CN103205956A - Method for controlling roadbed loading rate by observing pore water pressure - Google Patents
Method for controlling roadbed loading rate by observing pore water pressure Download PDFInfo
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- CN103205956A CN103205956A CN2012105698519A CN201210569851A CN103205956A CN 103205956 A CN103205956 A CN 103205956A CN 2012105698519 A CN2012105698519 A CN 2012105698519A CN 201210569851 A CN201210569851 A CN 201210569851A CN 103205956 A CN103205956 A CN 103205956A
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Abstract
The invention discloses a method for controlling a roadbed loading rate by observing pore water pressure. The method includes the steps: arranging and embedding pore water pressure gauges; connecting each pore water pressure gauge with a measuring device matched with the pore water pressure gauge; drawing a chart indicating the relation between the pore water pressure and time according to the measured relation between the pore water pressure and the time when a roadbed begins to be filled with earth and loaded; selecting two highest peak points on a pore pressure process line during initial loading, and connecting and extending the two highest peak points to serve as an early warning line for the pore water pressure; modifying the early warning line in a static load prepressing period after initial loading; and controlling subsequent earth filling speed according to the modified early warning line. The method avoids adverse effects of factors such as defects of static water pressure definition and difficult accurate quantification of earth filling increment in actual construction on pore water pressure coefficient values, and has the advantages of accuracy, intuition, easiness in operation and the like.
Description
Technical field
The present invention relates to a kind of expressway construction engineering, specifically refer to a kind of by the method for observation pore water pressure with control roadbed loading speed.
Background technology
In expressway construction, utilize pore pressure gauge observation soft foundation weak soil mesopore water pressure under the imposed load effect to rise by the process of disappearing with the control loading speed, obtained certain application at present.
Pore water pressure observation is implemented by pore pressure gauge.The hole presses the meter kind more, as waterpipe type, pressure measurement tubular type, differential resistance type etc., since the steel chord type pore pressure gauge have good stability, highly sensitive, use characteristics such as simple, convenient, thereby be widely used.Steel chord type pore pressure gauge component part and operating principle are as follows: the steel chord type pore pressure gauge is mainly constructed by permeable stone and pressure sensor two and partly formed: the permeable stone material is generally made by silica or rustless metal powder, has very high water permeability.The steel chord type pressure sensor.Formed by Stainless Steel pressure-bearing film, string wire, bracket shell and signal-transmitting cable.Its structure is that the end with a string wire is fixed on the pressure-bearing center membrane, and the other end is fixed on the support, and an electromagnetic coil is installed on the string wire next door, in order to exciting and induction frequencies signal.Steel chord type frequency measurement instrument.Be supporting (instrument) equipment of steel chord type pore pressure gauge, collect pore pressure gauge gauge head frequency with it.
The steel chord type pore pressure gauge is after gauge head pressure-bearing film bears pressure and makes film distortion, the feasible string wire relaxation of deformation that is fixed on the film, thereby change the natural frequency of string, use string wire frequency meter (plate reading) and receive its natural frequency, can try to achieve its active force (pore water pressure) according to following formula.Both sides relation is as follows:
u?=
?k（
f? 0? 2?–
?f 1? 2）………………………………………..(1)
In the formula:
uBe pore water pressure (kPa)
kBe constant, be called sensor coefficient, provided by indoor standardization;
f 0Zero pressure (atmospheric pressure) is the natural frequency (Hz) of string wire down
f 1For under the pore water pressure effect, the string wire natural frequency is read different string wire natural frequency (Hz) constantly by the survey of steel chord type frequency measurement instrument and just can be tried to achieve pore water pressure u(kPa).
The hole can be observed after pressing meter to bury.During observation, press meter H cable center tap to be connected in steel chord type frequency measurement instrument and hole, on steel chord type frequency measurement instrument, namely demonstrate the natural frequency (Hz) of this (pore pressure gauge) measuring point.This pore water pressure U (kPa) when this survey is inferior can be tried to achieve by (1) formula, accordingly, pore water pressure U and time t relational process line can be conveniently drawn out.
Because what cause soft base generation deformation is excess pore water pressure, therefore also need observe underground fluctuation in stage situation, in order to monitoring gained pore water pressure U is revised.Revised pore water pressure is excess pore water pressure u, can draw out the excess pore water pressure graph as stated above.
In addition, when carrying out pore water pressure observation, also need carry out the observation of load increment (thickness h of banketing), press fluctuation between the two to concern for ease of load increment relatively with excess pore water, can be with its compilation on same figure, i.e. load, excess pore water pressure and time relationship graph.Clearly, can
QualitativeUnderstand pore water pressure and load relation between the two.But from
QuantitativelyThe last relation of analyzing between the two then seems unable to do what one wishes to be used for the controlling speed of banketing.
Present stage, adopting pore water pressure is " coefficient is pressed in the single-stage hole " and " coefficient is pressed in comprehensive hole " monitoring method with the banket method of speed of control.According to the pore water pressure theory that Cape Town (A.W.Skempton) proposes, the pore pressure parameter expression formula is:
B Single-stage=
Δ u/ Δ P(2)
Comprehensive pore pressure parameter
B ComprehensivelyExpression formula is:
B Comprehensively=
(U i -U 0 )/Σ P i (3)
In last two formulas:
△ u--excess pore water pressure increment (
KPa);
△ P---load increment (
KPa);
U I ---the
IThe measuring point pore water pressure (
KPa);
U 0 ---initial pore water pressure (
KPa);
∑ △ P I ---be accumulated to
iThe total load of level (
KPa).
With above-mentioned data substitution (2) (3) formula, can calculate each measuring point and press coefficient and comprehensive hole to press coefficient in the single-stage hole that difference loads the phase.
Coefficient monitor control index and monitoring are pressed in the hole: the pore pressure parameter monitor control index is many to be provided in plan by designing institute: pressure coefficient in single-stage hole is 0.6 generally speaking, and it is 0.4 that coefficient is pressed in comprehensive hole.By above-mentioned observation and calculating, its monitoring standard is: coefficient is pressed in the single-stage hole
B Single-stage=
Δ u/ Δ P〉=0.6 or press coefficient when comprehensive hole
B Comprehensively=
(U i -U 0 )/Σ P i 〉=0.4 o'clock, stop to load.When stopping carrying a back roadbed and being in the static load preloading condition, As time goes on, pore water pressure dissipation, retry the pressure coefficient that portals
B Single-stage≤ 0.5, coefficient is pressed in comprehensive hole
B ComprehensivelyCan recover in≤0.3 o'clock to load,
Adopting ventage piezometer that roadbed is carried out monitoring is a kind of new technology that occurs last century Mo in China, belongs to stress trajectory.Compare with deformation (sedimentation, the displacement) observation of roadbed routine, its sensitivity is far above the latter.Practice shows, when load is applied on the roadbed, just can record the change that pore water pressure takes place.Obviously this is of great benefit to for control roadbed unstability.The embedding technology of pore pressure gauge has become ripe at present.In addition, data acquisition tube list and accurately be a big advantage of this technology.
From (2) (3) formula as can be known, find the solution pore pressure parameter and need obtain excess pore water pressure and its increment
△U also should obtain load and its increment
△P.In the soft base observation of routine, the total pore space water pressure U that measures by the pore water pressure probe comprises two partly: i.e. hydrostatic pressure h and by the caused excess pore water pressure u of subsidiary stress (banketing on the roadbed) (excess pore-water pressure).The excess pore water pressure expression formula is
:
u=U-h （4）
In the formula:
U--excess pore water pressure (
KPa);
H--hydrostatic pressure (is pressed
hγ
ω Be converted into
KPa);
U --total pore space water pressure (
KPa);
Above-mentioned three elements is in speedway observation, and because being subjected to multifactor restrictions such as geology and geomorphology, construction condition, except total pore space water pressure U can obtain the accurate values very much, obtaining of all the other two yuan of numbers all has following some shortcomings part:
The definition defective that a, hydrostatic pressure are calculated
Hydrostatic pressure h is defined as in " Standard for fundamental erms of geotechnical engineering ": " water pressure that set point and table depth displacement cause "
[1]This definition owes accurately:
The soil body in the steady seepage that is located in sloping body (as speedway cut and fill section), by this definition, its hydrostatic pressure u=γ
ω H is that the soil body arrives sloping body table depth displacement in the h(formula).
But, if from this soil body gravitational potential of living in and pressure potential analysis, calculating by simple geometric, the soil body should be projection h'(h ' on the vertical vertical line of this soil body of the equipotential lines of this soil body＜h) rather than the h in the following formula to the table depth displacement in the following formula.If this steady seepage flow direction and horizon angle are α, its hydrostatic pressure u=γ
ω Hcos2 α.Both difference is obvious.
As seen, the definition of " in the Standard for fundamental erms of geotechnical engineering " hydrostatic pressure owes accurately, will directly have influence on the uniqueness that excess pore water pressure calculates.
Hydrostatic pressure observation
How observation for the embankment both sides all are located in visible table roadbed hydrostatic pressure arranges the water-level observation point in roadbed both sides side slope.Extrapolate it to the phreatic line of roadbed according to observed result.After this foundation two survey time phreatic lines press measuring point vertically to the changing value of the difference in change of fixing a point with definite hydrostatic pressure value in the hole.
Be in the roadbed that pull up on the He Hu pool that communicates with the external world for both sides, by the observation to its table elevation, adopt said method to determine
hBe feasible.But do not having visible table (pool, river) section for roadbed both sides (or a side), owing to be subjected to highway expropriation of land influence, many observers survey pipe with groundwater table and are arranged on from the position of roadbed side slope 1m-3m.
The calculating of phreatic line
After obtaining roadbed both sides table elevation, then can carry out the roadbed phreatic line and calculate to determine that A order among Fig. 1 water level elevation change location is with definite hydrostatic pressure h.
The phreatic line design formulas is many and calculate numerous and diverse.The fringe conditions that each formula has each formula to use, it is also many to relate to parameter.As: ground transmission coefficient, roadbed transmission coefficient, pervious foundation thickness, seepage line length, roadbed two side slopes ratio and water level etc.Parameter is more many, and it is also just relatively large to calculate the error that produces.
The load metering
Load and load increment are one of parameters of calculating pore pressure parameter.Since engineering observation mostly is on-the-spot interim measurement or with the method for transportation metering to determine load increment.Practice shows no matter adopt which kind of method, and the error in measurement of its load increment is common occurrence in native 2cm～native 4cm scope: result of calculation has illustrated that the load increment error judges the influence that produces to monitored results in that 1cm scope soil is thick, sees some from this.
The change of pore pressure gauge position
Pore pressure gauge is embedded in the weak soil, weak soil must produce sedimentation in consolidation process, undoubtedly, the pore pressure gauge position also can change thereupon, and how does its deflection measure? how is fall rate? pore pressure gauge sinks the problems such as influence of pore water pressure value is not seen the data of literatures report so far yet.It sinks and presses the influence of coefficient not learn to the hole.
Summary of the invention
In order to overcome above-mentioned deficiency, the object of the present invention is to provide a kind of more near true, simple and easy to do, the workable observation pore water pressure that passes through with the method for control roadbed loading speed.
For solving the problems of the technologies described above, the technical solution adopted in the present invention is:
By the method for observation pore water pressure with control roadbed loading speed, may further comprise the steps:
The layout of A, pore pressure gauge and burying underground: in each layout points boring of roadbed, pore pressure gauge is buried underground wherein; At least arrange a hole pressure meter at the soil layer of different nature of roadbed; The soft thicker soil of homogeneity, but then meter is pressed in a plurality of holes of equidistant placement.
B, the sensing equipment that each pore pressure gauge and its is supporting are connected, and sensing equipment obtains the pore water pressure value in order to receive the pressure parameter that pore pressure gauge transmits by this pressure parameter.
C, roadbed is begun to banket in the process that loads, draw the chart of pore water pressure and time relationship by the pore water pressure and the time relationship that record, with the location point of each pore water pressure of the different time in the chart formation hole pressure graph that is connected;
D, the hole during original upload press graph to select two peak-peak points, connect and prolong, and this line is the pore water pressure early warning line;
E, in the static load precompressed phase after original upload is finished: be steady dissipation for pore water pressure, get its total squeeze time median as revising the early warning line starting point, put the parallel lines of making above-mentioned early warning line with this and be the correction early warning line; Be for pore water pressure that non-stationary dissipates, get each arithmetic mean of instantaneous value loca of surveying time gained pore water pressure as revising the early warning line starting point, put the parallel lines of making above-mentioned early warning line with this and be the correction early warning line;
F, with the follow-up speed of banketing of revised early warning line control: when loading when roadbed is continued to banket, to be painted on the hole in the pore water pressure value that each time detecting point records presses on the chart of graph, whenever measure a pore water pressure value, draw this value immediately in the position of chart, in the time of below early warning line is being revised in the position of pore water pressure value, can continue the loading of banketing; Revise early warning line when the pore water pressure value approaches, then slow down the loading speed of banketing; When the position of pore water pressure value meets or exceeds the correction early warning line, loading then stops to banket.
In the steps A, the mode of drilled dry is adopted in described boring, and the spacing between the described pore pressure gauge layout points is 2m～3m.
Among the step B, described pore water pressure is counted the steel chord type pore pressure gauge, and its supporting sensing equipment is steel chord type frequency measurement instrument, and steel chord type frequency measurement instrument is connected described steel with H cable joint on the steel chord type pore pressure gauge
String formula frequency measurement instrument is received in the natural frequency (Hz) of the measuring point of pore pressure gauge transmission, utilizes following formula can try to achieve this pore water pressure when inferior:
u=
k(
f 0 2–
f 1 2), in the formula:
uBe pore water pressure (kPa);
kBe constant, be called sensor coefficient, provided by indoor standardization;
f 0Zero pressure (atmospheric pressure) is the natural frequency (Hz) of string wire down;
f 1For under the pore water pressure effect, the string wire natural frequency is read different string wire natural frequency (Hz) constantly by the survey of steel chord type frequency measurement instrument and just can be tried to achieve pore water pressure u(kPa).
Be 10～15 days during the described original upload.
Beneficial effect of the present invention is:
A,Adopt the pore water pressure graphical method, inherited whole advantages of prior art.Thereby layout, method of installation and the observation procedure of prior art mesopore WG all do not change.
B,Pore water pressure value U and time t that utilization observes draw " pore water pressure graph " on computers, because the pore water pressure U that collects is accurate, thereby the pore water pressure graph of drawing out can reach the effect of " thousand people, one figure ".
C,Draw " early warning line " with the control loading speed at the pore water pressure graph, have accurately, characteristics such as directly perceived, easy operating.
D,Draw " early warning line " on the pore water pressure graph with the control loading speed, wherein " early warning line " generation is " get back in the practice again from practice and go " Successful Practice with application, and its marrow is " particular problem concrete analysis ".
E,Because the uncertainty that influence deformation of ground is too many, with to adopt hyperbolic method to inquire into final settlement the same, determine a superior in quality early warning line also " (practice) experience and skill that needs are certain ".This is the weak point of this method.But concerning an engineering, tens at least of design pore water pressure observation point positions, tens at most.As long as press loading to perform design by this method to several initial holes, and by the design organization construction, all can obtain " early warning line " of fine quality.Then just made easy progress from experience later on.
Description of drawings
Below in conjunction with the drawings and specific embodiments the present invention is described in further detail:
Fig. 1 is pore water pressure of the present invention and the pore water pressure of time relationship drafting and the curve map of time relationship.
The specific embodiment
By the method for observation pore water pressure with control roadbed loading speed, may further comprise the steps:
The layout of A, pore pressure gauge and burying underground: in each layout points boring of roadbed, pore pressure gauge is buried underground wherein; At least arrange a hole pressure meter at the soil layer of different nature of roadbed; The soft thicker soil of homogeneity, but then meter is pressed in a plurality of holes of equidistant placement.The ordinary circumstance pore pressure gauge is to be arranged in place, roadbed axis, and also installation position is adjusted in visual geological condition and designing requirement.Soil layer of different nature is arranged a hole pressure meter at least; Thicker as homogeneity weak soil layer, but then meter is pressed in a plurality of holes of equidistant placement, and its distance is advisable with 1/2m-3m; Non-weak soil layer also can be arranged a hole pressure meter under the processing soft soil boundary face.The embedding employing boring of pore pressure gauge is buried underground, and boring is advisable with dry drill method.Measure at first at the scene pore pressure gauge be numbered measure each hole and press the original frequency of meter after, the permeable stone that will boil is contained on the pore pressure gauge in water, make it simultaneously in the situation that does not break away from water moves down into the hole of filling with clear water, press to behind designing requirement elevation+30cm cable is adjourned outward in the side slope observation case.In addition, be in anti-this " string hole ", be advisable in " hole one " (namely meter is pressed in the embedding hole of boring).
B, the sensing equipment that each pore pressure gauge and its is supporting are connected, and sensing equipment obtains the pore water pressure value in order to receive the pressure parameter that pore pressure gauge transmits by this pressure parameter.The concrete scheme of this step is: described pore water pressure is counted the steel chord type pore pressure gauge, its supporting sensing equipment is steel chord type frequency measurement instrument, steel chord type frequency measurement instrument is connected with H cable joint on the steel chord type pore pressure gauge, described steel chord type frequency measurement instrument is received in the natural frequency (Hz) of the measuring point of pore pressure gauge transmission, utilizes following formula can try to achieve this pore water pressure when inferior:
u=
k(
f 0 2–
f 1 2), in the formula:
uBe pore water pressure (kPa);
kBe constant, be called sensor coefficient, provided by indoor standardization;
f 0Zero pressure (atmospheric pressure) is the natural frequency (Hz) of string wire down;
f 1For under the pore water pressure effect, the string wire natural frequency is read different string wire natural frequency (Hz) constantly by the survey of steel chord type frequency measurement instrument and just can be tried to achieve pore water pressure u(kPa).
C, as shown in Figure 1, roadbed is begun to banket in the process that loads, the pore water pressure and the schematic diagram of time relationship drawn by the pore water pressure that records and time relationship, the location point of each pore water pressure of the different time among the figure is connected forms hole pressure graph; Pore water pressure observation graphical method is on its plinth of prior art, get rid of complexity and the ambiguity of above-mentioned hydrostatic pressure in observation, calculating, the influence of factors such as load increment error in measurement, directly the value U of pore water pressure accurately and the time t that utilizes observation to obtain draws pore water pressure and time relationship graph (being U～t curve) on computers.During original upload, (also claim first order loading duration) and seem particularly important.Practice by Xingning～the She nationality, distributed over Fujian, Zhejiang, Jiangxi and Guangdong's river speedway, Guangzhou～Wuzhou speedway, Yunfu～Luoding speedway draws: first order loading duration was advisable with 10～15 days.(also claim first order loading duration) during original upload, therefore the thickness that bankets is many can carry out loading continuously fast in " the roadbed limit banket elevation ", load soil thick by designing requirement with the 25cm/ layer.The load increase causes pore water pressure to rise, and pore water pressure rises and causes weak soil mesopore water to be discharged, and weak soil mesopore water is discharged the fixed bearing capacity of foundation soil that causes of soft soil generation and risen to convention.Because discharging, pore water cause soil solidifying to need the regular hour to finish, i.e. so-called " time effect ", therefore, after finishing first order loading, requirement stops carrying one all left and right sides time of precompressed and descends to load together operation again, to improve " limit banket high level " of ground, for loading, subordinate prepares.
D, the hole during original upload press graph to select two peak-peak points, connect and prolong, and this line is the pore water pressure early warning line, among Fig. 1, are the pore water pressure early warning line as the straight line of solid line;
In the practical operation, utilize computer can easily obtain pore water pressure and time relationship graph, close examination pore pressure graph is got two peak points and is connected and extend to X, and then the AX line is the pore water pressure early warning line of this measuring point.
E, in the static load precompressed phase after original upload is finished: be steady dissipation for pore water pressure, get its total squeeze time median as revising the early warning line starting point, put the parallel lines of making above-mentioned early warning line with this and be the correction early warning line; Be for pore water pressure that non-stationary dissipates, get each arithmetic mean of instantaneous value loca of surveying time gained pore water pressure as revising the early warning line starting point, putting the parallel lines of making above-mentioned early warning line with this and be the correction early warning line, among Fig. 1, is the correction early warning line of pore water pressure as the straight line of dotted line.
The pore water pressure early warning line is the product that the first order loads practice, and its line slope reflects that faithfully the raising that in this grade loading procedure load increases with the ground bearing capacity is coadapted.Undoubtedly, this coadapted relation loads the imminent second level and plays certain directive function surely.But exist the variation of size quantitatively.For caution's sake, be necessary the pore water pressure early warning line is revised.
The modification method of pore water pressure early warning line: get the first order and load and to stop carrying the measured pore water pressure in back and add U
1Load preceding observation station to the second level and get U
2Arithmetic mean of instantaneous value as the starting point O that revises early warning line, calculating formula is (U
1+ U
2)/2 are that starting point is made ray OY//AX and got final product with O, and the OY line of doing is the early warning line after being corrected.With this pore water pressure early warning line that loads as follow-up one-level.In practice of construction, owing to be subjected to all multifactor impacts such as weather, stock ground, machinery allotment, duration, loading fragmentary, discontinuous form often appears also during stopping carrying.This loading causes the hole press to increase being reflected in the hole with dissipation pressing to be on the conditional curve figure and crossing fluctuation on the sawtooth pattern shape.But as long as the overall horizontal or downward trend of this curve all can adopt this method to revise described early warning line.
F, with the follow-up speed of banketing of revised early warning line control: when loading when roadbed is continued to banket, to be painted on the hole in the pore water pressure value that each time detecting point records presses on the chart of graph, whenever measure a pore water pressure value, draw this value immediately in the position of chart, in the time of below early warning line is being revised in the position of pore water pressure value, can continue the loading of banketing, if between the two apart from bigger, then can appropriateness increase the speed of banketing with the short duration; Revise early warning line when the pore water pressure value approaches, then slow down the loading speed of banketing; When the position of pore water pressure value meets or exceeds the correction early warning line, the loading that then stops to banket, after stopping to load, under normal circumstances pore water pressure U can dribble, and when it drops to " early warning line " below, then can recover to load; Otherwise, stop carrying leave standstill during the abnormal conditions that go up not down of pore water pressure value U.At this moment, the data of other observation point (as sedimentation, displacement) that can arrange with same section is carried out network analysis, to determine whether " off-load back-pressure " is with plan safety.
Case history:
Wide Chinese parasol tree speedway 18 contract section k118+250～k118+360 section left side is massif, and the right side is soft foundation, belongs to typical cut and fill highway section, and this section adopts 3 settlement plates, 2 displacement skirt piles and 2 pore water pressures that roadbed is loaded and monitor.The designing requirement monitor control index is: the single-stage hole press coefficient＜0.6, comprehensive hole press coefficient＜0.4, sedimentation every day＜10mm, horizontal movement the every day＜can load during 5mm.
In the present embodiment, can find out March 18 from line chart is buckled in the hole, two hole measuring point pore water pressures have all surpassed early warning line.Should assign and stop carrying notice, be prudent meter, simultaneously also for the reliability for check " early warning line ", so to the same day rate of settling and hole press coefficient to calculate, it the results are shown in Table 1 and table 2.
Table 1 instruction stops carrying phase settlement observation data summary sheet
Table 2 instruction stops carrying phase single-stage pore pressure parameter computational chart
As can be seen from the table: March 18, the rate of settling was 7.0mm/d, and it is 0.579 that coefficient is pressed in the single-stage hole, and it is 0.149 that coefficient is pressed in comprehensive hole.All less than the monitor control index of designing requirement, do not stop carrying notice so assign.Construction corps had filled one deck soil routinely again on that night.
Observation on March 19 pore water pressure value still surpasses " early warning line ", the rate of settling reaches 9.0mm/d near designing requirement monitor control index 10mm/d, the single-stage hole presses coefficient to surpass the designing requirement monitoring to refer to that 0.60 has reached 0.697, and only to press one of coefficient be 0.159 in monitor control index 0.4 in comprehensive hole.Assigned " stopping carrying notice " routinely.
Found that this section roadbed gutter inwall produces the crack on March 23, gutter bottom protrusion (afterwards reporting designing institute to become engineering measures such as more having taked berm with superloading).Illustrate that " " assigning is timely, and the highly sensitive feasibility of loading speed being monitored in row change observation, " early warning line " of stress trajectory also is described simultaneously to stop carrying notice for this.
This period later stage loads and fails for a long time to carry out because of influenced by change in the work, builds when berm with superloading and finishes the back and recover loading when (belonging to the loading of the 6th phase), and for working to tight deadlines, construction corps has taked quick Loading Method, from 4 to 9 August, loads 1.58m in six days.In this period, the measured rate of settling rises to 13.5mm/d from the 11.0mm/d on August 6 always, the single-stage pore pressure parameter also from August 7 all above 0.6, reach 0.84 when maximum.Above-mentioned observation is all above design pore water pressure monitor control index 0.6.Should assign " stopping carrying notice " routinely.But, reflect on the pore water pressure curve map each measuring point hole voltage crest value all from " early warning line " very away from, the maximum pore water pressure value that a was ordered when maximum pore water pressure value and the first order loaded therebetween almost is on the same horizon.So do not assign " stopping carrying notice ".Not only last for roadbed has increased precompressed, also won the time for roadbed unloading in the future, build road surface.More than a year observed result shows after being open to traffic, and this time loads fast roadbed is not produced any disease, shows that the practice that this engineering adopts pore water pressure graphical method control roadbed to load is successful.
In a word; though the present invention has enumerated above-mentioned preferred embodiment, should illustrate, though those skilled in the art can carry out various variations and remodeling; unless such variation and remodeling have departed from scope of the present invention, otherwise all should be included in protection scope of the present invention.
Claims (4)
1. one kind is passed through the observation pore water pressure with the method for control roadbed loading speed, it is characterized in that: may further comprise the steps:
The layout of A, pore pressure gauge and burying underground: in each layout points boring of roadbed, pore pressure gauge is buried underground wherein; At least arrange a hole pressure meter at the soil layer of different nature of roadbed; The soft thicker soil of homogeneity, but then meter is pressed in a plurality of holes of equidistant placement;
B, the sensing equipment that each pore pressure gauge and its is supporting are connected, and sensing equipment obtains the pore water pressure value in order to receive the pressure parameter that pore pressure gauge transmits by this pressure parameter;
C, roadbed is begun to banket in the process that loads, draw the chart of pore water pressure and time relationship by the pore water pressure and the time relationship that record, with the location point of each pore water pressure of the different time in the chart formation hole pressure graph that is connected;
D, the hole during original upload press graph to select two peak-peak points, connect and prolong, and this line is the pore water pressure early warning line;
E, in the static load precompressed phase after original upload is finished: be steady dissipation for pore water pressure, get its total squeeze time median as revising the early warning line starting point, put the parallel lines of making above-mentioned early warning line with this and be the correction early warning line; Be for pore water pressure that non-stationary dissipates, get each arithmetic mean of instantaneous value loca of surveying time gained pore water pressure as revising the early warning line starting point, put the parallel lines of making above-mentioned early warning line with this and be the correction early warning line;
F, with the follow-up speed of banketing of revised early warning line control: when loading when roadbed is continued to banket, to be painted on the hole in the pore water pressure value that each time detecting point records presses on the chart of graph, whenever measure a pore water pressure value, draw this value immediately in the position of chart, in the time of below early warning line is being revised in the position of pore water pressure value, can continue the loading of banketing; Revise early warning line when the pore water pressure value approaches, then slow down the loading speed of banketing; When the position of pore water pressure value meets or exceeds the correction early warning line, loading then stops to banket.
2. according to claim 1 by the method for observation pore water pressure with control roadbed loading speed, it is characterized in that: in the steps A, the mode of drilled dry is adopted in described boring, and the spacing between the described pore pressure gauge layout points is 2m～3m.
3. according to claim 1 by the method for observation pore water pressure with control roadbed loading speed, it is characterized in that: among the step B, described pore water pressure is counted the steel chord type pore pressure gauge, its supporting sensing equipment is steel chord type frequency measurement instrument, steel chord type frequency measurement instrument is connected with H cable joint on the steel chord type pore pressure gauge, described steel chord type frequency measurement instrument is received in the natural frequency (Hz) of the measuring point of pore pressure gauge transmission, utilizes following formula can try to achieve this pore water pressure when inferior:
u=
k(
f 0 2–
f 1 2), in the formula:
uBe pore water pressure (kPa);
kBe constant, be called sensor coefficient, provided by indoor standardization;
f 0Zero pressure (atmospheric pressure) is the natural frequency (Hz) of string wire down;
f 1For under the pore water pressure effect, the string wire natural frequency is read different string wire natural frequency (Hz) constantly by the survey of steel chord type frequency measurement instrument and just can be tried to achieve pore water pressure u(kPa).
4. according to claim 1 by the method for observation pore water pressure with control roadbed loading speed, it is characterized in that: among the described step D, be 10～15 days during the original upload.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210569851.9A CN103205956B (en) | 2012-12-25 | 2012-12-25 | Method for controlling roadbed loading rate by observing pore water pressure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210569851.9A CN103205956B (en) | 2012-12-25 | 2012-12-25 | Method for controlling roadbed loading rate by observing pore water pressure |
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| Publication Number | Publication Date |
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| CN103205956A true CN103205956A (en) | 2013-07-17 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104076131A (en) * | 2014-06-27 | 2014-10-01 | 中国地质科学院水文地质环境地质研究所 | Preloading multifunctional automatic testing system and method |
| CN115031889A (en) * | 2022-04-21 | 2022-09-09 | 中国公路工程咨询集团有限公司 | Pore water pressure monitoring method and device, electronic equipment and storage medium |
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| JP2002054128A (en) * | 2000-08-11 | 2002-02-20 | Misawa Homes Co Ltd | Ground analyzing apparatus for building plot |
| CN1587523A (en) * | 2004-09-21 | 2005-03-02 | 武汉理工大学 | Dynamic simulation design method for highway soft foundation treatment construction |
| CN1773022A (en) * | 2005-11-05 | 2006-05-17 | 陶钧炳 | Fast soft foundation dyke building method and technology |
| CN101358449A (en) * | 2008-09-11 | 2009-02-04 | 中国科学院武汉岩土力学研究所 | Pore water pressure measuring device in foundation stabilization zone |
| JP2011047676A (en) * | 2009-08-25 | 2011-03-10 | Ritsumeikan | Soil moisture and water level detector, and slope failure prediction system using the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002054128A (en) * | 2000-08-11 | 2002-02-20 | Misawa Homes Co Ltd | Ground analyzing apparatus for building plot |
| CN1587523A (en) * | 2004-09-21 | 2005-03-02 | 武汉理工大学 | Dynamic simulation design method for highway soft foundation treatment construction |
| CN1773022A (en) * | 2005-11-05 | 2006-05-17 | 陶钧炳 | Fast soft foundation dyke building method and technology |
| CN101358449A (en) * | 2008-09-11 | 2009-02-04 | 中国科学院武汉岩土力学研究所 | Pore water pressure measuring device in foundation stabilization zone |
| JP2011047676A (en) * | 2009-08-25 | 2011-03-10 | Ritsumeikan | Soil moisture and water level detector, and slope failure prediction system using the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104076131A (en) * | 2014-06-27 | 2014-10-01 | 中国地质科学院水文地质环境地质研究所 | Preloading multifunctional automatic testing system and method |
| CN115031889A (en) * | 2022-04-21 | 2022-09-09 | 中国公路工程咨询集团有限公司 | Pore water pressure monitoring method and device, electronic equipment and storage medium |
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| CN103205956B (en) | 2014-10-01 |
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