Rapid detection method for roadbed compactness

Abstract

The invention discloses a rapid roadbed compactness detection method, which adopts dynamic sounding detection equipment, and the dynamic sounding detection equipment comprises a probe rod device and an orifice stool. The method comprises the following steps: before field testing, carrying out indoor testing by adopting dynamic penetration detection equipment to obtain penetration PL of each N times of hammering at a drop distance H corresponding to the compaction degree DF required by a roadbed, and taking the penetration PL as a field detection standard; then, according to the determined field detection standard, the dynamic penetration detection equipment is adopted for engineering field detection, and the penetration degree of each N times of hammering at the drop distance H is obtained through detection of roadbed detection points of the engineering field and recorded as PF; and when the PF is not greater than the PL, determining that the compactness of the detection point is qualified, otherwise, determining that the compactness is not qualified. The method is easy to operate, high in detection speed and small in damage to the compacted roadbed, indoor tests are not needed after field tests are started, and the roadbed compactness can be obtained on site.

Description

Technical Field

[0001] The invention belongs to the technical field of rapid detection of roadbed compaction construction quality, and in particular relates to a method for rapid detection of roadbed compaction degree. Background Art

[0002] Compaction is an important indicator for controlling the quality of roadbed construction. In actual projects, the common methods for testing compaction are sand filling method, water filling method and ring knife method. These methods can accurately and truly obtain compaction indicators, and their test results can be used as the basis for acceptance. However, these methods also have disadvantages: first, these detection methods are destructive detection and cause great damage to the roadbed. For example, the sand filling method and the water filling method both require excavating test pits on the compacted roadbed to achieve; second, the detection speed of these methods is slow. Taking the sand filling method as an example, for a measuring point, it is necessary to conduct on-site pit digging, sand filling, weighing and other tests, and indoor moisture content tests, which is very inefficient and sometimes affects the progress of the project. In fact, for some situations, such as the construction party's compaction self-inspection, it is not necessary to use such cumbersome detection methods. Therefore, it is necessary to develop a faster compaction detection device.

[0003] Dynamic penetration is a field testing method that can reflect indicators such as the bearing capacity or strength of the roadbed. The bearing capacity or strength is often closely related to the compaction degree. Therefore, dynamic penetration can be used to detect the compaction degree of the roadbed. Dynamic penetration can be divided into three types: super heavy, heavy and light. Among them, light dynamic penetration is the lightest and can be completed by manpower without the help of large mechanical equipment. Conventional light dynamic penetration uses a 10kg drop hammer, and the number of hammer strikes with a penetration of 30cm is used as the test value. There have been attempts to use light dynamic penetration to detect the compaction degree of the roadbed, but these attempts still have some defects, mainly reflected in the detection accuracy and applicability. For the roadbed, its rolling construction process is layered, and the compaction degree detection is also carried out in layers. The thickness of each layer of the roadbed after rolling is mostly less than the penetration target value of 30cm for light dynamic penetration. When the penetration depth does not reach 30cm, it must be converted, and this conversion will bring corresponding errors. Secondly, the impact energy of a 10kg drop hammer is relatively large, and the penetration depth of each drop hammer is relatively large, so it is difficult to accurately make the total penetration depth reach the predetermined value, which will also cause errors, because the farther away from the predetermined value, the greater the error caused by conversion. Thirdly, conventional dynamic probing takes penetration as the target. For example, 30cm penetration is often counted as one hammer blow. In fact, the number of hammer blows required for 30cm penetration is basically impossible to be an integer, because the penetration depth of the probe rod is difficult to be exactly 30cm. In addition, the penetration depth is generally based on the roadbed hole as a reference. During the penetration process, the hole will be deformed or collapsed due to extrusion and vibration, which also makes it difficult to accurately measure the penetration depth. Some attempts are to use the cumulative number of hammer blows and cumulative penetration of multiple 30cm penetrations to obtain indicators similar to or closely related to compaction, such as relative density or maximum dry density. This method is not suitable for the needs of roadbed layered rolling and layered detection. Roadbed layers generally do not exceed 30cm. Therefore, it is necessary to improve the dynamic probing device and detection method to make it better adapt to the detection of compaction. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, the present invention provides a method for quickly detecting the compaction degree of a roadbed.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for quickly detecting the compaction degree of a roadbed, the method using a dynamic penetration testing device, the dynamic penetration testing device comprising a probe rod device and an orifice stool;

[0007] The probe rod device comprises a drop hammer, a probe rod and a probe head; the probe head is installed at the bottom end of the probe rod, an expanded diameter section is fixedly arranged in the middle of the probe rod, and the drop hammer is slidably sleeved on the probe rod section above the expanded diameter section; two sections of scales are arranged on the probe rod, wherein the first section of the scale is arranged on the probe rod section below the expanded diameter section, and is used to indicate the depth of the probe rod's downward penetration; the second section of the scale is arranged on the probe rod section above the expanded diameter section, and is used to indicate the drop distance of the drop hammer;

[0008] The orifice stool is used in conjunction with the probe rod device. The orifice stool includes a stool surface and stool legs supporting the stool surface. A through hole is provided at the center of the stool surface for the probe rod to pass through. A reading probe is provided on the stool surface of the orifice stool for assisting in reading the reading of the first section of the scale on the probe rod.

[0009] The method for quickly detecting the compaction degree of a roadbed using the dynamic penetration detection equipment comprises the following steps:

[0010] Step 1: Before the on-site test, the dynamic penetration test equipment is used to conduct indoor tests to obtain the compaction degree D required for the roadbed. F The penetration rate P per hammer blow N at the corresponding drop distance H L , as the engineering site inspection standard; including the following steps:

[0011] Step 1.1, take the same soil sample as the roadbed engineering site, and make a sample with a compaction degree D in the test pit. D is the same as the compaction degree D required at the engineering site. F close to or equal to;

[0012] Step 1.2, testing the soil sample in the test pit using the dynamic penetration testing equipment to obtain the penetration P of each N hammer strikes at a set drop distance H;

[0013] Step 1.3: Repeat steps 1.1 to 1.2 above and conduct at least three groups of tests. In each group of tests, the compaction degree D is greater than or less than the required compaction degree D on site. F There shall be no less than one test specimen for each of the following types of testing:

[0014] Step 1.4: Draw the compaction degree D-penetration degree P curve by group, and deduce the D F The corresponding penetration P Li ;

[0015] Step 1.5, take multiple groups of test P Li The arithmetic mean of L , P L That is the compaction degree D required at the engineering site F The corresponding penetration rate per hammer blow N times at a drop distance H is used as the standard for on-site inspection of the project;

[0016] Step 2: According to the engineering site inspection standard determined in step 1, the dynamic penetration inspection equipment is used to conduct engineering site inspection, the steps are as follows:

[0017] Step 2.1, determine the location of the inspection points at the project site and mark them according to the requirements;

[0018] Step 2.2: For a single detection point, the dynamic penetration detection equipment is used to detect and obtain the penetration rate per N hammer strikes at a drop distance H, which is recorded as P F ;

[0019] Step 2.3, when P F Not greater than P L When the compaction degree of the test point is qualified, otherwise it is unqualified;

[0020] Step 2.4: Repeat steps 2.2 to 2.3 to complete the inspection of all inspection points.

[0021] In the above technical solution, the process of using the dynamic penetration detection equipment to detect and obtain the penetration of each N hammer blows at a drop distance H is as follows:

[0022] (1) Place the orifice stool firmly at the target location, and place the probe and the probe of the probe device through the through hole in the center of the stool surface on the target to be measured;

[0023] (2) Pre-driving: lift the drop hammer and hammer the expanded diameter section of the probe rod for 1-3 times as a pre-driving of the probe rod, so that the probe is initially placed in the target soil to be measured and stabilized therein;

[0024] (3) After the pre-punching is completed, align the top of the reading probe with the position of the first scale section of the probe rod, which is taken as the reading of the first scale section, recorded as p1;

[0025] (4) Start the formal dynamic penetration test: refer to the second section scale, raise the drop hammer to the required drop distance H, hammer the expanded diameter section of the probe rod N times, and then read the reading of the first section scale on the probe rod again, recorded as p2;

[0026] (5) According to the formula P = p2-p1, the penetration P of the target to be tested per N hammer strikes at a specific drop distance H is obtained.

[0027] In the above technical solution, the diameter of the probe rod is 20-30 mm; the probe is conical with a cone angle of 50-70 degrees; the diameter of the expanded section is 55-60 mm; and the mass of the drop weight is 6-8 kg.

[0028] In the above technical solution, the second section of the scale is marked from 0mm on the top surface of the expanded diameter section upward along the rod section, and the maximum marked size is 600mm.

[0029] In the above technical solution, the diameter of the through hole on the stool surface of the hole stool is 45-50 mm.

[0030] In the above technical solution, the reading probe adopts an elastic metal sheet set at an angle, the bottom of which is fixed on the bench surface by bolts, and the top of which is used to point to the first section of the scale on the probe rod. The pointed position is used as the reading of the first section of the scale, so as to accurately read the penetration depth of the probe rod device during the test.

[0031] The advantages and beneficial effects of the present invention are:

[0032] 1. Compared with the conventional sand filling method, water filling method and ring knife method, the method of the present invention is simple to operate, has a fast detection speed, and causes little damage to the compacted roadbed. After the field test begins, there is no need to conduct indoor tests, and the roadbed compaction degree can be obtained on site.

[0033] 2. The dynamic penetration detection equipment used in the present invention has two millimeter-level scales engraved on its probe device; the first scale is set on the probe rod section below the expansion section to indicate the depth of the probe rod's downward penetration; the second scale is set on the probe rod section above the expansion section to indicate the drop distance of the drop hammer. In addition, the dynamic penetration rapid detection device of the present invention uses an orifice stool with a reading elastic metal sheet as an auxiliary support base for use with the probe device, which can quickly and accurately detect the penetration P of the target to be tested at a specific drop distance H for every N hammer strikes.

[0034] 3. The dynamic penetration testing equipment adopted by the present invention is more lightweight, which reduces the labor intensity of the testing personnel. The weight of the drop hammer is about 7.5 kg, and the penetration degree produced by each hammer blow is small, which also reduces the probability of the probe penetrating the test roadbed into the non-test roadbed.

[0035] 4. Compared with other methods that use dynamic penetration as a detection method, the general method records the number of blows N required for each specific penetration such as 30 cm, but when the actual number of blows is N, the penetration degree is often greater than 30 cm, which will cause measurement errors due to excessive penetration. The method of the present invention uses the penetration degree corresponding to a specific number of hammer blows (generally 10 to 15) at a specific drop distance as a measurement indicator, avoiding errors caused by excessive penetration. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the structure of the probe device in the present invention.

[0037] Figure 2 It is a schematic structural diagram of the hole stool in the present invention.

[0038] Figure 3 Shown is a schematic diagram of the detection state of the dynamic probing detection equipment of the present invention.

[0039] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with specific embodiments.

[0041] A dynamic penetration testing device comprises a probe rod device and a hole stool.

[0042] The probe device comprises a drop weight 1, a probe rod 2 and a probe head 4. Figure 1 Its structure is introduced in detail.

[0043] A probe 4 is installed at the bottom end of the probe rod 2, the diameter of the probe rod 2 is 25 mm, the probe 4 is conical, the maximum diameter of the probe 4 is 40 mm, and the cone angle is 60 degrees; an expanded diameter section 21 is fixedly arranged in the middle of the probe rod 2, and the diameter of the expanded diameter section 21 is 55 mm; the drop hammer 1 is slidably mounted on the rod section of the probe rod 2 above the expanded diameter section 21, and the mass of the drop hammer 1 is preferably 7.5 kg. When the drop hammer 1 is lifted, the drop hammer 1 falls freely along the probe rod 2, and will hammer the expanded diameter section 21, thereby causing the entire probe rod 2 to generate a downward impact force.

[0044] Two sections of scales are provided on the probe rod 2, wherein the first section of the scale 31 is provided on the section of the probe rod 2 below the enlarged diameter section 21, and during the test, is used to indicate the depth of the probe rod 2 penetrating downward into the target to be measured (such as a roadbed or a soil sample) (needs to be used in conjunction with the reading probe 6 on the orifice stool 5, which will be described in detail later); the second section of the scale 32 is provided on the section of the probe rod 2 above the enlarged diameter section 21, and the second section of the scale 32 is marked upward along the section from 0mm on the top surface of the enlarged diameter section 21, with a maximum marked size of 500mm. The function of the second section of the scale 32 is to indicate the drop distance of the drop hammer 1 (i.e., indicate from what height the drop hammer 1 falls) during the test, that is, during the detection process, the drop hammer 1 is lifted, and the scale of the second section of the scale 32 corresponding to the bottom surface of the drop hammer 1 is used as the drop distance of the drop hammer 1. After the lifting reaches the required drop distance, the drop hammer 1 is lowered for hammering.

[0045] The orifice stool 5 is used in conjunction with the probe device, as shown in the following Figure 2 -Attached Figure 3 The structure and function of the orifice stool 5 are specifically introduced.

[0046] The orifice stool 5 comprises a stool surface 51 and a plurality of stool legs 52 supporting the stool surface 51 , and the material is a light and high-strength aluminum alloy.

[0047] A through hole 53 is provided at the center of the stool surface 51 of the orifice stool 5 . The diameter of the through hole 53 is 45-50 mm. During detection, the probe rod 2 of the probe rod device passes through the through hole 53 .

[0048] A reading probe 6 is arranged on the stool surface 51 of the hole stool 5. The reading probe 5 adopts an elastic metal sheet set at an angle. The bottom of the reading probe 5 is fixed on the stool surface 51 by bolts 7, and the top of the reading probe 6 is used to point to the first section scale 31 on the probe rod 2. The pointed position is used as the reading of the first section scale 31, so as to accurately read the penetration depth of the probe rod device into the target to be measured during detection.

[0049] The above dynamic penetration testing equipment can measure the penetration P of each N hammer strikes at a set drop distance H for the target to be tested (which can be a sample of the roadbed or roadbed soil at the engineering site). The specific testing process is as follows (see Appendix Figure 3 ):

[0050] (1) Place the orifice stool 5 firmly at the target position, and place the probe 4 and the probe 2 of the probe device through the through hole 53 in the center of the stool surface and stand on the target to be measured;

[0051] (2) Pre-driving: lift the drop hammer 1 and hammer the expanded diameter section 21 of the probe rod 1-3 times as a pre-driving of the probe rod, so that the probe 4 is initially placed in the target soil to be measured and stabilized therein;

[0052] (3) After the pre-punching is completed, the top of the reading probe 6 is aligned with the position of the first section scale 31 of the probe rod 2, and the reading of the first section scale 31 is recorded as p1;

[0053] (4) Start the formal dynamic penetration test: refer to the second section scale 32, lift the drop hammer 1 to the required drop distance H, hammer the expanded diameter section of the probe rod 2 N times, and then read the reading of the first section scale 31 on the probe rod 2 again, which is recorded as p2;

[0054] (5) According to the formula P = p2-p1, the penetration P of the target to be tested per N hammer strikes at a specific drop distance H can be obtained.

[0055] Based on the above-mentioned dynamic penetration detection equipment and detection method, the present invention designs a new method for rapid detection of roadbed compaction, and the steps are as follows:

[0056] Step 1: Before the on-site test, the dynamic penetration test equipment is used to conduct indoor tests to obtain the compaction degree D required for the roadbed. F The penetration rate P per hammer blow N at the corresponding drop distance H L , as the engineering site inspection standard; including the following steps:

[0057] Step 1.1, take the same soil sample as the roadbed engineering site, and make a sample with a compaction degree D in the test pit. D is the same as the compaction degree D required at the engineering site. F close to or equal to;

[0058] Step 1.2, testing the soil sample in the test pit using the dynamic penetration testing equipment to obtain the penetration P of each N hammer strikes at a set drop distance H;

[0059] Step 1.3: Repeat steps 1.1 to 1.2 above and conduct at least three groups of tests. In each group of tests, the compaction degree D is greater than or less than the required compaction degree D on site. F There shall be no less than one test specimen for each of the following types of testing:

[0060] Step 1.4: Draw the compaction degree D-penetration degree P curve by group, and deduce the D F The corresponding penetration P Li ;

[0061] Step 1.5, take multiple groups of test P Li The arithmetic mean of L , P L That is the compaction degree D required at the engineering site F The corresponding penetration rate per hammer blow N times at a drop distance H is used as the standard for on-site inspection of the project;

[0062] Step 2: According to the engineering site inspection standard determined in step 1, the dynamic penetration inspection equipment is used to conduct engineering site inspection, the steps are as follows:

[0063] Step 2.1, determine the location of the inspection points at the project site and mark them according to the requirements;

[0064] Step 2.2: For a single detection point, the dynamic penetration detection equipment is used to detect and obtain the penetration rate per N hammer strikes at a drop distance H, which is recorded as P F ;

[0065] Step 2.3, when P F Not greater than P L When the compaction degree of the test point is qualified, otherwise it is unqualified;

[0066] Step 2.4: Repeat steps 2.2 to 2.3 to complete the inspection of all inspection points.

[0067] The present invention is described above by way of example. It should be noted that, without departing from the core of the present invention, any simple deformation, modification or other equivalent replacement that can be made by those skilled in the art without inventive effort falls within the protection scope of the present invention.

Claims

1. A method for rapid detection of roadbed compaction, characterized in that: The method adopts a dynamic penetration detection device, which includes a probe rod device and an orifice stool; The probe rod device comprises a drop hammer, a probe rod and a probe head; the probe head is installed at the bottom end of the probe rod, an expanded diameter section is fixedly arranged in the middle of the probe rod, and the drop hammer is slidably sleeved on the probe rod section above the expanded diameter section; two sections of scales are arranged on the probe rod, wherein the first section of the scale is arranged on the probe rod section below the expanded diameter section, and is used to indicate the depth of the probe rod's downward penetration; the second section of the scale is arranged on the probe rod section above the expanded diameter section, and is used to indicate the drop distance of the drop hammer; The orifice stool is used in conjunction with the probe rod device. The orifice stool includes a stool surface and stool legs supporting the stool surface. A through hole is provided at the center of the stool surface for the probe rod to pass through. A reading probe is provided on the stool surface of the orifice stool for assisting in reading the reading of the first section of the scale on the probe rod. The method for quickly detecting the compaction degree of a roadbed using the dynamic penetration detection equipment comprises the following steps: Step 1: Before the on-site test, the dynamic penetration test equipment is used to conduct indoor tests to obtain the compaction degree D required for the roadbed. F The penetration rate P per hammer blow N at the corresponding drop distance H L , as the engineering site inspection standard; including the following steps: Step 1.1, take the same soil sample as the roadbed engineering site, and make a sample with a compaction degree D in the test pit. D is the same as the compaction degree D required at the engineering site. F close to or equal to; Step 1.2, testing the soil sample in the test pit using the dynamic penetration testing equipment to obtain the penetration P of each N hammer strikes at a set drop distance H; Step 1.3: Repeat steps 1.1 to 1.2 above and conduct at least three groups of tests. In each group of tests, the compaction degree D is greater than or less than the required compaction degree D on site. F There shall be no less than one test specimen for each of the following types of testing: Step 1.4: Draw the compaction degree D-penetration degree P curve by group, and deduce the D F The corresponding penetration P Li ; Step 1.5, take multiple groups of test P Li The arithmetic mean of L , P L That is the compaction degree D required at the engineering site F The corresponding penetration rate per hammer blow N times at a drop distance H is used as the standard for on-site inspection of the project; Step 2: According to the engineering site inspection standard determined in step 1, the dynamic penetration inspection equipment is used to conduct engineering site inspection, the steps are as follows: Step 2.1, determine the location of the inspection points at the project site and mark them according to the requirements; Step 2.2: For a single detection point, the dynamic penetration detection equipment is used to detect and obtain the penetration rate per N hammer strikes at a drop distance H, which is recorded as P F ; Step 2.3, when P F Not greater than P L When the compaction degree of the test point is qualified, otherwise it is unqualified; Step 2.4: Repeat steps 2.2 to 2.3 to complete the inspection of all inspection points.

2. The method for rapid detection of roadbed compaction according to claim 1, characterized in that: The process of using the dynamic penetration detection equipment to obtain the penetration of each N hammer strikes at a drop distance H is as follows: (1) Place the orifice stool firmly at the target location, and place the probe and the probe of the probe device through the through hole in the center of the stool surface on the target to be measured; (2) Pre-driving: lift the drop hammer and hammer the expanded diameter section of the probe rod for 1-3 times as a pre-driving of the probe rod, so that the probe is initially placed in the target soil to be measured and stabilized therein; (3) After the pre-punching is completed, align the top of the reading probe with the position of the first scale section of the probe rod, which is taken as the reading of the first scale section, recorded as p1; (4) Start the formal dynamic penetration test: refer to the second section scale, raise the drop hammer to the required drop distance H, hammer the expanded diameter section of the probe rod N times, and then read the reading of the first section scale on the probe rod again, recorded as p2; (5) According to the formula P = p2-p1, the penetration P of the target to be tested per N hammer strikes at a specific drop distance H is obtained.

3. The method for rapid detection of roadbed compaction according to claim 1, characterized in that: The diameter of the probe rod is 20-30mm; the probe is conical with a cone angle of 50-70 degrees; the diameter of the expanded section is 55-60mm; the mass of the drop weight is 6-8kg.

4. The method for rapid detection of roadbed compaction according to claim 1, characterized in that: The second section of the scale starts from 0mm on the top surface of the expanded diameter section and marks upward along the rod section, with the maximum marked size being 600mm.

5. The method for rapid detection of roadbed compaction according to claim 1, characterized in that: The diameter of the through hole on the stool surface of the orifice stool is 45-50 mm.

6. The method for rapid detection of roadbed compaction according to claim 1, characterized in that: The reading probe adopts an elastic metal sheet set at an angle, the bottom of which is fixed on the bench surface by bolts, and the top of which is used to point to the first section of the scale on the probe rod, and the pointed position is used as the reading of the first section of the scale.

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