An indoor test method for detecting the performance of subgrade fillers

Abstract

The present invention relates to the technical field of subgrade filler detection, and particularly to an indoor detection test method for the performance of subgrade fillers, including: laying a subgrade filler sample on a detection platform for pretreatment; applying pressure to the subgrade filler sample in its initial state to obtain a stable subgrade filler sample, and recording the pressure changes and surface height changes at each layer; evaluating whether the subgrade filler meets the deformation standard according to the detection results; adding equal volumes of water to the subgrade filler samples in their initial and stable states, measuring and recording the water immersion height, and determining whether the subgrade filler samples meet the stability standard; simulating the filling of the subgrade filler in its initial state, performing pressure deformation detection using a second deformation pressure group to determine the performance grade of the filler; repeatedly detecting the simulated subgrade filler using the second deformation pressure, and adjusting the filler performance grade according to the final deformation amount. The present invention can accurately evaluate the pressure resistance performance and deformation characteristics of the filler, ensuring that the filler meets the requirements of different grades of highways.

Description

Technical Field

[0001] The present invention relates to the technical field of subgrade filler detection, and particularly relates to an indoor detection test method for subgrade filler performance. Background Art

[0002] Methods for detecting subgrade fillers usually involve in-situ compaction tests and indoor geotechnical tests such as penetration tests, Benkelman beam tests, and nuclear density meters. These methods can evaluate the compaction degree and uniformity of fillers, but often cannot comprehensively simulate the influence of actual traffic loads on subgrade fillers, and lack the evaluation of the long-term stability and durability of fillers. In addition, traditional detection methods may have problems such as complex operation, low efficiency, or inaccurate results, which limit their application in the evaluation of subgrade filler performance.

[0003] Chinese Patent Publication No.: CN106093346B discloses a method for evaluating the filling quality of soft rock embankments. The steps are as follows: 1. Take representative soft rock samples before subgrade filling, conduct 0, 1, 3, and 5 wet-dry cycle tests on them in sequence, and conduct sieve tests after each wet-dry cycle test to obtain the corresponding grain component fractal dimensions; 2. Detect the settlement difference of the last two compaction passes of the subgrade; 3. Conduct sieve tests on the soft rock samples after on-site compaction to determine their grain component fractal dimensions; 4. Based on the detection results in step 2 and in combination with the comparison results of the grain component fractal dimensions obtained in steps 1 and 3, comprehensively evaluate the filling quality of the soft rock embankment. It can be seen that the method for evaluating the filling quality of soft rock embankments has the following problems: When different types of roads are filled, the standards for filler performance are not considered, resulting in inaccurate evaluation results and affecting the subsequent construction quality. Summary of the Invention

[0004] Therefore, the present invention provides an indoor detection test method for subgrade filler performance to overcome the problems in the prior art that when different types of roads are filled, the standards for filler performance are not considered, resulting in inaccurate evaluation results and affecting the subsequent construction quality.

[0005] To achieve the above object, the present invention provides an indoor detection test method for subgrade filler performance, including:

[0006] Take samples of the subgrade filler to be detected, lay the subgrade filler samples on a number of detection platforms, and level them preliminarily respectively to obtain a number of initial-state subgrade fillers, and detect the height of the initial-state subgrade fillers;

[0007] Use the first deformation pressure to conduct a pressure stability detection on the initial-state subgrade filler to obtain a stable subgrade filler sample, record the pressure changes and surface height changes of each layer of the initial-state subgrade filler, and determine whether the subgrade filler to be detected meets the filler deformation standard according to the pressure stability detection result;

[0008] Add the same volume of water to a sample of the initial subgrade filler and the stabilized subgrade filler, measure the water immersion height on the corresponding test platform respectively, and record the test results;

[0009] Judge whether the subgrade filler to be tested meets the filler stability standard according to the test results of the water immersion height;

[0010] Conduct simulated filling on a number of the initial subgrade fillers to obtain simulated subgrade fillers, use the second deformation pressure group to conduct pressure deformation tests on each simulated subgrade filler, and determine the performance grade of the initial subgrade filler according to the test results; Repeatedly use the pressure in the corresponding second deformation pressure group to conduct simulated deformation tests on each of the simulated subgrade fillers, and determine whether to adjust the performance grade of the initial subgrade filler according to the simulation results.

[0011] Further, the pressure stabilization test on the initial subgrade filler includes:

[0012] Apply pressure to the initial subgrade filler using the first deformation pressure;

[0013] Detect and record the pressure change at the midpoint of the initial subgrade filler and the bottom of the initial subgrade filler;

[0014] After the pressure application is completed, detect and record the height change of the initial subgrade filler.

[0015] Further, determining whether the subgrade filler to be tested meets the filler deformation standard according to the pressure stabilization test results includes:

[0016] If the surface height change is less than the standard surface height change, and the pressure at each layer is within the corresponding change threshold range, it is determined that the subgrade filler to be tested meets the filler deformation standard.

[0017] Further, the height of the same volume of water added to a sample of the initial subgrade filler and the stabilized subgrade filler is lower than the height of the initial subgrade filler, and the water immersion height is higher than the midpoint of the initial subgrade filler.

[0018] Further, judging whether the subgrade filler to be tested meets the filler stability standard according to the test results of the water immersion height includes:

[0019] Calculate the height difference between the water immersion height of the initial subgrade filler and the water immersion height of the stabilized subgrade filler sample;

[0020] If the height difference is greater than the water immersion height difference threshold, it is determined that the subgrade filler to be tested does not meet the filler stability standard.

[0021] Further, performing the pressurized deformation detection on each of the simulated subgrade fillers using the second deformation pressure group includes:

[0022] Pressurizing the simulated subgrade fillers using the Class I load pressure, Class II load pressure, and Class III load pressure respectively;

[0023] When the height of each of the simulated subgrade fillers no longer changes, determining the height change amount of each simulated subgrade filler respectively, which is recorded as the pressurized deformation detection result;

[0024] Wherein, the second deformation pressure group includes the Class I load pressure, the Class II load pressure, and the Class III load pressure.

[0025] Further, determining the initial subgrade filler performance grade in combination with the pressurized deformation results of each of the simulated subgrade fillers includes:

[0026] If the pressurized deformation result meets the first load condition, determining that the initial subgrade filler grade is a Class I subgrade filler;

[0027] If the pressurized deformation result meets the second load condition, determining that the initial subgrade filler grade is a Class II subgrade filler;

[0028] If the pressurized deformation result meets the third load condition, determining that the initial subgrade filler grade is a Class III subgrade filler.

[0029] Further, the first load condition is that the deformation amount corresponding to the Class I load pressure is less than the Class I deformation amount;

[0030] The second load condition is that the deformation amount corresponding to the Class I load pressure is greater than or equal to the Class I deformation amount, and the deformation amount corresponding to the Class II load pressure is less than the Class II deformation amount;

[0031] The third load condition is that the deformation amount corresponding to the Class I load pressure is greater than or equal to the Class I deformation amount, the deformation amount corresponding to the Class II load pressure is greater than or equal to the Class II deformation amount, and the deformation amount corresponding to the Class III load pressure is less than the Class III deformation amount.

[0032] Further, repeatedly performing the simulated deformation detection on the simulated subgrade fillers using the pressure in the corresponding second deformation pressure group includes:

[0033] Obtaining the performance grade of the initial subgrade filler, and determining the corresponding second deformation pressure and the preset number of simulation times;

[0034] Pressurizing the simulated subgrade fillers repeatedly using the corresponding second deformation pressure according to the preset number of simulation times, and recording the final deformation amount.

[0035] Further, determining whether to adjust the performance grade of the initial subgrade filler according to the simulation results includes:

[0036] If the final deformation amount meets the corresponding load condition, it is determined not to adjust the performance grade of the initial subgrade filler, and it is recorded as the performance grade of the subgrade filler to be detected;

[0037] If the final deformation amount does not meet the corresponding load condition, it is determined to adjust the performance grade of the initial subgrade filler.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows. An indoor detection test method for the performance of subgrade filler provided by the present invention can accurately evaluate the pressure resistance performance and deformation characteristics of the filler by simulating the pressurized deformation of the filler under actual traffic loads, ensuring that the filler meets the requirements of different grades of highways. By simulating multiple repeated pressurizations to characterize the performance changes of the subgrade under long-term traffic loads, it effectively tests the performance stability of the filler under repeated loads, improves the economy and applicability of road construction, ensures the safety of high-speed vehicles, reduces maintenance costs, extends the service life of the road, and provides a scientific decision-making basis for road design and construction.

[0039] Further, by simulating the pressurization conditions that the filler may encounter in actual road construction, the reliability of the test results and the relevance of actual applications are ensured. It helps to determine the deformation and stability of the filler under different pressures, providing a scientific basis for subgrade design and construction.

[0040] Further, by detecting the deformation amount of the subgrade filler, the uniformity and integrity of the subgrade are ensured, avoiding pavement damage caused by uneven settlement and ensuring the stability of the road structure. Secondly, by setting the pressure change amount in the middle layer and the bottom within a specific range, the stability and bearing capacity of the filler under pressure can be evaluated. A subgrade with high bearing capacity can better support the upper structure, reduce the deformation caused by traffic loads, and extend the service life of the road. By detecting whether the pressure change amount exceeds the change range, the stability of the filler particles can be identified, and problems that may affect the subgrade performance can be discovered in a timely manner, thereby providing a more accurate scientific basis for subgrade design and construction.

[0041] Further, the stability of the subgrade filler is judged based on the detection result of the water immersion height. By comparing the water immersion height difference between the initial state subgrade filler and the stable subgrade filler sample, the particle breakage situation of the filler after being subjected to pressure can be evaluated, thereby judging whether the filler meets the stability standard. If the water immersion height difference is greater than the set threshold value, it is considered that the filler is unstable and does not meet the standard.

[0042] Furthermore, by simulating the load pressures of different grades of roads, the pressure resistance performance and deformation characteristics of the filling materials are accurately evaluated to ensure that the filling materials can meet the requirements of different grades of roads. This method not only improves the economy and applicability of road construction, but also ensures the safety of high-speed vehicles, reduces maintenance costs, extends the service life of the road, and provides a scientific decision-making basis for road design and construction.

[0043] Furthermore, by simulating actual traffic loads, repeated pressure tests are carried out on subgrade filling materials of different grades to evaluate their stability and durability under long-term loads. According to the test results, it can be determined whether the filling materials meet the requirements of a specific road grade, and the performance grade of the filling materials can be adjusted accordingly to ensure that suitable filling materials are used in road construction, improve road quality and reduce maintenance costs. Brief Description of the Drawings

[0044] Figure 1 is a flowchart of the indoor detection test method for the performance of the subgrade filling material in the embodiment of the present invention;

[0045] Figure 2 is a flowchart of the pressure stability detection of the initial subgrade filling material in the embodiment of the present invention;

[0046] Figure 3 is a logic diagram for judging whether the subgrade filling material to be detected meets the filling stability standard in the embodiment of the present invention;

[0047] Figure 4 is a logic diagram for determining whether to adjust the performance grade of the initial subgrade filling material in the embodiment of the present invention. Detailed Embodiments

[0048] In order to make the objectives and advantages of the present invention clearer, the present invention will be further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present invention and do not limit the protection scope of the present invention.

[0050] It should be noted that in the description of the present invention, the terms indicating directions or positional relationships such as "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0051] Please refer to Figure 1As shown, it is a flowchart of an indoor detection test method for the performance of subgrade fillers in an embodiment of the present invention; an indoor detection test method for the performance of subgrade fillers includes:

[0052] Step S1, take samples of the subgrade fillers to be detected, lay the subgrade filler samples on several detection platforms, and perform preliminary leveling respectively to obtain several initial-state subgrade fillers, and detect the height of the initial-state subgrade fillers.

[0053] Step S2, use the first deformation pressure to perform a pressure stability detection on the initial-state subgrade fillers to obtain stable subgrade filler samples, record the pressure changes and surface height changes of each layer of the initial-state subgrade fillers, and determine whether the subgrade fillers to be detected meet the filler deformation standard according to the pressure stability detection results.

[0054] Step S3, add the same volume of water to one portion of the initial-state subgrade fillers and the stable subgrade filler samples, respectively detect the water immersion height of the corresponding detection platforms, and record the detection results.

[0055] Step S4, judge whether the subgrade fillers to be detected meet the filler stability standard according to the detection results of the water immersion height.

[0056] Step S5, perform simulated filling on several of the initial-state subgrade fillers to obtain simulated subgrade fillers, use a second set of deformation pressures to perform pressure deformation detection on each simulated subgrade filler, and determine the performance grade of the initial subgrade fillers according to the detection results; repeatedly use the pressures in the corresponding second set of deformation pressures to perform simulated deformation detection on each of the simulated subgrade fillers, and determine whether to adjust the performance grade of the initial subgrade fillers according to the simulation results.

[0057] In implementation, the detection platform is a square box closed on five sides, and the maximum pressure that the square box can withstand is greater than the pressure exerted by the vehicle on the road surface and is a rigid container. The height of the square box is 30 - 40 cm, and the height of all the initial-state subgrade fillers is 30 cm.

[0058] When performing preliminary leveling on the subgrade filler samples, first vibrate the detection platforms to change the distribution positions of large and small particles in the subgrade filler samples, reduce the voids in the samples. After vibration, place a bearing plate with an area slightly smaller than the square box on the top of the samples, and apply a pressure of 5 kPa perpendicular to the horizontal plane until the position of the bearing plate no longer changes and the bearing plate is parallel to the horizontal plane.

[0059] In the above embodiment, the pressurization method and the pressure detection method are both prior arts, and the implementation method is not specifically limited. The pressurization process is uniformly pressurized starting from 0.

[0060] An indoor test method for detecting the performance of subgrade fillers provided by the present invention can accurately evaluate the pressure resistance performance and deformation characteristics of fillers by simulating the actual traffic load to apply pressure and deformation to the fillers, ensuring that the fillers meet the requirements of different grades of highways. By simulating multiple repeated pressurizations, this method characterizes the performance changes of the subgrade under long-term traffic loads, effectively tests the performance stability of the fillers under repeated loads, improves the economy and applicability of road construction, ensures the safety of high-speed vehicles, reduces maintenance costs, extends the service life of roads, and provides a scientific decision-making basis for road design and construction.

[0061] Please refer to Figure 2 as shown, which is a flowchart for detecting the pressure stability of the initial-state subgrade fillers in an embodiment of the present invention. The steps for detecting the pressure stability of the initial-state subgrade fillers include:

[0062] Applying pressure to the initial-state subgrade fillers using a first deformation pressure;

[0063] Detecting and recording the pressure change amounts at the midpoint and the bottom of the initial-state subgrade fillers;

[0064] After the pressure application ends, detecting and recording the height change of the initial-state subgrade fillers.

[0065] In practice, the first deformation pressure is 20 kPa, and a pressure application moving rate of 0.5 - 1 mm / min is adopted. It can be understood that if the pressure application moving rate is too fast, the material does not have enough time to fully deform and adjust, and the measured deformation amount may be small; on the contrary, if the pressure application moving rate is too slow, the deformation amount of the material will be too large. Therefore, selecting a pressure application moving rate of 0.5 - 1 mm / min can make the pressure stability detection more in line with the actual requirements.

[0066] It can be understood that if the filler is an ideal rigid body that does not deform at all, according to Pascal's law, in a closed static fluid (or a small-diameter solid can be analogized in this case), the pressure applied to the static liquid (or rigid body) is transmitted unchanged in all directions. When a continuous and constant pressure is applied to the surface of this ideal non-deforming filler, the pressure in the shallow layer (close to the surface) theoretically does not change. Because no deformation means that the relative positions and contact states between particles do not change, the pressure will be evenly transmitted inside the filler, and the pressure borne by the shallow layer is the same as the applied pressure and remains constant at each point.

[0067] In the present invention, by simulating the pressurization situations that the fillers may encounter in actual road construction, the reliability of the test results and the relevance of practical applications are ensured. It helps to determine the deformation and stability of the fillers under different pressures and provides a scientific basis for subgrade design and construction.

[0068] Specifically, determining whether the subgrade filler to be detected meets the filler deformation standard according to the pressurization stability detection result includes:

[0069] If the change in surface height is less than the standard surface height change, and the pressures at each layer are within the corresponding change threshold ranges, it is determined that the subgrade filler to be detected meets the filler deformation standard.

[0070] In practice, the standard surface height change is 1% - 2%. If the deformation amount of the subgrade filler is too large, it will affect the stability of the road structure. A smaller deformation amount helps to maintain the uniformity and integrity of the subgrade, reducing pavement damage caused by uneven settlement. In addition, too large a deformation amount may lead to uneven settlement of the subgrade, which is not conducive to the long-term use and maintenance of the road. A small deformation amount means a higher degree of compaction of the filler, indicating a high bearing capacity of the subgrade. A subgrade with a high bearing capacity can better support the upper structure, reducing deformation caused by traffic loads, thereby extending the service life of the road.

[0071] The pressure change amount at the midpoint is selected within the range [1 kPa, 2 kPa], and the pressure change amount at the bottom is selected within the range [2 kPa, 4 kPa]. In an ideal situation, the subgrade filler is a homogeneous and isotropic elastic material, and the pressure is evenly distributed. According to the basic principles of elasticity mechanics, during the vertical pressure transmission process, the pressure decreases linearly. For a 30-cm-thick filler, when a 20-kPa pressure is applied on the surface, the pressure at the middle layer after stabilization is 10 kPa. Based on the linear stress distribution model, the internal pressure is distributed proportionally.

[0072] In addition, considering the influence of the actual filler characteristics, for coarse-grained fillers, since the main interactions between particles are point contact and friction, after the pressure stabilizes, the pressure magnitude at the middle layer depends on the particle gradation and arrangement. If the particle gradation is good and a stable skeleton structure is formed, the pressure transmission mainly occurs through the particle skeleton. At this time, with constraints around the filler, the diffusion of pressure in the horizontal direction is restricted, which will make the pressure at the middle layer relatively high. In this case, the stable pressure at the middle layer is 11 - 12 kPa.

[0073] In actual situations, if the subgrade filler particles are unstable and are prone to further fragmentation under pressure, the pressures at the bottom and in the middle will be less than the standard situation, that is, outside the change range.

[0074] In the present invention, by detecting the deformation amount of the subgrade filler, the uniformity and integrity of the subgrade are ensured, pavement damage caused by uneven settlement is avoided, and the stability of the road structure is ensured. Secondly, by setting the pressure change amounts of the intermediate layer and the bottom layer within a specific range, the stability and bearing capacity of the filler under pressure can be evaluated. A subgrade with high bearing capacity can better support the upper structure, reduce the deformation caused by traffic loads, and extend the service life of the road. By detecting whether the pressure change amount exceeds the change range, the stability of the filler particles can be identified, and problems that may affect the performance of the subgrade can be discovered in a timely manner, thereby providing a more accurate scientific basis for subgrade design and construction.

[0075] Specifically, the height of the same volume of water added to a sample of the initial-state subgrade filler and the stable subgrade filler is lower than the height of the initial-state subgrade filler, and the water immersion height is higher than the midpoint of the initial-state subgrade filler.

[0076] It can be understood that if the subgrade material is under pressure, the particles in it will break to produce finer particles for gap filling, and the finer particles will fall to a lower position in the detection platform. Because This this results in more solid volume in the lower layer and less water that can infiltrate.

[0077] Please refer to Figure 3 as shown, which is a logic diagram for judging whether the subgrade filler to be detected meets the filler stability standard in an embodiment of the present invention. Judging whether the subgrade filler to be detected meets the filler stability standard according to the detection result of the water immersion height includes:

[0078] Calculating the height difference between the water immersion height of the initial-state subgrade filler and the water immersion height of the stable subgrade filler sample;

[0079] If the height difference is greater than the water immersion height difference threshold, it is determined that the subgrade filler to be detected does not meet the filler stability standard.

[0080] In practice, the water immersion height difference threshold is 5% of the water immersion height of the initial-state subgrade filler. It can be understood that rural roads have lighter traffic loads and slower vehicle speeds, and have a higher tolerance for filler fragmentation. Under the designed pressure, as long as the pavement does not show large potholes or serious deformations after the filler breaks, it is generally acceptable. Measured by height change (the filler is tested under pressure in a certain container), an increase in the filler layer height due to fragmentation not exceeding 5% of the original filler layer height is acceptable, and this amount of fragmentation can ensure the basic traffic needs of rural vehicles.

[0081] In the present invention, the stability of the subgrade filler is judged by the detection result of the water immersion height. By comparing the water immersion height difference between the initial subgrade filler and the stable subgrade filler sample, the particle breakage of the filler under pressure can be evaluated, so as to judge whether the filler meets the stability standard. If the water immersion height difference is greater than the set threshold, it is considered that the filler is unstable and does not meet the standard.

[0082] This method is particularly applicable to rural roads because rural roads have a higher tolerance for filler fragmentation. As long as there are no large potholes or serious deformations on the road surface after the filler breaks, it can generally meet the basic traffic needs.

[0083] Specifically, using the second deformation pressure group to perform the pressure deformation detection on each of the simulated subgrade fillers includes:

[0084] Applying the Class I load pressure, Class II load pressure, and Class III load pressure to the simulated subgrade fillers respectively;

[0085] When the height of each of the simulated subgrade fillers no longer changes, determine the height change amount of each simulated subgrade filler respectively, which is recorded as the pressure deformation detection result;

[0086] Among them, the second deformation pressure group includes the Class I load pressure, the Class II load pressure, and the Class III load pressure.

[0087] In practice, the Class I load pressure is 100 - 120 kPa, the Class II load pressure is 40 - 60 kPa, and the Class III load pressure is 25 - 30 kPa.

[0088] Each load pressure acts on different initial subgrade fillers to avoid repeated pressurization affecting the detection result. The number of selected simulated subgrade fillers is a multiple of 3.

[0089] Specifically, determining the performance grade of the initial subgrade filler in combination with the pressure deformation results of each of the simulated subgrade fillers includes:

[0090] If the pressure deformation result meets the first load condition, it is determined that the grade of the initial subgrade filler is a first-class subgrade filler;

[0091] If the pressure deformation result meets the second load condition, it is determined that the grade of the initial subgrade filler is a second-class subgrade filler;

[0092] If the pressure deformation result meets the third load condition, it is determined that the grade of the initial subgrade filler is a third-class subgrade filler.

[0093] In implementation, the first-class subgrade filler corresponds to the highway-Class I load standard and can be used for expressways and first-class highways. The second-class subgrade filler corresponds to the highway-Class II load standard and can be used for second-class highways. The third-class subgrade filler is lower than the highway-Class II load standard and can be used for rural roads.

[0094] The design of expressways usually adopts the highway-Class I load standard. Taking the dual-axis double-wheel group as an example, its standard axle load is 100 kN (about 10.2 tons). After considering factors such as vehicle dynamic impact, the actual pressure acting on the road surface and subgrade will be greater. According to the pavement structural mechanics calculation model, for example, the pavement structural thickness is 70 cm (including surface layer, base layer, etc.), and the elastic modulus of the subgrade filler is 40 MPa. Through the calculation of the multi-layer elastic system theory, under the action of the standard axle load, the pressure on the top surface of the subgrade is about 60 - 80 kPa. Moreover, the traffic flow of expressways is large and vehicles pass frequently, and this pressure will act repeatedly, requiring the subgrade filler to be able to bear such pressure for a long time without excessive deformation. In addition, for areas such as toll stations and service areas where vehicles frequently brake and start, the force exerted by vehicles on the road surface will generate large pressure pulses in a short time. For example, in the toll station lane, the braking force when the vehicle brakes will instantaneously increase the axle load by 30% - 50%. Therefore, the subgrade filler in this part of the area has to bear a pressure of 100 - 120 kPa.

[0095] Second-class highways generally adopt the highway-Class II load standard, which is a certain proportion (such as about 80%) of the standard axle load of 100 kN for the dual-axis double-wheel group, that is, about 80 kN (about 8.2 tons). For example, the pavement structural thickness is 60 cm, and the elastic modulus of the subgrade filler is 30 MPa. After calculation, the pressure on the top surface of the subgrade is approximately 40 - 60 kPa. Compared with expressways, the pressure requirement is reduced, mainly because the traffic flow and vehicle load of second-class highways are relatively small, and the requirement for the pressure resistance of the subgrade filler is also correspondingly reduced.

[0096] Rural roads mainly serve small vehicles, agricultural machinery, etc. in rural areas. The vehicle load is light, and the design load is generally based on the common vehicle types and the maximum axle weight in the local area. For example, the single-axle weight of common small agricultural vehicles in rural areas may be about 3 - 5 tons. For example, the thickness is 30 - 40 cm, and the elastic modulus of the subgrade filler is 20 MPa. It can be calculated that the pressure on the top surface of the subgrade is 20 - 30 kPa. Due to the small traffic flow and light vehicle load of rural roads, the requirement for the pressure resistance of the subgrade filler is relatively low, mainly to ensure that the subgrade can maintain basic stability under limited traffic loads and avoid obvious deformation and damage.

[0097] Specifically, the first load condition is that the deformation corresponding to the Class I load pressure is less than the Class I deformation;

[0098] The second load condition is that the deformation corresponding to the Class I load pressure is greater than or equal to the Class I deformation, and the deformation corresponding to the Class II load pressure is less than the Class II deformation;

[0099] The third load condition is that the deformation corresponding to the Class I load pressure is greater than or equal to the Class I deformation, the deformation corresponding to the Class II load pressure is greater than or equal to the Class II deformation, and the deformation corresponding to the Class III load pressure is less than the Class III deformation.

[0100] In practice, the Class I deformation is 0.5% - 1%, the Class II deformation is 1% - 2%, and the Class III deformation is 2% - 3%. It can be understood that the driving speed on expressways is fast, and vehicles are very sensitive to the pavement smoothness. Even a tiny subgrade deformation may cause a chain reaction in the pavement structure. If the deformation of the coarse-grained soil filler is too large, it will lead to pavement unevenness, and then cause bumps and vibrations when the vehicle is driving. When the vertical deformation exceeds 1% of the filler layer height, the pavement may produce slight undulations, affecting the comfort and safety of vehicles driving at high speed. In the long term, it may also lead to the damage of the pavement structure and the risk of crack generation.

[0101] For secondary roads, allowing a certain amount of deformation is considered in view of the economy and feasibility of actual projects. Within this deformation range, the basic smoothness of the pavement can be ensured to meet the driving requirements of vehicles on secondary roads, and excessive engineering costs, such as excessive compaction measures, will not be increased due to excessive restriction of deformation. In addition, the requirement for pavement smoothness of secondary roads is lower than that of expressways. Controlling the vertical deformation within the range of 1% - 2% of the filler layer height can meet the normal passage of vehicles while avoiding excessive deformation leading to serious pavement diseases and affecting the normal use of the road.

[0102] For rural roads, these roads mainly serve rural areas or regions with relatively low traffic flow, and the vehicle speed is relatively slow, so the requirement for pavement smoothness is relatively low. Therefore, on the premise of ensuring the basic stability of the subgrade, appropriately relaxing the deformation requirements of the coarse-grained soil filler can reduce the engineering cost and meet the local traffic needs at the same time. In actual situations, considering the occasional passage of heavy agricultural machinery, etc., the control of the deformation amount needs to be within an interval. Generally speaking, the deformation range is lower than the standards of expressways, first-class roads, and secondary roads, which can meet the basic passage requirements of roads at or below the third-class level.

[0103] In the present invention, by simulating the load pressures of different grades of roads, the pressure resistance performance and deformation characteristics of the filler are accurately evaluated to ensure that the filler can meet the requirements of different grades of roads. This method not only improves the economy and applicability of road construction, but also ensures the safety of vehicles driving at high speed, reduces the maintenance cost, extends the service life of the road, and provides a scientific decision-making basis for road design and construction.

[0104] Please refer to Figure 4 shown in the figure, which is the logic diagram for determining whether to adjust the performance grade of the initial subgrade filler in the embodiment of the present invention. Repeatedly using the pressures in the corresponding second deformation pressure group to perform simulated deformation detection on the simulated subgrade filler, including:

[0105] Obtain the performance grade of the initial subgrade filler, and determine the corresponding second deformation pressure and the preset number of simulation times;

[0106] According to the preset number of simulation times, repeatedly apply pressure to the simulated subgrade filler using the corresponding second deformation pressure, and record the final deformation amount.

[0107] In practice, the preset number of simulation times for first-class subgrade filler is 10 - 15 times, the preset number of simulation times for second-class subgrade filler is 6 - 10 times, and the simulation times for third-class subgrade filler is 2 - 3 times. The final deformation amount is the simulation result.

[0108] The traffic flow on expressways is large and vehicles pass frequently. Within the design life, a lane will bear millions of vehicle loadings. Through 10 - 15 times of pressure application simulation, the performance changes of the subgrade under long-term traffic loads can be approximately reflected to a certain extent. For example, each pressure application is equivalent to the cumulative effect after a certain number of vehicle axle loads pass, so that the deformation accumulation and strength attenuation of the filler under repeated compression can be observed. Expressways have extremely high requirements for the durability of subgrades. Multiple pressure application tests can better detect whether problems such as excessive deformation, particle breakage, and structural damage will occur to the filler under repeated loads. If the filler can still maintain stable performance after 10 - 15 times of pressure application, that is, the deformation amount is within the allowable range, it can be determined that the long-term stability of the subgrade can be ensured during the actual use of expressways, reducing the later maintenance and repair costs.

[0109] The traffic flow on secondary roads is relatively less than that on expressways, and the vehicle passing frequency is lower. 6 - 10 times of pressure application can simulate the vehicle loading conditions on secondary roads over a relatively long period (such as within the design service life). For example, considering factors such as the number of lanes, daily traffic volume, and vehicle types on secondary roads, such a number of pressure application times can reasonably evaluate the performance of the filler under actual traffic loads. Compared with expressways, the requirements for subgrade performance on secondary roads are slightly lower. 6 - 10 times of pressure application tests can not only effectively detect whether the filler meets the basic use requirements of secondary roads, ensuring flatness and bearing capacity, but also will not increase unnecessary costs due to excessive test times. At the same time, through this number of tests, the main problems that may occur to the filler under repeated loads can be observed, such as whether the deformation will gradually accumulate to an extent that affects the normal use of the road.

[0110] Highways of Class III and below mainly serve areas with low traffic flow and light vehicle loads. In actual use, the number of vehicle loads borne by the road is relatively small. The number of pressurization times of 3 to 5 can simulate the main load conditions of such roads during their service life. For example, rural roads are mainly used by agricultural vehicles and a small number of small cars, and the frequency of their load effects is low. Pressurization 3 to 5 times can reflect the performance of the subgrade filler under the long-term action of these vehicles. In addition, the main requirement for the subgrade of such roads is to ensure the basic traffic function. Through the pressurization test of 3 to 5 times, it can be detected whether obvious deformation, damage, etc. will occur to the filler under the action of the load, so as to judge whether it can meet the normal traffic needs of local vehicles. Too many tests for highways of Class III and below may over-require the performance of the filler, increase the project cost and do not meet the actual needs.

[0111] Specifically, determining whether to adjust the performance grade of the initial subgrade filler according to the simulation result includes:

[0112] If the final deformation meets the corresponding load conditions, it is determined not to adjust the performance grade of the initial subgrade filler, and it is recorded as the performance grade of the subgrade filler to be detected;

[0113] If the final deformation does not meet the corresponding load conditions, it is determined to adjust the performance grade of the initial subgrade filler.

[0114] In implementation, if the initial subgrade filler grade is a Class I subgrade filler, it is adjusted to a Class II subgrade filler when it is determined to adjust the performance grade of the initial subgrade filler; if the initial subgrade filler grade is a Class II subgrade filler, it is adjusted to a Class III subgrade filler when it is determined to adjust the performance grade of the initial subgrade filler; if the initial subgrade filler grade is a Class III subgrade filler, it is determined that the subgrade filler to be detected is unqualified.

[0115] In the present invention, by simulating the actual traffic load, repeated pressurization tests are carried out on subgrade fillers of different grades to evaluate their stability and durability under long-term loads. According to the test results, it can be determined whether the filler meets the requirements of a specific highway grade, and the performance grade of the filler can be adjusted accordingly to ensure that suitable fillers are used in road construction, improve the road quality and reduce the maintenance cost.

[0116] If the indoor detection test method for the performance of the subgrade filling material of the present invention is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical discs that can store program codes.

[0117] So far, the technical solution of the present invention has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of the present invention.

[0118] The foregoing are only the preferred embodiments of the present invention and are not used to limit the present invention; for those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An indoor test method for detecting the performance of subgrade filling materials, characterized in that, Including: Sampling the subgrade filler to be detected, laying the subgrade filler samples on several detection platforms, and respectively performing preliminary leveling to obtain several initial-state subgrade fillers, and detecting the height of the initial-state subgrade fillers; Using a first deformation pressure to perform a pressure stability detection on the initial-state subgrade filler to obtain a stable subgrade filler sample, recording the pressure changes and surface height changes of each layer of the initial-state subgrade filler, and determining whether the subgrade filler to be detected meets the filler deformation standard according to the pressure stability detection result. If the surface height change is less than the standard surface height change and the pressures of each layer are within the corresponding change threshold range, it is determined that the subgrade filler to be detected meets the filler deformation standard; Adding the same volume of water to one portion of the initial-state subgrade filler and the stable subgrade filler sample, respectively detecting the water immersion height of the corresponding detection platform, and recording the detection results; Judging whether the subgrade filler to be detected meets the filler stability standard according to the detection result of the water immersion height, and calculating the height difference between the water immersion height of the initial-state subgrade filler and the water immersion height of the stable subgrade filler sample; if the height difference is greater than the water immersion height difference threshold, it is determined that the subgrade filler to be detected does not meet the filler stability standard; Performing simulated filling on several of the initial-state subgrade fillers to obtain simulated subgrade fillers, and using a second deformation pressure group to perform pressure deformation detection on each simulated subgrade filler, including respectively using a level I load pressure, a level II load pressure, and a level III load pressure to pressurize the simulated subgrade filler; when the height of each simulated subgrade filler no longer changes, respectively determining the height change amount of each simulated subgrade filler, which is recorded as the pressure deformation detection result; Determining the performance grade of the initial subgrade filler according to the detection result; Repeatedly using the pressures in the corresponding second deformation pressure group to perform simulated deformation detection on each simulated subgrade filler, including obtaining the performance grade of the initial subgrade filler and determining the corresponding second deformation pressure and the preset number of simulated times; Repeatedly pressurizing the simulated subgrade filler according to the preset number of simulated times using the corresponding second deformation pressure, and recording the final deformation amount as the simulation result; Determining whether to adjust the performance grade of the initial subgrade filler according to the simulation result.

2. The indoor test method for the performance of subgrade filler according to claim 1, wherein, Performing the pressure stability detection on the initial-state subgrade filler includes: Pressurizing the initial-state subgrade filler using a first deformation pressure; Detecting and recording the pressure change amounts at the midpoint of the initial-state subgrade filler and the bottom of the initial-state subgrade filler; After the pressurization ends, detecting and recording the height change of the initial-state subgrade filler.

3. The indoor test method for the performance of subgrade filler according to claim 2, characterized in that, The height of the same volume of water added to one portion of the initial-state subgrade filler and the stable subgrade filler sample is lower than the height of the initial-state subgrade filler, and the water immersion height is higher than the midpoint of the initial-state subgrade filler.

4. The indoor test method for the performance of subgrade filling materials according to claim 3, characterized in that, Determining the performance grade of the initial subgrade filler by combining the pressure deformation results of each simulated subgrade filler, including: If the pressure deformation result meets the first load condition, it is determined that the initial subgrade filler grade is a first-class subgrade filler; If the pressure deformation result meets the second load condition, it is determined that the initial subgrade filler grade is a second-class subgrade filler; If the pressure deformation result meets the third load condition, it is determined that the initial subgrade filler grade is a grade-three subgrade filler.

5. The indoor detection test method for the performance of subgrade filling materials according to claim 4, wherein The first load condition is that the deformation corresponding to the grade-I load pressure is less than the grade-I deformation; The second load condition is that the deformation corresponding to the grade-I load pressure is greater than or equal to the grade-I deformation, and the deformation corresponding to the grade-II load pressure is less than the grade-II deformation; The third load condition is that the deformation corresponding to the grade-I load pressure is greater than or equal to the grade-I deformation, the deformation corresponding to the grade-II load pressure is greater than or equal to the grade-II deformation, and the deformation corresponding to the grade-III load pressure is less than the grade-III deformation.

6. The indoor detection test method for the performance of subgrade filler according to claim 5, characterized in that, Determining whether to adjust the performance grade of the initial subgrade filler according to the simulation result includes: If the final deformation meets the corresponding load condition, it is determined not to adjust the performance grade of the initial subgrade filler, and it is recorded as the performance grade of the subgrade filler to be detected; If the final deformation does not meet the corresponding load condition, it is determined to adjust the performance grade of the initial subgrade filler.

Images