CN203132748U - Soil internal stress change monitoring system in loess place immersing condition - Google Patents

Soil internal stress change monitoring system in loess place immersing condition Download PDF

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Publication number
CN203132748U
CN203132748U CN 201320124525 CN201320124525U CN203132748U CN 203132748 U CN203132748 U CN 203132748U CN 201320124525 CN201320124525 CN 201320124525 CN 201320124525 U CN201320124525 U CN 201320124525U CN 203132748 U CN203132748 U CN 203132748U
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soil
soil pressure
data
pressure sensor
host computer
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王家鼎
马闫
彭淑君
李家栋
谢婉丽
谷天峰
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Northwest University
Northwestern University
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Northwest University
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Abstract

The utility model discloses a soil internal stress change monitoring system in a loess place immersing condition, which comprises a power supply, a host computer, a plurality of soil pressure sensors and at least one data collector. The output ends of the soil pressure sensors are respectively connected with the input end of the data collector. The data collector is connected with the host computer. The power supply is connected with the soil pressure sensors, the data collector and the host computer. The sensors are used for acquiring the internal soil pressure data of soil in the loess place immersing condition. The acquired data are sent to the data collector. The data collector sends the data to the host computer. Then the host computer processes the received data. The monitoring system can monitor the soil internal stress development condition in a rapid, continuous and accurate way when the near-surface of a loess place is immersed and provide feedback on the loess place soil internal stress state. The monitoring system further provides reliable parameters for saturated yielding sensitivity evaluation and lateral deformation influence evaluation.

Description

Inside soil body STRESS VARIATION monitoring system under the loess place immersion condition
Technical field
The utility model belongs to the engineering monitoring technical field, is specifically related to a kind of inside soil body stress monitoring system, particularly inside soil body stress monitoring system under a kind of loess place immersion condition.The utility model be used for loess body internal stress intensity and stress distribution under the face of land large tracts of land immersion condition rapidly, continuously, accurately monitoring.
Background technology
Loess is because its special formation epoch and form environment, caused it to have open grain and then caused it to have strong water sensitivity, and the most outstanding form of expression of loess water sensitivity is exactly saturated yielding.Sustained and rapid development and policy inclination along with national economy, construction speed and the scale of China central and west regions day by day strengthen, cause each big city land used day of loess area to be becoming tight, infant industry and covil construction present gradually and turn to high terrace developing state by low terrace, and prospecting, evaluation and the handling problem of the big thickness self-weight collapse loess of thing followed ground becomes the primary difficult problem that loess area engineering technical personnel face.Getting appraisement system for the collapsibility of loess place among " Code for building construction in collapsible loess zone " (GB 50025-2004) is to be guiding with the settling amount, emphasize net result rather than take much count of process, this appraisement system has instructed a large amount of construction in considerable time, achieve noticeable achievement.But we must recognize that along with the increasing of engineering construction scale, the important engineering of " long, big, height " is more and more, and a lot of engineering accidents show the saturated yielding susceptibility of loess and the safety that final saturated yielding amount is determining engineering equally.In addition, the inventor is also noted that: it is not that the simple soil body vertically compresses that saturated yielding causes the process of land subsidence, but vertically compression and side direction are extruded and be accompanied this point that the investigation of some engineering accidents is verified.Because different regions soil property difference, so extruded and to be reflected in the ground settlement value also different by side direction.Therefore, the data of inside soil body stress intensity and stress distribution in estimating the immersion process that need obtain when loess saturated yielding susceptibility and lateral deformation influence at water, and still do not obtain at present the system, science of these class data, device efficiently, research and development to this device is very necessary, and the various Important Project ground treatment constructions in loess area are of great immediate significance.
Summary of the invention
Blank and not enough at what exist in the prior art, the purpose of this utility model is, inside soil body stress monitoring system under a kind of loess place immersion condition is provided, this system realizes that by power supply, collector and host computer full-automatic data obtain, can monitor loess body internal stress intensity and stress distribution under the face of land large tracts of land immersion condition rapidly, continuously, exactly, provide parameter accurately and reliably thereby estimate for loess saturated yielding susceptibility and lateral deformation influence.
In order to achieve the above object, the utility model adopts following technical scheme to be solved:
Inside soil body stress monitoring system under a kind of loess place immersion condition comprises power supply, host computer, a plurality of soil pressure sensor and at least one data acquisition unit; Wherein, the output terminal of each described soil pressure sensor connects the input end of data acquisition unit respectively, and the output terminal of data acquisition unit connects host computer respectively, and it is its power supply that described power supply connects soil pressure sensor, data acquisition unit and host computer;
By the soil pressure data that described a plurality of soil pressure sensors are gathered inside soil body under the loess place immersion condition in real time, the data that collect send to data acquisition unit, and data acquisition unit sends it to host computer, by host computer the data that receive are handled.
System of the present utility model also comprises following other technologies feature:
Described soil pressure sensor comprises box body, resistance strain gage, terminal block and the top cover of stainless steel, the zinc coat of box bottom is as stressed film, fixing by the bridge circuit of being formed by resistance strain gage and terminal block in the box body, the bridge circuit that resistance strain gage is formed is close to the box body inner bottom surface, and described terminal block is positioned at the top of the bridge circuit of resistance strain gage composition; The bridge circuit that resistance strain gage is formed is drawn box body by terminal block by signal wire, and top cover is installed at the box body top.
Compared with prior art, the beneficial effects of the utility model are:
(1) monitoring system of the present utility model with horizontal vertical two to soil pressure included the monitoring content in, stress intensity and the stress distribution of comprehensive inside soil body, remedied and do not considered in the prior art that lateral deformation causes the place settlement by soaking is estimated inaccurate and lacked the defective that data can't be estimated saturated yielding susceptibility, be conducive to safety Design.
(2) adopt a plurality of high precision soil pressure monitoring elements, picking rate is fast and full-automatic, sample rate reaches per second 1 time, feed back the Changing Pattern of inside soil body stress intensity and stress distribution under the Riddled Condition serially, and can gather density to data and precision carry out dynamically adjusting in good time according to the soil layer pressure changing, estimating for saturated yielding sensitivity assessment and lateral deformation influence provides reliable parameter.
(3) system architecture of the present utility model is simple, and is simple to operate, installation, easy to use.
Description of drawings
Fig. 1 is the connection block diagram of monitoring system of the present utility model.
Fig. 2 is the structural representation of soil pressure sensor.
Fig. 3 is U-iron bar synoptic diagram.
Fig. 4 is pre-manufactured steel mould synoptic diagram.
Fig. 5 is the laying synoptic diagram of sensor.
Fig. 6 is demarcation and the fitted calibration curve of a soil pressure sensor.
Fig. 7 is vertical soil pressure tense curve.
Fig. 8 is lateral earth pressure tense curve.
Number in the figure: 1, stressed film, 2, resistance strain gage, 3, terminal block, 4, signal wire, 5, top cover, 6, box body.
Below in conjunction with drawings and Examples the utility model is further explained explanation.
Embodiment
As shown in Figure 1, inside soil body stress monitoring system under the loess of the present utility model place immersion condition comprises power supply, host computer, a plurality of soil pressure sensor and at least one data acquisition unit; Wherein, the output terminal of each described soil pressure sensor connects the input end of data acquisition unit respectively, and the output terminal of data acquisition unit connects host computer respectively, and it is its power supply that described power supply connects soil pressure sensor, data acquisition unit and host computer.
As shown in Figure 2, described soil pressure sensor comprises box body 6, resistance strain gage 2, terminal block 3 and the top cover 5 of stainless steel, the zinc coat of box body 6 bottom surfaces is as stressed film 1, fixing by the bridge circuit of being formed by resistance strain gage 2 and terminal block 3 in the box body 6, the bridge circuit that resistance strain gage 2 is formed is close to box body 6 inner bottom surfaces, and described terminal block 3 is positioned at the top of the bridge circuit of resistance strain gage 2 compositions.The bridge circuit that resistance strain gage 2 is formed is drawn box body 6 by terminal block 3 by signal wire 4, the outlet epoxy sealing, and top cover 5 is installed with sealing, box body 6 whole tool water resistancees in box body 6 tops.
Described data acquisition unit is used for the output signal of collection soil pressure sensor rapidly, continuously and is uploaded to host computer handling and storing.
As shown in Figure 5, described a plurality of sensor is installed in apart from the bottom in immersion district, loess place respectively and estimates inside soil body in the extent of flooding.The soil pressure sensor mounting means has level and vertical two kinds, respectively in order to monitor the development of horizontal and vertical soil pressure in the immersion process.
The method of utilizing the monitoring system of inside soil body stress under the loess of the present utility model place immersion condition to monitor specifically comprises the steps:
1, the assembling of monitoring system
Monitoring system comprises the welding of soil pressure sensor, the assembling of power module, the installation of host computer, the connection of signal wire and the matching and debugging of soil pressure sensor and data acquisition unit by artificial assembling.
2, the demarcation of sensor
Each soil pressure sensor is demarcated, obtained all soil pressure sensor calibration curves.
3, sensor buries underground
Referring to Fig. 5, first, in zone excavation immersion hole to be monitored.The diameter in immersion hole will be with reference to the lower limit depth H (being the self-collapsibility soil thickness) of local self-weight collapse loess distribution, and the diameter D in immersion hole is more than or equal to this lower limit depth H (soil test of H from sitework geologic prospect report partly obtains); In addition, the degree of depth in immersion hole is not more than 0.8m, is advisable with 0.5m, and needs the thick sandy gravel (with reference to " Code for building construction in collapsible loess zone " (GB 50025-2004)) at the end, hole laying 0.1m.
The second, the ground excavation was buried well underground outside ground and immersion were cheated in the immersion hole.Bury quantity, position and the degree of depth of well underground and should follow following rule:
In order to satisfy monitoring requirements, to bury well quantity underground and should not be less than 4, the work funds of considering are buried well quantity underground and should not be advisable with 6 more than 8.
Result of study according to this area, bury well location underground and put and to arrange according to loess body immersion characteristic, (with reference to " the on-the-spot immersion of big western Line for Passenger Transportation and middle and south heavy haul railway passage collapsible loess pit retting water test research report ", " the on-the-spot immersion of the lucky new-energy automobile of Yuci District Hao family ditch plant area collapsible loess pit retting water test research report " and " the big thickness self-weight collapse loess place submerging test INTEGRATED SIGHT research in area, Lanzhou ").Suppose that immersion hole radius is R, then set out by the center of circle, immersion hole, 1) (namely in the immersion hole) is the important area of vertical soil pressure intensity and changes in distribution in the R scope, should in this scope, excavate 1~2 and bury well underground, if one of excavation is buried well underground and then should be opened on the 1/2R position, if burying well underground, then should open respectively in two parts immersion hole that separates with 1/2R two of excavations; 2) be positioned in R~2R scope beyond the flood zone be underground moisture to external diffusion must be through the zone, also be because the interior vertically soil pressure in the hole of soaking increases the seepage force that causes soil body side direction to extrude and produce side direction owing to moisture to side direction seepage flow, and then cause the critical area that soil lateral pressure intensity and distribution change, should in this scope, excavate 3~4 and bury well underground, at first at R+1 rice and two of 2R place excavations bury well underground, if 3 of excavations are buried well underground then one of 1.5R place increase, if burying well underground, 4 of excavations then should bury well underground in R+1/3R, two of R+2/3R place increases; 3) be the Far Range of moisture sideways diffusion in 2R~2.5R scope, it is relative faint that this regional soil pressure intensity and distribution are influenced by immersion, should bury well underground at 1 of excavation in 2.5R ± 3 meter; If immersion hole radius R>30m then rises to 2 and buries well underground, should excavate the 1st midpoint of burying well and 2R underground in this scope.
Burying the well cutting depth underground is advisable with the lower limit depth H that self-weight collapse loess distributes.
Three, in burying well underground, each buries soil pressure sensor underground.It is buried form underground, buries density underground and bury quantity underground and should follow following rule:
Soil pressure sensor is buried form underground and is divided into and horizontally embedded and vertically buries two kinds underground, is respectively applied to test vertical soil pressure and lateral earth pressure.Be that the starting point different distance is that the emphasis that the scope of radius is paid close attention to is distinguished to some extent with immersion center, hole as mentioned before, therefore, the center of circle, hole that is arranged on to soak is that burying underground in the R scope of starting point only buried the soil pressure sensor of measuring vertical soil pressure underground in the well; The borehole measurement horizontal stroke, vertical two of burying underground in R~2R scope is buried underground to the sensors cooperation of soil pressure; The sensor of measuring vertical soil pressure is only buried in burying underground of 2R~2.5R scope underground in the well.
Soil pressure sensor from the close-by examples to those far off reduces to cheat the center of circle apart from immersion gradually in each density of burying underground in the well (also namely burying number underground) of burying underground.Specifically arrange as follows: from the center of circle, immersion hole, the interior average 2~3m of well that buries underground that arranges in the R scope buries a soil pressure sensor of measuring vertical soil pressure underground; Average 2~the 3m that buries underground in the well at R+1 rice buries one group of sensor (measure respectively horizontal, vertically soil pressure) underground, bury that average 4~6m buries one group of sensor underground in the well underground in R+1 rice~2R scope, average 10~the 12m in the well of burying underground at 2R place buries 1 sensor of measuring vertical soil pressure underground, pays close attention to middle part and bottom soil layer; The well of burying underground that is arranged in 2.5R ± 3m is buried 1 sensor of measuring vertical soil pressure underground near self-collapsibility soil layer lower limit depth H.
Because soil pressure sensor has different ranges, the more little precision of range is more high, but surpass range and can damage sensor, so before soil pressure sensor is buried underground, utilize inspection of the scene of a crime data to calculate the maximum soil pressure value of each sensor burial place, to choose the soil pressure sensor of suitable range.Begin sensor then and bury the work of well excavation underground, mechanical Luoyang Spade excavation should be used in the area that makes things convenient for machinery to march into the arena, otherwise pleasant worker excavates into well.It is vertical that the borehole wall of well is buried in requirement underground, and bury the well diameter underground greater than 0.6m, to make things convenient for about the staff.
When burying the soil pressure sensor of measuring vertical soil pressure underground, at first needing to bury underground on the relevant position of soil pressure sensor respectively level at the borehole wall sets out identical with soil pressure sensor width, thickness, the degree of depth is slightly larger than the rectangular parallelepiped soil box of soil pressure sensor diameter (in the utility model, soil pressure sensor is oblate column), soil pressure sensor is put into this soil box, guarantee the stress surface level of soil pressure sensor bottom and up, with soil that the dead zone training is real, only expose data line.
When burying the sensor of measuring lateral earth pressure underground, at first on the borehole wall needs to bury underground the relevant position of soil pressure sensor, vertically set out identical with soil pressure sensor width, thickness, the degree of depth is slightly larger than the rectangular parallelepiped soil box of soil pressure sensor diameter, the thickness direction of soil box points to the center of circle, immersion hole, then soil pressure sensor is put into soil box, the stress surface that guarantees the soil pressure sensor bottom is vertical direction and towards the center of circle, immersion hole; With soil that the dead zone training is real again, only expose data line.
Because the same well domestic demand of burying underground is buried a plurality of soil pressure sensors underground at the different depth place, the signal of each sensor all needs to be transferred to data acquisition unit with data line, so have a large amount of numerous and disorderly data lines in the well, it should be concentrated to have pricked and fix.
After all soil pressure sensors are buried underground and finished, need to bury all underground well backfill and compacting.
4, data acquisition
The collecting work of data is divided into three phases:
First stage: before the monitoring beginning, need to check that whole circuit has or not short circuit, breaking phenomena, guarantee errorless back power-on.
Second stage, i.e. before monitoring beginning back, immersion hole began immersion, log-on data collector, data acquisition unit recorded the initial value of each soil pressure sensor and send to host computer;
At three phases, after the i.e. immersion beginning, the reading of each soil pressure sensor changes along with the variation of soil pressure, soil pressure sensor is gathered the soil pressure data in real time and is sent signal to data acquisition unit in real time, data acquisition unit is with certain frequency collection and tracer signal, and in real time the signal that collects being sent to host computer, the frequency acquisition in the observation process and data sum are decided by demand.Generally speaking, the frequency of data acquisition along with the immersion process from high to low, when a certain data acquisition unit with near the rreturn value of soil pressure sensor when all certain numerical value, fluctuating, show stable, can suitably reduce frequency acquisition this moment, frequency acquisition is the highest to be no more than 30min/ time, minimum being not less than 2h/ time.
5, data are handled
The signal that host computer sends by data acquisition unit obtains the initial value of soil pressure sensor, also the soil layer primary stress of each monitoring point before the i.e. monitoring beginning.The output signal of soil pressure sensor and pressure are the better linearity relation, for improving monitoring accuracy, calibration curve is carried out match again obtain fitted calibration curve and corresponding fitting formula.Obtain calibration coefficient A, the B of each soil pressure sensor by fitting formula, wherein A be matched curve in the intercept of soil pressure mechanical axis, B is the slope of matched curve.
Calculate soil pressure σ by formula 1:
σ=A+X*B (formula 1)
In the formula, σ-total stress; X-output microstrain value; A, B-calibration coefficient.
With a certain moment t 1The output microstrain value X substitution formula 1 of certain soil pressure sensor of gathering obtains monitoring point that this soil pressure sensor buries underground the soil pressure σ in this moment 1, the output microstrain value X to the soil pressure sensor of each collection handles in the same way, can obtain n group data: (σ 1, t 1), (σ 2, t 2) ... .., (σ n, t n); Wherein, n represents the times of collection in experimental period; Being the longitudinal axis with soil pressure σ, is that transverse axis is set up coordinate system with time t, and the n group data that obtain are expressed as σ-t tense curve (being soil pressure tense curve) in this coordinate system.
In like manner, can handle the soil pressure tense curve that obtains by the data of all the other soil pressure sensor collections.Soil pressure tense curve can be used for the analysis of place saturated yielding sensitivity assessment and lateral deformation influence.
Monitoring test:
In order to obtain the loess place under large tracts of land immersion condition, the data of inside soil body stress intensity and stress distribution and situation of change thereof, the problem that may exist in the feedback work progress, think that timely adjustment arrangement and method for construction provides theoretical foundation, the inventor utilizes system of the present utility model to carry out the soil pressure dynamic monitoring in loess platform plateau area, Shanxi Province.Detailed process is as follows:
1, the assembling of monitoring system
The host computer installation and debugging have at first been carried out, to adapt to following data acquisition unit to the data transmission of host computer; Carry out the coupling of data acquisition unit and host computer then, guarantee normally to connect and to transmit data, data acquisition unit changes the usb data line by RS485 and connects host computer; Be the assembling of power module afterwards, the alternating current of 220v directly connects host computer and data acquisition unit, converts the alternating current of 220v to the 24v direct current and connects soil pressure sensor, to guarantee its operate as normal under rated voltage; Carry out the work that is connected of soil pressure sensor and data acquisition unit at last, share to 38 soil pressure sensors as required in the present embodiment, each soil pressure sensor connects data acquisition unit by the four-core shielded cable, positive source, negative pole (red, green) and signal positive pole, negative pole (black, indigo plant) are connected on the corresponding binding post, check circuit does not have short circuit, after the problem that opens circuit, connect power supply, open data acquisition unit and host computer, in host computer, there are data to show that normally namely system assembles finishes.
Totally 2 of data acquisition units, the JC-4A data acquisition unit that all adopts Beijing Sichuanger Building Test Technology Development Co., Ltd. to produce, wherein, 1 possesses 30 data passages, and 1 possesses 10 data passages, totally 40 passages in addition, distribute to 38 soil pressure sensors respectively, 2 passages give over to standby.
2, the demarcation of sensor
The soil pressure sensor thickness 15mm of this use, diameter 68mm, its structure is as shown in Figure 2.
Because monitoring system is subjected to artificial assembling and working-yard to influence bigger, manually-operated may produce error, in this monitoring, each soil pressure sensor is demarcated separately, obtain 38 soil pressure sensor calibration curves, because quantity is big, only provide the calibration curve (referring to Fig. 6) of burying 8 soil pressure sensors in the well D1 for No. one underground here.
3, sensor buries underground
According to the self-collapsibility soil thickness H of prospecting data and shop experiment announcement, designed the required soil pressure sensor of this test and buried scheme underground, as shown in Figure 5.
At first excavated diameter 30m, the immersion hole of degree of depth 0.8m.
Follow scheme of the present utility model then, specifically excavate 6 mouthfuls and be used for burying well D1~D6 underground, the well head diameter is 0.6m.D1~D6 is followed successively by 2m, 10m, 16m, 22m, 30m, 40m apart from immersion hole centre distance.It is inner that wherein D1, D2 are positioned at the immersion hole, and D3 is positioned at the R+1m place, and D4 is positioned at the 1.5R place, and D5 is positioned at the 2R place, and D6 is positioned at 2.5R ± 3 meter scope.
Bury each underground well required soil pressure sensor and be placed in the well head place, put circuit in order in order to burying underground.
The soil pressure sensor unification is embedded on the borehole wall of burying well underground, soil pressure sensor is in the distribution situation of respectively burying underground in the well: among the D1 8, among the D2 6, among the D3 15, among the D4 6, among the D5 2, among the D6 1, totally 38, wherein each is buried borehole measurement transverse and longitudinal soil pressure sensor underground and buries situation underground and see the following form.The soil pressure sensor stress surface of measuring vertical soil pressure makes progress and maintenance bottom surface level, measures the soil pressure sensor stress surface of lateral earth pressure towards the immersion center.When burying underground, the inner chamber that has cutting edge that at first will process is steel mould (participation Fig. 4) level of rectangular parallelepiped or vertically pounds into burying the well borehole wall underground, pull out mould then, then can draw out identical with soil pressure sensor width, thickness at the borehole wall, the degree of depth is the soil box about 10cm, with soil the dead zone is trained in fact again after then soil pressure sensor being put into soil box, only expose data line.Same well is interior to begin to bury underground one by one by the sensor arrangenent diagram to superficial part from the deep, and every layer is buried the back and with the U-shaped iron (Fig. 3) of processing data line gathered nail generation destruction when the hole wall avoids backfill to bury well underground.After treating that the interior sensor of a bite well is all buried underground, check the signal communication situation, if can return data and data area reasonable, then bury all the sensors underground the well tamping in layers with the windlass sash weight, the soil that digs out when burying excavation underground well is whole to be rammed back to bury underground in the well and is advisable.
4, data acquisition
Need check that at first whole circuit has or not short circuit, breaking phenomena, guarantee errorless back power-on.
Monitoring beginning back, begin immersion before, the log-on data collector records and preserves the initialize signal of each soil pressure sensor, the basic value when being converted into physical quantity as the post-processed data.
After the immersion beginning, the signal that each strain-type soil pressure sensor returns changes along with the variation of soil pressure, and this monitoring is total to image data 90 days.30 days setting data collectors of beginning are with 30min/ time frequency acquisition collection and record each signal of sensor, and the signal that collects is sent to host computer in real time, and then 60 days frequency acquisition is 2h/ time.All gather 2160 times to testing each unspoiled strain-type soil pressure sensor that finishes.
5, data are handled
Find out from the calibration curve that step 2 obtains, the output signal of soil pressure sensor and soil pressure are the better linearity relation, for improving monitoring accuracy, the calibration curve of all soil pressure sensors is carried out match again obtain fitting formula respectively, only provide 8 calibration curves that step 2 obtains fitting formula after the match again herein, see the following form.
The principle of work of soil pressure sensor is the strain that the bridge circuit that resistance strain gage 2 is formed reflects to be converted into changes in resistance and with the form output of voltage.The computing formula of soil pressure:
σ=A+X*B (formula 1)
In the formula, σ-total stress; X-output microstrain value; A, B-calibration coefficient.
With t 1The calibration formula of this soil pressure sensor correspondence of output valve X substitution of certain soil pressure sensor obtains this moment soil pressure σ constantly 1, the output valve X to the soil pressure sensor of each collection handles in the same way, obtains n group data altogether: (σ 1, t 1), (σ 2, t 2) ... .., (σ n, t n); Wherein, n represents the times of collection in experimental period; Being the longitudinal axis with soil pressure σ, is that transverse axis is set up coordinate system with time t, and 2160 groups of data that obtain are expressed as σ-t tense curve, i.e. soil pressure tense curve in this coordinate system.The data of utilizing above principle processing all the sensors to gather can obtain whole 38 soil pressure tense curves.
According to above-mentioned application process of the present utility model, the inside soil body stress monitoring continues 90 days (on Dec 21st, 1 2012 on September 21st, 2012) altogether under this loess place large tracts of land immersion condition, frequency acquisition is 30min/ time, Fig. 7 is that D1 buries the vertical soil pressure σ of each degree of depth soil layer of well-t tense curve (depth of burying of the corresponding soil pressure sensor of numeral in the bracket after the pound sign D1 among the figure underground, because 8m place sensor damages, so unlisted among the figure), Fig. 8 buries each degree of depth soil layer lateral earth pressure σ-t tense curve of well underground D3 number.As can be seen from Figure 7, deep soil body compressive stress is bigger, and it is fast than middle level and the deep layer soil body that the soil pressure that immersion causes is increased response; But it is bigger that the soil pressure that middle layer soil body causes immersion increases response amplitude, and increment is higher relatively; The shallow-layer soil body is that response time or response amplitude are all minimum; Layer soil body susceptibility is stronger in can tentatively judging thus, will note more in ground is handled.Can find out that from Fig. 8 peripheral soil body deep, immersion district, deep is subjected to outside pressure under the immersion influence, but amplitude is less, almost reduces to zero along with soaking time increases extruding force; The lateral compression power maximum that middle layer soil body (about 10m) is subjected to; The extrusion stress that the shallow-layer soil body (about 4m) is then born, that is the phenomenon of subsiding to flood zone appears; To sum up the distribution situation of lateral stress becomes spindle.The soil body is systems stabilisation under the state that does not have the extra-stress effect, the transmission of power and rigid body have essential distinction in the soil body in addition, because causing inside soil body stress to occur in loading process, various uncertain factors concentrate, and the position that stress is concentrated can produce bigger sedimentation naturally, has also disclosed this phenomenon by monitoring result of the present utility model.
By above monitoring result as can be seen, use monitoring system of the present utility model to monitor and obtain a soil layer soil pressure intensity, soil pressure increase and descend under the immersion condition amount and rate, and disclose the soil pressure distribution situation.By case verification, system of the present utility model is feasible, and monitoring result is accurate, precision is higher, can estimate and formulate Ground Treatment Schemes for the place foundation is provided.

Claims (2)

1. inside soil body STRESS VARIATION monitoring system under the loess place immersion condition is characterized in that, comprises power supply, host computer, a plurality of soil pressure sensor and at least one data acquisition unit; Wherein, the output terminal of each described soil pressure sensor connects the input end of data acquisition unit respectively, and the output terminal of data acquisition unit connects host computer respectively, and it is its power supply that described power supply connects soil pressure sensor, data acquisition unit and host computer;
By the soil pressure data that described a plurality of soil pressure sensors are gathered inside soil body under the loess place immersion condition in real time, the data that collect send to data acquisition unit, and data acquisition unit sends it to host computer, by host computer the data that receive are handled.
2. inside soil body STRESS VARIATION monitoring system under the loess place immersion condition as claimed in claim 1, it is characterized in that, described soil pressure sensor comprises the box body (6) of stainless steel, resistance strain gage (2), terminal block (3) and top cover (5), the zinc coat of box body (6) bottom surface is as stressed film (1), bridge circuit and the terminal block of being made up of resistance strain gage (2) (3) fixedly arranged in the box body (6), the bridge circuit that resistance strain gage (2) is formed is close to box body (6) inner bottom surface, and described terminal block (3) is positioned at the top of the bridge circuit of resistance strain gage (2) composition; The bridge circuit that resistance strain gage (2) is formed is drawn box body (6) by terminal block (3) by signal wire (4), and top cover (5) is installed at box body (6) top.
CN 201320124525 2013-03-19 2013-03-19 Soil internal stress change monitoring system in loess place immersing condition Expired - Fee Related CN203132748U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103196599A (en) * 2013-03-19 2013-07-10 西北大学 System and method for monitoring soil body inner stress variation of loess field under soaking condition

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103196599A (en) * 2013-03-19 2013-07-10 西北大学 System and method for monitoring soil body inner stress variation of loess field under soaking condition
CN103196599B (en) * 2013-03-19 2014-11-26 西北大学 System and method for monitoring soil body inner stress variation of loess field under soaking condition

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