aHR0cDovL2ZyZWVzaGlwLmNvLmty
- ¸ðµ¨ ¹øÈ£: HDL302
- ÃÖ´ë ÃøÁ¤ ¹üÀ§: 400 ¹Ù & À§ÀÇ
- ºê·£µå À̸§: NoEnName_Null
- ±Ù¿ø: CN (Á¤Ç°)
- Model: HDL 302 Porosimeter
- Product name: Porosimeter Sensor
- Measuring medium: soil etc.
- Measuring range: 0-10Mpa
- Output signal: frequency output, etc.
- Shell protection: IP68
- Working temperature: -20~60¡É
- Material: 304 probe ,Core 316 diaphram ,shell 304 , rubber wire
- Certificates: ISO9001 CE RoHs FCC
ì飺product description
Vibrating wire piezometer (as shown in Figure 1), also known as pore water pressure
gauge, is mainly used for long-term automatic monitoring of pore water pressure or
infiltration lines in structures such as slopes, dams, and tailings ponds. Pore water
pressure meter directly outputs frequency signal, which has the characteristics of
strong anti-interference ability, little influence of electrical parameters, little zero
drift, little influence by temperature, stable and reliable performance.
£¨ Pore pressure gauge£©
Product principle
(1) Working principle: The pore water pressure gauge is mainly composed of permeable stones,
pressure-bearing membranes, steel strings, clamping chucks and coils (as shown in Figure 2). A
certain tension is fixed in the sensor. According to the classical string principle, the natural
frequency of a steel string is fixed under the condition of a certain chord length and force. When
the length of the string is constant, the square of the natural frequency of the steel string is only
proportional to the tension of the string. When the external water pressure acts on the
pressure-bearing membrane of the pore water pressure gauge through the permeable stone to
cause slight deformation, the tension of the steel string connected to the pressure-bearing
membrane changes, and its natural frequency also changes. The square of the natural frequency
of the steel string is proportional to the water pressure on the diaphragm. By measuring the
change of the frequency of the steel string, the measured pore water pressure can be known.
£¨
Internal structure diagram of porosimeter£©(2) Principle of data acquisition: The excitation circuit in the vibrating wire acquisition
instrument drives the induction coil of the porosimeter to generate a magnetic field, thereby
triggering the steel string in the porosimeter to vibrate. After the steel string vibrates, it cuts the
magnetic field generated by the induction coil according to a certain frequency, and generates an
induced potential of the same frequency in the induction coil. , The shaping circuit is transmitted
to the single-chip microcomputer, and the single-chip computer analyzes and processes the signal
to obtain the output frequency of the sensor.
Main Specifications
Size
para
mete
rs
Dimensions
(outer
diameter*lengt
h):mm
¥Õ32x110
Measurement
range
Circumferenc
e: Mpa
0
~
0
~
0
~
0
~
0
~
0
~
0
0
0
0
1
2
.
.
.
.
.
.
2
4
6
8
0
0
distinguish
¡Â0.1%
force:
F?S
Perf
orma
nce
para
mete
rs
Temperatur
e
measure
ment
range:
¡É
-20¢¦+70
Temperatur
e
measure
ment
accurac
y:£º ¡É
(-20¡ÆC¢¦-10¡ÆC temperature measurement accuracy is within
2¡ÆC,-10¡ÆC¢¦80¡ÆC temperature measurement accuracy is
within 2¡ÆC within 0.5¡É)
temperature
effect£ºF
?S/¡É
after
fixing¡Â0.04%Water
pressure
resistance£º
MPa
1.2 times full
scale
Insulation
resistance£º
M¥Ø
¡Ã50
installation method
Preparation before installation
(1) Processing of water level pipe/inclinometer pipe
After the water level pipe/inclinometer pipe is installed, use a hacksaw
to cut off the excess part of the water level pipe/inclinometer pipe, so
that the part of the water level pipe/inclinometer pipe above the surface
is unified to 200mm, and at the same time, use a hacksaw to cut a width
at the pipe mouth. 20mm, 40mm depth groove, for the sensor outlet in the
tube.
(2) Confirmation and classification of the wiring length of the
porosimeter
Before the project is implemented, the wiring length of each sensor must be
calculated according to the installation depth of the on-site pore water pressure
gauge, which should be 3m higher than the installation hole depth, and indicated
in the equipment list. The cable length is insufficient and there is a cable
connector. On-site After receiving the goods, classify them according to the
length of the porosimeter cable, determine the position of the corresponding
installation hole, and make corresponding marks.
6 Zhongtian Internet of Things piezometer sensor user manual The content of the
record can be expressed by the depth of the installation hole.
(3) Pore pressure test and initial value determination
After the sensor classification is completed, the initial frequency of each pore
water pressure meter is collected one by one with a portable engineering signal
analyzer, and 5 sets of data are collected for each pore water pressure meter.
The initial frequency value of the company's self-developed pore water pressure
meter should normally be between 1550 and 1650 Hz, and the amplitude should be
greater than 0.8mv (the initial frequency of the company's purchased pore waterpressure meter should refer to the delivery parameter table), and the output
of each pore water pressure meter should be The fluctuation of the 5 groups of
data does not exceed 2Hz.
The average value of the 5 sets of data output by the porosimeter is
calculated as the initial reading of the porosimeter and recorded.
Note: The initial reading of the porosimeter needs to be taken before
installation.
(4) Pore pressure meter saturation treatment
Before installation of the pore water pressure gauge, the air in the cavity in front
of the permeable stone and the pressure-bearing membrane should be excluded,
otherwise serious lag or measurement error or even unstable reading will occur after
installation, so exhausting is necessary, and the exhausting operation should be
at least 2h before installation. After the porosimeter is tested and the initial
value is determined, it should be soaked in water. In order to speed up the soaking
process, the permeable stone can be removed, then the pore water pressure gauge can
be completely immersed in a container filled with clean water, and the permeable
stone can be slowly re-installed on the pore water pressure gauge under water. Put
a layer of geotextile on the outside of the gauge, and the pore water pressure gauge
should always be soaked in water before installation.
Note: When implementing steps (2) and (3), the porosimeter should be
transported to the site one day before installation, complete steps (2)
and (3) on the same day, and then store the instrument in the on-site
duty room or Hidden place to avoid the impact of vibration and collision
on the initial value of the instrument during transportation on the day
of installation.
Independent installation (only pore water pressure gauge is
installed in the pipe)
(1) According to the installation depth of the pore water pressure gauge,
determine the actual length of the cable that should be laid down for the pore
water pressure gauge. Mark the length position so that the pore water pressure
gauge can be accurately lowered to the design point when it is installed in the
piezometer;
(2) Determine the wire rope for hoisting the pore water pressure gauge according
to the length of the lowering cable determined by the pore water pressure gauge
(3) During installation, close the ¦3mm stainless steel wire rope to the pore
water pressure gauge, wrap it with geotextile, and use 4¡¿280mm cable ties on
the outside. 1 30mm lashing, a total of 3 lashings. When binding, the orientation
of the self-locking buckle of the cable tie should be the same, so as to avoid
increasing the installation diameter of the pore water pressure gauge (as shown
in the figure below)(4) Bind the porosimeter transmission cable along the steel wire rope with 2.5¡¿200mm cable
ties at intervals of about 1 meter;
(5) Then hold the wire rope by hand and slowly put the porosimeter into the water level pipe
until the porosimeter is placed in the designated position (the porosimeter cable mark is at the
nozzle position). Stop lowering, pass the wire rope through the center hole of the nozzle fixing
plate and reserve a length of about 100mm, fold it in half at the midpoint, and fasten and fold the
wire rope buckle to fix the wire rope on the nozzle fixing plate, then Lead the porosimeter cable
through the groove of the nozzle (as shown in the figure below).
(6) Record the installation information of the pore water pressure gauge, such as the instrument
number, the date of burial, the initial reading, etc., and fill it in the "Embedding Verification
Form"Remarks: If the pore water pressure gauge is installed in the subway water level well, there is no
need to install the water level pipe, and proceed directly to the installation steps in 4.3.
Mixed installation (installed with tandem idler type fixed inclinometer)
In order to reduce the cost of system construction, the pore water pressure gauge is
generally installed in a monitoring hole together with the guide wheel type fixed
inclinometer. The installation steps are as follows:
(1) Determine the installation distance between each sensor and the distance between the
top inclinometer and the nozzle according to the mixed installation drawing of the pore
water pressure gauge and the inclinometer;
(2) Cut out the wire rope according to the installation distance of each sensor determined in
the previous step. The length of the wire rope should be 200mm longer than the distance
between each sensor, so that 100mm is left at each end of the wire rope for folding in half,
which is used to connect each sensor and the uppermost inclinometer. According to the
nozzle section is connected and fixed by ¦6mm stainless steel screw rod;
(3) On an open field, place the pore water pressure gauge and the inclinometer along the
straight line according to the sensor spacing indicated in the mixed installation drawings of
the pore water pressure gauge and the inclinometer (when the inclinometer is placed, the
placement sequence is the same as the other one. The length of the factory wiring is related,
and the inclinometer with the corresponding line length should be selected according to the
wiring length requirements of each inclinometer installation point on the design drawing,
and the transmission cables of each sensor should be laid along the sensor placement
direction;(4) According to the installation distance between the sensors of each monitoring hole,
select the steel wire rope of the corresponding length, and place it between the sensors laid
on the open field in turn.
(5) Fold the wire rope in half at a length of about 100mm at both ends of the wire rope, and
fasten it with wire rope buckles after passing through the sensor rings or slings on both sides,
and use 2 wire rope buckles to fix each folded position (as shown in the figure below);
(6) After the sensors are connected by wire ropes, tie each sensor cable to the wire rope with a
2.5¡¿200mm cable tie every 1 meter or so along the wire rope from bottom to top (the lower
part is the position of the pore water pressure gauge). After completion, hold the wire rope by
hand, and slowly put each sensor into the monitoring hole inclinometer pipe (at this time, please
pay attention to the XY direction of the inclinometer should be consistent with the required
direction, please refer to the guide wheel type fixed inclinometer installation instructions) ;
(7) When the last inclinometer (the uppermost inclinometer) is to be put in, screw the ¦6mm
stainless steel lead screw to the internal thread interface on the top of the inclinometer, and then
pass the lead screw through the center hole of the nozzle fixing plate And reserve a length of
100mm, and then insert M6mm nut on the screw rod to fix the sensor on the nozzle fixing plate.
The length of the screw rod is about 100mm, and each sensor cable is led out from the nozzle
groove. The schematic diagram of the overall installation of the sensor is shown in Figure 6.
(8) Record the installation information of the porosimeter, such as the instrument number, date
of burial, initial reading, etc., and fill it in the "Embedding Verification Form".Connection cable, cable sequence and wiring method
connecting cables
The porosimeter usually uses a two-core shielded cable, and if it is equipped with a
temperature sensor, a four-core shielded cable is used.
cable sequence
Red line black line???????measure frequency cable
Green Line????????Temperature+ (If it is not equipped with a temperature
sensor, it will be left open)
White line????????
temperature? (without a temperature sensor, leave it
in the air)
Wiring method
The cables should be connected as shown in the figure below. For the wiring process,
see "Cable Wiring Process on the Project Site".£¨
Pore pressure meter wiring method£©
Instrument connection
Connects to a portable single-channel vibrating wire acquisition instrument
(1) Supporting facilities: wire stripper
(2) Description: The connection between the pore water pressure gauge and the
portable engineering signal analyzer is mainly used for the initial value acquisition
before the instrument is installed and the detection after the installation. The
connection method is as follows;
Connection with multi-channel vibrating wire acquisition instrument
(1) Supporting facilities: wire strippers, insulating tape, rubber self-adhesive tape;
(2) Description: The connection method between the pore water pressure gauge and
the multi-channel vibrating wire acquisition instrument is mainly used for long-term
automatic monitoring of the instrument. The connection method is shown in the
figure below. Engineers and technicians can use the computer to collect pore water
pressure meter data through the RS485 interface of the multi-channel vibrating wire
collector.How to judge the normal installation of the instrument
(1) Installation value: use a portable single-channel vibrating wire collector to collect
the initial frequency of the porosimeter before installation, and its value must be
between 1550 and 1650 Hz. After installation, test 10 sets of data on the sensor
continuously, and the frequency value should Stable, the fluctuation is within 0~2Hz,
and the frequency value should be less than the initial frequency value of the sensor
before installation and greater than 1000Hz (according to the statistics of the quality
department, the frequency value of the new version of the porosimeter is close to
but not less than 1000Hz under the full scale). The amplitude needs to be greater
than 0.8mv. Using the pore water pressure meter physical quantity calculation
formula
, it can be concluded that the water level in the hole
measured by the sensor should not be greater than the hole depth;
(2) Location: Comparing with the design scheme and system layout diagram, the
sensor layout position must be consistent with the design scheme and related
materials submitted to the customer;
Installation measuring point number
(1) A single structure
Reference format: SY-W
in:
SY------- is the acronym for osmotic pressure;
W------- is the number of on-site monitoring holes;
(2) Multiple structures
Reference format: SYN-W
Among them: SY------- is the acronym for osmotic pressure;
N------- is the number of the on-site structure;
W------- is the number of on-site monitoring holes;
Reference format: XXXSY-Win:
XXX------- is the acronym of the structure name;
SY------- is the acronym for osmotic pressure;
W------- is the number of on-site monitoring holes;
data calculation
Calculation formula of pore water pressure gauge variable:
£¨
Calculation formula with temperature measurement function£©
£¨
Calculation formula without temperature measurement function£©
formula:
p??the pressure at the current moment relative to the initial moment, MPa;
k is the calibration coefficient of the pore water pressure gauge,
MPa/(Hz);
f2??the output frequency modulus of the pore water pressure gauge at the current moment,
Hz2; f2??the output frequency modulus of the porosimeter at the initial moment,
Hz2; KT?temperature correction coefficient of pore water pressure gauge, MPa/C;
Ti??the temperature value of the porosimeter at the current moment, C;
To??the initial moment temperature value of the porosimeter, C.