A device and method for in-situ multi-field performance active monitoring and age period mechanical testing of a filling body

Abstract

The application discloses a kind of filling body in situ multi-field performance active monitoring and age period mechanical testing device, it is related to in-situ test and monitoring technical field of mine filling engineering. Including: device main body, for being immersed in underground filling slurry;Sample forming mold array, for accommodating with the filling slurry of same batch in underground to form filling body sample;Multi-field environment communication structure, for making filling slurry and external filling body keep heat, water, force, chemical field communication;In-situ multi-field monitoring system, for synchronously monitoring the multiple environmental parameters of the external filling body;Age period mechanical testing system, for the filling body sample of different curing age is carried out in-situ uniaxial compression test.The application can keep heat-water-force-chemical communication with external filling body in underground and establish pore pressure transmission condition under the premise, sample curing, without artificial coring / blocking can be completed in the same device, according to age batch to obtain uniaxial compression such as mechanical data.

Description

Technical Field

[0001] This invention relates to the field of in-situ testing and monitoring technology for mine backfilling engineering, specifically to a device and method for in-situ multi-field active monitoring of the performance of backfill bodies and age-appropriate mechanical testing. Background Technology

[0002] As mines expand to deeper levels, the requirements for the early and long-term performance of backfill materials are increasingly stringent, particularly regarding goaf backfilling, stope recovery, and surrounding rock stability control. After underground casting, the strength, deformation, and permeability of backfill materials (such as cemented backfill slurry and cemented paste backfills) do not evolve under a single factor but are controlled by multiple fields: temperature, hydraulics, mechanics, and chemistry. For example, the exothermic hydration of cement-based binders leads to changes in the temperature field, which in turn affects the hydration rate and pore structure; pore water pressure and seepage processes influence effective stress and structural densification. Therefore, the performance evolution of backfill materials during solidification exhibits significant time-varying and spatial non-uniformity, necessitating characterization and evaluation under multi-field conditions.

[0003] In existing engineering projects, the acquisition of the curing properties of filling materials mainly relies on two methods: one is to manually core / strip samples and conduct uniaxial compression tests in the laboratory to obtain parameters such as compressive strength at different ages; the other is to install sensors downhole for single-field or multi-field monitoring (such as temperature, stress, pore pressure, etc.). However, the above methods generally have shortcomings: the sampling and recovery process often disturbs the sample, and the sampling location and time are difficult to completely match the actual curing environment downhole, making it difficult to truly reflect the evolution of the mechanical properties of the filling material under multiple downhole conditions; while relying solely on sensor monitoring can obtain continuous data, the mapping relationship between the monitored quantities and mechanical properties is greatly affected by the mix ratio, temperature gradient, pore pressure conditions, and differences in the chemical environment, making it difficult to reliably invert the strength and deformation parameters of the filling material.

[0004] Meanwhile, existing laboratory curing and multi-field coupling test devices typically simulate temperature, humidity, or pressure conditions in controlled containers, but still struggle to simultaneously meet the following requirements: (1) the same batch of slurry and curing process as the underground material; (2) communication with the pore water pressure and ion exchange of the external filling body; (3) demolding and in-situ acquisition of mechanical parameters at different ages within the same device without manual core / block sampling; and (4) maintaining structural sealing, preventing blockage, resisting abrasion, and ensuring long-term stable operation during the measurement process. Therefore, there are often discrepancies between laboratory simulation results and actual underground working conditions, resulting in a lack of highly reliable basis for evaluating the quality of the filling body curing process, judging the timing of support / recovery, and providing early warning of safety risks.

[0005] In view of the above problems, there is an urgent need for a device and method that can realize in-situ testing and continuous monitoring of multiple parameters in multiple environments during the solidification process of downhole filling bodies. Summary of the Invention

[0006] The purpose of this invention is to address the problem that existing methods for obtaining performance data during the solidification process of mine backfill bodies are insufficient to accurately reflect the influence of multiple underground environmental factors. To this end, this invention proposes an in-situ multi-field active monitoring and age-appropriate mechanical testing device and method for backfill bodies. This device and method enable in-situ testing and monitoring of samples under the premise of maintaining thermal-hydraulic-mechanical-chemical connectivity between the backfill body and the external backfill body and establishing pore pressure transfer conditions. It allows for sample solidification and curing without manual core / block removal, enabling demolding within the same device, batch acquisition of uniaxial compression and other mechanical data according to age, and simultaneous acquisition of parameters such as temperature, stress, pore water pressure, pH, and resistivity. This achieves more reliable in-situ characterization and evaluation of the performance evolution during the backfill body solidification process. Furthermore, the device should be able to form standardized samples and obtain mechanical parameters such as compressive strength in batches according to age under conditions of maintaining thermal-hydraulic-mechanical-chemical communication with the external filling material through the membrane and transfer pores; through an in-situ multi-field monitoring system, key parameters reflecting curing and structural evolution such as temperature, pore water pressure, stress, pH, and resistivity should be acquired simultaneously, thereby establishing a calibration relationship between monitoring signals and mechanical parameters based on samples cured in the same batch and environment, improving the ability to identify the evolution law of the curing performance of the filling material and its engineering usability.

[0007] Specifically, the specific technical solution adopted in this invention is as follows: According to a first aspect of the technical solution of the present invention, an in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials is provided, comprising: The main body of the device is used to be immersed in the downhole filling slurry. An array of sample forming molds is set inside the main body of the device to accommodate the same batch of filling slurry as the downhole material to form filling body samples; A multi-field environmental communication structure is disposed on the main body of the device to maintain thermal, water, mechanical, and chemical field communication between the filling slurry in the sample forming mold array and the external filling body; wherein, the multi-field environmental communication structure includes: a permeable membrane located on a circular protrusion arranged in an array on the bottom shell of the main body of the device, having the same cross-sectional size as the sample forming mold, the permeable membrane allowing water molecules and ions to pass through; and a transfer hole located on the bottom shell of the main body of the device, corresponding to the bottom position of the circular protrusion; An in-situ multi-field monitoring system is installed on the main body of the device to simultaneously monitor multiple environmental parameters of the external filling body; The age-appropriate mechanical testing system, located inside the main body of the device, is used to conduct in-situ uniaxial compression tests on the filling material samples at different curing ages. The system includes a small uniaxial compression device comprising a pressure rod, a drive unit for axial movement of the pressure rod, and a pressure sensor for measuring pressure. The system simultaneously performs demolding of the filling material sample and uniaxial compression testing on the sample within the same pressure rod stroke.

[0008] Furthermore, the main body of the device is cubic in shape, and its outer surface is provided with structural reinforcing ribs; the sample forming mold array is a regular array of M×M, where M is a positive integer.

[0009] Furthermore, the transfer pores and permeable membrane are configured to allow the transfer of temperature, hydraulic and chemical fields between the filling slurry within the sample forming mold and the external filling body, while limiting the transfer of mechanical fields primarily along the axial direction of the sample forming mold.

[0010] Furthermore, the in-situ multi-field monitoring system includes at least three of the following sensors: temperature sensor, stress sensor, pore water pressure sensor, pH sensor, and resistivity sensor. The stress sensor is configured to monitor stress changes inside the filling body from three mutually perpendicular directions.

[0011] Furthermore, the age-appropriate mechanical testing system also includes: an XY two-axis moving positioning mechanism, which is disposed on the upper side inside the main body of the device; The small single-axis compression device is fixedly connected to the XY two-axis moving positioning mechanism, and can be moved to the top of any mold in the sample forming mold array through the XY two-axis moving positioning mechanism.

[0012] Furthermore, the drive unit includes a hydraulic pump, a pressurized oil pipe, a return oil pipe, a support gasket, a support rod, and a compression sleeve. The hydraulic pump has a built-in hydraulic cylinder and is fixedly installed on the side of the main body of the device. It is connected to the compression sleeve through a pressurization oil pipe and a return oil pipe. The compression sleeve is fixedly connected to the XY two-axis moving positioning mechanism; The pressure rod is coaxially connected to the compression sleeve. The hydraulic pump controls the extension and retraction of the pressure rod by pressurizing and depressurizing, which can simultaneously complete demolding, uniaxial compression and depressurization operations. The support rod is fixedly installed on the other end face of the compression sleeve, and the support rod is fixedly connected to the support pad; the support pad is in direct contact with the main body shell of the device, and lubricating oil is applied between the support pad and the main body shell of the device.

[0013] Further, the pressure sensor is located at the lower end of the pressure rod.

[0014] Further, the sample forming mold is composed of two separable shells that are butt-joined, the two shells are locked by a locking mechanism and fixed on the bottom outer shell of the device main body; the locking mechanism is made of shape memory metal, and the austenite finish temperature of the locking mechanism is higher than the maximum temperature during the hydration process of the filling body.

[0015] Further, the locking mechanism comprises a first lock and a second lock mounted with a magnetic conductive sheet.

[0016] Further, 4 ear plates are symmetrically distributed on both sides of the sample forming mold, the ear plates of the two shells are locked by the first lock, so that the two separable shells form an integral body; a groove is respectively provided at the lower part of the outer side of the sample forming mold and the lower part of the circular boss, and the sample forming mold is fixed on the bottom outer shell of the device main body through the second lock.

[0017] Further, the device further comprises a heating unit, configured to selectively heat the locking mechanism to unlock the same; an N×N array of compartments is arranged inside the device main body, where N is a positive integer, for accommodating the sample forming molds, and strong magnets are fixedly arranged on the opposite inner walls of the compartments, configured to adsorb and fix the locks and the shells after the first lock and the second lock are unlocked and the two shells are separated.

[0018] Further, the heating unit is a miniature infrared heating device.

[0019] Further, the value of M < the value of N.

[0020] Further, mutually matching chamfers are respectively arranged at the lower end of the pressure rod and the upper end of the sample forming mold, so that when the pressure rod contacts the sample forming mold downward, the generated axial pressure can decompose a lateral component force, which promotes the separation of the sample forming mold for demolding; meanwhile, the pressure rod can continue to load the filling body sample downward, and a uniaxial compression test is performed.

[0021] Therefore, through the above unique structural arrangement, the device main body, the sample forming mold and the staged mechanical testing system which interact and combine with each other, demolding and the uniaxial compression experiment can be completed simultaneously downhole only through the pressure rod.

[0022] Further, the device further comprises a visual monitoring unit, the visual monitoring unit is fixed on the staged mechanical testing system and configured to record the failure morphology of the filling body sample during the uniaxial compression test.

[0023] According to a second aspect of the present invention, a testing method based on the above-mentioned in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials is provided, the method comprising the following steps: The main body of the device is immersed in the filling slurry to be tested downhole; Through the multi-field environment interconnection structure, the filling slurry inside the sample molding mold and the external filling body can be simultaneously cured in a multi-field environment; The in-situ multi-field monitoring system continuously collects multiple environmental parameters of the external filling body. The filling samples formed by the M×M array sample forming mold are divided into multiple groups, with no fewer than 3 filling samples in each group to reduce errors; and each group is set to a different curing age. When the predetermined curing age is reached, the age-specific mechanical testing system is operated to perform in-situ demolding and uniaxial compression tests on the corresponding filling samples to obtain the mechanical property parameters for that age. Establish and analyze the correlation between the environmental parameters and the mechanical performance parameters at different ages.

[0024] The beneficial effects of this invention are: In the in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials of the present invention, by setting mutually cooperating chamfer structures at the lower end of the pressure bar and the upper end of the sample forming mold, the axial load when the pressure bar is pressed down is automatically decomposed at the contact interface to generate a lateral component force. This drives the two sample forming molds to separate rapidly without the need for an additional mold opening actuator, realizing in-situ demolding of the filling material sample. After the molds are separated, the pressure bar can continue to load downward along the same axis, and the demolded sample can be directly subjected to a uniaxial compression test. This structure integrates the "demolding action" and the "uniaxial loading action" within the same pressure bar stroke, which can simply and quickly realize the demolding and uniaxial compression test of the sample, while avoiding sample disturbance caused by repeated disassembly and assembly, making the obtained mechanical parameters more representative and repeatable.

[0025] The device of this invention can operate in the downhole filling body, allowing the sample inside the mold to maintain thermal-hydraulic-mechanical-chemical communication with the external filling body through a thin film and transfer holes. This allows the device to reflect the solidification and performance evolution of the filling body under conditions that are closer to the field multi-field environment, reducing the deviation caused by laboratory simulation and sampling recovery.

[0026] The device integrates a small uniaxial compression system, which can demold array samples in batches and directly perform uniaxial compression tests at different curing ages to obtain mechanical parameters such as compressive strength at each age. This enables in-situ testing of samples from the same source as the downhole filling material, cured in the same environment, and improved data reliability and repeatability.

[0027] The device uses an in-situ multi-field monitoring system to simultaneously collect parameters such as temperature, pore water pressure, pH, and resistivity, and correlates them with mechanical results at different ages. This establishes a correlation between the monitoring signals of the curing process and mechanical indicators such as strength, providing a more reliable basis for assessing the curing degree of the filling material, determining the time to meet standards, and identifying anomalies. Attached Figure Description

[0028] 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.

[0029] Figure 1 The diagram shows an overall view of an in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to an embodiment of the technical solution of the present invention. Figure 2 The diagram shows the internal structure of an in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to an embodiment of the technical solution of the present invention. Figure 3 The diagram shows a structural diagram of an XY-axis two-axis moving positioning mechanism and a small uniaxial compression testing device according to an embodiment of the technical solution of the present invention. Figure 4 The diagram shows a sample forming mold array and compression process according to an embodiment of the technical solution of the present invention; Figure 5 The diagram shown is a structural diagram of a sample forming mold array according to an embodiment of the technical solution of the present invention; Figure 6 The diagram shown is a structural diagram of a sample molding die according to an embodiment of the technical solution of the present invention; Figure 7 The diagram shows a mold clamp according to an embodiment of the technical solution of the present invention.

[0030] in: 1-Power supply and communication cable; 2-Stress sensor; 3-Porous water pressure sensor; 4-Temperature sensor; 5-Resistivity sensor; 6-pH sensor; 7-Hydraulic pump; 8-Pressure oil pipe; 9-XY two-axis moving positioning mechanism; 10-Compression sleeve; 11-Pressure rod; 12-Support pad; 13-Support rod; 14-Camera; 15-Miniature infrared heater; 16-Compartment; 17-Sample forming mold; 18-Back pressure oil pipe; 19-Strong magnet; 20-Bottom latch; 21-Pressure sensor; 22-Sealing ring; 23-Mold top cover; 24-Filling sample; 25-Thin film; 26-Transfer hole; 27-Ear plate; 28-Upper latch; 29-Magnetic plate The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0032] The terms "first," "second," etc., used in this disclosure are for distinguishing similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented, for example, in orders other than those illustrated or described herein.

[0033] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0034] Multiple, including two or more.

[0035] And / or, it should be understood that, for the purposes of this disclosure, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0036] This invention proposes a device and method for in-situ multi-field active monitoring of infill material properties and age-appropriate mechanical testing. Its core lies in the synergistic coupling of the device body, the sample forming mold, and the age-appropriate mechanical testing system, enabling the pressure rod to complete in-situ demolding and sampling of the sample within the same stroke downhole, followed by uniaxial compression testing. Specifically, the device body provides arrayed installation, guiding and limiting, and a reaction force closed path for the sample forming mold; the sample forming mold forms a standardized cylindrical sample under the constraint of the body, and the chamfered structure that cooperates with the pressure rod decomposes the axial load of the pressure rod into a lateral component to promote mold separation and demolding; the age-appropriate mechanical testing system drives the pressure rod to align at different ages and continuously press down, thereby directly loading the sample after demolding to complete uniaxial compression. These three components influence and combine with each other, and none can be omitted, jointly ensuring the synchronous realization of in-situ sampling and age-appropriate mechanical testing. Meanwhile, the in-situ monitoring data such as temperature, pore water pressure, stress, pH, and resistivity in the device correspond synchronously with the above-mentioned uniaxial compression results at different ages under the same source sample and the same environmental curing conditions. The mechanical parameters obtained from the uniaxial compression test are used as calibration benchmarks to establish and correct the calibration relationship between "multi-field monitoring signals and mechanical properties", thereby realizing continuous evaluation and reliable determination of the curing performance evolution of the filling body.

[0037] Specifically, this invention provides an in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials. The device mainly includes a 6×6 array of sample forming molds, a small uniaxial compression testing device, an XY-axis two-axis moving and positioning mechanism, and an in-situ multi-field monitoring system (temperature sensor, stress sensor, pore water pressure sensor, pH sensor, and resistivity sensor). After pre-filling the mold array with the same batch of filling slurry as the downhole filling material, the main body of the device is completely immersed in the filling slurry, and the coupling of the multi-field environment is achieved through the transfer hole at the bottom of the device.

[0038] The device is generally cubic in shape, with structural reinforcing ribs on each side to ensure the overall strength of the device. The top of the device has a power supply and communication cable and a stress sensor. Two additional stress sensors are installed on two mutually perpendicular sides of the device to monitor the stress changes inside the filling body from three mutually perpendicular directions. A pore water pressure sensor, a temperature sensor, a resistivity sensor, and a pH sensor are also installed on the two mutually perpendicular sides. Each sensor can continuously monitor the real-time data of the downhole filling body.

[0039] The device has a 7×7 array of detachable compartments on its lower interior. A 6×6 array of sample forming molds is located at the center of each compartment, with each mold composed of two identical pieces. The upper end of each sample forming mold has a chamfer. The mold top cover is inserted into the sample forming mold through a groove on the upper inner side. Four symmetrical ear plates are distributed on both sides of each sample forming mold; these ear plates, composed of two sample forming mold pieces, are locked together by upper locking buckles, forming a single unit. A sealing ring further seals the upper part of the sample forming mold. The bottom outer shell of the device has a circular boss with the same cross-sectional dimensions as the sample forming mold. A thin film is installed on each circular boss, allowing ions and water molecules to pass through, ensuring that pore water caused by the hydration reaction between the filling sample and the external filling material is contained during the curing process. The pressure and ion concentration change synergistically; at the same time, avoid the filling sample forming a direct connection structure with the external filling material, so that the bottom of the filling sample is flat and the boundary conditions are consistent with the laboratory uniaxial compression test; after the inner wall of the sample forming mold is coated with a release agent, the sample forming mold is filled with the same batch of filling slurry as downhole, and the sample forming mold is placed on the circular boss with the film installed. There is a groove on the lower part of the outer side of the sample forming mold and the lower part of the circular boss. The sample forming mold is fixed to the bottom shell of the device by the bottom lock and the sealing space is formed inside the sample forming mold by the sealing ring; the bottom lock and the upper lock are both made of shape memory metal and are fixedly installed with magnetic plates. The highest temperature during the hydration exothermic process of the filling material is below 50°C, and the austenite termination temperature of the shape memory metal is set at 80°C.

[0040] The circular boss on the bottom shell of the device has several transfer holes along its axis. Before the main body of the device is completely immersed in the downhole filling slurry, the transfer holes are filled with filling slurry of the same batch as that used in the downhole.

[0041] The membrane and transfer holes connect the filling slurry inside the sample molding die with the temperature-hydraulic-mechanical-chemical environment of the surrounding filling slurry, forming a multi-field environmental condition. Among them, the membrane and transfer holes can only transfer the mechanical field of the sample molding die along the axial direction; however, compared with the temperature and chemical fields, the stress field has little effect on the curing process of the filling material, and the error caused by considering only the mechanical field in a single direction is very small.

[0042] The upper part of the device is equipped with an XY-axis two-axis moving positioning mechanism and a small single-axis compression system. The small single-axis compression system consists of a hydraulic pump, a pressurizing oil pipe, a return oil pipe, a support pad, a support rod, a compression sleeve, and a pressure rod. The hydraulic pump has a built-in hydraulic cylinder and is fixedly installed on the side of the device, connected to the compression sleeve through the pressurizing and return oil pipes. The compression sleeve is fixedly connected to the XY-axis two-axis moving positioning mechanism. The pressure rod is coaxially connected to the compression sleeve, and the hydraulic pump controls the extension and retraction of the pressure rod by pressurizing and depressurizing to complete the single-axis compression and depressurization operations. A pressure sensor is installed at the lower end of the pressure rod. The lower end of the pressure rod is chamfered. A support rod is fixedly installed on the other end face of the compression sleeve, and the support rod is fixedly connected to the support pad. The support pad is in direct contact with the outer shell of the device, and lubricating oil is applied between the support pad and the outer shell of the device.

[0043] The miniature infrared heater is fixedly mounted on the compression sleeve.

[0044] The 6×6 array of sample forming molds can prepare several groups of filling body samples at different curing ages according to actual needs. When each group of filling body samples has completed curing, the miniature infrared heater is turned on to heat the bottom and top latches of the sample forming mold to be demolded. When the temperature of the bottom and top latches exceeds their austenite termination temperature, they begin to recover their initial shape and fall off, guided by the magnetic sheet to be adsorbed onto a strong magnet, avoiding interference with demolding and uniaxial compression testing; thus unlocking the sample forming mold. After being positioned by the XY two-axis moving positioning mechanism, the pressure rod extends downward (the pressure rod matches the chamfer of the sample forming mold) and contacts the sample forming mold. The axial pressure generates a lateral component force through the contact surface between the pressure rod and the sample forming mold, causing the two sample forming mold pieces to separate, thus demolding the filling body sample. After applying a release agent to the inner wall of the sample forming mold, demolding is very easy, so the demolding process through the interaction of the pressure rod and the mold will not damage the filling body sample.

[0045] The strong magnets are fixed on two opposite surfaces inside the compartment; after the two sample molding molds are separated, they are attracted by the strong magnets on both sides and stick tightly to the inner wall of the compartment, which will not interfere with the uniaxial compression test.

[0046] The camera is fixedly installed on the outer wall of the compression sleeve; after the filling sample is demolded, the pressure rod continues to press down to load the filling sample and perform a uniaxial compression test; the compression failure process and failure result are monitored by the camera.

[0047] like Figure 1 and Figure 2As shown, this invention discloses an in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials. The device mainly includes a 6×6 array of sample forming molds 17, a small uniaxial compression system, an XY-axis moving and positioning mechanism 9, and an in-situ multi-field monitoring system (temperature sensor 4, stress sensor 2, pore water pressure sensor 3, pH sensor 6, and resistivity sensor 5). After pre-filling the mold array with the same batch of filling slurry as the downhole filling material, the main body of the device is completely immersed in the filling slurry, and the coupling of the multi-field environment is achieved through the transfer hole at the bottom of the device.

[0048] The device is generally cubic in shape, with structural reinforcing ribs arranged on each side to ensure the overall strength of the device. The top of the device has a power supply and communication cable 1 and a stress sensor 2. Two additional stress sensors 2 are installed on two mutually perpendicular sides of the device to monitor the stress changes inside the filling body from three mutually perpendicular directions. A pore water pressure sensor 3, a temperature sensor 4, a resistivity sensor 5, and a pH sensor 6 are also installed on the two mutually perpendicular sides. Each sensor can continuously monitor the real-time data of the downhole filling body.

[0049] like Figure 5 As shown, the device has a 7×7 array of detachable compartments 16 on its lower side; the middle part of the 7×7 array of compartments 16 is used to install the sample forming mold 17, and the outer compartments 16 are used to provide movement space for the XY two-axis moving positioning mechanism 9; the 6×6 array of sample forming molds 17 is located at the center of each compartment, and each mold is assembled from two identical pieces; the upper end of the sample forming mold 17 is chamfered; the mold top cover 23 is embedded into the sample forming mold 17 through a groove on the upper inner side of the sample forming mold 17; as shown Figure 6As shown, four ear plates 27 are symmetrically distributed on both sides of the sample forming mold 17. The ear plates 27, composed of two sample forming mold pieces 17, are locked together by upper locking buckles 28, forming a single unit. A sealing ring 22 seals the upper part of the sample forming mold 17. The bottom outer shell of the device has an array of circular bosses with the same cross-sectional dimensions as the sample forming mold 17. A thin film 25 is installed on each circular boss. This film allows ions and water molecules to permeate, ensuring coordinated changes in pore water pressure and ion concentration caused by the hydration reaction between the filling sample and the external filling material during the curing process; simultaneously preventing the filling material from... The specimen and the external filling material form a directly connected structure, making the bottom of the filling material specimen flat and ensuring that the boundary conditions are consistent with those of the laboratory uniaxial compression test. After the inner wall of the specimen forming mold 17 is coated with a release agent, the specimen forming mold 17 is filled with filling slurry of the same batch as that used in the well, and the specimen forming mold 17 is placed on the circular boss with the film 25 installed. There is a groove on the lower part of the outer side of the specimen forming mold 17 and the lower part of the circular boss. The specimen forming mold 17 is fixed to the bottom shell of the device by the bottom lock 20, and a sealed space is formed inside the specimen forming mold 17 by the sealing ring 22. Figure 7 As shown, both the bottom latch 20 and the top latch 28 are made of shape memory metal and are fixedly installed with magnetic plates 29. The highest temperature during the hydration and exothermic process of the filling body is below 50°C, and the austenite final temperature of the shape memory metal is set at 80°C.

[0050] The device has several transfer holes 26 on the axial direction of the circular boss on the bottom shell. Before the main body of the device is completely immersed in the downhole filling slurry, the transfer holes 26 are filled with the same batch of filling slurry as the downhole filling slurry to avoid the introduction of air bubbles.

[0051] The thin film 25 and the transfer hole 26 can connect the filling slurry inside the sample forming mold 17 with the temperature-hydraulic-mechanical-chemical environment of the surrounding filling slurry, forming a multi-field environmental condition. Among them, the mechanical field in the axial direction of the sample forming mold 17 can only be transferred through the thin film 25 and the transfer hole 26; however, compared with the temperature and chemical fields, the stress field has little effect on the curing process of the filling body, and the error caused by considering only the mechanical field in a single direction is very small.

[0052] like Figure 3As shown, an XY two-axis moving positioning mechanism 9 and a small single-axis compression system are installed on the upper side inside the device. The small single-axis compression system consists of a hydraulic pump 7, a pressurizing oil pipe 8, a return oil pipe 18, a support pad 12, a support rod 13, a compression sleeve 10, and a pressure rod 11. The hydraulic pump 7 has a built-in hydraulic cylinder and is fixedly installed on the side of the device. It is connected to the compression sleeve 10 through the pressurizing oil pipe 8 and the return oil pipe 18. The compression sleeve 10 is fixedly connected to the XY two-axis moving positioning mechanism 9. The pressure rod 11 is coaxially connected to the compression sleeve 10. The hydraulic pump 7 controls the extension and retraction of the pressure rod 11 by pressurizing and depressurizing to complete the single-axis compression and depressurization operations. Figure 4 As shown; a pressure sensor 21 is installed at the lower end of the pressure rod 11, which can provide feedback on the pressure data during loading; the lower end of the pressure rod 11 is chamfered; a support rod 13 is fixedly installed on the other end face of the compression sleeve 10, and the support rod 13 is fixedly connected to the support pad 12; the support pad 12 is in direct contact with the device housing, and lubricating oil is applied between the support pad 12 and the device housing; in the initial stage of the compression test, the reaction force of the load applied to the sample is transmitted to the device housing through the pressure rod 11-hydraulic oil-compression sleeve 10-support rod 13-support pad 12, and the reaction force is borne by the strength of the device housing itself.

[0053] The miniature infrared heater 15 is fixedly installed on the compression sleeve 10; by installing and adjusting the miniature infrared heater 15, it can only heat the internal area of ​​the compartment 16 below the pressure rod 11.

[0054] The strong magnet 19 is fixed on two opposite surfaces inside the compartment 16.

[0055] The 6×6 array of sample forming molds 17 can prepare several groups of filling body samples 24 at different curing ages according to actual needs. When each group of filling body samples 24 has completed curing, the miniature infrared heater 15 is turned on to heat the bottom latch 20 and the top latch 28 of the sample forming mold 17 to be demolded. When the temperature of the bottom latch 20 and the top latch 28 exceeds their austenite termination temperature, they begin to recover their initial shape and fall off, thus unlocking the sample forming mold 17. After the bottom latch 20 and the top latch 28 fall off, their magnetic plates 29 are attracted by the strong magnet 19 and adhere tightly to the inner wall of the compartment 16, without interfering with the uniaxial compression test. After being positioned by the XY-axis moving positioning mechanism 9, the pressure rod 11 extends downward (the pressure rod 11 matches the chamfer of the sample forming mold 17) and contacts the sample forming mold 17. The axial pressure generates a lateral component force through the contact surface between the pressure rod 11 and the sample forming mold 17, causing the two sample forming molds 17 to separate and demold the filling sample 24. Since the inner wall of the sample forming mold is coated with a release agent, demolding is very easy. Therefore, the demolding process through the interaction of the pressure rod and the mold will not damage the filling sample.

[0056] The miniature infrared heater 15 has a fast heating speed and a low heating temperature, which will not interfere with the test results of the filling sample 24.

[0057] After the two sample molding molds 17 are separated, they are attracted by the strong magnets 19 on both sides and stick tightly to the inner wall of the compartment 16, which will not interfere with the uniaxial compression test. The debris of the damaged filling sample 24 after the compression test is isolated in each compartment 16 and will not interfere with the uniaxial compression test in the adjacent compartment 16.

[0058] The camera 14 is fixedly installed on the outer wall of the compression sleeve 10; after the filling sample 24 is demolded, the pressure rod 11 continues to press down to load the filling sample 24 and perform a uniaxial compression test; the compression failure process and failure result are monitored by the camera 14.

[0059] All data and power required by the device are transmitted via the power supply and communication cable 1.

[0060] The wellhead collects and analyzes the data transmitted via power supply and communication cable 1.

[0061] The in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials includes the following steps: 1. Lock the two sample forming molds 17 with the upper locking buckle 28 and the sealing ring 22 to form a sealed space inside the sample forming molds 17. After applying a release agent to the inner wall of the sample forming molds 17, fill the sample forming molds 17 with filling slurry from the same batch as that used in the well. Install a film 25 on the circular boss on the bottom shell of the device; fix the sample forming molds 17 filled with filling slurry on the circular boss on the bottom shell of the device with the bottom locking buckle 20. Fill the transfer hole 26 with filling slurry from the same batch as that used in the well. Completely immerse the main body of the device in the filling slurry.

[0062] 2. When the main body of the device is completely immersed in the filling slurry, the filling slurry inside the sample forming mold 17 is connected to the temperature-hydraulic-mechanical-chemical environment of the surrounding filling slurry through the membrane 25 and the transfer hole 26, forming multiple environmental conditions.

[0063] Key state parameters during the curing process of the filling slurry are continuously monitored using an in-situ multi-field monitoring system (temperature sensor 4, stress sensor 2, pore water pressure sensor 3, pH sensor 6, resistivity sensor 5, and stress sensor 2).

[0064] 3. After each group of filling specimens 24 reaches the designed curing age, the bottom latch 20 and top latch 28 of the specimen molding mold 17 are heated by a miniature infrared heater 15. When the temperature of the bottom latch 20 and top latch 28 exceeds their austenite final temperature of 80°C, they begin to recover their initial shape and fall off, thus unlocking the specimen molding mold 17. After the bottom latch 20 and top latch 28 fall off, their magnetic plates 29 are attracted by a strong magnet 19 and adhere tightly to the inner wall of the compartment 16, without interfering with the uniaxial compression test. After being positioned by the XY two-axis moving positioning mechanism 9, the pressure rod 11 extends downward and contacts the specimen molding mold 17. The axial pressure generates a lateral component force through the contact surface between the pressure rod 11 and the specimen molding mold 17, causing the two specimen molding molds 17 to separate and demold the filling specimen 24. After demolding, the two specimen molding molds 17 adhere tightly to the inner wall of the compartment 16 under the attraction of the strong magnets 19 on both sides.

[0065] After the filling sample 24 is demolded, the pressure rod 11 continues to press down to load the filling sample 24 and conduct a uniaxial compression test to obtain mechanical parameters such as compressive strength at different curing ages; the compression failure process and failure result are monitored by the camera 14.

[0066] 4. Collect and analyze key state parameters of the curing process, and analyze them synchronously with the mechanical results at different ages.

[0067] In summary, this invention proposes an in-situ multi-field active monitoring device and method for mechanical testing of filling materials at different ages. The device includes a shell, a sample forming mold array, a small uniaxial compression system, a moving positioning mechanism, and a multi-parameter sensing and monitoring system. The mold array is pre-filled with filling slurry from the same batch as the downhole material. One end of the mold is covered to prevent the slurry from entering the device, while the other end has a thin film that allows water molecules and ions to pass through. The outer side of the film corresponds to a transmission hole array on the shell, ensuring communication between the sample inside the mold and the external filling material in terms of heat conduction, pore water pressure transmission, stress transmission, and chemical environment, achieving curing conditions closer to those in the downhole multi-field environment. The small uniaxial compression system uses an XY-axis moving frame to position and load each cylindrical sample. Combined with batch demolding and age-appropriate compression testing, mechanical parameters such as compressive strength at different curing ages are obtained. The in-situ multi-field monitoring system includes temperature, stress, pore water pressure, pH, and resistivity sensors to acquire key state parameters of the curing process in real time and establish a correspondence with the age-appropriate mechanical results. This invention enables in-situ continuous monitoring of the curing performance of filling materials and acquisition of in-situ measured mechanical parameters downhole, thereby improving the reliability of curing process evaluation and compliance determination.

[0068] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other modifications under the guidance of the present invention without departing from the spirit and scope of the claims. All of these modifications are within the protection scope of the present invention.

Claims

1. A device for in-situ multi-field active monitoring and age-appropriate mechanical testing of filling materials, characterized in that, include: The main body of the device is used to be immersed in the downhole filling slurry; the main body of the device is provided with N×N array of compartments, where N is a positive integer, for accommodating sample forming molds; A sample forming mold is disposed inside the main body of the device and is used to contain the filling slurry of the same batch as that in the well to form a filling body sample; the sample forming molds are arranged in an M×M sample forming mold array, where M is a positive integer and the value of M is less than the value of N; A multi-field environmental communication structure is disposed on the main body of the device to maintain thermal, water, mechanical, and chemical field communication between the filling slurry in the sample forming mold array and the external filling body; wherein, the multi-field environmental communication structure includes: a permeable membrane located on a circular protrusion arranged in an array on the bottom shell of the main body of the device, having the same cross-sectional size as the sample forming mold, the permeable membrane allowing water molecules and ions to pass through; and a transfer hole located on the bottom shell of the main body of the device, corresponding to the bottom position of the circular protrusion; An in-situ multi-field monitoring system is installed on the main body of the device to simultaneously monitor multiple environmental parameters of the external filling body; An age-appropriate mechanical testing system, installed inside the main body of the device, is used to conduct in-situ uniaxial compression tests on the filling material samples at different curing ages. The system includes a small uniaxial compression device comprising a pressure rod, a drive unit for driving the axial movement of the pressure rod, and a pressure sensor for measuring pressure, the pressure sensor being installed at the lower end of the pressure rod. The age-appropriate mechanical testing system achieves both demolding of the filling material sample and uniaxial compression testing of the filling material sample within the same pressure rod stroke. The sample forming mold is composed of two separable shell pieces that fit together. These two shell pieces are locked and fixed to the bottom outer shell of the main body of the device via a locking mechanism. The locking mechanism is made of shape memory metal, and its austenite termination temperature is higher than the highest temperature during the hydration process of the filling material. The locking mechanism includes a first lock and a second lock with magnetic plates installed on them. Four ear plates are symmetrically distributed on both sides of the sample forming mold. The first lock locks the ear plates of the two shell pieces, forming a single unit. The lower part of the outer side of the sample forming mold and the lower part of the circular boss each have a groove. The second lock fixes the sample forming mold to the bottom outer shell of the main body of the device. The device further includes a heating unit for selectively heating the locking mechanism to unlock it; strong magnets are fixedly arranged on the inner walls of the compartments to attract and fix the locking and housings after the first and second locking are unlocked and the two housings are separated. The lower end of the pressure rod and the upper end of the sample forming mold are both provided with matching chamfers, so that when the pressure rod contacts the sample forming mold downwards, the axial pressure generated can be decomposed into a lateral component force, causing the sample forming mold to separate for demolding; at the same time, the pressure rod continues to load the filling sample downwards to perform a uniaxial compression test.

2. The in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to claim 1, characterized in that, The main body of the device is cubic in shape, and its outer surface is provided with structural reinforcing ribs.

3. The in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to claim 1, characterized in that, The age-appropriate mechanical testing system also includes: an XY two-axis moving and positioning mechanism, which is disposed on the upper side inside the main body of the device; The small single-axis compression device is fixedly connected to the XY two-axis moving positioning mechanism, and can be moved to the top of any mold in the sample forming mold array through the XY two-axis moving positioning mechanism.

4. The in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to claim 3, characterized in that, The drive unit includes a hydraulic pump, a pressurizing oil pipe, a return oil pipe, a support gasket, a support rod, and a compression sleeve. The hydraulic pump has a built-in hydraulic cylinder and is fixedly installed on the side of the main body of the device. It is connected to the compression sleeve through a pressurization oil pipe and a return oil pipe. The compression sleeve is fixedly connected to the XY two-axis moving positioning mechanism; The pressure rod is coaxially connected to the compression sleeve. The hydraulic pump controls the extension and retraction of the pressure rod by pressurizing and depressurizing, which can complete demolding, uniaxial compression and depressurization operations. The support rod is fixedly installed on the other end face of the compression sleeve, and the support rod is fixedly connected to the support pad; the support pad is in direct contact with the main body shell of the device, and lubricating oil is applied between the support pad and the main body shell of the device.

5. The in-situ multi-field active monitoring and age-appropriate mechanical testing device for filling materials according to claim 1, characterized in that, The device also includes a visual monitoring unit, which is fixed to the age-appropriate mechanical testing system and is used to record the failure mode of the filling material specimen during the uniaxial compression test.

6. A testing method based on the in-situ multi-field active monitoring and age-appropriate mechanical testing device for infill bodies according to any one of claims 1 to 5, characterized in that, The method includes the following steps: The main body of the device is immersed in the filling slurry to be tested downhole; Through the multi-field environment interconnection structure, the filling slurry inside the sample molding mold and the external filling body can be simultaneously cured in a multi-field environment; The in-situ multi-field monitoring system continuously collects multiple environmental parameters of the external filling body. The filling samples formed by the sample forming mold are divided into multiple groups, with no less than 3 filling samples in each group, in order to reduce errors; and each group is set to a different curing age; when the predetermined curing age is reached, the age-separated mechanical testing system is operated to perform in-situ demolding and uniaxial compression tests on the corresponding filling samples to obtain the mechanical performance parameters of the curing age. Establish and analyze the correlation between the environmental parameters and the mechanical performance parameters at different ages.

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