CN103529237A - Method and device for measuring sediment group settling velocity - Google Patents

Abstract

The invention relates to a method and a device for measuring sediment group settling velocity and belongs to the field of river model tests. The device comprises a settling barrel, a plurality of pressure measurement devices and a computer, wherein the settling barrel is a cylindrical container which is placed perpendicularly and provided with a cross section of any shape; a plurality of pressure measurement holes are uniformly and perpendicularly formed in one side wall; no less than 3 pressure measurement holes are provided; the pressure measurement devices are perpendicularly mounted in the pressure measurement holes and are sealed with the side wall; centers of sensing elements of the pressure measurement devices are aligned with centers of the pressure measurement holes; the pressure measurement devices are connected with the computer; the pressure intensity is measured under the control of the computer; and a measurement result is returned to the computer for analysis and storage in real time. The method calculates a change process of the sediment concentration by measuring a change process of the pressure intensity, and the sediment group settling velocity is calculated further. According to the method and the device, the sediment group settling velocity in a sandy water body can be measured automatically, without interference and accurately.

Description

A kind of measuring method of fo Sediment Group Settling speed and measurement mechanism

Technical field

The invention belongs to river model test field, particularly the measurement to bulk settling of sediment speed.

Background technology

In the rational approach and engineering application of sediment movement, the Group Settling speed of silt is important parameter.For single spheroidal particle, fine grain heavy speed can be calculated with Stokes formula, and coarse grained heavy speed can be calculated with resistance formula, and the heavy speed of the zone of transition particle between large or fine granule needs experimental measurement; As the heavy speed of the out-of-shape particles such as natural sand also needs by test determination.The heavy speed test of traditional individual particle is generally a particle of each input in special settlement barrel, after reaching stabilized speed, it records settling height and corresponding time, can calculate heavy speed, repeatedly revision test, gets the statistical average of each test as the heavy speed of this kind of husky sample.

In natural situation and in engineering application, the silt that current contain all has certain concentration, i.e. the mode of sand grain Hui Yi colony sedimentation and diffusion in current, and the motion between particle also can influence each other, and its heavy speed can be variant with the heavy speed of individual particle.Particularly colony's sedimentation of fine sediment, also may flocculate, and makes the research of fo Sediment Group Settling speed more complicated.

For the silt of fines, normally will stir, have certain density slurry and contain in graduated cylinder, observation is clear, the decline rate of muddy water interface as this kind of silt the speed of the Group Settling under this concentration, this type of test often needs the time of several days.Group Settling speed test for general sand grain, typical method is a special settlement barrel of design, differing heights at barrel arranges thief hole, to stir, have certain density slurry contains in sedimentation, in the different moment from each thief hole sample drawn, carry out the analysis of sediment concentration and grating, according to sediment concentration, inquire into over time the Group Settling speed of silt.This kind of method workload is very big, and because sample drawn is by the liquid level reducing in settlement barrel, to data analysis, has increased difficulty.

Summary of the invention

The object of the invention is to overcome the weak point of prior art, a kind of measuring method and measurement mechanism of bulk settling of sediment speed is provided, automatic to realize, noiseless, measure bulk settling of sediment speed in silt-including water exactly.

The measurement mechanism that a kind of fo Sediment Group Settling speed measuring method that the present invention proposes adopts, is characterized in that, this device comprises settlement barrel, a plurality of pressure instrumentataion and computing machine three parts; Settlement barrel is the column shape container of the vertical Arbitrary Shape Cross Section of placing, and Bian Biyan is vertical is evenly arranged a plurality of pressure taps, and the number of pressure tap is no less than 3; Pressure instrumentataion is vertically mounted in pressure tap, and seals with limit wall, and the center of the sensing element of pressure instrumentataion flushes with pressure tap center; Each pressure instrumentataion is connected with computing machine, synchro measure pressure under the control of computing machine, and pass in real time measurement result back computing machine and analyze and store.

The present invention also proposes to adopt the fo Sediment Group Settling speed measuring method of said apparatus, it is characterized in that, comprises the following steps:

1) mortar to be measured is contained into settlement barrel, standing mortar, after liquid level build-up calmness, is opened each pressure instrumentataion by computing machine and is started to measure muddy water pressure by the Frequency Synchronization of setting, and each pressure instrumentataion is passed the pressure of measuring in real time back computing machine;

2) pressure of measuring according to each pressure instrumentataion calculates the mortar mean sediment concentration of t at any time: the number of establishing pressure instrumentataion is N, and the surface level at each pressure instrumentataion 2 and place is numbered respectively n(n=1, and 2 ... N), surface level n is H apart from the discrepancy in elevation of mortar liquid level _n(n=1,2 ... N), pressure instrumentataion n at any time the pressure readings of t be P _n(t) (n=1,2 ... N), the frequency that each pressure instrumentataion is measured pressure is f=1/ Δ t, and wherein Δ t is the pressure measurement time interval; According to the definition of hydrostatic pressure, the mortar between surface level n and liquid level is the volume averaging unit weight of t at any time

for:

$\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)=\frac{P_n\left(t\right)}{H_n},(n=\mathrm{1,2},...N)---\left(1\right)$

According to the definition of quality silt content, the mean sediment concentration of the mortar between surface level n and liquid level

with volume averaging unit weight

between meet following relation:

$\stackrel{\‾}{S_n}\left(t\right)={\mathrm{\γ}}_s\frac{\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)-\mathrm{\γ}}{{\mathrm{\γ}}_s-\mathrm{\γ}},(n=\mathrm{1,2},...N)---\left(2\right)$

γ in formula _sfor the unit dry weight of silt to be measured, the unit weight that γ is water;

3) according to formula (2), try to achieve the mean sediment concentration of the mortar between all surface levels and liquid level, the mortar obtaining between surface level n and surface level n-1 in the mean sediment concentration of moment t is:

$\stackrel{\‾}{S_{n-1,n}}\left(t\right)=\frac{H_n\stackrel{\‾}{S_n}\left(t\right)-H_{n-1}\stackrel{\‾}{S_{n-1}}\left(t\right)}{H_n-H_{n-1}},(n=\mathrm{1,2},...N)---\left(3\right)$

Will

being taken as with the liquid level discrepancy in elevation is (H _n+ H _n-1the silt content at the plane place of)/2, interpolation obtains the silt content S at surface level n place _n(t);

$S_n\left(t\right)=\frac{\stackrel{\‾}{S_{n-1,n}}\left(t\right)+\stackrel{\‾}{S_{n,n+1}}\left(t\right)}{2},(n=\mathrm{1,2},...N)---\left(4\right)$

4), according to the definition of silt discharge, between t-Δ t to t+ Δ t, the quantity of sand and mud by surface level n is silt discharge g divided by settlement barrel area of section A and time constantly _n(t), be calculated as follows:

$g_n\left(t\right)=\frac{(\stackrel{\‾}{S_n}(t+\mathrm{\Δt})-\stackrel{\‾}{S_n}(t-\mathrm{\Δt}))H_{n}A}{2\mathrm{A\Δt}},(n=\mathrm{1,2},...N)---\left(5\right)$

By g _n(t) be taken as surface level n at the instantaneous silt discharge of moment t;

5) according to formula (4) and formula (5), obtaining any time t is H apart from the liquid level discrepancy in elevation _nthe group settling velocity ω of the silt at place _n(t) be:

${\mathrm{\ω}}_n\left(t\right)=\frac{g_n\left(t\right)}{S_n\left(t\right)},(n=\mathrm{1,2},...N)---\left(6\right).$

Feature of the present invention and effect are:

(1) in measuring process, can the natural subsidence process of silt not produced and be disturbed;

(2) calculating of pressure measurement and settling velocity is all completed by computing machine, has realized the real-time automatic measuring of bulk settling of sediment speed;

(3) this method is specially adapted to measure the group settling velocity of silt in middle and high concentration slurry.

Accompanying drawing explanation

Fig. 1 is measurement mechanism schematic diagram.

Embodiment

Below in conjunction with drawings and Examples, technical scheme of the present invention is elaborated.

Ultimate principle of the present invention is: along settlement barrel short transverse, pressure instrumentataion is evenly installed, the slurry stirring is contained into settlement barrel standing rear sediment concentration because sediment settlement changes in time, and the pressure that causes each pressure instrumentataion to record changes in time.Because pressure and sediment concentration have strict mathematics corresponding relation, by measuring the change procedure of pressure, can calculate the change procedure of sediment concentration, and then calculate the group settling velocity of silt.

Based on above-mentioned principle, the measurement mechanism that a kind of fo Sediment Group Settling speed measuring method of the present invention adopts as shown in Figure 1, comprises that settlement barrel 1, a plurality of pressure instrumentataion 2 and computing machine 3 three parts form.Settlement barrel 1 is the column shape container of the vertical Arbitrary Shape Cross Section of placing, and is highly not less than 1m, the vertical pressure tap 4 that is evenly arranged of Bian Biyan, be used for installing pressure instrumentataion 2, pressure instrumentataion 2 is vertically mounted in pressure tap, and seals with limit wall, and the center of its sensing element flushes with pressure tap center; For guaranteeing measuring accuracy and being convenient to mathematics manipulation, the number of pressure tap is no less than 3; Pressure instrumentataion 2 is muddy water pressure measurement instrument; Pressure instrumentataion 2 is connected with computing machine, synchro measure pressure under the control of computing machine 3, and pass in real time measurement result back computing machine 3 and analyze and store.

The embodiment of each parts of this measurement mechanism is respectively described below:

Computing machine 3 is common desk-top computer or notebook computer.The present embodiment selects length to be respectively the rectangle settlement barrel of 80cm, 80cm and 200cm, and barrel is evenly arranged 6 pressure taps along vertical, and pitch of holes is 20cm; Pressure instrumentataion 2 is the German HeLM HM10 of company (0～40KPa)-3-D1-V1-F1-W1 type high precision muddy water pressure transducer, and measuring accuracy is full scale 0.1%; AC6616P board and pressure transducer that computing machine 3 is produced by Beijing Shuan Nuo company communicate.

Based on above-mentioned measurement mechanism, the measuring method of fo Sediment Group Settling speed of the present invention comprises the following steps:

1) mortar to be measured is contained into settlement barrel 1, standing mortar is opened each pressure instrumentataion 2 by computing machine 3 and is started to measure muddy water pressure by the Frequency Synchronization of setting after liquid level build-up calmness, and each pressure instrumentataion 2 is passed the pressure of measuring in real time back computing machine 3;

2) pressure of measuring according to each pressure instrumentataion calculates the mortar mean sediment concentration of t at any time: the number of establishing pressure instrumentataion 2 is N, and the surface level at each pressure instrumentataion 2 and place is numbered respectively n(n=1, and 2 ... N), surface level n is H apart from the discrepancy in elevation of mortar liquid level _n(n=1,2 ... N), pressure instrumentataion n at any time the pressure readings of t be P _n(t) (n=1,2 ... N), the frequency that each pressure instrumentataion is measured pressure is f=1/ Δ t, and wherein, Δ t is the pressure measurement time interval, and the present embodiment is 1 minute; According to the definition of hydrostatic pressure, the mortar between surface level n and liquid level is the volume averaging unit weight of t at any time

for:

$\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)=\frac{P_n\left(t\right)}{H_n},(n=\mathrm{1,2},...N)---\left(1\right)$

According to the definition of quality silt content, the mean sediment concentration of the mortar between surface level n and liquid level

with volume averaging unit weight

between meet following relation:

$\stackrel{\‾}{S_n}\left(t\right)={\mathrm{\γ}}_s\frac{\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)-\mathrm{\γ}}{{\mathrm{\γ}}_s-\mathrm{\γ}},(n=\mathrm{1,2},...N)---\left(2\right)$

γ in formula _sfor the unit dry weight of silt to be measured, the unit weight that γ is water;

3) according to formula (2), try to achieve the mean sediment concentration of the mortar between all surface levels and liquid level, the mortar obtaining between surface level n and surface level n-1 in the mean sediment concentration of moment t is:

$\stackrel{\‾}{S_{n-1,n}}\left(t\right)=\frac{H_n\stackrel{\‾}{S_n}\left(t\right)-H_{n-1}\stackrel{\‾}{S_{n-1}}\left(t\right)}{H_n-H_{n-1}},(n=\mathrm{1,2},...N)---\left(3\right)$

Will

being taken as with the liquid level discrepancy in elevation is (H _n+ H _n-1the silt content at the surface level place of)/2, interpolation obtains the silt content S at surface level n place _n(t); The embodiment of this method adopts linear interpolation, specific as follows:

$S_n\left(t\right)=\frac{\stackrel{\‾}{S_{n-1,n}}\left(t\right)+\stackrel{\‾}{S_{n,n+1}}\left(t\right)}{2},(n=\mathrm{1,2},...N)---\left(4\right)$

4), according to the definition of silt discharge, between t-Δ t to t+ Δ t, the quantity of sand and mud by surface level n is silt discharge g divided by settlement barrel area of section A and time constantly _n(t), be calculated as follows:

$g_n\left(t\right)=\frac{(\stackrel{\‾}{S_n}(t+\mathrm{\Δt})-\stackrel{\‾}{S_n}(t-\mathrm{\Δt}))H_{n}A}{2\mathrm{A\Δt}},(n=\mathrm{1,2},...N)---\left(5\right)$

By g _n(t) be taken as Plane n at the instantaneous silt discharge of moment t;

5) according to formula (4) and formula (5), obtaining any time t is H apart from the liquid level discrepancy in elevation _nthe group settling velocity ω of the silt at place _n(t) be:

${\mathrm{\ω}}_n\left(t\right)=\frac{g_n\left(t\right)}{S_n\left(t\right)},(n=\mathrm{1,2},...N)---\left(6\right).$

From above-mentioned steps, the advantage of this method is can the natural subsidence process of silt not produced and be disturbed in measuring process; In addition, the calculating of pressure measurement and settling velocity is all completed automatically by computing machine, has realized the real-time automatic measuring of bulk settling of sediment speed; Finally, the pressure change amount that this method requires to be caused by sediment settlement between double measurement is greater than the resolution of pressure instrumentataion, is specially adapted to measure the group settling velocity of silt in middle and high concentration slurry.

Claims (4)

1. the measurement mechanism that fo Sediment Group Settling speed measuring method adopts, is characterized in that, this device comprises settlement barrel, a plurality of pressure instrumentataion and computing machine three parts; Settlement barrel is the column shape container of the vertical Arbitrary Shape Cross Section of placing, and Bian Biyan is vertical is evenly arranged a plurality of pressure taps, and the number of pressure tap is no less than 3; Pressure instrumentataion is vertically mounted in pressure tap, and seals with limit wall, and the center of the sensing element of pressure instrumentataion flushes with pressure tap center; Each pressure instrumentataion is connected with computing machine, synchro measure pressure under the control of computing machine, and pass in real time measurement result back computing machine and analyze and store.

2. install as claimed in claim 1, it is characterized in that, described pressure instrumentataion is muddy water pressure measurement instrument.

3. install as claimed in claim 1, it is characterized in that, described column shape container, is highly not less than 1m, and the number of described pressure tap is no less than 3.

4. adopt a fo Sediment Group Settling speed measuring method for measurement mechanism as claimed in claim 1, it is characterized in that, comprise the following steps:

1) mortar to be measured is contained into settlement barrel, standing mortar, after liquid level build-up calmness, is opened each pressure instrumentataion by computing machine and is started to measure muddy water pressure by the Frequency Synchronization of setting, and each pressure instrumentataion is passed the pressure of measuring in real time back computing machine;

2) pressure of measuring according to each pressure instrumentataion calculates the mortar mean sediment concentration of t at any time: the number of establishing pressure instrumentataion is N, and the surface level at each pressure instrumentataion 2 and place is numbered respectively n(n=1, and 2 ... N), surface level n is H apart from the discrepancy in elevation of mortar liquid level _n(n=1,2 ... N), pressure instrumentataion n at any time the pressure readings of t be P _n(t) (n=1,2 ... N), the frequency that each pressure instrumentataion is measured pressure is f=1/ Δ t, and wherein Δ t is the pressure measurement time interval; According to the definition of hydrostatic pressure, the mortar between surface level n and liquid level is the volume averaging unit weight of t at any time

for:

$\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)=\frac{P_n\left(t\right)}{H_n},(n=\mathrm{1,2},...N)---\left(1\right)$

According to the definition of quality silt content, the mean sediment concentration of the mortar between surface level n and liquid level with volume averaging unit weight

between meet following relation:

$\stackrel{\‾}{S_n}\left(t\right)={\mathrm{\γ}}_s\frac{\stackrel{\‾}{{\mathrm{\γ}}_n}\left(t\right)-\mathrm{\γ}}{{\mathrm{\γ}}_s-\mathrm{\γ}},(n=\mathrm{1,2},...N)---\left(2\right)$

γ in formula _sfor the unit dry weight of silt to be measured, the unit weight that γ is water;

3) according to formula (2), try to achieve the mean sediment concentration of the mortar between all surface levels and liquid level, the mortar obtaining between surface level n and surface level n-1 in the mean sediment concentration of moment t is:

$\stackrel{\‾}{S_{n-1,n}}\left(t\right)=\frac{H_n\stackrel{\‾}{S_n}\left(t\right)-H_{n-1}\stackrel{\‾}{S_{n-1}}\left(t\right)}{H_n-H_{n-1}},(n=\mathrm{1,2},...N)---\left(3\right)$

Will

being taken as with the liquid level discrepancy in elevation is (H _n+ H _n-1the silt content at the plane place of)/2, interpolation obtains the silt content S at surface level n place _n(t);

$S_n\left(t\right)=\frac{\stackrel{\‾}{S_{n-1,n}}\left(t\right)+\stackrel{\‾}{S_{n,n+1}}\left(t\right)}{2},(n=\mathrm{1,2},...N)---\left(4\right)$

4), according to the definition of silt discharge, between t-Δ t to t+ Δ t, the quantity of sand and mud by surface level n is silt discharge g divided by settlement barrel area of section A and time constantly _n(t), be calculated as follows:

$g_n\left(t\right)=\frac{(\stackrel{\‾}{S_n}(t+\mathrm{\Δt})-\stackrel{\‾}{S_n}(t-\mathrm{\Δt}))H_{n}A}{2\mathrm{A\Δt}},(n=\mathrm{1,2},...N)---\left(5\right)$

By g _n(t) be taken as surface level n at the instantaneous silt discharge of moment t;

5) according to formula (4) and formula (5), obtaining any time t is H apart from the liquid level discrepancy in elevation _nthe group settling velocity ω of the silt at place _n(t) be:

${\mathrm{\ω}}_n\left(t\right)=\frac{g_n\left(t\right)}{S_n\left(t\right)},(n=\mathrm{1,2},...N)---\left(6\right).$