout to be injected to initiate supplementary grouting in the continuous area is obtained through the following steps: Using formula The grouting volume is calculated; wherein, This refers to the average change in resistivity within the monitoring area that belongs to the same construction layer as the continuous region. This refers to the average resistivity change over the continuous region. The estimated volume of the continuous region. The reinforcement coefficient is the one pre-calibrated through indoor testing. This represents the volume of enzyme-induced calcium carbonate precipitation solution required to increase the unit resistivity change per unit volume of packing material.

6. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 1, characterized in that, Step S3 includes the following steps: S31. During the construction of the new embankment, the settlement of the old embankment and the settlement of the new embankment fill are monitored simultaneously, and the absolute value of the difference in settlement between the new embankment fill and the old embankment is calculated. S32, determine whether the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement early warning threshold; S33, when the absolute value of the differential settlement difference is greater than or equal to the preset differential settlement warning threshold, the construction parameter adjustment is triggered, and at least one of the following control operations is performed: reduce the paving and compaction rate of the current filling layer, reduce the layer thickness of the subsequent filling layer, or increase the laying density of geogrid in the subsequent filling layer. S34, when the absolute value of the differential settlement difference is less than the preset differential settlement warning threshold, continue to fill the new embankment in layers outside the synergistic enhancement transition zone according to the current construction parameters, and connect the new embankment and the synergistic enhancement transition zone.

7. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 1, characterized in that, In step S3, the filling of the new embankment and the construction of the synergistic enhancement transition zones at each level are carried out in an interspersed manner, specifically including the following steps: S301, after completing the construction of the synergistic enhancement transition zone in the lowest step area, the new embankment is then constructed in layers outside the synergistic enhancement transition zone. S302, following the steps in a bottom-up order, for each upper step area currently under construction, execute the following sub-steps sequentially: S3021, carry out the construction of the coordinated reinforcement transition zone in the upper step area; S3022, When the top surface of the new embankment rises to be flush with the top surface of the completed upper-level synergistic reinforcement transition zone, the reinforcement layer of the new embankment is connected to the synergistic reinforcement transition zone. S3023, continue to fill the new embankment in layers upwards; Repeat step S302 until the construction of the collaborative enhancement transition zone for all step areas is completed and the new embankment is filled to the design elevation.

8. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 2, characterized in that, The following steps are included before step S1: S01, enzyme-induced calcium carbonate precipitation grouting reinforcement is carried out in the natural foundation and old embankment slope toe area under the widened area to form a foundation reinforcement area and a slope toe reinforcement area. The solution concentration and grouting pressure used in step S01 for enzyme-induced calcium carbonate precipitation grouting reinforcement are designed to be lower than the corresponding parameter levels used in step S23 for enzyme-induced calcium carbonate precipitation treatment. Meanwhile, the target cementitious content in the construction control of step S01 is lower than the target cementitious content in step S23, so that the overall stiffness and permeability of the formed foundation reinforcement zone and the slope toe reinforcement zone are between the untreated natural foundation and the synergistic enhancement transition zone, thereby forming a mechanical and hydraulic gradient transition layer from the natural foundation to the interface between the old and new roadbeds in the vertical direction.

9. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 2, characterized in that, The predetermined ratio in step S231 is: urea concentration 0.75-1.0 mol / L, calcium chloride concentration 0.5-0.75 mol / L, and urease activity not less than 3.0 U / mL.

10. The embankment widening construction method based on the synergistic effect of biomineralization and reinforcement as described in claim 9, characterized in that, In step S232, the enzyme-induced calcium carbonate precipitation solution is injected into the compacted filler through a grouting device, which includes the following steps: Use PVC pipes or seamless steel pipes with a diameter of 25-40mm as grouting pipes. Layout holes in a square or quincunx pattern with a spacing of 1.0-1.5 meters. Use a drilling rig to drill holes to the designed depth, insert the grouting pipes, and backfill the pipe area with coarse sand to form a filter layer. A dual-liquid grouting pump is used to inject the prepared enzyme-induced calcium carbonate precipitation solution into the packing material through the grouting pipe; wherein, the grouting pressure is 0.2-0.5MPa, the grouting rate is 5-10L / min, and the grouting volume per hole is based on achieving the designed diffusion radius or grout overflowing from the hole opening; For areas with a grouting depth greater than 2 meters, segmented retreat grouting is adopted. After a single grouting is completed, the area is left to stand for 36-48 hours to allow calcium carbonate to be initially formed.

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