Double-steel-sleeve batholith load plate test system and double-steel-sleeve batholith load plate test method

Abstract

The invention belongs to the technical field of geotechnical engineering, and particularly discloses a batholith load plate test system and method with double steel sleeves. The heaped load applying module is arranged on the pile top and applies a preset load to the pile top of the cast-in-situ bored pile; the external force eliminating module is arranged on the outer side of the cast-in-situ bored pile body in a sleeving mode and used for eliminating the frictional resistance influence of a soil body on the side wall of the cast-in-situ bored pile body The monitoring module is used for monitoring settlement displacement and stress of the cast-in-situ bored pile under the loading action of the pile loading applying module; and the control module is used for judging the bearing capacity of the deep rock mass foundation according to the monitoring data of the monitoring module. Lateral pressure of a soil body on a pile body can be effectively isolated, side wall friction resistance of the pile body can be eliminated, a real load applied to the pile bottom is ensured, the real bearing capacity of a deep foundation rock body can be accurately measured, test data are more accurate, influences of pile foundation side friction resistance are avoided, and therefore the accuracy and reliability of a test result are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering, and more specifically, relates to a double steel casing rock foundation load plate test system and method. Background Art

[0002] The load test (Landing Test) is a test that uses a rigid bearing plate to add loads step by step in the field to measure the deformation of the natural foundation or composite foundation as the load changes, so as to determine the bearing capacity and deformation modulus of the foundation. According to the setting depth and characteristics of the bearing plate, it can be divided into shallow and deep flat plate load tests and spiral plate load tests. Among them, the shallow flat plate load test is suitable for shallow foundations, and the spiral plate load test and deep flat plate load test are suitable for deep foundations or soil layers below the groundwater level.

[0003] There are two common deep load test methods at home and abroad, one is the flat plate static load test, and the other is the spiral plate load test. Among them, there are two key issues in the deep flat plate load test: one is to level the bottom of the hole and ensure that the pressure plate falls directly on the scraped natural rock and soil surface, that is, to remove the residue at the bottom of the hole and the stability of the hole wall; the other is to use the formula of the shallow load test to calculate the deformation modulus. Because the stress state of the foundation soil under the shallow and deep load test plates is different, it is believed that the calculation result is inconsistent with the actual situation. The development and application of the deep flat plate load test in my country is related to the needs of the development of high-rise buildings in my country. Engineering practice shows that this static load test is also adaptable and reliable under shallow hole conditions. However, it also reflects some problems that need to be solved in order to expand its application range and improve its test accuracy, including: the impact of the loading and transmission system and displacement test system of the experimental device on the test accuracy and depth measurement, as well as the bottom of the hole treatment and the verticality of the hole.

[0004] Based on the above defects and deficiencies, this field urgently needs to propose a double steel casing rock foundation load plate test system, which can carry out deep flat plate load test by heap loading method on the basis of considering the rationality of the test and determine the reasonable characteristic value of deep rock foundation bearing capacity. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a double steel casing rock foundation load plate test system and method, wherein a rock foundation load plate test system capable of eliminating the side wall friction of the pile foundation is designed in combination with the characteristics of the rock foundation load plate test itself and the characteristics of the influence of the side wall friction resistance during the loading process on the test accuracy, and the structure and specific setting methods of its key components such as the pile load application module, the internal and external force elimination module and the monitoring module are studied and designed, which can effectively isolate the lateral pressure of the soil on the pile body, eliminate the side wall friction resistance of the pile body, and ensure that the load applied to the bottom of the pile can accurately reflect the true bearing capacity of the deep foundation rock body. This isolation mechanism, combined with an accurate monitoring module (including a pressure gauge and a displacement sensor), makes the test data more accurate, eliminates the error of the side wall friction resistance of the pile foundation, and thus improves the accuracy and reliability of the test results.

[0006] To achieve the above object, according to one aspect of the present invention, a double steel casing rock foundation load plate test system is provided, comprising: A heap load application module is provided at the top of the pile and applies a preset load to the top of the bored pile; An external force elimination module which is sleeved on the outside of the bored pile body and is used to isolate the lateral pressure of the soil on the pile body, thereby eliminating the influence of the soil on the friction resistance of the side wall of the bored pile body; A monitoring module for monitoring the settlement displacement and stress of the bored pile under the loading of the heap loading module; and A control module for drawing load and settlement curves and settlement and time curves under various levels of load according to the monitoring data of the monitoring module, and thereby determining the bearing capacity of the weathered rock foundation.

[0007] As a further preferred embodiment, the external force elimination module includes an outer sleeve and an inner sleeve, the outer sleeve is lowered into the borehole, and the inner sleeve is sleeved on the outside of the bored pile body, the outer sleeve, the inner sleeve and the central axis of the bored pile are collinear, and a partition gap is provided between the inner wall of the outer sleeve and the outer wall of the inner sleeve for eliminating the influence of the friction resistance of the side wall of the bored pile, the bored pile is cast in the inner sleeve, and forms a force transmission column structure with the inner sleeve.

[0008] As a further preferred embodiment, a plurality of protective limit pads are provided in the partition gap, the protective limit pads are arranged circumferentially around the outer wall of the inner sleeve, and the outer side wall of the protective limit pads slides against the inner wall of the outer sleeve, and the plurality of protective limit pads are evenly arranged along the axial direction of the bored cast-in-place pile to ensure the verticality and vertical force of the inner sleeve.

[0009] As a further preferred embodiment, the load application module includes a jack and a load reaction platform, the jack is arranged between the pile top and the load assembly, the load reaction platform pressurizes the pile top through the jack, the jack transfers the vertical force to the foundation through bored cast-in-place piles, and the pile ends of the bored cast-in-place piles indirectly load the deep foundation rock mass to carry out a foundation bearing capacity test.

[0010] As a further preferred embodiment, the loading reaction platform includes a main beam, a secondary beam and a loading block which are sequentially arranged on the jack, and the central axes of the main beam, the secondary beam, the loading block and the jack are collinear with the central axis of the bored pile.

[0011] As a further preference, a pier is provided between the secondary beam and the foundation.

[0012] As further preferred, a foam layer is provided on the outer periphery of the jack.

[0013] As further preferred, the monitoring module includes a pressure gauge for measuring the pressure of the jack and a displacement sensor for measuring the displacement of the pile top.

[0014] According to another aspect of the present invention, a rock foundation load plate test method is provided, which is implemented by using a double steel casing rock foundation load plate test system of any of the above embodiments or a combination of multiple embodiments, and includes the following steps: Step 1: Drill a hole according to the design requirements, place an external force elimination module in the drilled hole, pour concrete inside the external force elimination module, cast the bored pile into shape, and install the monitoring module and the pile load application module after the strength of the bored pile meets the design requirements; Step 2: Calculate the loading load range according to the destructive test, divide the loading load range into loading levels, and apply the load to the bored piles in the order of small to large load levels by the heap load application module; Step 3: After each level of loading, within a preset time range, the monitoring module measures the displacement of the pile top and collects the settlement displacement and force of the bored pile; Step 4, repeat step 3 until the loading termination condition is met; Step 5, unloading the bored piles in equal amounts in batches, and recording the rebound value of the foundation corresponding to the pile bottom; Step six: the control module draws the load and settlement curves and the settlement and time curves under various levels of load according to the load test results, and uses them to determine the bearing capacity of the rock foundation.

[0015] As a further preferred embodiment, in step 1, lowering the external force elimination module into the drilled hole comprises: The outer sleeve is lowered into the drilled hole, the protective limit pad is welded to the outer wall of the inner sleeve, and then the inner sleeve is lowered along the inner wall of the outer sleeve. The protective limit pad is used to ensure the verticality of the inner sleeve.

[0016] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art: 1. Through the design of the external force elimination module, the system can effectively isolate the lateral pressure of the soil on the pile body, eliminate the influence of the friction resistance of the pile side wall on the test error, and ensure that the load applied to the pile top can truly reflect the actual bearing capacity of the deep foundation rock mass. This isolation mechanism, combined with the precise monitoring module (including pressure gauge, displacement sensor), makes the test data more accurate, thereby improving the accuracy and reliability of the test results. In addition, the introduction of the automated control system and data acquisition and analysis software further ensures the precise control of the test process and the real-time analysis of the data, providing a more reliable scientific basis for engineering design and construction.

[0017] 2. The protective limit pad design in the external force elimination module of the present invention not only protects the pile body from damage, but also ensures the verticality and stability of the entire system. At the same time, the safety protection mechanisms integrated in the automatic control system, such as overload protection and emergency stop button, significantly improve the safety during the test. The combination of these safety features ensures the safety of personnel and equipment when conducting tests under various geological conditions, while also reducing the risk of equipment damage and test failure due to unexpected situations during the test.

[0018] 3. The modular design of the external force elimination module and monitoring module of the inner and outer sleeves of the present invention enables the system to quickly adapt to the test requirements of different diameters and different geological conditions. This design not only improves the versatility and flexibility of the system, but also makes the replacement and upgrading of each module simple and fast, reducing maintenance costs and time. In addition, the automated control system reduces the need for manual operation, simplifies the operation process, and further improves the system's maintenance convenience and ease of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a rock foundation load plate test system for double steel casings involved in an embodiment of the present invention; Figure 2 The present invention is a flowchart of a rock foundation load plate test method based on double steel casings according to an embodiment of the present invention.

[0020] In all the drawings, the same figure marks represent the same technical features, specifically: 1-loading block, 2-secondary beam, 3-pier, 4-main beam, 5-jack, 6-displacement sensor, 7-foam layer, 8-bored piles, 9-protective limit pads, 10-outer sleeve, 11-inner sleeve. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] like Figure 1 As shown, a double steel casing rock foundation load plate test system provided by an embodiment of the present invention includes a pile load application module, an external force elimination module, a monitoring module and a control module. Specifically: Load application module: A jack 5 is installed on the top of the bored pile. The jack 5 is controlled by a hydraulic system and can apply a preset load. A load reaction platform is arranged above the jack 5, and the platform is connected to the jack 5 through the main beam 4, the secondary beam 2 and the load block 1 to ensure that sufficient reaction load can be provided. In one embodiment of the present invention, the load reaction platform is composed of a main beam 4, a secondary beam 2 and a load block 1. The main beam 4 is made of I-beam, and the jack 5 is placed at the bottom of the main beam 4, while the secondary beam 2 is made of H-beam and overlapped with the main beam 4. The load block 1 is a prefabricated concrete block, which is evenly placed on the secondary beam to ensure sufficient reaction load and uniform distribution of load. The base of the hydraulic jack is fixed to the top of the pile to ensure stability when applying load.

[0023] External force elimination module: an inner and outer double sleeve is set outside the pile body of the bored pile 8, and the inner and outer double sleeves are in line with the bored pile 8. The bored pile 8 is cast in the inner sleeve 11 and forms a force transmission column structure. A partition gap is formed between the inner wall of the outer sleeve 10 and the outer wall of the bored pile 8, which is used to eliminate the force effect of soil friction on the pile body. A plurality of protective limit pads 9 are set in the gap, which are arranged circumferentially around the outer wall of the pile body and evenly spaced along the axial direction to protect the pile body from damage.

[0024] Monitoring module: Based on the pile load application module and the external force elimination module, monitoring equipment is installed, including a pressure gauge for measuring the jack pressure and a displacement sensor for measuring the displacement of the pile top.

[0025] Based on any of the above embodiments or a combination of multiple embodiments, in this embodiment, a hydraulic jack is used, the base of which is fixed to the top of the pile, and the hydraulic cylinder is connected to the hydraulic pump station, and the loading of the pile top is achieved through the pressure change of the hydraulic oil. The loading reaction platform is composed of a main beam, a secondary beam and a loading block. The main beam and the secondary beam form a stable structure by overlapping, and the loading blocks are evenly distributed on the secondary beam to ensure the stability of the loading platform.

[0026] Based on any of the above embodiments or a combination of multiple embodiments, in this embodiment, both the inner and outer double sleeves are made of steel, and during the installation process, they are ensured to be in line with the bored pile body. The partition gap is set between the inner wall of the outer sleeve and the outer wall of the pile body, and the required gap is ensured by adjusting the thickness of the protective limit pad. The protective limit pad is made of high-strength plastic or rubber material, surrounds the outer wall of the pile body, and is evenly spaced along the axial direction.

[0027] Based on any of the above embodiments or a combination of multiple embodiments, in this embodiment, the monitoring module includes a pressure gauge and a displacement sensor that are communicatively connected to the control module. Among them, the pressure gauge is installed in the hydraulic system of the jack to monitor the pressure of the jack in real time. The displacement sensor is installed at the top of the pile and connected to the data acquisition system through a wire to measure the displacement of the pile top. The control software runs on the computer, and realizes the control of the loading process and real-time analysis of data through the interface with the hydraulic pump station and the data acquisition system. In one embodiment of the present invention, the pressure gauge is installed in the hydraulic system of the jack, connected to the hydraulic cylinder through a pipeline, and monitors the pressure of the jack in real time. The displacement sensor adopts a linear variable differential transformer (LVDT), which is installed between the pile top and the pile reaction platform, and is connected to the data acquisition system through a cable to measure the displacement of the pile top. Control module: Develop a control software that can receive data from the monitoring module and judge the bearing capacity of the weathered rock foundation based on these data. The software can set the loading level, control the loading process of the jack, and automatically stop loading when the termination loading condition is reached.

[0028] Based on any of the above embodiments or a combination of multiple embodiments, this embodiment further includes: Hydraulic control unit: integrated in the hydraulic pump station, it automatically adjusts the pressure of the hydraulic oil by receiving instructions from the control software to achieve precise control of the jack.

[0029] Data acquisition unit: integrated into the data acquisition system, automatically collects test data through connection with sensors.

[0030] Based on any of the above embodiments or a combination of multiple embodiments, this embodiment further includes: a security protection mechanism module, specifically including: Overload protection: An overload protection device is integrated into the hydraulic system, which automatically cuts off the supply of hydraulic oil when it detects that the pressure exceeds the preset value.

[0031] Emergency stop button: Installed on the operation panel, when an abnormal situation is detected, the operator can immediately press the button to stop all operations.

[0032] Based on any of the above embodiments or a combination of multiple embodiments, in this embodiment, the inner and outer double sleeves are telescopic sleeve structures with adjustable lengths, and the test requirements of different foundation depths can be met by adjusting the length of the sleeves.

[0033] The external force elimination module of the present invention isolates the direct force influence of the soil on the pile body by setting an inner and outer double sleeve on the outside of the bored pile body, which is colinear with the pile body. In this way, it can be ensured that when conducting a rock foundation load test, the force exerted on the pile body comes from the heap load application module, eliminating the side wall friction influence of the surrounding soil on the pile body. In addition, a plurality of protective limit pads are arranged in the partition gap set between the inner and outer sleeves. These pads are arranged circumferentially around the outer wall of the inner sleeve and evenly spaced along the axial direction, effectively ensuring the verticality of the bored pile and the vertical limit during the test. By eliminating the force influence of the soil on the pile body and eliminating the side wall friction, the force condition of the pile body during the actual test can be accurately obtained, thereby improving the accuracy and reliability of the test results.

[0034] like Figure 2 According to another aspect of the present invention, a rock foundation load plate test method is provided, comprising the following steps: Step 1: Experimental preparation Select a suitable test site and conduct geological surveys to determine the soil structure and rock characteristics of the test area. Determine the size, depth and location of the borehole according to geological conditions and design requirements. Install the external force elimination module in the borehole, ensure that the inner and outer double sleeves are collinear with the central axis of the bored pile, and adjust the partition gap to adapt to the soil conditions. Cast the bored pile in the inner sleeve to ensure that its verticality and strength meet the test requirements. After the strength of the bored pile reaches the test requirements, install the monitoring module, including the pressure gauge and displacement sensor, and perform preliminary calibration. Install the load application module, including the jack and the load reaction platform, and ensure that it is stably and reliably connected to the pile top and pile body.

[0035] Step 2: Check before loading Check and calibrate all monitoring equipment to ensure the accuracy of the data acquisition system. Check the settings of the automated control system to ensure that it can perform loading operations according to the predetermined procedures. Confirm that safety protection mechanisms, such as overload protection and emergency stop buttons, are in normal working condition.

[0036] Step 3: Loading in stages Based on the destructive test data, the loading range is calculated and divided into multiple loading levels. Starting from the minimum load, the load of the pile load application module is gradually increased, and each level of increase should be carried out according to the predetermined increment. After each level of loading, wait for a preset time for the pile body and foundation to stabilize.

[0037] Step 4: Data monitoring and recording After each level of loading, use the monitoring module to monitor and record the settlement displacement and force data of the bored pile in real time. Observe the pressure gauge reading to ensure that the pressure applied by the jack is within a safe range. Record the data of the displacement sensor and analyze the displacement changes at the top of the pile.

[0038] Step 5: Determine the loading termination condition Continue to monitor the settlement displacement and force data until any of the following loading termination conditions is met: The settlement increases sharply, a steep drop occurs in the load-settlement curve, and the settlement exceeds 0.04d.

[0039] Under a certain load level, the settlement rate cannot reach stability within 24 hours.

[0040] The settlement under this level of load is 5 times greater than the settlement under the previous level of load.

[0041] When the bearing layer soil is hard and the settlement is very small, the maximum load reaches twice the design requirement.

[0042] Step 6: Unloading and rebound observation After reaching the end loading condition, start unloading in equal amounts in batches, and record the rebound value of the foundation corresponding to the pile bottom after each unloading. Analyze the rebound data to evaluate the elastic characteristics and recovery capacity of the foundation.

[0043] Step 7: Data Analysis and Evaluation Use the control module to analyze the collected data and draw the load and settlement curves as well as the settlement and time curves under various load levels. According to the curve shape and data changes, the bearing capacity and deformation characteristics of the weathered rock foundation are determined. Compare the test results with the design requirements to evaluate the suitability and safety of the foundation.

[0044] Step 8: Preparation of test report Prepare a detailed test report, including the test purpose, methods, process, results and conclusions. Provide recommendations based on the test results to provide reference for engineering design and construction.

[0045] Step 9: Equipment disassembly and site restoration After the test, all monitoring and loading equipment shall be dismantled and necessary maintenance and care shall be carried out. The test site shall be restored to ensure that it does not affect the environment and subsequent use.

[0046] In a specific embodiment of the present invention, a loading block (loading reaction platform) and a load-displacement test system are designed, and loading is performed in stages according to the slow loading method specified in the specification until the load reaches a failure state or a state where the base stress is not less than 8.1 MPa, and the load and displacement during the loading process are recorded.

[0047] In order to obtain a more accurate in-situ ultimate bearing capacity of the foundation based on the test, this load test needs to be designed according to the destructive test. According to the average design stress of the base of 1620 kPa, considering 5 times the maximum loading stress, the maximum loading stress is 8100 kPa, and the base area is 0.5 m 2 The vertical pressure required for the test is 4050kN. In addition, considering the influence of pile friction, the maximum calculated friction is 2200kN. Therefore, the required maximum vertical loading tonnage is 6250kN. Considering the safety factor of 1.2 times, a 7500kN pile load block is prepared. The loading and unloading process is as follows: (1) Loading The load test load level is applied in grades according to 1 / 10 of the estimated ultimate bearing capacity; the load level is preferably 10. After each level of loading, the settlement is measured at intervals of 10min, 10min, 10min, 15min, 15min in the first hour, and every half an hour thereafter. When the settlement per hour is less than 0.1mm for two consecutive hours, it is considered to be stable and the next level of load can be added.

[0048] Loading termination conditions: Loading can be terminated when one of the following phenomena occurs.

[0049] ① The settlement s increases sharply, there is a steep drop section on the load-settlement (ps) curve that can determine the ultimate bearing capacity, and the settlement exceeds 0.04d (d is the diameter of the bearing plate).

[0050] ② Under a certain level of load, the settlement rate cannot reach stability within 24 hours.

[0051] ③ The settlement of this level is 5 times greater than the settlement of the previous level.

[0052] ④ When the bearing layer is hard and the settlement is very small, the maximum load shall not be less than twice the design requirement.

[0053] (2) Unloading and unloading settlement observation The unloading is carried out in 5 equal levels, and the unloading value of each level is twice the loading amount. After each level of load is unloaded, the rebound value is recorded until the deformation is stable.

[0054] The characteristic value of the pile end resistance of the bearing layer can be obtained through the deep flat plate load test: Where: A is the area of ​​the pressure plate, which is 0.5m when the diameter is 800mm 2 ; Q pu ——It is the ultimate bearing capacity of the bearing layer under the pressure plate.

[0055] According to the load test results, draw the load (p) and settlement (s) curves, and the settlement (s) and time (t) or time logarithm (logt) curves under various load levels. According to the inflection point of the ps curve, determine the proportional limit pressure and the ultimate pressure. If ps is a slow-changing curve, the pressure corresponding to a certain relative settlement value can be used to assess the bearing pressure.

[0056] The end resistance can also correspond to the end point of the starting straight line segment on the PS curve as the proportional limit. The previous load that meets the termination loading conditions is the ultimate load. The details are as follows: 1. When there is a proportional limit on the PS curve, take the load value corresponding to the proportional limit; 2. When one of the termination loading conditions is met, the corresponding previous load is set as the ultimate load; when this value is less than 2 times the load value of the corresponding proportional limit, half of the ultimate load value is taken; 3. When it is not possible to determine according to the above two requirements, the load corresponding to s / d=0.01~0.015 can be taken, but its value should not be greater than half of the maximum load; 4. The same soil layer shall be statistically tested at no less than three points. When the range of the measured value does not exceed 30% of its average value, the average value shall be taken as the basic allowable value of the foundation bearing capacity of the soil layer.

[0057] The changes of pile top and pile end settlement and pile body compression under different loads were statistically analyzed. It was found that as the load increased, the settlement of the pile top and pile end increased, the PS curves of the pile top and pile end were linear, and the compression of the pile body increased with the increase of load, but the numerical calculation results were not much different from the theoretical calculation results. Finally, under the load of 8.1MPa, the compression of the pile body was between 6 and 7mm.

[0058] Table 1 Calculation data of pile foundation settlement and compression deformation Serial number Pile top load / kPa Pile end reaction force / kN Pile top load / kPa Pile top settlement / mm Pile tip settlement / mm Pile compression / mm Theoretical compression value / mm 1 1620 810 919 1.14 0.36 0.78 0.86 2 2430 1215 1729 2.25 0.78 1.47 1.62 3 3240 1620 2539 3.40 1.24 2.16 2.38 4 4050 2025 3349 4.59 1.74 2.85 3.14 5 4860 2430 4159 5.78 2.24 3.54 3.90 6 5670 2835 4969 7.02 2.79 4.23 4.66 7 6480 3240 5779 8.25 3.33 4.92 5.42 8 7290 3645 6589 9.51 3.90 5.61 6.18 9 8100 4050 7399 10.80 4.49 6.31 6.94 It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A double steel casing rock foundation load plate test system, characterized in that: include: A pile load application module disposed on the pile top and applying a preset load to the bored pile (8); An external force elimination module which is sleeved on the outside of the bored pile (8) and is used to isolate the lateral pressure of the soil on the pile, thereby eliminating the influence of the soil on the frictional resistance of the side wall of the bored pile (8); A monitoring module for monitoring the settlement displacement and stress of a bored pile (8) under the loading action of the heap loading module; as well as A control module for drawing load and settlement curves and settlement and time curves under various levels of load according to the monitoring data of the monitoring module, and thereby determining the bearing capacity of deep rock foundation.

2. A double steel casing rock foundation load plate test system according to claim 1, characterized in that: The external force elimination module comprises an outer sleeve (10) and an inner sleeve (11), wherein the outer sleeve (10) is placed in a borehole, and the inner sleeve (11) is sleeved on the outer side of a bored pile (8), wherein the outer sleeve (10), the inner sleeve (11) and the central axis of the bored pile (8) are collinear, and a partition gap for eliminating the influence of frictional resistance of the side wall of the bored pile (8) is provided between the inner wall of the outer sleeve (10) and the outer wall of the inner sleeve (11), wherein the bored pile (8) is cast in the inner sleeve (11) and forms a force transmission column structure with the inner sleeve (11).

3. A double steel casing rock foundation load plate test system according to claim 2, characterized in that: A plurality of protective limit pads (9) are arranged in the partition gap, the protective limit pads (9) are arranged circumferentially around the outer wall of the inner sleeve (11), and the outer wall of the protective limit pad (9) is slidably abutted against the inner wall of the outer sleeve (10). The plurality of protective limit pads (9) are evenly spaced along the axial direction of the bored pile (8) to ensure the verticality and vertical force of the inner sleeve (11).

4. A double steel casing rock foundation load plate test system according to claim 1, characterized in that: The load application module comprises a jack (5) and a load reaction platform, wherein the jack (5) is arranged between the pile top and the load assembly, the load reaction platform applies pressure to the pile top via the jack (5), the jack (5) transmits the vertical force to the foundation via the bored pile (8), and the pile end of the bored pile (8) indirectly loads the deep foundation rock mass to perform a foundation bearing capacity test.

5. A double steel casing rock foundation load plate test system according to claim 4, characterized in that: The loading reaction platform comprises a main beam (4), a secondary beam (2) and a loading block (1) which are arranged on the jack (5) in sequence, and the central axis of the main beam (4), the secondary beam (2), the loading block (1) and the jack (5) is collinear with the central axis of the bored cast-in-place pile (8).

6. A double steel casing rock foundation load plate test system according to claim 5, characterized in that: A buttress (3) is provided between the secondary beam (2) and the foundation.

7. A double steel casing rock foundation load plate test system according to claim 4, characterized in that: The outer periphery of the jack (5) is provided with a foam layer (7).

8. A double steel casing rock foundation load plate test system according to claim 4, characterized in that: The monitoring module comprises a pressure gauge for measuring the pressure of the jack (5) and a displacement sensor for measuring the displacement of the pile top.

9. A rock foundation load plate test method, characterized in that: The double steel casing rock foundation load plate test system according to any one of claims 1 to 8 is implemented, characterized in that it includes the following steps: Step 1, drilling a hole according to design requirements, placing an external force elimination module in the drilled hole, pouring concrete inside the external force elimination module, casting the bored pile (8) into shape, and installing a monitoring module and a pile load application module after the strength of the bored pile (8) meets the design requirements; Step 2, calculating the loading load range according to the destructive test, dividing the loading load range into loading levels, and applying the load to the bored pile (8) by a heap load applying module in the order of small to large loads according to the divided load levels; Step 3, after each level of loading, within a preset time range, the monitoring module measures the displacement of the pile top and collects the settlement displacement and force of the bored pile (8); Step 4, repeat step 3 until the loading termination condition is met; Step 5, unloading the bored pile (8) in equal amounts in batches, and recording the rebound value of the foundation corresponding to the pile bottom; Step six: the control module draws the load and settlement curves and the settlement and time curves under various levels of load according to the load test results, and uses them to determine the bearing capacity of the rock foundation.

10. A rock foundation load plate test method according to claim 9, characterized in that: In step 1, lowering the external force elimination module into the drilled hole includes: An outer sleeve (10) is lowered into the drilled hole, a protective limit pad (9) is welded to the outer wall of the inner sleeve (11), and then the inner sleeve (11) is lowered along the inner wall of the outer sleeve (10), wherein the protective limit pad is used to ensure the verticality of the inner sleeve (11).

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