CN105180897A - Method for improving precision of opposite side measurement for settlement of tunnel vault - Google Patents

Abstract

The invention relates to a method for improving the measurement precision of the settlement amount of a tunnel vault, in particular to a method for improving the precision of opposite side measurement for the settlement of the tunnel vault. According to the method, a total station opposite side measuring method is adopted, and the measuring precision is improved by selecting a reasonable rearview point and a total station arrangement position based on the practical measurement situation of the amount of field tunnel vault settlement. The method comprises the steps that firstly, a monitoring point is embedded in the vault position of a monitoring section and is protected so as to prevent the monitoring point from being influenced and damaged in tunnel construction; secondly, a reasonable position is selected to embed a rearview reference point; thirdly, the erecting position of a total station is selected according to the horizontal distance between the embedded rearview reference point and the monitoring point; finally, measuring data are read through the opposite side measuring function of the total station, and protection on the monitoring point and the rearview point is restored after every time measurement is completed.

Description

A kind of method improving Opposite side survey tunnel arch top settlement precision

One, technical field:

The present invention relates to a kind of method improving tunnel arch top settlement measurement accuracy, be specifically related to a kind of method improving Opposite side survey tunnel arch top settlement precision.

Two, background technology:

Vault sinking be tunnel monitoring measurement must survey project, its importance is self-evident.Current vcehicular tunnel vault sinking mainly adopts precision level to measure, but this method for measurement labour intensity is large, efficiency is low, and normal and site operation disturbs mutually.During as stayed Core Soil Ring Cutting in employing arch, tunnel, before Core Soil does not excavate, due to the stop of Core Soil, spirit-leveling instrument and steel ruler cannot be utilized to carry out digital independent effectively, cause the delayed of first measured value, thus lose a part or even most in early stage tunnel wall rock deformation information, monitoring result truly can not intactly react tunnel top deformation.Equally, on-the-spot spirit-leveling instrument Exposure geodetic carries out also there is certain obstruction to normally carrying out of constructing tunnel, affects Tunnel Construction Schedule.Increasing along with current big cross section long tunnel, construction method is changeable, and traditional spirit-leveling instrument contact method for measurement cannot meet modern major long tunnel construction requirement fast and safely.Therefore, a kind of quick, easy, by the little non-contact measurement method of tunnel construction infection---total powerstation Opposite side survey method, be incorporated into gradually in tunnel arch top settlement monitoring measurement.But the measurement accuracy research at present about this measuring method is relatively less, there is no specifically quantitative conclusion as in-site measurement foundation, improve measuring accuracy.

Three, summary of the invention:

In order to solve the weak point in above-mentioned background technology, the invention provides a kind of method improving Opposite side survey tunnel arch top settlement precision, it adopts total powerstation opposite side to measure method, actual conditions are measured based on on-the-spot tunnel arch top settlement, by selecting rational backsight point and total powerstation installation position, improve measuring accuracy.

For achieving the above object, technical scheme of the present invention is: a kind of method improving Opposite side survey tunnel arch top settlement precision, is characterized in that: described method step is:

First, monitoring point is embedded in monitoring section keystone, and protects, avoid monitoring point to be affected destruction in constructing tunnel.

Secondly; rational position is selected to bury backsight reference point underground: two tracks, three lanes are consistent with four lane road tunnel; backsight reference point is embedded in monitoring section rear 50 ~ 150m; apart from the stabilization lining cutting wall within tunnel road surface vertical height 1.2 ~ 1.5m scope, meeting under above condition, if field condition allows; make backsight reference point burial place away from monitoring section as far as possible; after having buried underground, identical with monitoring point, it is protected.

Then, according to the horizontal range between the backsight reference point buried underground and monitoring point, select the decorating position of total powerstation:

When backsight point and monitoring point horizontal range are at 50m ~ 100m, after total powerstation being erected at distance monitoring section 30m;

When backsight point and monitoring point horizontal range are 100 ~ 120m, after total powerstation being erected at distance monitoring section 40m;

When backsight point and monitoring point horizontal range are 120m ~ 150m, after total powerstation being erected at distance monitoring section 50m, and total powerstation decorating position is all between backsight point and monitoring section.

Finally; total powerstation Opposite side survey function is utilized to complete measurement digital independent; and the protection of Restoration monitoring point and backsight point after having measured each time; so; according to the metric data of construction different phase; respectively itself and initial measurement are subtracted each other, calculate the vault sinking result of monitoring section relative to original bulk measured value.

Compared with prior art, the advantage that the present invention has and effect as follows: the advantage that the present invention improves tunnel arch top settlement measurement accuracy method relative to other is: the method is mainly from backsight point burial place and total powerstation installation position, optimal location parameter is quantized, visual result, easily performs; Sets forth corresponding optimal location parameter for two tracks, three lanes, four lane road tunnel, result is comprehensive, is more conducive to Fruits popularize; The method is strictly according to Opposite side survey principle and law of propagation of errors, and measure actual conditions in conjunction with on-the-spot tunnel arch top settlement, fiduciary level is high simultaneously.

Four, accompanying drawing illustrates:

Fig. 1 is Opposite side survey tunnel arch top settlement schematic diagram;

Fig. 2 calculates schematic diagram for measuring plane projection;

Fig. 3 is that reflection diaphragm is pasted;

Fig. 4 is measuring point protection;

Fig. 5 is the distance accuracy influence coefficient k of different vertical angle _s;

Fig. 6 is Three-Lane Highway Tunnel m _hwith x value situation of change;

Fig. 7 is LK26+233 section vault sinking tense curve;

Fig. 8 is LK26+239 section vault sinking tense curve;

Fig. 9 is LK26+245 section vault sinking tense curve.

Five, embodiment:

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail:

First, burying underground and protecting of monitoring point is carried out.

When tunnel arch top settlement measures, a monitoring point need be laid at monitoring section keystone place, the A point namely shown in Fig. 1.When monitoring point is buried underground, first using pre-processed steel plate as reflection diaphragm base, be welded on the keystone on face the one Pin shaped steel arch.Then, reflection diaphragm is pasted onto on the steel plate fixedly completed.Before construction of shotcrete, the object such as polybag or geotextile must be wrapped on measuring point and be protected, avoid reflection diaphragm contaminated, destroy.After sprayed concrete operation completes, untie protection object, carry out the reading of initial reading immediately.Initial measurement and afterwards after measurement completes each time, measuring point protection must be recovered in time, in order to avoid Tunnel during Construction reflection diaphragm surface is contaminated, affect the accuracy of measurement data.In addition, in whole observation process, the co-ordination with relevant departments should be strengthened, avoid causing the position skew of measuring point because of constructing tunnel or destroying.

Then, set up total powerstation Opposite side survey tunnel arch top settlement accuracy computation model, and analyze.

General measure precision is by measuring medial error evaluation.Can be obtained by Fig. 1, P, A point-to-point transmission discrepancy in elevation h _pAcomputing formula be:

h _PA＝h _P-h _A＝S _Psinα _P-S _Asinα _A(1)

Wherein, S _p, S _abe respectively OP, OA oblique distance, α _p, α _abe respectively OP, OA and measure vertical angle.

Do not consider the impact of earth curvature and Atmosphere Refraction, total differential carried out to formula (1), and according to law of propagation of errors, obtain tunnel arch top settlement medial error computing formula:

$\begin{array}{c}{m}_{h_{PA}}^2={\sin }^2{\mathrm{\α}}_A{m}_{S_A}^2+\frac{1}{{\mathrm{\ρ}}^2}{d}_A^2{m}_{{\mathrm{\α}}_A}^2+\\ {\sin }^2{\mathrm{\α}}_P{m}_{S_P}^2+\frac{1}{{\mathrm{\ρ}}^2}{d}_P^2{m}_{{\mathrm{\α}}_p}^2\end{array}---\left(2\right)$

Wherein, ρ=206265 ", be respectively S _p, S _a, α _p, α _ameasurement medial error.

Assuming that total powerstation distance accuracy ms and angle measurement accuracy m _αall equal, namely

$m_{S_P}=m_{S_A}=m_S,m_{a_P}=m_{a_A}=m_a,$ Then can obtain:

$\begin{array}{c}{m}_{h_{PA}}=\±\sqrt{({\sin }^2{\mathrm{\α}}_A+{\sin }^2{\mathrm{\α}}_P)m_S^2+\frac{1}{{\mathrm{\ρ}}^2}\left(D_A^2+D_P^2\right)m_{\mathrm{\α}}^2}\\ =\±\sqrt{(k_S^2{m}_S^2+k_{\mathrm{\α}}^2{m}_{\mathrm{\α}}^2)}\end{array}---\left(5\right)$

Wherein, k _sfor distance accuracy influence coefficient, k _αfor angle measurement accuracy influence coefficient for total powerstation Opposite side survey discrepancy in elevation medial error.

Based on this, measure actual conditions in conjunction with on-the-spot vault sinking, analyze different spans tunnel backsight reference point installation position different from total powerstation to the impact of vault sinking measuring accuracy.

Secondly, burying underground and total powerstation erection of backsight reference point is completed.

According to different spans tunnel Opposite side survey tunnel arch top settlement precision analysis result, determine backsight reference point and total powerstation Reasonable Arrangement position.Two tracks, three lanes are consistent with four lane road tunnel, and backsight reference point should be embedded in apart from tunnel road surface vertical height 1.2 ~ 1.5m place, makes it close with total powerstation antenna height, guarantee measurement vertical angle a _pbetween 0 ° ~ 5 °.Meanwhile, backsight reference point should be embedded in 50 ~ 150m stabilization lining cutting wall place, monitoring section rear, and at the scene in conditions permit situation, makes it near monitoring section as far as possible.The protection of backsight reference point is identical with monitoring point.Total powerstation is erected between backsight reference point and monitoring section, and particular location is as shown in table 1.

Finally, utilize total powerstation Opposite side survey function to complete the reading of metric data, calculate the vault sinking result of monitoring section relative to initial measurement.

After total powerstation has set up, the Opposite side survey function selecting instrument to carry, the reflection diaphragm central point of aiming point P and some A, just directly can read P, A 2 discrepancy in elevation h in screen respectively _pA.In essence, drawing of this value utilizes total powerstation self plug-in, by directly measuring oblique distance, the vertical angle between total powerstation center and measuring point, calculates by formula (1).After having measured each time, must the protection of Restoration monitoring point and backsight benchmark.So, measure according to construction different phase the h obtained _pAvalue, subtracts each other itself and initial measurement respectively, calculates the vault sinking result of monitoring section relative to original bulk measured value.

Embodiment

Measure for the maximum excavatoin line horizontal convergence of Shenmu County of Shaanxi Province to Fugu highway big cross section three lanes Highway Tunnel in Loess, describe in detail.

When measuring point is buried underground, first using pre-processed steel plate as reflection diaphragm base, be welded on the keystone on face the one Pin shaped steel arch after tunnel excavation, the A point correspondence position namely shown in Fig. 1.Then, reflection diaphragm is pasted onto on the steel plate fixedly completed, as shown in Figure 3.After reflection diaphragm has been pasted, geotextile be wrapped on measuring point, blend compounds band carries out winding and ties up (as shown in Figure 4), is protected, avoid reflection diaphragm contaminated when sprayed concrete, destroy.

According to the actual profile size of relied on big cross section Three-Lane Highway Tunnel, getting monitoring point far from the vertical height on road surface is 9.2m, apart from the vertical height h of total powerstation central point _afor 8m.In measuring process, be semiobservation angle value because opposite side measures angle measurement β, therefore get m _β=m _half-angle=± 2 ".Total station survey precision is " m _s=2+2ppm, m α=1 " ".Based on more than, computation and measurement vertical angle α _p, α _adistance accuracy k when getting different value respectively _ssize, as shown in Figure 5.

Can be obtained by Fig. 5, k _salong with measurement vertical angle a _pand a _aincrease and increase, and change is obviously.Therefore, during vault sinking measures at the scene, backsight reference point can be embedded in apart from vertical height 1.2 ~ 1.5m place, road surface, make it close with total powerstation antenna height, thus ensure vertical angle a _pbetween 0 ° ~ 5 °, to reduce angle measurement accuracy influence coefficient k _s, improve measuring accuracy.

Fig. 1 is carried out horizontal projection, and set the vertical range of total powerstation central point O to PA horizontal projection P ＇ A ＇ as y, its intersection point O ＇ be x apart from the distance of A ＇, as shown in Figure 2.Based on the geometrical property in tunnel, as backsight point and monitoring point horizontal range D _pAwhen being 50 ~ 150m, the change of y value is right impact less, therefore get y=0, and suppose a _p=5 °, only consider to calculate the impact of x value change on measuring accuracy, result of calculation as shown in Figure 6.

Can be obtained by Fig. 6, when total powerstation is erected at backsight point and monitoring section between the two, and 50m≤D _pA≤ 100m, x>=30m; 100m≤D _pA≤ 120m, x>=40m; 120m≤D _pA≤ 150m, x>=50m, measures medial error value all lower than 0.65mm.In addition, along with D _pAthe increase of value, medial error value entirety increases, and therefore, when backsight reference point is buried underground, at the scene in conditions permit situation, is embedded in away from monitoring section position as far as possible.During measurement, total powerstation decorating position is depending on backsight reference point location, and all between backsight reference point and monitoring section, particular location is as shown in table 1.

During table 1 tunnel arch top settlement measures, total powerstation rational position is selected

Note: total powerstation decorating position is all between backsight point and monitoring section.

After construction of shotcrete completes, take off the protection object of monitoring point and backsight point in time, and set up total powerstation, read metric data, as vault sinking monitoring initial reading.During measurement, first select the Opposite side survey function that total powerstation carries, then distinguish the reflection diaphragm central point of aiming point P and some A, so just can directly read PA point-to-point transmission discrepancy in elevation h on total powerstation screen _pA, complete initial measurement.

Initial measurement and afterwards after measurement completes each time, the protection of Restoration monitoring point and backsight point, avoids reflection diaphragm surface in constructing tunnel contaminated, affects the accuracy of measurement data all in time.Meanwhile, in whole observation process, strengthen the co-ordination with relevant departments, avoid causing the position skew of two monitoring points because of constructing tunnel or destroying.

So, according to the h that the measurement of construction different phase obtains _pAvalue, subtracts each other itself and initial measurement respectively, calculates the deflection of tunnel monitoring section vault relative to initial measurement.Monitoring result as figure 7 ?shown in 9.

From figure 7 ?9, this Opposite side survey method measurement result and measurement of coordinates basically identical, results change rule and spirit-leveling instrument are measured substantially identical.Therefore, the method not only compensate for the shortcoming that vault sinking shortage of data in early stage measured by spirit-leveling instrument, and ensure that measuring accuracy well, and measurement effect is desirable.

Claims (1)

1. improve a method for Opposite side survey tunnel arch top settlement precision, it is characterized in that: described method step is:

First, monitoring point is embedded in monitoring section keystone, and protects, avoid monitoring point to be affected destruction in constructing tunnel.

Secondly; rational position is selected to bury backsight reference point underground: two tracks, three lanes are consistent with four lane road tunnel; backsight reference point is embedded in monitoring section rear 50 ~ 150m; apart from the stabilization lining cutting wall within tunnel road surface vertical height 1.2 ~ 1.5m scope, meeting under above condition, if field condition allows; make backsight reference point burial place away from monitoring section as far as possible; after having buried underground, identical with monitoring point, it is protected.

Then, according to the horizontal range between the backsight reference point buried underground and monitoring point, select the decorating position of total powerstation:

When backsight point and monitoring point horizontal range are at 50m ~ 100m, after total powerstation being erected at distance monitoring section 30m;

When backsight point and monitoring point horizontal range are 100 ~ 120m, after total powerstation being erected at distance monitoring section 40m;

When backsight point and monitoring point horizontal range are 120m ~ 150m, after total powerstation being erected at distance monitoring section 50m, and total powerstation decorating position is all between backsight point and monitoring section.

Finally; total powerstation Opposite side survey function is utilized to complete measurement digital independent; and the protection of Restoration monitoring point and backsight point after having measured each time; so; according to the metric data of construction different phase; respectively itself and initial measurement are subtracted each other, calculate the vault sinking result of monitoring section relative to original bulk measured value.