A dynamic adaptive construction method for pipe jacking construction

Abstract

The application provides a ground dynamic adaptation construction method for pipe jacking construction, and relates to the technical field of municipal construction. The steps include: firstly, collecting three physical and mechanical parameters of rock fracture toughness, uniaxial tensile strength and saturated water absorption rate before pre-splitting drilling construction, and constructing a critical crack initiation grouting amount feedforward mapping function to calculate the baseline grouting amount; then collecting the minimum resistance line characteristic parameters of the pre-splitting hole, including the occurrence of rock mass structural plane, the drilling deflection and the free surface form, and substituting the minimum resistance line mapping function to obtain the minimum resistance line mapping index; finally, constructing a grouting amount dynamic adaptation correction function, inputting the minimum resistance line mapping index as a correction variable to output the final optimized grouting amount. The application realizes the real-time dynamic adaptation of the grouting amount with the ground condition through the dual-domain coupling driving of the rock mass crack resistance attribute and the free boundary condition, eliminates the deviation of the experience estimation, and guarantees the construction safety in combination with the safety limiting mechanism, and is suitable for the pipe jacking pre-splitting grouting construction of complex rock strata.

Description

Technical Field

[0001] This invention relates to the field of municipal construction technology, specifically to a dynamic geological adaptation construction method for pipe jacking. Background Technology

[0002] Pipe jacking, a trenchless underground pipeline construction technology, is widely used in urban water supply and drainage, power tunnels, highway and railway culverts, and integrated utility tunnels. When the pipe jacking machine traverses hard rock, unevenly distributed strata, or highly abrasive rock formations, pre-splitting grouting is usually required in front of the tunnel face. This involves injecting grout under high pressure to induce a controllable network of tensile fractures in the surrounding rock mass, thereby weakening the rock mass integrity, reducing jacking resistance, and ensuring the stability of the excavation face. Whether pre-splitting grouting achieves the desired effect largely depends on the reasonable determination of the grouting volume, which directly affects the quality of the fracture formation, material consumption, and construction safety.

[0003] In the prior art, Chinese Patent Publication No. CN117514187A discloses a method and system for differentiated grouting in large-section pipe jacking construction. This technology includes: designing the jacking machine's pushing route; obtaining a first stress value and an angle value; determining the soil conditions at the jacking machine's location based on the stress value; when the stress value is less than a preset first stress threshold, the geological condition is judged to be soft soil; determining the pipe jacking machine's deviation based on the angle value; when the angle value is greater than a preset angle threshold, the deviation indicates that the pipe jacking machine has deviated; when the geological condition is soft soil, spraying bentonite slurry onto the top and sides of the pipe jacking machine to lubricate the outer wall of the pipe section; spraying quick-setting cement slurry onto the bottom of the pipe jacking machine, which combines with the soft soil below the machine to form a load-bearing layer; and correcting the pipe jacking machine when the deviation indicates it has deviated. The above technical solution improves the efficiency of pipe jacking construction.

[0004] However, the aforementioned existing technologies, which use stress sensors to determine soil conditions and angle sensors to determine the deviation of the pipe jacking machine, and increase grouting volume to correct deviation, only adjust the grouting volume based on the deviation angle of the pipe jacking machine itself, without incorporating geometric boundary conditions such as borehole deviation, structural plane orientation, and free face morphology into the quantitative calculation system of grouting volume; this has the following shortcomings: First, there is a lack of quantitative assessment methods for free face boundary conditions, and the traction effect of factors such as borehole deviation, unfavorable combinations of structural plane orientation, and free face undulation on the grout diffusion path is not considered. The method is not effectively incorporated into the grouting volume calculation. When the borehole is obliquely intersecting the free face or encountering the bedding structure, the grout preferentially escapes along the low-resistivity channel, and the actual effective grout volume acting on the surrounding rock mass is seriously insufficient. The traditional empirical method cannot make adaptive compensation for this, which can easily cause grouting blind spots. Secondly, the above scheme lacks a safety limit mechanism. When encountering extremely unfavorable working conditions, increasing the grouting volume based solely on experience is often counterproductive and may even exacerbate the risk of pressure runaway. Under the condition of abnormally abundant resistance, it is impossible to provide a lower limit guarantee for the grouting volume, which may lead to the hidden danger that the cracks between the boreholes cannot be effectively connected.

[0005] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a dynamic adaptation method for strata in pipe jacking construction to solve the problems mentioned in the background art. This invention constructs a three-layer dynamic adaptation system: first, determining the basic grouting parameters; then, correcting the parameters according to the site conditions; and finally, setting a safe pressure upper limit. It establishes a quantitative mapping of grouting demand through three core physical and mechanical parameters, enabling the benchmark grouting volume to adaptively adjust with lithology. By using the minimum resistance line mapping index, it quantifies geometric boundaries such as structural plane attitude, borehole deviation, and free face morphology as correction variables, compensating for grout leakage when the resistance line is insufficient and solving grouting blind zones. Through threshold limiting, it avoids the risks of pressure runaway and fracture non-penetration. This method achieves dynamic adjustment of grouting volume according to strata conditions, effectively reducing material waste, improving fracture quality and surrounding rock stability, and upgrading traditional experience-based estimation to precise strata adaptation.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A method for dynamic geological adaptation in pipe jacking construction includes the following steps: S1: Before the pre-splitting drilling operation, the basic physical and mechanical characteristic parameters of the target rock stratum are extracted. The basic physical and mechanical characteristic parameters include: rock fracture toughness, rock uniaxial tensile strength and rock saturated water absorption rate. The collected basic physical and mechanical characteristic parameters are pre-processed to eliminate dimensional differences and obtain the processed rock crack resistance property evaluation feature vector. S2: Construct a critical crack initiation grouting quantity feedforward mapping function, input the preprocessed crack resistance attribute feature vector into the critical crack initiation grouting quantity feedforward mapping function, and calculate the benchmark grouting quantity; S3: Collect the minimum resistance line feature parameters of the pre-splitting borehole in the target rock stratum. The minimum resistance line feature parameters include the rock mass structure plane orientation, borehole deviation and free face morphology. Preprocess the collected minimum resistance line feature parameters to obtain the preprocessed minimum resistance line evaluation feature vector. S4: Establish the minimum resistance line mapping function, substitute the preprocessed resistance line evaluation feature vector into the function, and calculate the minimum resistance line mapping index. S5: Construct a dynamic adaptation correction function for grouting volume, input the minimum resistance line mapping index as a correction variable into the dynamic adaptation correction function for grouting volume, and output the final optimized grouting volume.

[0008] The process for acquiring the physical and mechanical characteristic parameters in S1 is as follows: The process for collecting rock fracture toughness data is as follows: the rock core or rock block drilled on site is processed into a standard fracture specimen, loaded at a constant displacement rate on a material testing machine, and the load and displacement data at the loading point are collected simultaneously, and the peak load at the critical instability is recorded; according to the specimen geometry and crack pre-fabrication size, the peak load is substituted into the corresponding fracture toughness calculation formula to obtain the critical stress intensity factor value of the rock sample, which is used as the rock fracture toughness value. Uniaxial tensile strength of rock: Rock samples are prepared into cylindrical or disc-shaped standard specimens. The direct tensile method is used for cylindrical specimens and the Brazilian splitting method is used for disc specimens. The load is continuously recorded during the loading process until the specimen fails. The maximum failure load is obtained. The tensile strength is calculated by combining the bearing area or diameter and thickness of the specimen. The average value of the specimens in the same group is taken as the uniaxial tensile strength of rock. Saturated water absorption rate of rock strata: Place regular rock samples in an oven to dry to constant weight, cool and weigh the dry weight, then put the rock samples into water and force saturation by boiling or vacuum pumping until no more bubbles escape and the mass no longer increases. Remove the samples, wipe off the surface moisture and weigh the saturated wet weight. Divide the difference between the saturated wet weight and the dry weight by the dry weight and multiply by 100% to obtain the saturated water absorption rate.

[0009] Furthermore, the obtained physical and mechanical characteristic parameters of rock fracture toughness, rock uniaxial tensile strength, and rock saturated water absorption rate are preprocessed to remove abnormal data, fill in missing parameters, unify data dimensions and formats, and form a standardized set of rock stratum characteristic parameters.

[0010] Furthermore, the feedforward mapping function for the critical initiation grouting volume is: ; in: This is the baseline grouting volume after pretreatment; This is the correction factor for slurry viscosity; The saturated water absorption rate of the pretreated rock strata; The fracture toughness of the pretreated rock; This refers to the uniaxial tensile strength of the pretreated rock. This is the correction factor for rock mass integrity.

[0011] Furthermore, S3 preprocesses the minimum resistance line feature parameters: removes abnormal poles on the structural surface and regularizes them by group; filters out invalid values ​​of inclination measurement and corrects errors, converts the skew rate and reconstructs the borehole trajectory; cleans up point cloud noise, unifies coordinates and extracts free surface morphological features; and then eliminates dimensions through normalization mapping to obtain the minimum resistance line evaluation feature vector.

[0012] Furthermore, the minimum resistance line mapping function is: ; in: This is the revised minimum resistance line; As the baseline resistance line; This is the correction factor for the attitude of rock mass structural planes; This is the correction factor for borehole deviation; This is the correction factor for the shape of the free surface.

[0013] Furthermore, it also includes the baseline resistance line. Acquisition process: ; in: This refers to the effective drilling depth of the pre-splitting hole; The spatial angle between the borehole axis and the direction of the normal to the free surface; The structural surface volume density; The weighting coefficients are used to determine the influence of surface density on the structure.

[0014] Furthermore, the index for the minimum resistance line mapping is: ; in: The index is the minimum resistance line mapping index; To design the spacing of the grouting holes; when When the value is ≥1.0, it indicates that the grouting coverage of a single hole is sufficient to overlap adjacent holes, and the grouting volume requirement is stable. when If the value is less than 1.0, it indicates that the hole spacing is too large or the resistance line is too small, and the grouting volume needs to be increased to ensure effective coverage.

[0015] Furthermore, the final optimized grouting volume formula is as follows: ; in: To ultimately optimize the grouting volume; The critical lower limit threshold for the minimum resistance line mapping index; This is the critical upper limit threshold of the minimum resistance line mapping index.

[0016] Furthermore, the critical lower limit threshold of the minimum resistance line mapping index. and critical upper limit threshold Calibrate as follows: Before construction, a test section was selected on-site in the target rock stratum, and multiple grouting test holes were arranged. Different gradients of grouting pressure and grouting volume were applied to each test hole to carry out pre-crack grouting tests. Simultaneously, the hole perimeter crack propagation range, grouting pressure response curve and grout diffusion radius data of each test hole were collected, and the minimum resistance line mapping index ξ corresponding to each test hole was calculated. The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 0.5 times the designed grouting hole spacing is taken as the effective coverage critical value and calibrated as the critical lower limit threshold. ; The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 1.5 times the designed grouting hole spacing is used as the critical value for saturation coverage, and is calibrated as the critical upper limit threshold. .

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention introduces a dual-domain coupling driving mechanism of intrinsic crack resistance properties of rock mass and free boundary conditions. It first determines the basic grouting parameters, then corrects the parameters based on site conditions, and finally sets a three-layer dynamic adaptation system for the upper limit of safe pressure. This method establishes a quantitative mapping relationship between three core physical and mechanical parameters—rock fracture toughness, uniaxial tensile strength, and saturated water absorption rate—and grouting requirements, enabling the benchmark grouting volume to automatically adjust with lithological changes. This eliminates the subjective bias of traditional empirical methods that rely on manual estimation, significantly improving the scientific rigor and relevance of grouting scheme design. Simultaneously, by introducing a minimum resistance line mapping index, it integrates factors such as structural plane attitude, borehole deviation, and free surface morphology. The boundary conditions are quantified as dynamic correction variables. When the resistance line is insufficient, the grouting volume is automatically compensated to overcome the preferential escape of grout along the free surface, effectively solving the problem of grouting blind zone under the combined conditions of oblique drilling and unfavorable structural surfaces. In addition, the grouting volume is locked within a reasonable range through a safety threshold limiting mechanism, which not only prevents the risk of face instability caused by uncontrolled grouting pressure, but also avoids the failure of joint formation due to insufficient grouting volume. This method enables the grouting volume to be dynamically adjusted in real time according to the formation conditions, effectively reducing material waste, improving the uniformity of pre-splitting joint formation and the stability of the surrounding rock, and shortening the construction cycle. It upgrades traditional pre-splitting grouting from static experience estimation to dynamic and precise adaptation to the formation. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the principle of a dynamic geological adaptation construction method for pipe jacking construction according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0020] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] Example: Please see Figure 1The present invention provides the following technical solutions: A method for dynamic geological adaptation in pipe jacking construction includes the following steps: S1: Before pre-splitting drilling, the basic physical and mechanical characteristic parameters of the target rock strata are extracted. These parameters include rock fracture toughness, rock uniaxial tensile strength, and rock saturated water absorption rate. The collected basic physical and mechanical characteristic parameters are preprocessed to eliminate dimensional differences and obtain the processed rock crack resistance evaluation feature vector. As the pre-sensing link of the entire dynamic adaptation system, the core objective is to establish a quantitative characterization basis for the crack resistance of the rock strata themselves. All parameters are taken from in-situ rock samples of the target construction section to ensure the consistency of data with actual geological conditions and avoid the impact of deviations between indoor tests and field conditions on calculation accuracy.

[0022] The process for obtaining rock fracture toughness is as follows: Rock cores or blocks drilled on-site are processed into standard fracture specimens. These specimens are then loaded at a constant displacement rate on a material testing machine, and load and displacement data at the loading point are collected simultaneously. The peak load at the critical instability point is recorded. Based on the specimen geometry and pre-fabricated crack size, the peak load is substituted into the corresponding fracture toughness calculation formula to obtain the critical stress intensity factor value of the rock sample, which is then used as the rock fracture toughness value. The specimen processing precision must meet the requirements of rock mechanics testing specifications. The pre-fabricated crack tip must be ground until there are no obvious defects to avoid additional stress concentration deviations interfering with the test results. The constant displacement rate is controlled within the range of 0.0005–0.001 mm / s to ensure that the loading process is a quasi-static fracture process, conforming to the applicable conditions of linear elastic fracture mechanics. The obtained fracture toughness value directly reflects the inherent ability of the rock to resist crack propagation and is a core indicator for judging the difficulty of grouting and splitting rock formations.

[0023] Uniaxial tensile strength of rock: Rock samples are prepared into cylindrical or disc-shaped standard specimens. For cylindrical specimens, the direct tensile method is used. The direct tensile method requires that both ends of the specimen be coaxially aligned with the loading fixture to avoid additional bending moments caused by eccentric loads, which would lead to lower test values. For disc specimens, the Brazilian splitting method is used. During the loading process, the load is continuously recorded until the specimen fails, and the maximum failure load is obtained. The tensile strength is calculated by combining the bearing area or diameter and thickness of the specimen, and the average value of the specimens in the same group is taken as the uniaxial tensile strength of the rock. The Brazilian splitting method requires symmetrical arrangement of rigid pads along the diameter of the specimen to ensure that the load is uniformly transmitted radially. Tensile strength is the core indicator for judging the initial crack initiation pressure of the grout. The higher the value, the higher the threshold for tensile failure of the rock strata.

[0024] Saturated water absorption rate of rock strata: Regular rock samples are dried in an oven to constant weight, cooled, and weighed. The rock samples are then placed in water and forced to saturate using boiling or vacuum extraction methods until no more air bubbles escape and the mass no longer increases. After removing the samples and wiping off the surface moisture, the saturated wet weight is measured. The difference between the saturated wet weight and the dry weight is divided by the dry weight and multiplied by 100% to obtain the saturated water absorption rate. The drying temperature is kept constant at 105~110℃. The saturated water absorption rate indirectly reflects the porosity and water sensitivity of the rock strata. The higher the value, the greater the porosity of the rock strata and the higher the basic requirements for grout seepage filling.

[0025] The acquired physical and mechanical characteristic parameters of rock fracture toughness, uniaxial tensile strength, and saturated water absorption rate were preprocessed to remove outlier data, fill in missing parameters, and unify data dimensions and formats to form a standardized set of rock strata characteristic parameters. Outlier data were statistically removed using the Grubbs test, and missing parameters were filled in by linear interpolation of data from adjacent boreholes in the same section. The unification of dimensions was achieved by using the extreme value mapping method to map all parameters to the [0,1] interval, ultimately forming a feature vector with unified dimensions and consistent magnitude, which eliminates the weight bias caused by dimensional differences in subsequent function calculations.

[0026] S2: Construct a critical crack initiation grouting volume feedforward mapping function. Input the preprocessed crack resistance attribute feature vector into the critical crack initiation grouting volume feedforward mapping function to calculate the benchmark grouting volume. This feedforward mapping function is established based on the coupling of rock fracture mechanics and seepage theory. It is directly related to the inherent crack resistance attribute of the rock strata and the benchmark grouting requirements. It is the calculation benchmark for subsequent dynamic correction and characterizes the theoretical critical crack initiation grouting volume under the condition of no free face interference.

[0027] The feedforward mapping function for the critical grouting volume at which cracks initiate is: ; in: This is the baseline grouting volume after pretreatment; This is the correction factor for slurry viscosity; For every change of 0.1, The corresponding fluctuation is about 10%, which needs to be carefully controlled during the slurry mix design stage.

[0028] The saturated water absorption rate of the pretreated rock strata is the positive driving force. Its physical logic is that the higher the water absorption rate of the rock mass, the more significant the ineffective loss of the grout infiltrating and diffusing into the distant micro-fractures. For the fracture toughness of pretreated rock; positive driving, its effect on Its pulling effect is extremely sensitive, especially when encountering highly tough rock formations. The increase in value will force the benchmark grouting volume to rise sharply in a near-linear manner; The uniaxial tensile strength of the pretreated rock; the increase in tensile strength leads to an exponential increase in the amount of grout injected, and the sensitivity is amplified sharply. This is the rock mass integrity correction factor; this index term determines the proportion of the contribution of tensile strength to the grouting volume.

[0029] S3: Collect the minimum resistance line characteristic parameters of the pre-fractured borehole in the target rock stratum. This set of parameters is used to quantify the "traction unloading" effect of the free face of the tunnel excavation (i.e. the free boundary in front of the pipe jacking direction) on the preferred path of high-pressure grout diffusion in the borehole. It is a bridge variable connecting the initiation conditions of the borehole and the constraint conditions of the borehole's outer boundary. The minimum resistance line characteristic parameters include the rock mass structure surface attitude, borehole deviation and free face morphology. The collected minimum resistance line characteristic parameters are preprocessed to obtain the preprocessed minimum resistance line evaluation feature vector. S3 preprocesses the feature parameters of the minimum resistance line: it removes abnormal poles of the structural surface and regularizes them by group; it filters out invalid values ​​of inclination measurement and corrects errors, converts the inclination rate and reconstructs the borehole trajectory; it cleans up point cloud noise, unifies coordinates and extracts free surface morphological features; and then it eliminates dimensions through normalization mapping to obtain the feature vector of the minimum resistance line evaluation.

[0030] S4: Establish a minimum resistance line mapping function, substitute the preprocessed resistance line evaluation feature vector into the function, and calculate the minimum resistance line mapping index; use stereographic projection and density contour statistical method to remove abnormal structural surface extremes caused by measurement errors or local collapse, and group and merge them according to the dominant attitude group to regularize the dip angle; use the full hole section apex angle and azimuth angle data recorded by the drilling rig to screen out invalid inclination values ​​caused by drill pipe elastic bending or zero drift of the inclination sensor, and use the minimum curvature method or natural curve method to correct the well track error, calculate the point-by-point deviation rate, and reconstruct the actual borehole spatial trajectory in three dimensions; Free face morphology preprocessing: use a 3D laser scanner to obtain the original point cloud data of the free face, clean up noise and outliers through statistical filtering and radius filtering, unify to the construction coordinate system, and use the moving least squares method to fit and extract the curvature radius, undulation amplitude, and slope change morphology features of the free face; The minimum resistance line mapping function is: ; in: This is the revised minimum resistance line; As the baseline resistance line; This is the correction factor for the attitude of rock mass structural planes; This is the correction factor for borehole deviation; This is the correction factor for the shape of the free surface.

[0031] Also includes the baseline resistance line Acquisition process: ; in: The effective drilling depth of the pre-splitting hole; the net length of the actual drilling extending to the designed bottom; The angle between the borehole axis and the normal direction of the free face is calculated by fitting the normal vector of the borehole inclination data and the point cloud of the free face. The value ranges from 0° to 90°. The more the borehole tends to be "oblique" rather than "orthogonal" to the free face, the smaller the normal contribution of its resistance line, and the easier it is for the slurry to flow to the free face along the oblique low-resistivity path. The volumetric density of the structural surface is obtained based on borehole core statistics or structural surface mapping. The weighting coefficient for the influence of structural surface density is determined by statistical regression of regional rock mass structural characteristics, and this additive term has a positive driving effect.

[0032] The index of the minimum resistance line is: ; in: It is the minimum resistance line mapping index; it is a comprehensive evaluation index of coverage effectiveness. The spacing of the grouting holes is determined by the perforation parameters given in the design drawings. when When the value is ≥1.0, it indicates that the grouting coverage of a single hole is sufficient to overlap adjacent holes, and the grouting volume requirement is stable. when If the value is less than 1.0, it indicates that the hole spacing is too large or the resistance line is too small, and the grouting volume needs to be increased to ensure effective coverage.

[0033] S5: Construct a dynamic adaptation correction function for grouting volume, input the minimum resistance line mapping index as the correction variable into the dynamic adaptation correction function for grouting volume, and output the final optimized grouting volume.

[0034] The final optimized grouting volume formula is: ; in: To ultimately optimize the grouting volume; it is the final output variable of the entire dynamic adaptation method; This is the critical lower limit threshold for the minimum resistance line mapping exponent; when ξ is below this threshold, the correction factor is locked at [value missing]. The grouting volume will no longer increase as ξ decreases, thus avoiding waste of grouting volume. This threshold acts as a constraint and alarm for abnormal working conditions. This is the critical upper limit threshold for the minimum resistance line mapping exponent. When ξ exceeds this threshold, the correction factor is locked at [value missing]. The grouting volume will no longer decrease as ξ increases. This threshold is set to prevent the theoretically calculated grouting volume from being too small due to an excessively large resistance line, which would cause the inter-hole crack network to fail to be effectively connected due to insufficient grout supply, forming a hidden grouting blind zone. When this threshold is exceeded, the system will still force the minimum grouting volume to be output to ensure that there is enough grout expansion energy between adjacent holes to achieve overlap. Normal dynamic adaptation segment: Within this range, the correction factor Follow As it increases, it continuously and monotonically decreases, exhibiting a strict inverse proportional control characteristic; The essence of reverse driving: As the denominator, the larger its value, the smaller the correction coefficient, and the lower the grouting volume; conversely, the smaller its value, the lower the correction coefficient, and the lower the grouting volume. The smaller the value, the larger the correction coefficient, and the higher the grouting volume. This inverse proportional relationship precisely matches the engineering physical requirements. When the resistance line is insufficient, the grouting volume needs to be increased to compensate, and when the resistance line is sufficient, the grouting volume can be appropriately reduced.

[0035] The critical lower limit threshold of the minimum resistance line mapping exponent and critical upper limit threshold Calibrate as follows: Before construction, a test section was selected at the target rock stratum, and multiple grouting test holes were arranged. Different gradients of grouting pressure and grouting volume were applied to each test hole to conduct pre-cracking grouting tests. Simultaneously, the crack propagation range around the hole, the grouting pressure response curve, and the grout diffusion radius data of each test hole were collected, and the minimum resistance line mapping index ξ corresponding to each test hole was calculated. Among them, the effective diffusion radius of the grout was measured by sketching the grout vein distribution of the excavated section after grouting or by observing the core drilling to ensure the authenticity and reliability of the diffusion radius data. The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 0.5 times the designed grouting hole spacing is taken as the critical value for effective coverage and calibrated as the critical lower limit threshold. Under this condition, the grout diffusion range can only cover a limited area around the hole. If ξ is lower than this critical value, it indicates that single-hole grouting can no longer effectively overlap with adjacent holes, and the amplitude must be forcibly limited and the grouting hole densification warning must be triggered. The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 1.5 times the designed grouting hole spacing is used as the critical value for saturation coverage and calibrated as the critical upper limit threshold. Under this condition, the grout diffusion range has fully covered and exceeded the designed hole spacing. If ξ is higher than this critical value, it indicates that the resistance line conditions are extremely sufficient. If the grouting volume is further reduced at this time, the crack network between holes will not be effectively connected due to insufficient grout supply. It is necessary to enforce the minimum grouting volume to ensure the continuity of cracks between adjacent holes. Through the above calibration process, both thresholds are directly derived from the physical critical points of field test data, avoiding the arbitrariness of human experience in taking values, and making the limiting logic of the grouting volume correction function have clear engineering physical boundaries.

[0036] The above formulas are all dimensionless calculations. The formulas are derived from software simulations using a large amount of collected data, and are the closest to the real situation. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0037] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0038] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0039] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for dynamic geological adaptation in pipe jacking construction, characterized in that, Includes the following steps: S1: Before the pre-splitting drilling operation, the basic physical and mechanical characteristic parameters of the target rock stratum are extracted. The basic physical and mechanical characteristic parameters include: rock fracture toughness, rock uniaxial tensile strength and rock saturated water absorption rate. The collected basic physical and mechanical characteristic parameters are pre-processed to eliminate dimensional differences and obtain the processed rock crack resistance property evaluation feature vector. S2: Construct a critical crack initiation grouting quantity feedforward mapping function, input the preprocessed crack resistance attribute feature vector into the critical crack initiation grouting quantity feedforward mapping function, and calculate the benchmark grouting quantity; S3: Collect the minimum resistance line feature parameters of the pre-splitting borehole in the target rock stratum. The minimum resistance line feature parameters include the rock mass structure plane orientation, borehole deviation and free face morphology. Preprocess the collected minimum resistance line feature parameters to obtain the preprocessed minimum resistance line evaluation feature vector. S4: Establish the minimum resistance line mapping function, substitute the preprocessed resistance line evaluation feature vector into the function, and calculate the minimum resistance line mapping index. S5: Construct a dynamic adaptation correction function for grouting volume, input the minimum resistance line mapping index as a correction variable into the dynamic adaptation correction function for grouting volume, and output the final optimized grouting volume.

2. The method for dynamic geological adaptation in pipe jacking construction according to claim 1, characterized in that: The process for acquiring the physical and mechanical characteristic parameters in S1 is as follows: The process for collecting rock fracture toughness data is as follows: the rock core or rock block drilled on site is processed into a standard fracture specimen, loaded at a constant displacement rate on a material testing machine, and the load and displacement data at the loading point are collected simultaneously, and the peak load at the critical instability is recorded; according to the specimen geometry and crack pre-fabrication size, the peak load is substituted into the corresponding fracture toughness calculation formula to obtain the critical stress intensity factor value of the rock sample, which is used as the rock fracture toughness value. Uniaxial tensile strength of rock: Rock samples are prepared into cylindrical or disc-shaped standard specimens. The direct tensile method is used for cylindrical specimens and the Brazilian splitting method is used for disc specimens. The load is continuously recorded during the loading process until the specimen fails. The maximum failure load is obtained. The tensile strength is calculated by combining the bearing area or diameter and thickness of the specimen. The average value of the specimens in the same group is taken as the uniaxial tensile strength of rock. Saturated water absorption rate of rock strata: Place regular rock samples in an oven to dry to constant weight, cool and weigh the dry weight, then put the rock samples into water and force saturation by boiling or vacuum pumping until no more bubbles escape and the mass no longer increases. Remove the samples, wipe off the surface moisture and weigh the saturated wet weight. Divide the difference between the saturated wet weight and the dry weight by the dry weight and multiply by 100% to obtain the saturated water absorption rate.

3. The method for dynamic geological adaptation construction of pipe jacking according to claim 1, characterized in that: The obtained physical and mechanical characteristic parameters of rock fracture toughness, rock uniaxial tensile strength, and rock saturated water absorption rate are preprocessed to remove abnormal data, fill in missing parameters, unify data dimensions and format, and form a standardized set of rock stratum characteristic parameters.

4. The method for dynamic geological adaptation construction of pipe jacking according to claim 1, characterized in that: The critical fracturing initiation grouting volume feedforward mapping function is: ； in: This is the baseline grouting volume after pretreatment; This is the correction factor for slurry viscosity; The saturated water absorption rate of the pretreated rock strata; The fracture toughness of the pretreated rock; This refers to the uniaxial tensile strength of the pretreated rock. This is the correction factor for rock mass integrity.

5. The method for dynamic geological adaptation construction of pipe jacking according to claim 1, characterized in that: The S3 process preprocesses the minimum resistance line feature parameters by: removing abnormal poles on the structural surface and regularizing them by group; filtering out invalid values ​​from inclination measurements and correcting errors, converting the skewness and reconstructing the borehole trajectory; cleaning up point cloud noise, unifying coordinates and extracting free surface morphological features; and then eliminating dimensions through normalization mapping to obtain the minimum resistance line evaluation feature vector.

6. The method for dynamic geological adaptation in pipe jacking construction according to claim 4, characterized in that: The minimum resistance line mapping function is: ; in: This is the revised minimum resistance line; As the baseline resistance line; This is the correction factor for the attitude of rock mass structural planes; This is the correction factor for borehole deviation; This is the correction factor for the shape of the free surface.

7. The method for dynamic geological adaptation in pipe jacking construction according to claim 6, characterized in that: Also includes the baseline resistance line Acquisition process: ； in: This refers to the effective drilling depth of the pre-splitting hole; The spatial angle between the borehole axis and the direction of the normal to the free surface; The structural surface volume density; The weighting coefficients are used to determine the influence of surface density on the structure.

8. The method for dynamic geological adaptation in pipe jacking construction according to claim 6, characterized in that: The index of the minimum resistance line is: ; in: The index is the minimum resistance line mapping index; To design the spacing of the grouting holes; when When the value is ≥1.0, it indicates that the grouting coverage of a single hole is sufficient to overlap adjacent holes, and the grouting volume requirement is stable. when If the value is less than 1.0, it indicates that the hole spacing is too large or the resistance line is too small, and the grouting volume needs to be increased to ensure effective coverage.

9. The method for dynamic geological adaptation in pipe jacking construction according to claim 8, characterized in that: The final optimized grouting volume formula is: ； in: To ultimately optimize the grouting volume; The critical lower limit threshold for the minimum resistance line mapping index; This is the critical upper limit threshold of the minimum resistance line mapping index.

10. A method for dynamic geological adaptation in pipe jacking construction according to claim 9, characterized in that: The critical lower limit threshold of the minimum resistance line mapping index and critical upper limit threshold Calibrate as follows: Before construction, a test section was selected on-site in the target rock stratum, and multiple grouting test holes were arranged. Different gradients of grouting pressure and grouting volume were applied to each test hole to carry out pre-crack grouting tests. Simultaneously, the hole perimeter crack propagation range, grouting pressure response curve and grout diffusion radius data of each test hole were collected, and the minimum resistance line mapping index ξ corresponding to each test hole was calculated. The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 0.5 times the designed grouting hole spacing is taken as the effective coverage critical value and calibrated as the critical lower limit threshold. ; The minimum resistance line mapping index when the effective diffusion radius of the grout in each test hole reaches 1.5 times the designed grouting hole spacing is used as the critical value for saturation coverage, and is calibrated as the critical upper limit threshold. .

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