CN105603940A - Stepped fish crest type water-stone separation system and design method - Google Patents

Abstract

The invention relates to a stepped fish crest type water-stone separation system and a design method therefor, and belongs to the field of debris flow control. The invention proposes the stepped fish crest type water-stone separation system. N stages of fish crest type water-stone separation structures are arranged by stage on a debris flow gully bed from the upstream part to the downstream part; each stage comprises a drainage dam, a fish crest type water-stone separation grid, a flow discharge chute and a corresponding stopping and accumulation field; the fish crest type water-stone separation grid is connected to the downstream face of the drainage dam and stretches across the two sides of the debris flow gully bed; and the top end of the front part of the fish crest type water-stone separation grid is tightly connected with the top end of a drainage hole of the drainage dam. The invention furthermore provides the design method for the system. The problem of limited separation capability and storage space of an existing single fish crest type water-stone separation system is solved; and the fish crest type water-stone separation structures are scientifically and reasonably arranged to form the stepped system, so that the damage of debris flow is reduced more effectively.

Description

Step fish ridge water stone piece-rate system and method for designing

Technical field

The present invention relates to a kind of mud-rock flow engineering structure and engineering design method, particularly relate to a kind of step fish ridge water stone isolating construction and method for designing thereof, belong to debris flow field.

Background technology

Mud-rock flow mitigation engineering structure, in development, from traditional entity gravity type debris dam to permeable debris dam miscellaneous, is all the harm in order to resist better mud-rock flow.

The patent No. is ZL201120352219.X, the Chinese utility model patent that name is called " a kind of mudstone flowing water stone piece-rate system " discloses a kind of fish ridge mudstone flowing water stone piece-rate system, and this system mainly separates grid, dredging flow groove by drainage dam, water stone and stops long-pending and forms; In the patent that is further ZL201310738319.X in the patent No., disclose the method for designing of this system main structure parameters, comprised that water stone separates definite method of grid span B, water stone separation height of grid H, water stone separation grid length L. But this system also has two crucial parameters: girt strip spacing also designs particle separation diameter D and stop long-pending capacity V less than determining, makes the design of this structure imperfect. Meanwhile, according to traditional engineering experience, for a debris flow gully, need take different measures to form organic system to reduce for the different section in basin the harm of mud-rock flow. And, even if same engineering measure as debris dam, is to be all arranged to many to form the serial harm of resisting mud-rock flow. Single fish ridge water stone piece-rate system separating power and storage area are limited, have limited the application of this structure. Therefore need a kind of novel fish ridge water stone piece-rate system of development and Design badly, to improve separating power and the storage area of this structure.

Summary of the invention

The object of the invention is for the limited problem of existing single fish ridge water stone piece-rate system separating power and storage area, arrange that scientifically and rationally multiple fish ridge water stone isolating constructions form stepped systems, the harm that more effectively alleviates mud-rock flow.

For achieving the above object, the present invention proposes a set of step fish ridge water stone piece-rate system, described step fish ridge water stone piece-rate system, hierarchical arrangement n level fish ridge water stone isolating construction from the debris flow gully bed in upstream to downstream, every one-level includes drainage dam, fish ridge water stone separates grid, dredging flow groove and stops accordingly long-pending; Connecting fish ridge water stone at drainage dam back and separating grid, fish ridge water stone separates grid across debris flow gully bed two sides, and the draining hole top on anterior top and drainage dam immediately.

Above-mentioned drainage dam is preferably gravity type entity debris dam.

Above-mentioned fish ridge water stone separates grid and can be two-sided fish ridge or one side fish ridge, and two-sided fish ridge cell structure is aforementioned thanking described in great waves patent (ZL201120352219.X, a kind of mudstone flowing water stone piece-rate system); One side fish ridge cell structure is mainly to consider in the unallowed situation of raceway groove orographic condition or when mud-rock flow main stream line is amesiality, only needs to arrange one side cell structure; As shown in Figure 3, one side fish ridge cell structure starts from one end of draining hole opening to tilt, and incline direction one side is only set and stops long-pending, and its action principle is with two-sided fish ridge cell structure.

The major parameter of above-mentioned step fish ridge water stone piece-rate system has: step progression n, the design particle separation diameter D of each level structure_(j), what each level structure was corresponding stops long-pending capacity V_(j)And other structural parameters of each level structure are as drainage height of dam degree, grid span, grid length etc., get respectively 1,2 from upstream to downstream j ..., n.

The present invention also provides the method for designing of above-mentioned step fish ridge water stone piece-rate system, for the design of step fish ridge water stone piece-rate system, comprises the following steps:

(1) collect initial data: field investigation, determine basic parameter according to mud-rock flow engineering investigation and design specification, can be divided into two large classes: a class is major parameter (n, the D for determining step fish ridge water stone piece-rate system_(j)And V_(j): comprise needing the building construction types of protection and intensity, once going out material total amount M, complete thing source grain composition, another kind of is basic parameter for the thin portion parameter designing of each level structure: comprise design mud-rock flow flow Q_c, unit weight ρ_c, the solid particle natural angle of respose and channel width B '.

(2) design separating substances rate P₀, progression n determine

Design separating substances rate P₀Be the controlling indicator of step fish ridge water stone piece-rate system material regulating effect, its value can be according to design debris flow scale, once go out material total amount and protected object and determine. According to tank simulated experiment, in the time of n=3, separating substances rate can reach 50～80%, therefore can 50% conduct design separating substances rate P₀Lower limit, corresponding n can tentatively get 3～5;

(3) impact the smallest particles particle diameter D that power is destroyed_minDetermine

Calculating according to boulder impulsive force and building impact resistance the largest block stone impulsive force of determining that building can be resisted under certain condition, is also the smallest particles particle diameter D of the power that the impacts destruction of required separation_min, specific as follows:

The building of state of debris flow disasters is generally building construction, bridge and debris dam structure itself, general house architectural structure member all can be regarded simply supported beam or cantilevered beam members as the bridge pier of post, beam, bridge, debris dam dam body, house wall etc. can be reduced to rigidity body of wall, formula 1, formula 2 are respectively the impulsive force formula of boulder to simply supported beam and cantilever beam, and formula 3 is the impulsive force formula of boulder to rigidity body of wall:

F_c＝(48EJv²W/gL_l ³)^1/2Formula 1

F_c＝(3EJv²W/gL_l ³)^1/2Formula 2

F_c＝k_cma^3/2Formula 3

$m={\left(\frac{16d}{9{\mathrm{\π}}^2{(k_1+k_2)}^2}\right)}^{1/2}$ Formula 4

$a={\left(\frac{5v^{2}W}{4m}\right)}^{2/5}$ Formula 5

Wherein, F_cFor the impulsive force of mud-rock flow boulder, E is construction material elastic modelling quantity (MPa); J is stressed second moment of area (m⁴); V is debris flow velocity (m/s); W is ratchel quality (kg); G is acceleration of gravity (m/s²)；L_lFor the effective span (m) of beam (when cantilever beam, L_lFor shock point is to the distance of stiff end; When simply supported beam, L_lFor beam length), k_cFor correction factor, get 0.1～0.2; k₁、k₂For the coefficient relevant with debris dam material to boulder; M in formula and a are the intermediate variable (Zhou Bifan, 1991) of formula 3. By the quality W of boulder in formula press equivalent sphere calculate, can draw the expression formula that contains piece stone diameter d in impact force's calculation formula, wherein, the computing formula of equivalent sphere as shown in Equation 6:

$W={\mathrm{\ρ}}_s\·\frac{{\mathrm{\πd}}^3}{6}$ Formula 6

In formula 6, ρ_sFor piece stone density, unit is g/cm³, get 2.65～2.75g/cm³。

Different component produces different failure mode (as bending failure, failure by shear, punching failure etc.) under impact force action, analyze the limit equilibrium condition (document 4 sees reference) that different failure modes is exerted oneself, the impact that can draw the largest block stone particle diameter that can bear at friction speed condition lower member;

Jiang family's gully mud-rock flow is the longest and observation statistics most complete mud-rock flow of current observation time, show according to Jiang family's gully mud-rock flow velocity observer data, when debris flow velocity is most, be less than 10m/s, therefore when other mud-rock flows processing, with reference to the flow speed data of Jiang family's gully mud-rock flow, desirable flow velocity while being 10m/s corresponding piece stone particle diameter as cut-off size, be also the minimum grain size D of the harmful boulder that must separate of system_min；

(4) other design particle separation diameters D_(j)Determine

According to thing source grain composition value, specific practice is as follows:

First by field investigation, obtain the complete particle grading distribution data of debris flow gully, grain diameter segmentation is as follows: for the particle diameter of particle diameter d<60mm, according to " Standard for test methods of earthworks " screen experiments standard particle diameter (60,40,20,10,5,2mm), (I is only assigned to 2mm in classification, because research shows, 2mm can be used as coarse granule and fine grain boundary particle diameter, and the present invention mainly pays close attention to coarse grained separation); For the particle diameter of 60≤d<800mm, with reference to " railway bridges and culverts rudimentary and foundation design code " to native particle criteria for classification (referring to table 1); The boulder of particle diameter d>=800mm, can be further by integer divide as 1000,2000, the classification such as 3000mm; D_(j)Value from these boundary particle diameters, the particle separation diameter D of afterbody structure_(n)≤D_min；

Table 1 " railway bridges and culverts rudimentary and foundation design code " soil particle criteria for classification

(5) the total separation rate P of stepped system material (n) and at different levelsly stop a long-pending capacity V_(j)Determine

N and the D of this step inspection Preliminary design value_(j)Reasonability. If P (n) < < P₀, or V_(j)Calculated value and site contour condition be not inconsistent, adjust value or the design particle separation diameter D of n_(j)Value, until P (n) approaches or reaches design separating substances rate P₀, the level V that stop at different levels_(j)Meet design requirement and site condition. Method is as follows:

Definition P (j) is the separating substances rate of front j level structure, before, the isolated material total amount of j level water stone isolating construction accounts for mud-rock flow and once goes out the percentage of material total amount M, and P (n) is the total separation rate of material of n level fish ridge water stone piece-rate system; V_(j)Be that j level is stopped the capacity of long-pending;

Relation between the combination of P (j) and thing source grain composition, water stone particle separation diameter is as shown in Equation 7:

$P\left(j\right)=100-i_{\left(j\right)}+j^2\&times;{\left(\underset{k=1}{\overset{j}{\&Sigma;}}\frac{D_{\left(k\right)}}{d_{ave\left(k\right)}}\right)}^{(-1.668)}\&times;i_{\left(j\right)},(j=1,2,...,n)$ Formula 7

In formula 7: D_(j)It is the design particle separation diameter of j level structure; i_(j)For being less than D in thing source grain diameter composition_(j)Material account for the cumulative percentage of total material; d_ave(j)For thing source particle forms medium and small in D_(j)Particle weighted average particle diameter, circular is:

$d_{ave\left(j\right)}=\frac{\mathrm{\&Sigma;}\stackrel{\&OverBar;}{d_k}\&CenterDot;f_k}{{\mathrm{\&Sigma;f}}_k}$ Formula 8

Wherein:Represent by above-mentioned standard, thing source grain diameter section to be divided, be less than D_(j)The arithmetic mean particle size values of each particle diameter section, as 40～20mm particle diameter section,Minimum grain size section is got this particle diameter section higher limit, as minimum grain size section is < 1mm, getsf_kRepresent that above-mentioned particle diameter section accounts for the ratio of thing source total amount;

V_(j)Computing formula as shown in Equation 9:

V_(j)=[P (j)-P (j-1)] × M, (j=1,2 ..., n) formula 9

Wherein, P (j) is separation rate, conventionally represents with percentage, but in formula 9, calculates with the form substitution of decimal, as P (j)=80%, in formula 9, calculates by 0.8; P (0)=0.

(6) a point progression n, particle separation diameter D at different levels have been determined_(j)Stop a long-pending capacity V with at different levels_(j)Afterwards, can carry out detailing to every grade of fish ridge water stone isolating construction, comprise determining of the main structure parameters such as drainage dam height H, grid span B, grid length L, specifically can be with reference to patent ZL201310738319.X.

Compared with existing additive method, the present invention forms stepped system by arranging scientifically and rationally multiple fish ridge water stone isolating constructions, progressively the bulky grain in mud-rock flow with destructive power is separated, make mud-rock flow change into silt carrying flow, alleviate step by step the harm of mud-rock flow, from reaching optimum with mitigation effect economically.

Bibliography:

[1] Chengdu Inst. of Mountain Disaster and Environment, Ministry of Water Resources. a kind of mudstone flowing water stone piece-rate system: China, ZL201120352219.X[P] ..

[2] Chengdu Inst. of Mountain Disaster and Environment, Ministry of Water Resources. fish ridge water stone piece-rate system method for designing: China, ZL201310738319.X[P] .2015-07-08.

[3] Zhou Bifan, Li Deji, Luo Defu, etc. debris flow guide [M]. Beijing: Science Press, 1991.

[4] GB50010-2010, " Code for design of concrete structures " [S]

[5] GB/T50123-1999, " Standard for test methods of earthworks " [S]

[6] TB10002.5-2005/J464-2005 " railway bridges and culverts ground and foundation design code " [S]

[7] once super, building vulnerability assessment method [D] under mud-rock flow effect. Beijing: university of the Chinese Academy of Sciences, 2014.

[8] Zhou Wei, Chen Ningsheng, Deng Mingfeng etc. Hydroelectric Power Station in Sichuan Dujiangyan Aug. 1st gully mud-rock flow dynamic characteristic and risk assessment [J]. water and soil conservation circular, 2011,31 (3), 138-143

Figure of description

Fig. 1 is that schematic diagram is arranged in the structural plan that step fish ridge water stone piece-rate system of the present invention is positioned on ditch bed, wherein: 1: drainage dam; 2: fish ridge water stone separates grid; 3: stop long-pending; 4: dredging flow groove; 5: debris flow gully bed; 6: bank slope.

Fig. 2 adopts two-sided water stone to separate the fish ridge water stone isolating construction of grid.

Fig. 3 is the fish ridge water stone isolating construction that one side water stone separates grid.

Fig. 4 is the relation between flow velocity and bulky grain under simple beam structure impulsive force bending failure condition.

Fig. 5 is the relation between flow velocity and bulky grain under simple beam structure impulsive force shear fracture conditions.

Detailed description of the invention

Embodiment mono-

According to the real orographic condition of Long Chi town Aug. 1st ditch, the present invention proposes a set of step fish ridge water stone piece-rate system, as shown in Figure 1, 2,4 grades of fish ridge water stone isolating constructions of hierarchical arrangement from the debris flow gully bed in upstream to downstream, every primary structure includes drainage dam 1, two-sided fish ridge water stone separates grid 2, dredging flow groove 4 and stops accordingly long-pending 3; Connecting two-sided fish ridge water stone at drainage dam back and separating grid, two-sided fish ridge water stone separates grid across debris flow gully bed two sides, and the draining hole top on anterior top and drainage dam immediately. Drainage dam 1 is gravity type entity debris dam.

Said structure calculates by following steps and design obtains:

According to once surpassing (2014) to the state of debris flow disasters field investigation of earthquake region, Wenchuan, can determine that the cylinder of the protected house architectural structure in this area can be divided into high, normal, basic three kinds of intensity, this example is calculated with low-intensity cylinder, and cylinder related data is in table 2. In calculating, cylinder can be reduced to simply supported beam member; Taking Dujiang weir, Zhou Wei (2011) earthquake region, Wenchuan Aug. 1st ditch mud-rock flow calculating chart on August 13rd, 2010 as foundation, supposing once to go out solid matter total amount M is 32 × 10⁴m³, design mud-rock flow flow Q_cFor 657m³/ s, the original unit weight ρ of mud-rock flow_cFor 1.82g/cm³, channel width B' is 20～40m, solid particle angle of repose is 38 °. This ditch thing source grain composition data of collection in worksite, as shown in table 3.

Table 2 building structure related data

Table 3 thing source grain composition data

Determine design separating substances rate P₀=80%, tentatively determine progression n=3.

Impulsive force formula according to boulder to simply supported beam, i.e. formula 1, in the time of simply supported beam generation impact bending destruction or failure by shear, the limit equilibrium condition according to power:

$F_c\&CenterDot;\frac{L}{2}=M_u,$ Or F_c＝Q_u,

Also be $\sqrt{48{\mathrm{EJv}}^{2}W/{\mathrm{gL}}^3}\&times;\frac{L}{2}=M_u$ Or $\sqrt{48{\mathrm{EJv}}^{2}W/{\mathrm{gL}}^3}=Q_u,$

By the relevant parameter in table 2 and formula 6 substitution above formulas, the relation between boulder particle diameter and flow velocity of can drawing as shown in Figure 4,5, can find out from scheming, in the time of v=10m/s, and D_min＝0.2m。

Preliminary definite design particle separation diameter D at different levels_(j)Be respectively 1.0m, 0.5m and 0.2m, as shown in table 4.

Table 4 Preliminary design and adjustment scheme

Preliminary design: calculate P (j) according to formula 7 and formula 8, then calculate V according to formula 9_(j), as shown in table 4, calculating the total separation rate P of system material (n) is 57.74%, much smaller than design separating substances rate P₀80%, therefore need preliminary project to adjust.

Scheme I: first only change design particle separation diameter D₍₃₎, keep progression constant, calculating the total separation rate P of scheme I material (n) is 72.5%, approaches design separating substances rate P₀80%, but the third level stops a long-pending capacity V₍₃₎Excessive, the channel conditions of Long Chi town Aug. 1st ditch is difficult to choose suitable site to meet the requirement of structure building and storage material, so scheme I also needs a step whole.

Scheme II: for further adjustments to design, as shown in scheme II, increasing progression is 4 grades, and calculating the total separation rate of material is 73.8%, approaches design separating substances rate P₀80%, and at different levelsly stop a long-pending capacity V_(j)Distributed uniform, easily chooses suitable site under current conditions.

According to above-mentioned result of calculation, in conjunction with the real orographic condition of Long Chi town Aug. 1st ditch, select such scheme II design step fish ridge water stone piece-rate system, Long Chi town Aug. 1st ditch designs a set of step fish ridge water stone piece-rate system, as shown in Figure 1, 2,4 grades of fish ridge water stone isolating constructions of hierarchical arrangement from the debris flow gully bed in upstream to downstream, every primary structure includes drainage dam 1, fish ridge water stone separates grid 2, dredging flow groove 4 and stops accordingly long-pending 3; Connecting fish ridge water stone at drainage dam back and separating grid, fish ridge water stone separates grid across debris flow gully bed two sides, and the draining hole top on anterior top and drainage dam immediately. Drainage dam 1 is gravity type entity debris dam. Design particle separation diameter D at different levels₍₁₎～D₍₄₎Be respectively 1000mm, 500mm, 200mm, 100mm, the capacity V that stop long-pending at different levels₍₁₎～V₍₄₎Be respectively: 5.38 × 10⁴m³、5.96×10⁴m³、7.14×10⁴m³、5.14×10⁴m³。

According to design mud-rock flow flow Q_cFor 657m³/ s, the original unit weight ρ of mud-rock flow_cFor 1.82g/cm³, channel width B' is that 20～40m, solid particle angle of repose are 38 °, the detailing of each level structure can, referring to patent ZL201310738319.X, repeat no more.

Claims (3)

1. step fish ridge water stone piece-rate system, is characterized in that: from upstream to the debris flow gully bed in downstreamUpper hierarchical arrangement n level fish ridge water stone isolating construction, every one-level includes drainage dam, fish ridgeWater stone separates grid, dredging flow groove and stops accordingly long-pending; Connecting fish at drainage dam backRidge water stone separates grid, and fish ridge water stone separates grid across debris flow gully bed two sides, front portionThe draining hole top on top and drainage dam immediately.

2. step fish ridge water stone piece-rate system as claimed in claim 1, is characterized in that: described fishThe structure that ridge water stone separates grid is two-sided fish ridge or one side fish ridge.

3. the method for designing of step fish ridge water stone piece-rate system as claimed in claim 1 or 2, comprisesDetermine point progression n, a design particle separation diameter D at different levels_(j)Stop a long-pending capacity V with at different levels_(j), andThe thin step design of each level structure, is characterized in that, described point of progression n, design at different levels separate grainFootpath D_(j)Stop a long-pending capacity V with at different levels_(j)Determine by following steps:

(1) collect initial data: field investigation, true according to mud-rock flow engineering investigation and design specificationDetermine basic parameter, comprising: need protection building construction types and intensity, once to go out material totalAmount M, complete thing source grain composition, design mud-rock flow flow Q_c, unit weight ρ_c, solidThe grain natural angle of respose and channel width B ';

(2) design separating substances rate P₀, the determining of progression n: design separating substances rate P₀Be greater thanEqual 50%, corresponding n tentatively gets 3～5;

(3) impact the smallest particles particle diameter D that power is destroyed_minDetermine:

F_c＝(48EJv_s ²W/gL_l ³)^1/2Formula 1

F_c＝(3EJv_s ²W/gL_l ³)^1/2Formula 2

F_c＝k_cma^3/2Formula 3

$m={\left(\frac{16d}{9{\mathrm{\&pi;}}^2{(k_1+k_2)}^2}\right)}^{1/2}$ Formula 4

$a={\left(\frac{5v^{2}W}{4m}\right)}^{2/5}$ Formula 5

$W={\mathrm{\&rho;}}_s\&CenterDot;\frac{{\mathrm{\&pi;d}}^3}{6}$ Formula 6

Wherein, F_cFor the impulsive force of mud-rock flow boulder; E is construction material elastic modelling quantity(MPa); J is stressed second moment of area (m⁴)；v_sFor debris flow velocity (m/s); W isRatchel quality (kg); G is acceleration of gravity (m/s²)；L_lFor the effective span (m) of beam,When cantilever beam, L_lFor shock point is to the distance of stiff end, when simply supported beam, L_lFor beam length; k_cFor correction factor, get 0.1～0.2; k₁、k₂For relevant with debris dam material to boulder isNumber; The quality W of boulder presses equivalent sphere and calculates; According to the construction of structures class of required protectionType, becomes beam-type member or rigidity body of wall, the impact of selecting respectively formula 1～3 by its Rational SimplificationPower formula, according to stressed limit equilibrium condition, can draw at different debris flow velocity lower membersThe impact of the largest block stone particle diameter that can bear, according to statistics, with the mud-rock flow of 10m/sPiece stone particle diameter corresponding under flow velocity is as cut-off size, is also having of must separating of systemThe minimum grain size D of evil boulder_min；

(4) other design particle separation diameters D_(j)Determine:

By field investigation, obtain the complete particle grading distribution data of debris flow gully, particleParticle diameter segmentation is as follows: for the particle diameter of particle diameter d < 60mm, according to " soil test method markAccurate " screen experiments standard grain size grading; For the particle diameter of 60≤d < 800mm, with reference to " ironRoad and bridge are contained rudimentary and foundation design code " to native particle criteria for classification; Particle diameter d >=800mmBoulder, can further press integer sorting; D_(j)Value from these boundary particle diameters, lastThe particle separation diameter D of primary structure_(n)≤D_min；

(5) the total separation rate P of stepped system material (n) and at different levelsly stop a long-pending capacity V_(j)Determine:

Relation between P (j) and thing source grain composition, the combination of water stone particle separation diameter is suc as formula 7Show:

$P\left(j\right)=100-i_{\left(j\right)}+j^2\&times;{\left(\underset{k=1}{\overset{j}{\&Sigma;}}\frac{D_{\left(k\right)}}{d_{ave\left(k\right)}}\right)}^{(-1.668)}\&times;i_{\left(j\right)},(j=1,2,...,n)$ Formula 7

In formula 7: D_(j)It is the design particle separation diameter of j level structure; i_(j)For thing source grain diameterIn composition, be less than D_(j)Material account for the cumulative percentage of total material; d_ave(j)For thing source particle compositionIn be less than D_(j)Particle weighted average particle diameter, circular as shown in Equation 8:

$d_{ave\left(j\right)}=\frac{\mathrm{\&Sigma;}\stackrel{\&OverBar;}{d_k}\&CenterDot;f_k}{{\mathrm{\&Sigma;f}}_k}$ Formula 8

Wherein:Represent by above-mentioned standard, thing source grain diameter section to be divided, be less than D_(j)The arithmetic mean particle size values of each particle diameter section; f_kRepresent that above-mentioned particle diameter section accounts for the ratio of thing source total amountExample;

V_(j)Computing formula as shown in Equation 9:

V_(j)=[P (j)-P (j-1)] × M, (j=1,2 ..., n) formula 9

If P (n) < < P₀Or V_(j)Calculated value and site contour condition are not inconsistent, and adjust getting of nValue or design particle separation diameter D_(j)Value, until P (n) approaches or reaches design separating substances rateP₀, the level capacity V that stop at different levels_(j)Meet design requirement and site condition.