Static force touching equipment, commonly known as static force touching instrument, generally consists of three parts, namely:
(1) static force touching probe: ground resistance sensing;
(2) measurement and recording instrument: measurement and recording of all kinds of resistance to the probe;
(3) penetration system: including touching the main body and the counterforce device,**** the same is responsible for the probe pressed into the soil.
Touching the main body with the help of the probe rod will be mounted on the bottom end of the probe pressed into the soil; counterforce device to provide the main body in the process of penetrating the probe in the required counterforce.
At present, the widely used static touching vehicle combines the above three parts into a whole. Static touch probing car with penetration depth (penetration force is generally greater than 10t), high efficiency and low labor intensity advantages. But it is only suitable for convenient transportation, flat terrain and can drive into the car survey site use. Penetration force equal to 5t or less than 5t, generally for light static touch instrument. When using, generally will be the above three parts of the separate shipment to the survey site, the test and then the three parts of the organic connection. In inconvenient transportation, survey depth is not large or soft soil layer area, lightweight static touch probe is widely used. It has the advantages of easy transportation, low testing cost and flexibility. Static touch probe penetration force is generally 2 ~ 20t, the maximum penetration force of 20t, because the slender probe force limit can not be too large, too easy to bend or break. Penetration force of 2 ~ 3t, generally hand-cranked chain type electric cross plate - touch probe dual-purpose instrument. Penetration force greater than 5t, generally hydraulic host. Now introduces several major and commonly used touch probing instrument.
One, some commonly used static touch probing instrument
1. Lightweight touch probing machine
2Y-5A touch probing machine (Figure 3-11), rated penetration force: 50kN; pulling up force: 80kN; 80kN penetration speed: 1.2m/min host quality: 350kg; pulling up speed: 2.5/min power match: 5.5kw Motor or 180 diesel engine.
Figure 3-11 2Y-5A light touch probe machine
2. static touch probe - cross plate shear dual-purpose machine
CLD-1 type touch probe machine (Figure 3-12), penetration force: 2t; penetration speed: 0.8 ~ 1.2m/min, the host quality: 200kg. CLD-3 type touch probe machine, penetration force: 3t; penetration speed: 0.8 ~ 1.2m/min; host quality: 200kg. ~ 1.2m/min, host quality: 210kg.
3. Static touch engineering vehicle
At present, China's production of static touch engineering vehicle manufacturers, mainly in Ningbo, Zhejiang Province, 215 Machinery Factory, Jiangsu Province, Rugao Survey Machinery Factory, Dalian Tensile Machinery Factory, Shenyang Prospecting Machinery Factory and Shanghai Geological Instrumentation Factory. Each factory production of touch probe engineering car penetration capacity has reached 20t, have closed carriages, can not be affected by climatic conditions in the field operation. Touching the structure of the car form: bus type, pontoon type; balance form: hydraulic legs manual leveling; external dimensions: 9.8m × 2.5m × 2.8m; anchor form: hydraulic anchor automatic anchor; power matching: automotive power; vehicle quality: 8500kg.
Figure 3-12 CLD3-type touching machine
Figure 3-13 static touching engineering vehicles
Two, probing engineering car
The CLD3-type touching machine
Figure 3-13 static touching engineering vehicles
Touching engineering vehicles
Touching engineering vehicles
Second, the probe
(See Section II, Part II)
Third, measurement and recording instrumentation
China's static touch engineering is almost entirely used in resistance strain sensors. Therefore, with its supporting recording instruments are mainly the following four types: ① resistance strain gauge; ② automatic recording plotter; ③ digital force gauge; ④ data acquisition instrument (microcomputer).
1. Resistance Strain Gauge
From the 1960s until the mid-1970s, resistance strain gauges have been used. Resistance strain gauge has the advantages of high sensitivity, large measuring range, high precision and good stability. However, its operation relies on manually adjusting the balance and tracking the readings, which is prone to errors. And can not be read continuously, can only be carried out at intervals (generally 5 ~ 10 s, i.e., every penetration 10 ~ 20cm read once), can not get a continuous change of the touch probe curve. After improvement, the emergence of a digital force gauge, such as Shanghai Xinwei machine factory production of digital force gauge and Xinda telecommunication factory production of JC-X2 static touch probe measuring instrument.
2. Automatic recording plotter
In order to realize automatic recording, there is an automatic recording instrument. Our current production of static touch automatic recorder are modified with electronic potential difference meter. These electronic potential difference meter are only one range range. In order to be able to measure the rated resistance value of the probe in the resistance layer, but also in order to ensure the accuracy of measurement in the soft layer, are generally used to change the supply bridge voltage to realize the method.
Early instruments for the optional fixed bridge voltage method, generally divided into 4 to 5 gears, the bridge voltage were 2, 4, 6, 8, 10V, according to the softness and hardness of the stratum can be selected. The advantage of this method is that the voltage is stable and reliable; however, the data collation workload is large. Now there are automatic recorders that can make the bridge voltage continuously adjustable.
Figure 3-14 ZSJ-2-type dual-pen automatic recorder working principle
(1) automatic recorder working principle: Figure 3-14 shows ZSJ-2-type dual-pen automatic recorder working principle, the measured DC signal sent by the sensor, the measurement circuit and the instrumentation within the compensating voltage is compared to produce an unbalanced voltage, amplified by 105 ~ 6 times to obtain a large enough power to drive the amplifier. After the amplifier amplifier 105 ~ 6 times to obtain a large enough power to drive the reversible motor rotation. Reversible motor through a set of mechanical transmission device, one side of the sliding wire resistance in the measurement circuit to drive the rolling contacts, so that the compensation voltage and the measured signal balance; one side of the pointer and the recording pen along the graduated scale left and right to move. At this time there is no signal input and output in the amplifier, the motor stops rotating, and the indicated value of the pointer on the index scale is the voltage value of the measured signal. If the measured signal changes, the newly generated potential difference value signal is sent to the amplifier, so that the rolling contacts of the slide wire resistor and move to a new balance point, the measured signal and the compensation voltage and reach a new balance, the pointer moves to a new position ....... At the same time, the self-rectifying machine through a set of transmission mechanism, with a certain speed scrolling recording paper. In this way, as the pointer moves and the recording paper scrolling, the recording pen will be recorded on the recording paper continuously recorded the size of the measured signal at each depth, this is the static touch probe curve.
(2) the main components of the instrument: in addition to the paper mechanism, double pen recorder parts are composed of two (double) sets: it includes ① measurement circuit; and strain gauge, is also the use of double bridge circuit, the difference is that the automatic recorder is used in the DC bridge, the transmission of DC signals; in order to provide a stable DC voltage to the external bridge circuit, the automatic recorder is specifically set up to stabilize the bridge power supply: Voltage regulator range is generally 0 ~ 20V, continuously adjustable to adapt to the calibration probe and penetrate into different hard and soft ground layer needs; ② transistor amplifier: in the recorder, the amplifier's role is to measure the circuit to send the DC signal ΔU amplified into a sufficient to drive the reversible motor rotation of the AC signal, and when the DC signal ΔU change in polarity, the phase of the output AC signal also changed, so that it can drive reversible Motor positive and negative rotation, so that the measurement system to achieve automatic balance; ③ reversible motor; ④ instrument paper mechanism: static touchdown automatic recorder in addition to the measured signal display, but also the signal with the depth of the change must be recorded on the paper tape, in order to accurately and promptly record the resistance value of the stratum at various locations. For this reason, the recorder replaces the synchronous motor in the original potentiometer paper walking system with a pair of self-rectifying angle machines. At the same time, the sending angle machine and the friction wheel are connected together through a gear set and mounted on the chassis of the touch probe host, so that the friction wheel is close to the touch probe rod. When the touch probe rod downward pressure, the friction wheel will rotate with. The rotor of the transmitter is driven to rotate. Receiver is fixed in the instrument, and the paper walking mechanism is connected to the gear set. When the transmitter rotates it also follows the rotation, driving the recording paper to move in the ratio of 1:100 (or other), so that the probing depth is recorded.
3. Digital force gauge
Digital force gauge is a precision test instrument. This instrument can display a number of digits, with a small size, light weight, high precision, stable and reliable, easy to use, can be read directly into the total resistance and calculate the penetration index is simple, etc., is a lightweight chain cross plate - static touching of the dual-use machine supporting the measurement of the instrument, there are many manufacturers have been produced in the country. The disadvantage of this instrument is interval reading, manual record.
Digital force gauge and the past use of strain gauge comparison, its advantages are: small size, light weight, without manual tracking, and digital display is not easy to see the error, but also rate coefficients can be entered into the instrument to directly read the resistance value. Designed by the Wuhan Municipal Survey Institute, Wuhan radio factory production of digital force gauge that has the above features.
In addition, the automatic recorder and strain gauge compared to the sensitivity of the strain gauge, it is small range. However, the automatic recorder has a depth control device, can continuously and automatically record the penetration resistance curve of the soil layer, thus improving the efficiency and quality of field work, and thus is currently the most widely used.
4. Data acquisition instrument (microcomputer) in the application of static probe
The above introduction of the measurement and recording instruments are not perfect, some can only be manually spaced readings, can not draw; some can only draw, but can not display print data. These instruments can still meet the needs of general production, but the information is organized in a large workload, low efficiency. Therefore, the use of microcomputer data acquisition and processing, has been widely used in static touch testing.
Four, penetration system
Static sounding penetration system by touching the main body (penetration device) and counterforce device composed of two major parts.
Touching the role of the host is the bottom of the probe equipped with a probe one by one into the soil. Touching the host according to its penetration mode, can be divided into intermittent penetration type and continuous penetration type; according to its transmission mode, can be divided into mechanical and hydraulic; according to its assembly mode can be divided into car mounted, drag bucket type and floor type, etc..
The role of the counterforce device is to balance the penetration resistance to the counteraction of the penetration device. From the equipment point of view, the size of the static contact penetration depth depends mainly on three factors: ① the size of the penetration equipment capacity; ② the size of the contact probe cross-section and its cooperation with the probe rod; ③ the size of the reaction force. Counterforce is not enough, the ability of the whole penetration equipment will not give full play to, visible counterforce device is very important. Counterforce acquisition, generally under the ground anchor and the use of the car's own weight two kinds. Now the touchdown car are comprehensive utilization of these two methods, the effect is good.
The screwing anchor machine has hydraulic, electric, hand-cranked three types.
Five, probe rod
Probe rod has certain specifications and requirements. Probe rod should have sufficient strength, should use high-strength seamless pipe, its yield strength should not be less than 600MPa.
Probe rods and connectors should have good interchangeability. With conical thread connection probe, connection shall not have shaking phenomenon; with cylindrical thread connection probe, between the buckle, all should be able to screw tightly affixed.
Probe rod should be straight, no cracks and damage. The length of each rod is generally 1m, its diameter should be the same as the diameter of the probe; but single probe rod diameter should be smaller than the diameter of the probe.
Six, cable
The role of the cable is to connect the probe and measurement recording instrument. Because the probe function is different, the corresponding cable core number is also different, the least with a single bridge probe four-core cable, more than dozens of cores, the core should be shielded from each other, the field out of the signal can not interfere with each other. Wire should be good waterproof and insulation, joints should be sealed. Its diameter should be smaller than the inner diameter of the probe rod, so that it can be smoothly through the probe rod, connecting the probe and the instrument.