Specific quantities and standards for ring knife sampling

Ring Knife

It is traditional practice to use the ring knife to measure on-site density. The ring knife has a volume of 200cm3 and a ring knife height of about 5cm. Use the ring knife to measure the density and average it within the depth range of the soil inside the ring knife. Density can represent the average density of the entire compacted layer. Since the density of the compacted soil layer generally decreases, if the ring knife is taken from the part of the rolled layer, the value will tend to be biased. If the ring knife is taken from the bottom of the rolled layer, the value will be obviously biased. Check the compaction of the subgrade soil and pavement structure layer. I need the average compaction degree of the whole rolling layer. The compaction degree of a certain part of the rolling layer should be measured with a ring knife so that the density can represent the average density of the whole rolling layer. Actual detection is difficult; it is difficult to make sure that the soil taken by the ring knife is exactly The soil ring cutter between the rolled layers can form the same knot as the sand filling. In addition, the ring cutter has a narrower application range and is suitable for use with stabilized soil containing granular materials and loose materials

1. Instruments and materials

(1) Manual earth retriever or electric earth retriever: The manual earth retriever includes a ring knife, a ring cover, a directional cylinder hammer system (guide rod drop weight, handle), an inner diameter of the ring knife 6 to 8 cm, a height of 23 cm, and a wall thickness of 1 ．The 52mm electric soil extractor consists of a base, traveling wheel, column, gear box, lifting mechanism, coring, etc. The main technical parameters of the electric soil extractor are: working voltage DC24V (36Ah); speed adjustment at 5070r/min; overall machine weight is about 35kg

(2) Flat: 0.1g (for weighing products with a core diameter of 70mm) or 1.0g (for weighing products with a core diameter of 100mm)

(3) Other: picks, shovels, soil trimming knives, brushes, rulers, wire saws, Vaseline, wooden boards and equipment for measuring moisture content, etc.

2. Tests and steps

(1) Use a manual soil picker to measure the density of cohesive soil and fine-grained soil stabilized by mechanical binders

① Wipe the ring knife and weigh the ring knife mass m2, accurate to 0.1g

② The area of ??the test point is about 30cmx 30cm. Clean and compact the surface of the layer. The surface of the layer shovel and the flat part reach a certain depth so that the ring knife can reach the required soil borrowing depth and disturb the layer.

③ The toothed nails of the directional cylinder are fixed on the shovel plane, along with the ring cutter, and the ring cover is placed in the directional cylinder perpendicular to the surface

④ Keep the guide rod vertical and use the earth retriever to drop the hammer and ring cutter to compact the layer to the top surface of the ring cover Until it is flush with the mouth of the directional cylinder

⑤ Remove the compaction hammer, use a pickaxe ring cutter and test dig the directional barrel

6. Gently remove the ring cover, use a soil trimming knife to trim the ring cutter from the edge Use a ruler to check the remaining soil at both ends until it is leveled

7. Wipe the outer wall of the ring knife and use a flat scale to take out the ring knife and test the total mass m1, accurate to 0.1g

8. Take the test tool from the ring knife to measure its moisture content

(2) Use a manual soil tool to measure the density of sandy soil or sand layer

①Moist sandy soil: the test needs to use The compacting hammer is oriented to the plane of the bucket shovel, and the fine digging diameter is slightly smaller than the outer diameter of the ring knife. Place the ring knife edge on the sand column flat and use both hands to press the ring knife vertically until the protruding ring knife end of the sand column is about 2cm.

②Peel off the residual sand on the edge of the ring knife and scrape it smooth with a ruler

③Cover the ring knife edge with a smooth wooden board. Hold the board with one hand, and use the other hand to cut off the bottom of the ring knife with a shovel and fill it with the test ring knife. Turn the remaining sand and soil on the cutting edge of the ring cutter and scrape it flat with a ruler

④Clean the outer wall of the ring cutter and weigh the total mass of the ring cutter and the test, m1, accurate to 0.1g

⑤Self-ring cutter Take a representative test to determine its water content

6. Dry sand can be dug into the sand column and directly pressed with a ring knife or driven into the soil

(3) Use an electric soil extractor to measure the element Density of machine-bonded fine-grained soil and hard plastic soil

① Install the required specifications and take cores. Before taking cores at the construction site, select a flat road section, drive the four-wheel drive, and drive the root positioning pins into the subgrade soil with manual pressure. Layer, loosen the locking handle and turn the lifting handwheel to make the coring just contact the layer. Lock the handle

2. Connect the battery to the speed regulator and connect the output end of the speed regulator to the power socket of the core machine. The indicator light is on. The circuit is connected; the motor works with the coring mechanism to turn on and off, and the rotation speed is adjusted according to the moisture content of the soil layer. The lift handle is operated to extract the core mechanism. It is stopped and moved. Due to several spiral protrusions on the surface of the coring cylinder, the soil cuttings discharge cylinder rotates along the outer thread of the coring cylinder. Throw out the coring sleeve, cut the soil core column, and shake to get the product

③ Take the product and immediately trim it with a soil trimmer or wire saw at both ends according to the angle of the coring sleeve. Make the soil core of the required specifications. The test items are packed in aluminum boxes and sent to the laboratory for later use

④Use a flat weighing soil core with a sleeve mass of m1 to take a test to determine the moisture content of the soil core

3. Calculation

Calculate the test wet density ρw and dry density ρd according to the formula

1 compaction degree

On-site measured dry density Laboratory measured dry density ratio compaction

The key indicators for quality inspection of subgrade and pavement construction represent on-site compaction density conditions. The higher the degree of compaction, the better the overall performance of the material. Compared with subgrade, semi-rigid pavement base and granular flexible base, the degree of compaction refers to the actual dry density of the construction and the indoor density. The dry density ratio of the standard compaction laboratory; the compaction degree of asphalt surface layer and asphalt stabilized base layer refers to the ratio of on-site density to indoor standard density

Ring knife tester

Ring knife measurement Compaction Degree

2 Ring Knife Determination of Compaction Degree

, Scope of application: This regulation uses ring knife to measure the density and compaction degree of soil base and pavement materials at highway engineering sites 2. This product is suitable for fine-grained soil and mechanical binder to stabilize the density of fine-grained soil. The age of fine-grained soil stabilized by mechanical binder should exceed 2 days and is suitable for compaction inspection of construction projects. 2. Instruments and Materials This test requires instruments and instruments. Materials and materials: 1. Manual earth extractor: See Figure 4-6, including ring cutter, ring cover, directional cylinder hammer system (guide rod, drop weight, handle). Ring cutter inner diameter 6~8cm, height 2~3 cm, wall thickness 1.5 ~2 mm 2. Electric soil extractor: As shown in Figure 4-7, it consists of a base, a traveling wheel, a column, a gear box, a lifting mechanism, and a coring system (1) Base: it consists of a base platform (16) and a positioning pin (15) , running wheels (14) form the platform to form the instrument support foundation; positioning pins are used for positioning operating instruments; running wheels are used for positioning when changing points and coring instruments at short distances. Four wheels are used to pull up and lift off the table (2). Column: from the column (1) Assemble the base platform with the column cover (11) to serve as the lifting mechanism, coring mechanism, and force transmission mechanism bracket (3) Lifting mechanism: It is composed of a lifting handwheel (9) and a locking handle (8) for adjusting the height of the coring mechanism. The locking handle turns the lifting handwheel to the coring mechanism, that is, tighten the handle to the required lifting position (4). The coring mechanism: consists of the coring (10) and the lifting shaft (2). The coring metal cylinder mouth weighs welding of two alloy steel cutting knives. The welding nut of the end-face welded flat cover is screwed to the lifting shaft. There are three specifications for coring exchange, namely 50mm × 50mm, 70mm × 70mm, and 100mm × 100mm. It is also equipped with corresponding coring sleeves, wrenches, lead boxes, etc. (5) Force transmission Mechanism: It is mainly composed of DC motor (4), speed regulator (12), gearbox group and a battery charger. The motor works through the gearbox gear force and is transmitted to the coring mechanism. The lifting shaft rotates and the coring enters the rotary cutting working state (6 ) Main technical parameters of the electric soil extractor: Working voltage DC24V (36A·h); Speed ??adjustment of 50~70r/min; The whole machine mass is about 35kg Figure 4-7 Electric soil extractor 1- column; 2- lifting shaft; 3 - Power input; 4- DC motor; 5- Lift handle; 6, 7- Power indicator; 8- Locking handle; · 9- Lift handwheel; 10- Coring; 11- Column cover; 12- Speed ??regulator; 13- Battery; 14- Running wheel; 15- Positioning pin; 16- Base platform 3. Flat: 0.1g (for weighing products with a core diameter of 70mm) or 1.0g (for weighing products with a core diameter of 100mm) ) 4. Among them: pickaxe, shovel, soil trimming knife, brush, ruler, wire saw, Vaseline, wooden board and equipment for measuring moisture content, etc. 3. Use the same material for compaction test as in step 1. Press the test to test. Density (ρ dm) and optimal moisture content (w 0) 2. Use a manual soil picker to measure the density of clay soil and fine-grained soil stabilized by mechanical binder. Steps: (1) Clean the ring knife and weigh the ring knife mass M2 accurately to 0. 1g. (2) The area of ??the test point is about 30cm × 30cm. Clean and compact the surface of the shovel and the flat part to a certain depth so that the ring cutter can reach the required depth of soil. (3) The directional barrel tooth nail is fixed on the shovel. Put the ring cutter and ring cover into the directional cylinder perpendicular to the plane (4) Keep the guide rod vertical and use the earth picker to drive the ring cutter into the compacted layer until the top surface of the ring cover is flush with the mouth of the directional cylinder (5) Remove it Use a pickaxe ring knife to test dig the directional cylinder of the hammer (6) Gently remove the ring cover and use a soil trimming knife to trim the remaining soil from the edge to both ends of the ring knife. Use a ruler to check the remaining soil until it is leveled. (7) Wipe the ring knife wall and use a flat scale to remove the remaining soil. The total mass M 1 of the ring cutter and the test is accurate to 0.1g. (8) Take a representative test from the ring cutter to determine its water content (w) 3. Take it manually

Steps for measuring the density of sandy soil or sand layer with soil tools: (1) The wet sand soil test requires the use of a compacting hammer, a directional barrel shovel, and a fine excavation with a diameter slightly larger than the outer diameter of the ring knife. Press the ring knife vertically and steadily until the protruding ring knife end of the sand column is about 2cm away (2) Cut off the remaining sand on the edge of the ring knife and scrape it flat with a ruler (3) Cover the edge of the ring knife with a smooth wooden board, hold the board with one hand and use a shovel to test the ring with the other hand Cut off the bottom of the knife and fill it with the test ring. Turn the knife back to cut the remaining sand on the edge of the ring knife and scrape it flat with a ruler. (4) Wipe the outer wall of the ring. Weigh the total mass of the ring knife and the test ring (M 1) accurate to 0.1g. (5) Self-ring Use a representative test to measure the water content of the tool. (6) Dry sand can be dug into the sand soil column, and the ring knife can be directly pressed or driven into the soil. 4. Use an electric soil tool to determine the density of fine soil and hard plastic soil combined with a machine. Steps: (1 ) Install the required specifications for coring. Before coring at the construction site, select a flat road section, drive the four positioning pins with four running wheels, and use manual pressure to press into the subgrade soil layer. Loosen the locking handle and turn the lifting hand wheel to make the coring just contact with the soil layer. Lock the handle (2) Connect the battery to the speed regulator, connect the speed regulating output end to the power socket of the coring machine, and the indicator light is on to show that the circuit is connected; turn on and off the motor, work with the coring mechanism, adjust the speed according to the moisture content of the soil layer, and operate the lifting handle The core extraction mechanism is stopped and the machine is moved. Due to several spiral protrusions on the surface of the coring cylinder, the soil cuttings are discharged from the cylinder and rotated along the thread. The coring cylinder sleeve is used to cut the soil core column and shake to remove the product (3) To remove the product, press the coring sleeve immediately. Use a soil trimming knife or a wire saw to trim both ends of the soil core to the required specifications. The test items to be carried out are to be put into a lead box and put into the laboratory for later use. (4) Weigh the soil core with a flat sleeve and measure the mass M 1 of the soil core. Determination of moisture content 5. This test must be carried out in two parallel measurements. The parallel difference is 0.03g/cm 3 and the arithmetic mean value is found. 4. Calculate the test humidity and dry density according to formulas (4-11) and (4-12). : (4 — 11) (4 — 12) Formula: ρ w ——test wet density (g/cm 3 ); ρ d ——test dry density (g/cm 3 ); M 1 ——ring knife or coring Total mass of sleeve and test (g); M 2 - mass of ring knife or core sleeve (g); d - diameter of ring knife or core sleeve (cm); h - ring knife or core sleeve Cylinder height (cm); w - Test moisture content (%) Calculate the construction compaction degree according to the formula (4 - 13): (4 - 13) Formula: K - Construction compaction degree of the test point (%): ρ d ——Test dry density (g/cm 3 ); ρ dm ——Test dry density from compaction test (g/cm 3 )