CN102864754A - Measuring and controlling method of scouring depth of training wall of river reach of bridge site - Google Patents

Abstract

The invention belongs to the field of bridge design, and provides a measuring and controlling method of scouring depth of a training wall of a river reach of a bridge site. The method comprises the following steps of: carrying out a stream deviation scouring experiment, a multi-stream scouring shifting bed model experiment and a projection flow rate shifting bed model experiment; and analyzing the experiment results. A hydraulics generalization experiment for the flood peak constant flow process and a typical shifting bed model experiment for flood peak non-constant flow process are adopted to research the training wall scouring depth problem, and the problem that when the scouring depth of the training wall of the river reach of the bridge site is calculated by the existing formula, the scouring depth does not meet the actual situation of a high-gradient gravel-cobble river is solved, so that the scientific and reasonable arrangement of the training river at the river reach of the bridge site is ensured, and the water flow conditions at the bridge site are improved, water and sand are discharged smoothly at the bridge opening, the approach embankment of a bridge and a bridge head is protected, the bridge site is stabilized, and the bridge crossing safety is prevented from being threatened by disadvantageous evolution of the river reach.

Description

The investigating method of a kind of bridge location section trraning pole scour depth

Technical field

The invention belongs to the bridge design field, relate in particular to the investigating method of a kind of bridge location section trraning pole scour depth.

Background technology

According to many years of experience, mainly be trraning pole than the regulating structure that falls the use of ovum Gravel River greatly at present.Trraning pole is divided into closed trraning pole, shaped form trraning pole and three kinds of plane patterns of pyriform dike, wherein adopts closed trraning pole more.Current specifications mainly adopts the Wang Di of Research Institute of Highway, Ministry of Communications hold to wait at " standard " (JTJ062-91) the following formula of suggestion employing in (nineteen ninety):

$h_b=1.45{\left(\frac{D_t}{h}\right)}^{0.4}\left(\frac{v-v_0^{\′}}{v_0}\right)h{K}_m---\left(1\right)$

h _b---trraning pole head scour depth;

D _i---upstream trraning pole head end points is to water depth, in the projected length (m) of Transverse to the flow direction;

H---trraning pole head washes away the front depth of water (m);

V---trraning pole head wash away front flow velocity;

v ₀---dike head sediment moving incipient velocity, adopt the Zhang Ruijin formula;

D---get d ₅₀(m);

V ' ₀---dike head silt plays swash of wave speed;

K _m---the side slope reduction coefficient; K _m=e ^-0.2m, m is the jetty head slope coefficient.

Suppose to arrange the curve trraning pole at three village river bridges and Baicheng bridge, its design discharge, riverbed width see Table 1, and according to (1) formula, the trraning pole scour depth of river, three villages bridge, Baicheng bridge is respectively 4.06m, 11.62m.

Table 1 three village river bridge and Baicheng bridge trraning pole scour depths

Fall the characteristics that ovum Gravel River bridges and culverts is constructed according to large ratio, because groundwater level is higher, be generally about 2m in cutting depth possible below the riverbed, maximum value is 3m.Can't reach construction requirement from river, the three villages bridge that calculates, the trraning pole scour depth of Baicheng bridge.

Have wide shallow property, transition than falling the ovum Gravel River greatly, its bed sloped is large, the riverbed composition is mainly the ovum gravel.It is the most violent that trraning pole mainly is that the plume in flood water-break process washes away, and the magnitude relationship of peak flood flow is little, and practical experience for many years also shows this point, and present method and actual conditions are inconsistent.

Summary of the invention

The invention provides the investigating method of a kind of bridge location section trraning pole scour depth, being intended to solve large ratio falls the ovum Gravel River and has wide shallow property, transition, its bed sloped is large, the riverbed composition is mainly the ovum gravel, trraning pole mainly is that the plume in flood water-break process washes away the most violent, and the magnitude relationship of peak flood flow is little, and present method is when determining bridge location section trraning pole scour depth and the inconsistent problem of actual conditions.

The object of the present invention is to provide the investigating method of a kind of bridge location section trraning pole scour depth, described investigating method may further comprise the steps:

The first step: get sand in river bed boring by bridge location section rig, with the sieve sorting bed materials at different levels of different screen apertures, use scales/electronic balance weighing, calculate the quality less than a certain particle diameter, particle diameter is determined with particle size analyzer less than the bed material of 1mm, draws graduation curve and determines bed material median particle diameter d ₅₀

Second step: collect the front bridge location section topographic map of bridge construction, respectively select a section as calculating starting point in straight section of bridge location upstream and downstream 1～2km river course, choose near the river bed landform altitude minimum point main flow riverbed, between two sections, draw talweg along the main flow riverbed, measure two section spacings from, obtain spacing between two sections of natural section according to the drawing guide, calculate the bed surface ratio and fall J;

The 3rd step: fall ovum Gravel River factual survey result according to large ratio, in the 1m tank, concentrate plume deflection washout test; Use the frequency converter automatic control flow, measure water level and wash away the section landform with level gauge, local velocity is measured with revolving oar flow velocity device;

The 4th step: according to concentrated plume deflection washout test, model bed sloped J=0.01, toe slope coefficient are got 0 and 1.5 liang of group, the angle that becomes a mandarin and are got 90 ° and 60 ° of two angles, bed material median particle diameters and get 0.054m, and three groups of bed materials of 0.033m and 0.013m, control discharge per unit width Q are 1.74m ³/ s, 2.90m ³/ s, 4.07m ³/ s and 5.81m ³Four groups of/s amount to 48 groups experiments, measure scour depth with level gauge, and adopt least square method to carry out the multi-parameter correlated fitting to draw trraning pole plume scour depth h _D1Design formulas;

The 5th step: arrange that the multiply plume washes away movable bed model, the trraning pole form adopts the straight curve closing form, according to being arranged symmetrically with, trraning pole length arranges 70m and two schemes of 50m, model bed sloped J gets 0.015,0.01,0.005,0.003 and five kinds of situations such as 0.001 grade, 9 kinds of situations of bridge location discharge per unit width control, the angle of cut of trraning pole and flood main flow is 30 °, and bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranges, the span layout spacing is the bridge pier of 1m, measures scour depth with level gauge;

The 6th step: to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, adopt correlation analysis to carry out match and draw the multiply plume and wash away trraning pole bed surface limiting scour h _D2Design formulas;

The 7th step: trraning pole is arranged 30 ° of trraning poles, 60 ° of trraning poles, three kinds of schemes of 90 ° of trraning poles, the bed material median particle diameter is 0.03315m, the three kinds of situations such as 0.005,0.01 and 0.015 of getting fall in the model ratio, the many groups of control projection flow is tested, amount to 30 groups experiments, measure scour depth with level gauge;

The 8th step: to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, trraning pole curved section central angle β adopts correlation analysis to carry out match and gets the degree of depth h that the projection flow washes away trraning pole _D3Design formulas.

Further, when arranging that the projection flow washes away movable-bed model test, trraning pole also can be arranged 30 ° of pyriform dikes, 60 ° of pyriform dikes, three kinds of schemes of 90 ° of pyriform dikes.

Further, concentrate plume deflection washout test to be arranged in the tank of wide 1m in the described investigating method and carry out, trraning pole meets water and has domaticly carried out altogether 48 groups times test under two kinds of gradients.

Further, basis is large than falling ovum Gravel River water-sediment movement rule and experimental phenomena analysis as can be known in the described investigating method, and plume is subjected to following factor affecting to the trraning pole scour depth:

Plume is big or small, mainly refers to the size of plume flow, represents with discharge per unit width that still test shows that plume is larger, and the lumped scour degree of depth is darker;

The plume inflow angle, plume and trraning pole angle are larger, then wash away deeplyer, and scour depth is maximum when plume vertically washes away trraning pole;

The riverbed particle diameter, the riverbed particle diameter is thinner, and silt is easier to be washed away by plume, and trraning pole washes away darker;

Trraning pole upstream face side slope, grade of side slope is more slow, and then plume washes away also less.When trraning pole adopted straight wall type side slope, scour depth was maximum.

Further, adopt least square method to carry out the multi-parameter correlated fitting to each factor in the described investigating method, draw trraning pole plume scour depth design formulas:

$h_{d1}=2.02q^{0.46}{e}^{-0.2n}\left(\frac{\mathrm{\α}}{90}\right){d_{50}}^{-0.07}$

In the formula, h _D1The degree of depth that the lower plume of-different angles impact washes away trraning pole, unit is m;

N-trraning pole grade of side slope, 1: m;

α-plume flows to and the trraning pole axis angle of cut, and α gets 90 ° during the pyriform dike; In the time of can't determining, suggestion is got 60 °.

Further, arrange when the multiply plume washes away movable bed model in the described investigating method, the trraning pole form adopts the straight curve closing form, according to being arranged symmetrically with, the angle of cut of trraning pole and flood main flow is 30 °, bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranged, the span layout spacing was the bridge pier of 1m.

Further, adopt correlation analysis to carry out match to the result who washes away statistics in the described investigating method, set up the trraning pole scour depth with discharge per unit width Q, than falling J, interrelation of particle size:

$h_{d2}=0.975Q^{0.57}{J}^{0.3}{d}_{50}^{-0.08}$

In the formula: h _D2-multiply plume washes away the following limiting scour of trraning pole bed surface, and unit is m;

Q-trraning pole projection flow, m ³/ s.

Further, in the described investigating method in typical peak flood flow process, position and time that the plume deflection is washed away trraning pole all have very large randomness, index of correlation is relatively poor, the formation of plume is relevant with the riverbed fringe conditions with inlet flow conditions, the multiply plume is united time, position and the degree of depth of washing away trraning pole and is had very strong randomness, also can express with following relation:

$h_{d2}=\left\{\begin{array}{c}2.0m....................J\&le;0.005\\ 2.0-3.0m.............0.005\&le;J<0.008\\ 3.0-3.5m.............0.008\&le;J<0.01\\ 3.5-4.5m.............0.010\&le;J\&le;0.015\end{array}\right.$

Further, adopt correlation analysis to carry out match to washing away statistics in the described investigating method, set up the trraning pole scour depth with discharge per unit width Q, than falling J, particle diameter d ₅₀Correlation:

$h_{d3}=0.7Q^{067}{J}^{0.33}{d}_{50}^{-008}{\left(\frac{\mathrm{\&beta;}}{90}\right)}^{0.5}$

In the formula: h _D3-projection flow washes away the degree of depth of trraning pole, and unit is m;

Discharge per unit width and trraning pole are at the product of cross section of bridge site projected length before the Q-trraning pole projection flow, bridge construction, and unit is m ³/ s;

β-trraning pole curved section central angle, β gets 90 ° during the pyriform dike.

The investigating method of bridge location provided by the invention section trraning pole scour depth; carried out respectively plume deflection washout test; the multiply plume washes away movable-bed model test; the projection flow washes away movable-bed model test; and experimental result analyzed; employing only has the hydraulics of flood peak steady flow process generally to change test and typical flood peak unsteady flow process movable-bed model test research trraning pole scour depth problem; solve existing formula and when calculating bridge location section trraning pole scour depth, fallen the inconsistent problem of ovum Gravel River actual conditions with large ratio; guaranteed to arrange in the bridge location section science of trraning pole; reasonability; improved the flow condition at bridge location place; make the unobstructed draining sand discharge of bridge opening; bridge and bridge approach embankment have been protected; stablized bridge location, prevented that the unfavorable differentiation in river course from threatening bridge to cross safety.

Description of drawings

Fig. 1 shows the realization flow figure of the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides;

Fig. 2 shows the schematic diagram of trraning pole deflection flush water mechanical test of the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides;

Fig. 3 shows the different angles plume deflection of the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides and washes away trraning pole schematic design schematic diagram;

The trraning pole projection flow that Fig. 4 shows the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides washes away the movable-bed model test schematic diagram;

The multiply plume that Fig. 5 shows the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides washes away movable bed test schematic layout diagram.

The specific embodiment

In order to make purpose of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further described in detail.Should be appreciated that specific embodiment described herein only in order to explaining the present invention, and be not used in and limit invention.

Fig. 1 shows the realization flow of the investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides.

This investigating method may further comprise the steps:

In step S101, get sand by bridge location section rig in river bed boring, sieve sorting bed materials at different levels with different screen apertures, use scales/electronic balance weighing, calculating is less than the quality of a certain particle diameter, particle diameter is determined with particle size analyzer less than the bed material of 1mm, draws graduation curve and determines bed material median particle diameter d ₅₀

In step S102, collect the front bridge location section topographic map of bridge construction, respectively select a section as calculating starting point in straight section of bridge location upstream and downstream 1～2km river course, choose near the river bed landform altitude minimum point main flow riverbed, between two sections, draw talweg along the main flow riverbed, measure two section spacings from, obtain spacing between two sections of natural section according to the drawing guide, calculate the bed surface ratio and fall J;

In step S103, ovum Gravel River factual survey result falls according to large ratio, in the 1m tank, concentrate plume deflection washout test; Use the frequency converter automatic control flow, measure water level and wash away the section landform with level gauge, local velocity is measured with revolving oar flow velocity device;

In step S104, according to concentrated plume deflection washout test, model bed sloped J=0.01, toe slope coefficient are got 0 and 1.5 liang of group, the angle that becomes a mandarin and are got 90 ° and 60 ° of two angles, bed material median particle diameters and get 0.054m, and three groups of bed materials of 0.033m and 0.013m, control discharge per unit width Q are 1.74m ³/ s, 2.90m ³/ s, 4.07m ³/ s and 5.81m ³Four groups of/s amount to 48 groups experiments, measure scour depth with level gauge, and adopt least square method to carry out the multi-parameter correlated fitting to draw trraning pole plume scour depth h _D1Design formulas;

In step S105, arrange that the multiply plume washes away movable bed model, the trraning pole form adopts the straight curve closing form, according to being arranged symmetrically with, trraning pole length arranges 70m and two schemes of 50m, model bed sloped J gets 0.015,0.01,0.005,0.003 with five kinds of situations such as 0.001 grade, 9 kinds of situations of bridge location discharge per unit width control, the angle of cut of trraning pole and flood main flow is 30 °, bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranged, the span layout spacing was the bridge pier of 1m, measures scour depth with level gauge;

In step S106, to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, adopt correlation analysis to carry out match and draw the multiply plume and wash away trraning pole bed surface limiting scour h _D2Design formulas;

In step S107, trraning pole is arranged 30 ° of trraning poles, 60 ° of trraning poles, three kinds of schemes of 90 ° of trraning poles, the bed material median particle diameter is 0.03315m, the three kinds of situations such as 0.005,0.01 and 0.015 of getting fall in the model ratio, the many groups of control projection flow is tested, amount to 30 groups experiments, measure scour depth with level gauge;

In step S108, to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, trraning pole curved section central angle β adopts correlation analysis to carry out match and gets the degree of depth h that the projection flow washes away trraning pole _D3Design formulas.

In embodiments of the present invention, concentrate plume deflection washout test to be arranged in the tank of wide 1m and carry out, trraning pole meets water and has domaticly carried out altogether 48 groups times test under two kinds of gradients.

In embodiments of the present invention, fall ovum Gravel River water-sediment movement rule and experimental phenomena analysis as can be known according to large ratio, plume is subjected to following factor affecting to the trraning pole scour depth:

Plume is big or small, mainly refers to the size of plume flow, represents with discharge per unit width that still test shows that plume is larger, and the lumped scour degree of depth is darker;

The plume inflow angle, plume and trraning pole angle are larger, then wash away deeplyer, and scour depth is maximum when plume vertically washes away trraning pole;

The riverbed particle diameter, the riverbed particle diameter is thinner, and silt is easier to be washed away by plume, and trraning pole washes away darker;

Trraning pole upstream face side slope, grade of side slope is more slow, and then plume washes away also less.When trraning pole adopted straight wall type side slope, scour depth was maximum.

In embodiments of the present invention, adopt least square method to carry out the multi-parameter correlated fitting to each factor, draw trraning pole plume scour depth design formulas:

$h_{d1}=2.02q^{0.46}{e}^{-0.2n}\left(\frac{\mathrm{\&alpha;}}{90}\right){d_{50}}^{-0.07}$

In the formula, h _D1The degree of depth that the lower plume of-different angles impact washes away trraning pole, unit is m;

N-trraning pole grade of side slope, 1: m;

α-plume flows to and the trraning pole axis angle of cut, and α gets 90 ° during the pyriform dike; In the time of can't determining, suggestion is got 60 °.

In embodiments of the present invention, arrange that when the multiply plume washed away movable bed model, the trraning pole form adopted the straight curve closing form, according to being arranged symmetrically with, the angle of cut of trraning pole and flood main flow is 30 °, and bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranged, the span layout spacing was the bridge pier of 1m.

In embodiments of the present invention, adopt correlation analysis to carry out match to the result who washes away statistics, set up the trraning pole scour depth with discharge per unit width Q, than falling J, interrelation of particle size:

$h_{d2}=0.975Q^{0.57}{J}^{0.3}{d}_{50}^{-0.08}$

In the formula: h _D2-multiply plume washes away the following limiting scour of trraning pole bed surface, and unit is m;

Q-trraning pole projection flow, m ³/ s.

In embodiments of the present invention, in typical peak flood flow process, position and time that the plume deflection is washed away trraning pole all have very large randomness, index of correlation is relatively poor, the formation of plume is relevant with the riverbed fringe conditions with inlet flow conditions, the multiply plume is united time, position and the degree of depth of washing away trraning pole and is had very strong randomness, also can express with following relation:

$h_{d2}=\left\{\begin{array}{c}2.0m....................J\&le;0.005\\ 2.0-3.0m.............0.005\&le;J<0.008\\ 3.0-3.5m.............0.008\&le;J<0.01\\ 3.5-4.5m.............0.010\&le;J\&le;0.015\end{array}\right.$

In embodiments of the present invention, adopt correlation analysis to carry out match to washing away statistics, set up the trraning pole scour depth with discharge per unit width Q, than falling J, particle diameter d ₅₀Correlation:

$h_{d3}=0.7Q^{067}{J}^{0.33}{d}_{50}^{-0.08}{\left(\frac{\mathrm{\&beta;}}{90}\right)}^{0.5}$

In the formula: h _D3-projection flow washes away the degree of depth of trraning pole, and unit is m;

Discharge per unit width and trraning pole are at the product of cross section of bridge site projected length before the Q-trraning pole projection flow, bridge construction, and unit is m3/s;

β-trraning pole curved section central angle, β gets 90 ° during the pyriform dike.

Below in conjunction with drawings and the specific embodiments application principle of the present invention is further described.

The effect of trraning pole and flat linearity:

Arrange the medical treatment structure in the bridge location section, not only confinement of flow improves the flow condition at bridge location place, makes the unobstructed draining sand discharge of bridge opening, but also will protect bridge and bridge approach embankment, stablizes bridge location, prevents that the unfavorable differentiation in river course from threatening bridge to cross safety.Bridge crosses the medical treatment structure and is divided into four classes by effect: diversion structure, choose the stream building, Gu end building, the slope reinforcement building.

Diversion structure also claims trraning pole, and Main Function is medical treatment upstream current, makes water flow mud-sand pass through smoothly bridge opening.Bridge trraning pole form is more, and commonly used have a shaped form, straight bent complex, and pyriform dike etc., large is at most closed form than falling the employing of ovum Gravel River section.

The pyriform dike is a kind of special shape of trraning pole, is mainly used in the larger section of cross flow or breadth depth ratio.The pyriform dike generally is comprised of forward and reverse circular arc line.

Large larger than falling ovum Gravel River section plume swing property, scouring capability is strong, and washes away angle direction and have randomness, and the different angle trraning pole scour depths that become a mandarin differ very large.Although the water-break flow in process of flood is little, because of the lumped scour of plume, usually cause the scour depth of trraning pole larger than flood peak period.Concentrate plume deflection washout test to be arranged in the tank of wide 1m and carry out, trraning pole meets water and has domaticly carried out altogether 48 groups times test under two kinds of gradients.Test is arranged schematic diagram as shown in Figure 2, test parameters and the results are shown in Table 2.

Table 2 plume deflection is washed away trraning pole degree of depth statistical form

Fall ovum Gravel River water-sediment movement rule and experimental phenomena analysis as can be known according to large ratio, plume is subjected to following factor affecting to the trraning pole scour depth:

1. plume is big or small.Mainly refer to the size of plume flow, still represent with discharge per unit width that test shows that plume is larger, the lumped scour degree of depth is darker.

2. plume inflow angle.Plume and trraning pole angle are larger, then wash away deeplyer, and scour depth is maximum when plume vertically washes away trraning pole.

3. riverbed particle diameter.The riverbed particle diameter is thinner, and silt is easier to be washed away by plume, and trraning pole washes away darker.

4. trraning pole upstream face side slope.Grade of side slope is more slow, and then plume washes away also less.When trraning pole adopted straight wall type side slope, scour depth was maximum.

According to above analysis, adopt least square method to carry out the multi-parameter correlated fitting to each factor, draw trraning pole plume scour depth design formulas:

$h_{d1}=2.02q^{0.46}{e}^{-02n}\left(\frac{\mathrm{\&alpha;}}{90}\right){d_{50}}^{-007}---(6-1)$

In the formula, h _D1The lower plume of-different angles impact washes away the degree of depth (referring to the distance that bed surface is following) of trraning pole, m;

N-trraning pole grade of side slope, 1: m;

α-plume flows to and the trraning pole axis angle of cut, and α gets 90 ° during the pyriform dike; In the time of can't determining, suggestion is got 60 °; E=2.7183.

Following formula is according to drawing than falling ovum Gravel River section movable bed test simulation greatly, good relationship, has certain representativeness, but still there are in actual use some problems, at first the size of plume flow is difficult for determining, next is that the inflow angle of plume is difficult to determine, thereby it is larger really to use difficulty.But however, it still has definite meaning, and this formula can illustrate the plume scour depth is subjected to the impact of which factor, and can make an estimate on affecting size by formula.

The multiply plume washes away movable-bed model test

Movable-bed model test shows, trraning pole washes away and is generally the multiply plume and unites and wash away.Washing away the position can be the dike head part, also can be the levee body part.Washing away maximum time of origin may be flood peak period, also may be plume lumped scour in the flood water-break process.Namely in the whole process of flood, trraning pole base angle position maximum is washed away the optional position that may occur in any time.Owing to determine in the movable bed model comparatively difficulty of plume discharge per unit width size, so the scour depth of trraning pole sub-thread plume when washing away formula and can only reflect larger estimation plume, the trraning pole scour depth in the various plume situations can not be reflected fully.

The multiply plume washes away the movable bed model layout and sees Fig. 5.The trraning pole form adopts the straight curve closing form, and according to being arranged symmetrically with, the angle of cut of trraning pole and flood main flow is 30 °, and bridge length is generalized as 1m and two kinds of situations of 3m.And when 3m arranged, the span layout spacing was the bridge pier of 1m.

Flood events in the test, multiply plume wash away the position of trraning pole in continuous variation.During later water-break process 30min of flood peak duration, the trraning pole limiting scour is 15cm, and the position is at the 2m place.During 150min in the water-break process, two larger scour holes appear, i.e. 4m place and 1m place, and scour depth is respectively 13cm, 12cm.When 180min, 3 scour holes appear, i.e. 4m place, 2m place, 0m place, scour depth is respectively 20cm, 10cm, 9cm.When the maximum scour hole of whole peb process appears at 210min in the water-break process, trraning pole 5m place, washing away depth capacity is 22cm, is equivalent to prototype 3.3m.

Multiply plume washout test the results are shown in Table 3.

The movable-bed model test of many groups the analysis showed that, there is very large randomness depth capacity and position that multi-strand flow washes away trraning pole, namely washing away maximum time of origin may be any time of flood peak period and flood water-break process, and washing away the position may be any position of trraning pole.

Table 3 trraning pole multiply plume limiting scour statistics

Adopt correlation analysis to carry out match to the result who washes away statistics, set up the trraning pole scour depth with discharge per unit width Q, than falling J, particle diameter d ₅₀Correlation:

$h_{d2}=0.975Q^{0.57}{J}^{0.3}{d}_{50}^{-0.08}---\left(2\right)$

In the formula: h _D2-multiply plume washes away the following limiting scour of trraning pole bed surface, m; Q-trraning pole projection flow, m ³/ s.

In typical peak flood flow process, position and time that the plume deflection is washed away trraning pole all have very large randomness, and index of correlation is relatively poor.The formation of plume is relevant with the riverbed fringe conditions with inlet flow conditions, and the multiply plume is united time, position and the degree of depth of washing away trraning pole and had very strong randomness, also can express with following relation.

$h_{d2}=\left\{\begin{array}{c}2.0m....................J\&le;0.005\\ 2.0-3.0m.............0.005\&le;J<0.008\\ 3.0-3.5m.............0.008\&le;J<0.01\\ 3.5-4.5m.............0.010\&le;J\&le;0.015\end{array}\right.---\left(3\right)$

The projection flow washes away movable-bed model test

Behind the trraning pole compression riverbed, trraning pole is not only wanted the training current, also will bear in the scope of meeting water and wash away.It is the principal mode that full riverbed flood washes away the trraning pole that meets water that the projection flow washes away, larger on the impact of trraning pole embedded depth of foundation, the projection flow washes away the trraning pole movable-bed model test and sees Fig. 4, arranges the three kinds of forms that mainly contain: 30 ° of trraning poles, 60 ° of trraning poles, 90 ° of trraning poles (pyriform dike).

The result of the test arrangement sees Table 4.Adopt correlation analysis to carry out match to washing away statistics, set up the trraning pole scour depth with discharge per unit width Q, than falling J, particle diameter d ₅₀Correlation, as shown in Figure 4.

$h_{d3}=0.7Q^{0.67}{J}^{033}{d}_{50}^{-008}{\left(\frac{\mathrm{\&beta;}}{90}\right)}^{05}---(6-4)$

In the formula: h _D3-projection flow washes away the degree of depth (referring to the degree of depth that natural bed surface is following) of trraning pole, m;

Discharge per unit width and trraning pole are at the product of cross section of bridge site projected length, m before the Q-trraning pole projection flow, bridge construction ³/ s;

β-trraning pole curved section central angle, β gets 90 ° during the pyriform dike.

Table 4 trraning pole projection flow limiting scour statistics

The investigating method of the bridge location section trraning pole scour depth that the embodiment of the invention provides; carried out respectively plume deflection washout test; the multiply plume washes away movable-bed model test; the projection flow washes away movable-bed model test; and experimental result analyzed; employing only has the hydraulics of flood peak steady flow process generally to change test and typical flood peak unsteady flow process movable-bed model test research trraning pole scour depth problem; solve existing formula and when calculating bridge location section trraning pole scour depth, fallen the inconsistent problem of ovum Gravel River actual conditions with large ratio; guaranteed to arrange in the bridge location section science of trraning pole; reasonability; improved the flow condition at bridge location place; make the unobstructed draining sand discharge of bridge opening; bridge and bridge approach embankment have been protected; stablized bridge location, prevented that the unfavorable differentiation in river course from threatening bridge to cross safety.

The above only is preferred embodiment of the present invention, not in order to limiting the present invention, all any modifications of doing within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. the investigating method of a bridge location section trraning pole scour depth is characterized in that, described investigating method may further comprise the steps:

The first step: get sand in river bed boring by bridge location section rig, with the sieve sorting bed materials at different levels of different screen apertures, use scales/electronic balance weighing, calculate the quality less than a certain particle diameter, particle diameter is determined with particle size analyzer less than the bed material of 1mm, draws graduation curve and determines bed material median particle diameter d ₅₀

Second step: collect the front bridge location section topographic map of bridge construction, respectively select a section as calculating starting point in straight section of bridge location upstream and downstream 1～2km river course, choose near the river bed landform altitude minimum point main flow riverbed, between two sections, draw talweg along the main flow riverbed, measure two section spacings from, obtain spacing between two sections of natural section according to the drawing guide, calculate the bed surface ratio and fall J;

The 3rd step: fall ovum Gravel River factual survey result according to large ratio, in the 1m tank, concentrate plume deflection washout test; Use the frequency converter automatic control flow, measure water level and wash away the section landform with level gauge, local velocity is measured with revolving oar flow velocity device;

The 4th step: according to concentrated plume deflection washout test, model bed sloped J=0.01, toe slope coefficient are got 0 and 1.5 liang of group, the angle that becomes a mandarin and are got 90 ° and 60 ° of two angles, bed material median particle diameters and get 0.054m, and three groups of bed materials of 0.033m and 0.013m, control discharge per unit width Q are 1.74m ³/ s, 2.90m ³/ s, 4.07m ³/ s and 5.81m ³Four groups of/s amount to 48 groups experiments, measure scour depth with level gauge, and adopt least square method to carry out the multi-parameter correlated fitting to draw trraning pole plume scour depth h _D1Design formulas;

The 5th step: arrange that the multiply plume washes away movable bed model, the trraning pole form adopts the straight curve closing form, according to being arranged symmetrically with, trraning pole length arranges 70m and two schemes of 50m, model bed sloped J gets 0.015,0.01,0.005,0.003 and five kinds of situations such as 0.001 grade, 9 kinds of situations of bridge location discharge per unit width control, the angle of cut of trraning pole and flood main flow is 30 °, and bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranges, the span layout spacing is the bridge pier of 1m, measures scour depth with level gauge;

The 6th step: to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, adopt correlation analysis to carry out match and draw the multiply plume and wash away trraning pole bed surface limiting scour h _D2Design formulas;

The 7th step: trraning pole is arranged 30 ° of trraning poles, 60 ° of trraning poles, three kinds of schemes of 90 ° of trraning poles, the bed material median particle diameter is 0.03315m, the three kinds of situations such as 0.005,0.01 and 0.015 of getting fall in the model ratio, the many groups of control projection flow is tested, amount to 30 groups experiments, measure scour depth with level gauge;

The 8th step: to bed material median particle diameter d ₅₀, bed sloped J, trraning pole projection flow Q, trraning pole curved section central angle β adopts correlation analysis to carry out match and gets the degree of depth h that the projection flow washes away trraning pole _D3Design formulas.

2. investigating method as claimed in claim 1 is characterized in that, when arranging that the projection flow washes away movable-bed model test, trraning pole also can be arranged 30 ° of pyriform dikes, 60 ° of pyriform dikes, three kinds of schemes of 90 ° of pyriform dikes.

3. investigating method as claimed in claim 1 is characterized in that, concentrates plume deflection washout test to be arranged in the tank of wide 1m in the described investigating method and carries out, and trraning pole meets water and domaticly carried out altogether 48 groups times test under two kinds of gradients.

4. investigating method as claimed in claim 1 is characterized in that, basis is large than falling ovum Gravel River water-sediment movement rule and experimental phenomena analysis as can be known in the described investigating method, and plume is subjected to following factor affecting to the trraning pole scour depth:

Plume is big or small, mainly refers to the size of plume flow, represents with discharge per unit width that still test shows that plume is larger, and the lumped scour degree of depth is darker;

The plume inflow angle, plume and trraning pole angle are larger, then wash away deeplyer, and scour depth is maximum when plume vertically washes away trraning pole;

The riverbed particle diameter, the riverbed particle diameter is thinner, and silt is easier to be washed away by plume, and trraning pole washes away darker;

Trraning pole upstream face side slope, grade of side slope is more slow, and then plume washes away also less.When trraning pole adopted straight wall type side slope, scour depth was maximum.

5. investigating method as claimed in claim 1 is characterized in that, adopts least square method to carry out the multi-parameter correlated fitting to each factor in the described investigating method, draws trraning pole plume scour depth design formulas:

$h_{d1}=2.02q^{0.46}{e}^{-0.2n}\left(\frac{\mathrm{\&alpha;}}{90}\right){d_{50}}^{-0.07}$

In the formula, h _D1The degree of depth that the lower plume of-different angles impact washes away trraning pole, unit is m;

N-trraning pole grade of side slope, 1: m;

α-plume flows to and the trraning pole axis angle of cut, and α gets 90 ° during the pyriform dike; In the time of can't determining, suggestion is got 60 °.

6. investigating method as claimed in claim 1, it is characterized in that, arrange when the multiply plume washes away movable bed model in the described investigating method, the trraning pole form adopts the straight curve closing form, according to being arranged symmetrically with, the angle of cut of trraning pole and flood main flow is 30 °, and bridge length is generalized as 1m and two kinds of situations of 3m, and when 3m arranged, the span layout spacing was the bridge pier of 1m.

7. investigating method as claimed in claim 1 is characterized in that, adopts correlation analysis to carry out match to the result who washes away statistics in the described investigating method, sets up the trraning pole scour depth with discharge per unit width Q, than falling J, interrelation of particle size:

$h_{d2}=0.975Q^{0.57}{J}^{0.3}{d}_{50}^{-0.08}$

In the formula: h _D2-multiply plume washes away the following limiting scour of trraning pole bed surface, and unit is m;

Q-trraning pole projection flow, m ³/ s.

8. investigating method as claimed in claim 1, it is characterized in that, in the described investigating method in typical peak flood flow process, position and time that the plume deflection is washed away trraning pole all have very large randomness, index of correlation is relatively poor, the formation of plume is relevant with the riverbed fringe conditions with inlet flow conditions, and the multiply plume is united time, position and the degree of depth of washing away trraning pole and had very strong randomness, also can express with following relation:

$h_{d2}=\left\{\begin{array}{c}2.0m....................J\&le;0.005\\ 2.0-3.0m.............0.005\&le;J<0.008\\ 3.0-3.5m.............0.008\&le;J<0.01\\ 3.5-4.5m.............0.010\&le;J\&le;0.015\end{array}\right.$

9. investigating method as claimed in claim 1 is characterized in that, adopts correlation analysis to carry out match to washing away statistics in the described investigating method, sets up the trraning pole scour depth with discharge per unit width Q, than falling J, particle diameter d ₅₀Correlation:

$h_{d3}=0.7Q^{0.67}{J}^{0.33}{d}_{50}^{-0.08}{\left(\frac{\mathrm{\&beta;}}{90}\right)}^{0.5}$

In the formula: h _D3-projection flow washes away the degree of depth of trraning pole, and unit is m;

Discharge per unit width and trraning pole are at the product of cross section of bridge site projected length before the Q-trraning pole projection flow, bridge construction, and unit is m ³/ s;

β-trraning pole curved section central angle, β gets 90 ° during the pyriform dike.

Images