CN-121997423-A - Test method, system and medium for ultra-large cross-cavity excavation supporting indoor model

CN121997423ACN 121997423 ACN121997423 ACN 121997423ACN-121997423-A

Abstract

The application discloses a test method, a system and a medium for an indoor model of ultra-large cross-cavity excavation support, and relates to the technical field of geotechnical engineering physical model tests. According to the application, the real non-uniform three-dimensional ground stress field is accurately restored through the reaction frame and the three-dimensional gradient active loading system. By means of the numerical control mechanical arm, the finish milling cutting head and the negative pressure suction system which are carried with the replaceable head end effector, extra disturbance of excavation on surrounding rock is reduced. The switching of the actuator tool is controlled by presetting the excavation supporting triggering condition, so that the time sequence linkage of excavation and supporting is achieved. The full-dimensional data are acquired by combining the cooperative acquisition and analysis of the embedded sensor, the model box peripheral monitoring equipment and the multi-source data acquisition cabinet, the finally constructed four-dimensional surrounding rock damage evolution comprehensive spectrum completely presents the whole process from microscopic crack initiation to macroscopic instability, and provides high-fidelity test basis for risk pre-judgment and design optimization of ultra-large cross-cavity engineering.

Inventors

ZHOU QIANG
YAN DI
LEI WEN
HUANG ZHAOYUAN
WANG QIANG
YIN BENLIN
WANG JUN
XIAO QINGHUA
YU YIHUA
ZHENG YAO

Assignees

中国水利水电第七工程局有限公司

Dates

Publication Date: 20260508
Application Date: 20260123

Claims (10)

1. A test method of an indoor model of an oversized cross-cavity excavation support is characterized by comprising the following steps: In an indoor model body of an oversized cross-cavity excavation support in a model box carried in a reaction frame, a three-dimensional gradient active loading system is adopted to establish a non-uniform three-dimensional initial ground stress field, and the three-dimensional initial ground stress field comprises vertical stress and gradient distributed horizontal stress; Leading in a preset three-dimensional profile of a cavity and a layered and block excavation sequence file, driving a finish milling cutting head on an end effector of a replaceable head to excavate in a layered manner along a preset path through a numerical control mechanical arm carrying the end effector of the replaceable head, and synchronously starting a negative pressure suction system matched with the finish milling cutting head to clean excavation fragments in real time; Presetting an excavation supporting triggering condition, controlling the numerical control mechanical arm to switch the tool type of the end effector with the replaceable head when the triggering condition is detected to be met in the excavation process, sequentially completing the implantation of the miniature anchor rod, the tensioning of the prestressed anchor cable and the paving of the spraying layer, and recovering the excavation operation after the supporting is completed; and synchronously acquiring multi-source data of internal strain, surface displacement and internal micro damage of the indoor model through a sensor pre-embedded in the indoor model and monitoring equipment arranged around the model box, transmitting the multi-source data to a multi-source data acquisition cabinet, and carrying out space-time alignment and superposition analysis on the multi-source data to obtain a comprehensive map of surrounding rock damage evolution.
2. The method for testing the indoor model of the ultra-large cross-cavity excavation supporting structure according to claim 1, wherein the method for establishing the non-uniform three-dimensional initial ground stress field in the indoor model of the ultra-large cross-cavity excavation supporting structure in the model box carried in the reaction frame by adopting the three-dimensional gradient active loading system comprises the following steps: Preparing similar materials, and performing pouring molding, curing and solidifying operations in the model box; A three-dimensional gradient active loading system consisting of a reaction frame, a hydraulic servo array, a flexible pressure transmission-rigid pressure bearing composite loading plate and a hydraulic oil source is adopted, vertical stress and horizontal stress distributed in gradient are applied to the indoor model through the flexible pressure transmission-rigid pressure bearing composite loading plate, and a non-uniform initial ground stress field matched with an engineering scene is established.
3. The test method for the ultra-large cross-cavity excavation supporting indoor model according to claim 2, wherein the similar materials are prepared by the following weight ratio of 48% of barite powder, 30% of quartz sand, 12% of gypsum and 10% of water; and when casting and forming operation is carried out in the model box, synchronously embedding the distributed optical fiber sensor and the acoustic probe in the indoor model, and after the casting and forming operation is finished, maintaining the model box for at least 7 days under the conditions that the ambient temperature is 25+/-2 ℃ and the relative humidity is more than 90 percent until the uniaxial compressive strength of the similar material reaches the set 0.3-0.5MPa.
4. The method for testing an indoor model of an oversized cross-cavern excavation support of claim 2, wherein the applying vertical stress and gradient distributed horizontal stress to the indoor model through the flexible pressure-transmitting-rigid pressure-bearing composite loading plate comprises: Slowly applying vertical stress in multiple stages through a hydraulic servo actuator array arranged at the top of the model box, wherein the application rate is controlled within a first set rate, and each stage of load is held for a first set time until a target value is reached; Through arrange in hydraulic servo actuator array of both sides of model case, the step applys horizontal stress, through the independent control pressure of different position actuators, make vertical stress with the ratio of horizontal stress changes to the second ratio of lower part from the first ratio on model upper portion gradually, and every level load holds the load second settlement time, waits after the indoor model warp steadily applys next level horizontal stress, first ratio is less than the second ratio, horizontal stress pass through set up in the flexible transmission of both sides of model case presses-rigid pressure-bearing composite loading board is transmitted to indoor model.
5. The test method for the ultra-large cross-cavity excavation supporting indoor model is characterized in that the geometric similarity ratio of the indoor model is 1:100, the method is poured into the model box with the length, the width and the height of 2.9m, 1m and 1.8m, and the similar materials are filled into the model box in three layers and tamped and flattened during pouring, so that the compactness of the indoor model is uniform.
6. The test method of the ultra-large cross-cavity excavation supporting indoor model is characterized in that the milling depth of the finish milling cutting head is 1-3mm, the milling linear speed is 100-200mm/min, the rotating speed of the milling head is 3000-5000rpm, the negative pressure value of the negative pressure suction system is stabilized between-60 kPa and-80 kPa, the sequence of the layered and segmented excavation sequence file is that a pilot tunnel is advanced, and the two sides of the pilot tunnel are excavated in an expanding manner; The method for carrying out layered excavation on the finish milling cutting head on the replaceable head end effector along a preset path by a numerical control mechanical arm carrying the replaceable head end effector comprises the following steps: After the single-layer excavation of one partition is completed, the excavation progress is automatically recorded, and the numerical control mechanical arm is controlled to drive the finish milling cutting head to transfer to the next partition or the next layer of excavation until all excavation procedures are completed.
7. The method for testing the indoor model of the ultra-large span cavity excavation supporting of claim 1, wherein the preset excavation supporting triggering condition is that the excavation depth is accumulated to reach a set depth or a target part in the indoor model is exposed, and the target part comprises a cavity arch foot and a top arch; The miniature anchor rod implantation, the tensioning of the prestressed anchor cable and the paving of the spraying layer are completed in sequence, and the method comprises the following steps: The numerical control mechanical arm is controlled to switch a tool head of the end effector with the replaceable head from a finish milling cutting head to an anchor rod installer, a miniature anchor rod meeting the set diameter is grabbed by the anchor rod installer, and the miniature anchor rod is implanted in a preset position of the indoor model; the numerical control mechanical arm is controlled to switch the tool head of the end effector with the replaceable head to a miniature tensioning jack, and the miniature tensioning jack is used for applying preset prestress to the prestress anchor cable and locking the prestress anchor cable; and controlling the numerical control mechanical arm to switch the tool head of the end effector with the replaceable head to a miniature spray nozzle, spraying the quick-setting material through the miniature spray nozzle at a set pressure, and forming a uniform spray layer with a set thickness at a corresponding position of the indoor model.
8. The method for testing an indoor model of ultra-large span cavern excavation supporting according to claim 1, wherein the sensor pre-embedded in the indoor model comprises a distributed optical fiber sensor and an acoustic probe, and the monitoring equipment arranged on the periphery of the model box comprises two high-speed cameras of a 3D-DIC system; synchronously acquiring multi-source data of internal strain, surface displacement and internal micro-damage of the indoor model through a sensor pre-embedded in the indoor model and monitoring equipment arranged around the model box, wherein the multi-source data comprises: continuously monitoring internal strain distribution of the indoor model at a set sampling frequency by the distributed optical fiber sensor; Acquiring surface displacement data of the indoor model at a second set rate by two high-speed cameras of the 3D-DIC system; continuously collecting internal micro-fracture events of the indoor model by using the sound emitting probe with a set decibel as a threshold value; The distributed optical fiber sensor, the sound emitting probe and the high-speed camera of the 3D-DIC system are networked with a central controller, and the central controller sends synchronous trigger signals to all devices to ensure that the timestamps of the data are uniform; performing space-time alignment and superposition analysis on the multi-source data to obtain a comprehensive surrounding rock destruction evolution map, wherein the method comprises the following steps: After the test is finished, the internal strain data of the distributed optical fiber sensor, the surface displacement data of the 3D-DIC system and the micro-damage positioning data of the sound emitting probe are obtained from the multi-source data acquisition cabinet, and the internal strain data, the surface displacement data and the micro-damage positioning data are subjected to space-time alignment and superposition; And constructing a surrounding rock destruction evolution comprehensive spectrum containing three-dimensional space and time dimension, and completely presenting the whole process from microscopic crack initiation to macroscopic instability of the indoor model.
9. An experimental system for an ultra-large cross-cavern excavation supporting indoor model, comprising: The building module is used for building a non-uniform three-dimensional initial ground stress field in an indoor model body of the ultra-large cross-cavity excavation support in a model box carried in the reaction frame by adopting a three-dimensional gradient active loading system, wherein the three-dimensional initial ground stress field comprises vertical stress and gradient distributed horizontal stress; The starting module is used for importing a preset three-dimensional profile of a cavity and a layered and block excavation sequence file, driving a finish milling cutting head on the end effector of the replaceable head to excavate in a layered manner along a preset path through a numerical control mechanical arm carrying the end effector of the replaceable head, and synchronously starting a negative pressure suction system matched with the finish milling cutting head to remove excavation fragments in real time; The support module is used for presetting an excavation support triggering condition, controlling the numerical control mechanical arm to switch the tool type of the end effector with the replaceable head when the triggering condition is detected to be met in the excavation process, sequentially completing the implantation of the miniature anchor rod, the tensioning of the prestressed anchor cable and the paving of the spraying layer, and recovering the excavation operation after the support is completed; The analysis module is used for synchronously collecting multi-source data of internal strain, surface displacement and internal micro damage of the indoor model through a sensor pre-embedded in the indoor model and monitoring equipment arranged around the model box, transmitting the multi-source data to the multi-source data collection cabinet, and carrying out space-time alignment and superposition analysis on the multi-source data to obtain a comprehensive map of surrounding rock damage evolution.
10. A computer readable storage medium, wherein a program is stored in the computer readable storage medium, the program being capable of being loaded by a processor and executing the test method of the indoor model of the ultra-large cross-cavern excavation support of any one of claims 1 to 8.

Description

Test method, system and medium for ultra-large cross-cavity excavation supporting indoor model Technical Field The application relates to the technical field of geotechnical engineering physical model tests, in particular to a test method, a system and a medium for an indoor model of ultra-large cross-cavity excavation support. Background At present, a construction method of layering, blocking and dividing is commonly adopted for excavating a large underground cavity. The method is mature in application in the middle-span and small-span caverns, and the surrounding rock deformation during construction is effectively controlled by stepwise construction from large sections to small sections, so that the construction risk is controllable. However, with the continuous promotion of engineering scale in the fields of hydropower, traffic, national defense and the like, oversized cross-caverns with spans of 30 meters and more are gradually increased, the spans of underground engineering can break through to 70m and more, and the traditional construction method exposes obvious limitations in the engineering. Specifically, when the cavern span reaches 70m, the mechanical response thereof shows a difference in quality. Firstly, the step-by-step excavation process is more complex, the excavation steps are obviously increased, the surrounding rock stress state is subjected to severe redistribution for tens of times or even hundreds of times, and the deformation accumulation effect is abnormal and prominent. Secondly, before forming a stable bearing arch, the stability of the top arch and the high side wall of the ultra-large span cavity is highly dependent on the timeliness and effectiveness of a supporting system after each step of excavation, and the traditional method of 'middle pilot tunnel + expanding excavation' is difficult to ensure that the surrounding rock can form a complete and effective 'arch effect' in time under such a large span, so that the top arch settlement and the side wall convergence are difficult to control, the structural deformation risk is obviously improved, and even potential safety hazards such as local collapse or integral instability and the like can be possibly caused. In order to pre-judge the risks and optimize the excavation and support schemes before construction, a physical model test becomes an indispensable research means. In the conventional technology, similar materials are poured in a model test groove, and ground stress is simulated by applying boundary load through a jack, so that a cavity excavation test is carried out. However, these conventional model test methods have fundamental shortcomings when simulating a 70 m-class oversized cavern. Firstly, the size of a laboratory limits the scale of a model, so that the geometric similarity ratio is too large, the complex step-by-step excavation procedure is extremely difficult to accurately simulate on a tiny model, and the conventional manual excavation mode has huge disturbance and cannot restore the low-disturbance mechanical construction process. Secondly, the traditional loading technology is difficult to restore the complex gradient ground stress field of the engineering site in the model body, so that the initial stress state of the model is distorted. Thirdly, the lack of a micro support system installation technology capable of being linked with a precisely controlled excavation step cannot realize the real construction time sequence of 'excavation one step and support one step', so that the interaction mechanism of a support system and surrounding rock cannot be truly reflected. Therefore, the conventional test of the indoor model of the ultra-large cross-cavity excavation support is easy to generate distortion, and the accuracy of test results is low. Disclosure of Invention The application aims to provide a test method, a system and a medium for an indoor model of an oversized-span chamber excavation support, which are used for solving the problem that the test result of the traditional oversized-span chamber indoor model test is difficult to ensure to match the stress state and the destruction rule of an actual project. In order to achieve the above object, a first aspect of the present application provides a method for testing an indoor model of an oversized cross-cavern excavation support, including: In an indoor model body of an oversized cross-cavity excavation support in a model box carried in a reaction frame, a three-dimensional gradient active loading system is adopted to establish a non-uniform three-dimensional initial ground stress field, and the three-dimensional initial ground stress field comprises vertical stress and gradient distributed horizontal stress; Leading in a preset three-dimensional profile of a cavity and a layered and block excavation sequence file, driving a finish milling cutting head on an end effector of a replaceable head to excavate in a layered manner along a preset path through a