CN102628281A - Horizontal displacement monitoring method for measuring point in foundation pit engineering - Google Patents

Abstract

The invention discloses a method for monitoring horizontal displacement of a measuring point in foundation pit engineering, which is characterized in that M point and N point are set as datum points for observing the horizontal displacement of a foundation pit, a total station is erected at a certain point A on a MN connection line, and the point A is a station point; the horizontal displacement value of any observation point i is: delta_i＝K_i1·Δβ_i+K_i2Δ A; the horizontal displacement monitoring method of the measuring point in the foundation pit engineering can freely set the station, and has the advantages of flexibility, extremely simple field operation and convenient use compared with the prior method.

Description

The horizontal displacement monitoring method of measuring point in a kind of base pit engineering

Technical field

The present invention relates to the horizontal displacement monitoring method of measuring point in a kind of base pit engineering.

Background technology

Because base pit engineering is a kind of temporary works, and appears in a large number again in city underground station Foundation Design or the Tall Building Foundation engineering construction process.Therefore, also be provisional as the safety monitoring in the work progress, treat that usually city underground station or building foundation major project are accomplished after, its construction safety monitoring has also just been accomplished naturally.The horizontal displacement monitoring number of spots of deep foundation pit engineering in urban is many, and monitoring accuracy requires high.Traditional collimation line method, little horn cupping receive the factor affecting such as landform place of job site, and be poor for applicability.Existing method; Be according to city deep foundation ditch actual conditions; In conjunction with single station correction method principle,, carry out precision analysis according to the error propagation theory satisfying on the base pit engineering horizontal displacement observation required precision basis; Inverse distance and angle measurement accuracy are confirmed the angle survey time number of selecting for use instrument required to the influence of the positional accuracy of observation point.Because horizontal displacement monitoring is complicated, and different monitoring method, its observation is also different, cause monitored data handle loaded down with trivial details, very easily form than mistake or mistake, institute's monitored data can not intuitively reflect city deformation of deep excavation situation in addition.

Summary of the invention

Technical problem to be solved by this invention provides the horizontal displacement monitoring method of measuring point in a kind of base pit engineering, and the horizontal displacement monitoring method of measuring point is easy and simple to handle in this base pit engineering, and efficiency of measurement is high.

The technical solution of invention is following:

The horizontal displacement monitoring method of measuring point in a kind of base pit engineering, setting M point and N point earlier is the reference point of foundation ditch horizontal displacement observation, and certain the some A on the MN line sets up total powerstation, and the A point is website; Then the horizontal movement value of arbitrary observation point i is:

Δ _i＝K _i1·Δβ _i+K _i2·ΔA；

Wherein, Δ _ABe website horizontal movement value, Δ _A=K _AΔ β _a

Wherein, first coefficient $K_A=\frac{S_{\mathrm{MA}}\·S_{\mathrm{NA}}}{S_{\mathrm{MA}}+S_{\mathrm{NA}}}\·\frac{1}{\mathrm{\ρ}},$ Second coefficient $K_{\mathrm{Il}}=\frac{S_{\mathrm{IA}}}{\mathrm{\ρ}},$ Tertiary system number $K_{i2}=\frac{S_{\mathrm{IA}}}{S_{\mathrm{MA}}}-1;$

Δ β _iAngle changing value for ∠ MAi;

Δ β _aAngle changing value for ∠ MAN;

S _MAThe distance of ordering to M for the A point;

S _NAThe distance of ordering to N for the A point;

ρ=206265 "; (ρ is a constant in the mapping specialty)

S _IA---the distance that the A point is ordered to i;

(above angle measurement degree is surveyed the length of side and all adopted same total powerstation observation, and through calculating) observation point i is positioned at the outer point of MN line.

The middle error of i point horizontal movement does $m_i=\±\frac{1}{2\mathrm{\ρ}}\sqrt{({4\mathrm{\Δ\; \β}}_i^2+{2\mathrm{\Δ\; \β}}_a^2)\·m_S^2+({5S}_{\mathrm{IA}}^2+S_{\mathrm{MA}}^2)m_a^2},$ m _S, m _a---be respectively in the instrument nominal range error in the sum of errors angle, producer provides when dispatching from the factory by instrument.

The survey time of ordering for i counts n and confirms

n round numbers according to following formula; M is the building that requires or the horizontal movement precision of building.

Beneficial effect:

The horizontal displacement monitoring method of measuring point in the base pit engineering of the present invention can freely be established the station, compares with previous methods, has more flexibility, and execute-in-place is also extremely simple, easy to use.The present invention carries out checking computations according to precision, observed range and the angular error of instrument to measuring point, and satisfies the monitoring accuracy requirement through increasing observation frequency; Adopt the present invention to carry out city deep foundation pit fender post (wall) top horizontal displacement monitoring; The know-how personnel operation of monitoring principle and monitoring method might not be required to be familiar with,, the threshold of being engaged in monitoring can be reduced as long as according to procedure operation of the present invention; Embody hommization, and greatly improved operating efficiency.

Method of the present invention, simple and easy and workable, solved the complexity of foundation ditch horizontal displacement monitoring, and the different monitoring points certainty of measurement has been carried out checking computations, the instrument that can adopt different accuracy realizes satisfying the monitoring accuracy requirement through calculating the survey time number automatically;

Further, binding data is handled and management software, with the monitoring method sequencing, reduces loaded down with trivial details workload, has avoided human error simultaneously; Original observed data is handled, deformation values is added up above the point of alarming value; And alarm point is incorporated a bit plan analyze; Automatic then curve plotting figure; Realized that city deep foundation pit fender post (wall) top horizontal movement situation of change adopts predefined output format output and prints achievement data, intuitive display.The chart module of system's design has been realized the visual of deep foundation pit engineering in urban monitored data, the deformation tendency of ability analysis-by-synthesis deep foundation pit engineering in urban fender post; The report output module has realized designing statement form voluntarily according to the form needs, has reduced the loaded down with trivial details of manual work, has greatly improved operating efficiency.

Description of drawings

Fig. 1 is the observation sketch map of the horizontal displacement monitoring method of measuring point in the base pit engineering;

Fig. 2 asks the method sketch map for B point correction;

The specific embodiment

Below will combine accompanying drawing and specific embodiment that the present invention is explained further details:

The influence of tested district landform and construction environment, the used collimation line method of foundation ditch horizontal displacement observation can't satisfy condition usually, and additive method can't reach the accuracy of observation requirement.

The reference point of single station correction method is laid and is not then received the influence of topography, and instrument stan is located at the displacement monitoring point, and is flexible and changeable, can once establish the monitoring that several displacement measuring points are accomplished at the station through instrument, calculates easyly, has significantly reduced workload.

The reference point that M and N are the foundation ditch horizontal displacement observations is established in single station correction method observation (Fig. 1 has represented general general situation, promptly has generality and versatility) as shown in Figure 1; A, B, C are the horizontal displacement monitoring points; A, B and C horizontal displacement observation method and calculate as follows:

(1) before the excavation of foundation pit, set up instrument at the A point, backsight M as initial zero direction, observes A to M successively, B, the inceptive direction angle of C and N and apart from S _MA, S _AB, S _ACAnd S _NAThe angle changing value of ∠ MAN, ∠ MAB and ∠ NAC can be tried to achieve in repeated measures all directions angle, is designated as Δ β respectively _a, Δ β _bWith Δ β _c

If the lateral displacement of website A is suc as formula (1):

${\mathrm{\Δ}}_A=\frac{S_{\mathrm{MA}}\·S_{\mathrm{NA}}}{S_{\mathrm{MA}}+S_{\mathrm{NA}}}\·\frac{{\mathrm{\Δ\β}}_a}{\mathrm{\ρ}}---\left(1\right)$

(2) suppose that the A point is motionless, try to achieve the lateral displacement Δ of 2 of B and C _B' and Δ _C'.

${{\mathrm{\Δ}}_B}^{\′}=\frac{S_{\mathrm{AB}}\·{\mathrm{\Δ\β}}_b}{\mathrm{\ρ}}---\left(2\right)$

${{\mathrm{\Δ}}_C}^{\′}=\frac{S_{\mathrm{AC}}\·{\mathrm{\Δ\β}}_c}{\mathrm{\ρ}}---\left(3\right)$

(3) calculate because the A point moves; Cause correction

and

that B and C WAWQ prosposition move, the lateral displacement of each monitoring point and its correction sum are horizontal displacement.

Be example in the hope of B point correction, as shown in Figure 2, establish Δ A and be the amount of movement when observing two phases an of A, a and a ' they are the two phases view angle of ∠ MAB, in Δ ABM and Δ A ' BM, have:

a+Δβ＝a′+Δb (4)

In the formula (4):

$\mathrm{\Δb}=\frac{\mathrm{\ΔA}\·\mathrm{\ρ}}{S_{\mathrm{AB}}},$ $\mathrm{\Δ\β}=\frac{\mathrm{\ΔA}\·\mathrm{\ρ}}{S_{\mathrm{MA}}}.$

Because the A point moves the corrected value that causes the displacement of B point:

Can try to achieve B point horizontal movement value by formula (2) and formula (5) is:

A and B point are the arbitrfary point, are the convenience for the general formula of deriving.

Be generalized to deep foundation pit engineering in urban fender post (wall) top, press the set arbitrary monitoring point i of regulation and stipulation, its horizontal movement ask method following:

Order:

First coefficient $K_A=\frac{S_{\mathrm{MA}}\·S_{\mathrm{NA}}}{S_{\mathrm{MA}}+S_{\mathrm{NA}}}\·\frac{1}{\mathrm{\ρ}},$ Tertiary system number $K_{\mathrm{Il}}=\frac{S_{\mathrm{IA}}}{\mathrm{\ρ}},$ Tertiary system number $K_{i2}=\frac{S_{\mathrm{IA}}}{S_{\mathrm{AM}}}-1,,;$

In the formula: A is for establishing website, and M, N are reference points, and i is each monitoring point numbering.

Formula (1) and formula (6) abbreviation can get:

Δ _A＝K _A·Δβ _a (7)

Δ _i＝K _i1·Δβ _i+K _i2·ΔA (8)

Δ in the formula _A---establish website horizontal movement value;

Δ _i---any point horizontal movement value.

For large-scale base pit engineering; Horizontal displacement observation is normally by the requirement of one-level foundation ditch monitoring accuracy; Setting has the observation pier and the prism platform with pressure centralising device of forced centering device; At this moment, the instrument error of centralization and target eccentric error precision can reach ± 0.1mm in, its instrument error of centralization and target eccentric error can be ignored.Therefore, on the basis of not considering the influence of the instrument error of centralization, it is equal apart from the distance of two reference points to suppose to establish website, and according to law of propagation of errors, formula (1) and formula (6) differential can get:

$\left.\begin{array}{c}{d}_A=\frac{S_{\mathrm{MA}}{d}_a+{\mathrm{\Δ\β}}_a{d}_S}{2\mathrm{\ρ}}\\ d_B=\frac{2S_{\mathrm{AB}}{d}_b+2{\mathrm{\Δ\β}}_b{d}_S+S_{\mathrm{AB}}{d}_a+{\mathrm{\Δ\β}}_a{d}_S-S_{\mathrm{MA}}{d}_a-{\mathrm{\Δ\β}}_a{d}_S}{2\mathrm{\ρ}}\end{array}\right\}---\left(9\right)$

D in the formula (9) _a=d _b, error formula is suc as formula (10) in converting to:

$\left.\begin{array}{c}{m}_A=\±\frac{1}{2\mathrm{\ρ}}\sqrt{{\mathrm{\Δ\β}}_a^2\·m_S^2+S_{\mathrm{AM}}^2\·m_a^2}\\ m_B=\±\frac{1}{2\mathrm{\ρ}}\sqrt{({4\mathrm{\Δ\β}}_b^2+{2\mathrm{\Δ\β}}_a^2)\·m_S^2+({5S}_{\mathrm{AB}}^2+S_{\mathrm{AM}}^2)m_a^2}\end{array}\right\}---\left(10\right)$

M in the formula _A, m _B---error in the horizontal movement;

m _S, m _a---be respectively in the instrument nominal range error in the sum of errors angle, different instruments is middle error different (this is to be provided when dispatching from the factory by instrument producer).

Thereby the middle error that can derive arbitrfary point i is:

$m_i=\±\frac{1}{2\mathrm{\ρ}}\sqrt{({4\mathrm{\Δ\β}}_i^2+{2\mathrm{\Δ\β}}_a^2)\·m_S^2+({5S}_{\mathrm{Ai}}^2+S_{\mathrm{AM}}^2)m_a^2}---\left(11\right)$

In the formula: m _i---the middle error of some i horizontal movement;

Δ β _i---the angle changing value of ∠ MAi;

S _Ai---the distance that the A point is ordered to i.

If the precision of the building horizontal movement of code requirement is m, then can calculate the required precision that the required n of carrying out survey time number in the actual observation just can reach regulation and stipulation:

$m\≥\frac{m_i}{\sqrt{n}}---\left(12\right)$

Through being converted to: $n\≥{\left(\frac{m_i}{m}\right)}^2---\left(13\right)$

Therefore, n round numbers.

Embodiment 1:

Certain subway station is underground two-layer station, adopts open cut along practice construction, and foundation depth 19.4m, standard paragraphs width are 20.7m.The district's scope traffic above-ground of standing is busy, the building comparatively dense, and the various pipelines of underground distribution, pipeline etc., the station left-external side is underground to have a bomb shelter planning to build.The place belongs to the II alluvial terrace, and landform is more smooth, ground elevation 75.86～77.89m, relative relief 2.03m.The terrain table is urban road and many highrise buildings.Foundation ditch monitoring grade is an one-level.

According to code requirement, error amount m=± 1.5mm during one-level foundation ditch maximum horizontal displacement allows, selecting the range finding nominal accuracy during monitoring be (2mm+2ppm), the nominal accuracy of angle measurement is ± 2 " the guest get R-422N all can total powerstation, total powerstation monitored data such as table 1.

Table 1 observation data

Can know from table 1; If adopt total powerstation survey time of observation; Distance, angle and the accuracy of instrument parameter substitution formula (11) of each point can be known; The precision of A point and No. 1 point satisfies code requirement, and the error in point measurement of No. 2 points, No. 3 points, No. 4 points is bigger, and particularly the error in point measurement of No. 4 points is much larger than setting.Therefore, more in the absence of high precision instrument, observe a survey time be difficult to satisfy the precision index requirement with conventional method.Therefore, through calculating the survey time number of each measuring point, the average of getting observation can reach required precision as calculated value.

Suppose that error is m in the horizontal movement of a survey time, need n survey time of observation could satisfy required precision, then have:

$\frac{m}{\sqrt{n}}\≤1.5---\left(12\right)$

Calculate No. 1 point, No. 2 points, No. 3 points, No. 4 points and satisfy the required survey time number of observing of required precision respectively 1,2,4; 10 survey time, according to the survey time number observation of the premises, the middle error of accessible these 4 some positions is distinguished as follows: 0.712mm; 1.350mm, 1.379mm, 1.453mm; All, can know that error all meets the demands in the each point less than the middle error 1.5mm of regulation and stipulation.Calculate the final mean annual increment movement value of each point, and with the observation of adopting existing high precision machines people (0.5 " TCA2003) relatively, result such as table 2:

Table 2 displacement data relatively

Can know the shift value and 0.5 that existing instrument adopts existing method to measure by table 2 " the displaced plate ratio that the TCA2003 high precision instrument is measured, gap is bigger; maximum difference is No. 3 points, and its difference reaches 2.317mm, and " the TCA2003 high precision instrument is relatively through taking method of the present invention and 0.5; Maximum difference is No. 4 points, and the displacement difference is merely 0.147mm, and the method for the present invention that adopts is described; Significantly reduce error, can satisfy required precision, reached the observation purpose.

Can know by above analysis, under the instrument condition restriction, adopt conventional measurement; Because the angle measurement of total powerstation is limit with survey limit precision, can not reach the required precision of regulation and stipulation, and because the influence of error in point measurement; The measuring point horizontal movement that causes calculating changes greatly, does not meet with actual conditions, therefore; Through analyzing the positional accuracy of survey station point and monitoring point, adopt the inventive method, calculate its number of many survey time that meet the demands.Its advantage is: 1) can spend a large amount of funds and buy high end instrument, and reach the positional accuracy requirement, and reduce error; 2) station can be established arbitrarily, under difficult observation condition, the observation purpose can be reached; 3) operate and layout simple.

Horizontal displacement monitoring method to measuring point in the base pit engineering of the present invention is equipped with data processing management software (relevant software is prior art):

1) monitored data is handled management software, possesses the measuring point of drafting bit map/bitmap function, makes that measuring point and foundation ditch position relation is directly perceived, and for the monitored data analysis provides the foundation, the analyst can go to the scene, and from figure, carries out the data exception analysis of causes;

2) because varying level displacement monitoring point is different with angle with respect to the distance of reference point, and the precision of monitoring instrument is different; Cause the error of monitoring point also different; Therefore in order to satisfy the monitoring class requirement, must carry out checking computations, and confirm the survey time number of each measuring point the accuracy of observation of measuring point; The present invention is met the monitoring point survey time number of requirement automatically through the Input Software of measuring point relevant parameter.

3) original data processing module can import the initial data of in-site measurement in the software, and computing automatically obtains the achievement data of each point, and according to the alarm parameters that is provided with, automatically alarm point reported to the police.

4) curve map module.Can load required monitored data according to user's request, draw each phase horizontal movement change curve, each phase horizontal movement rate of change curve map, accumulative total horizontal movement change curve automatically.

5) report output module.This module is provided with initial data output, the output of achievement data, curve map output, can select according to user's request, satisfies engineering demand.

This method has the following advantages:

1) through single station correction method, obtains deep foundation pit engineering in urban horizontal displacement monitoring data.This method is easy and simple to handle, precision is high.

2) owing to different monitoring instruments, its monitoring accuracy is different.Based on the different monitoring accuracy requirements of deep foundation pit engineering in urban, the present invention can calculate the positional accuracy and the survey time number of single station correction method of different measuring points automatically.

3) data subprogram of the present invention has realized the Unified Treatment of original observed data, and possesses the early warning and alarming function.

4) graph making subprogram of the present invention has realized achievement visualization of data function, generates each the phase change curve and the accumulative total change curve of each point automatically, and can visual feedback arrive construction, management, owner unit.

5) data output processing subprogram of the present invention; Realized the formization of monitoring achievement: can be according to the requirement of each monitoring project; With Automatic Combined as requested such as initial data output, the output of achievement data, each phase change curve, accumulative total change curve, and statement form is set automatically.

Claims (3)

1. the horizontal displacement monitoring method of measuring point in the base pit engineering is characterized in that, setting M point and N point earlier is the reference point of foundation ditch horizontal displacement observation, and certain on the MN line is put A and is set up total powerstation, and the A point is website; Then the horizontal movement value of arbitrary observation point i is:

Δ _i＝K _i1·Δβ _i+K _i2·ΔA；

Wherein, Δ _ABe website horizontal movement value, Δ _A=K _AΔ β _a

Wherein, first coefficient $K_A=\frac{S_{\mathrm{MA}}\·S_{\mathrm{NA}}}{S_{\mathrm{MA}}+S_{\mathrm{NA}}}\·\frac{1}{\mathrm{\ρ}},$ Second coefficient $K_{i1}=\frac{S_{\mathrm{IA}}}{\mathrm{\ρ}},$ Tertiary system number $K_{i2}=\frac{S_{\mathrm{IA}}}{S_{\mathrm{MA}}}-1;$

Δ β _iAngle changing value for ∠ MAi;

Δ β _aAngle changing value for ∠ MAN;

S _MAThe distance of ordering to M for the A point;

S _NAThe distance of ordering to N for the A point;

ρ=206265 "; (ρ is a constant in the mapping specialty)

S _IA---the distance that the A point is ordered to i;

Observation point i is positioned at the outer point of MN line.

2. the horizontal displacement monitoring method of measuring point is characterized in that in the base pit engineering according to claim 1, and the middle error of i point horizontal movement does $m_i=\±\frac{1}{2\mathrm{\ρ}}\sqrt{({4\mathrm{\Δ\; \β}}_i^2+{2\mathrm{\Δ\; \β}}_a^2)\·m_S^2+({5S}_{\mathrm{IA}}^2+S_{\mathrm{MA}}^2)m_a^2},$ m _S, m _a---be respectively in the instrument nominal range error in the sum of errors angle, producer provides when dispatching from the factory by instrument.

3. the horizontal displacement monitoring method of measuring point in the base pit engineering according to claim 2; It is characterized in that; The survey time of ordering for i counts n and confirms

n round numbers according to following formula; M is the building that requires or the horizontal movement precision of building.

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