CN105547960A - Transparent sand-based visualized simulation test method for foundation pit dewatering groundwater seepage - Google Patents

Abstract

The invention discloses a transparent sand-based visualized simulation test method for foundation pit dewatering groundwater seepage. The method comprises the steps of transparent sand model test parameter similarity relation determining, transparent sand material preparing, pore fluid preparing, tracer agent preparing, model device designing and test procedure performing. The method is suitable for the technical fields of geological engineering and geotechnical engineering and can be widely applied to visualized simulation of various foundation pit groundwater seepage problems.

Description

A kind of base pit dewatering seepage action of ground water visual Simulation test method based on transparent sand

Technical field

The invention belongs to Geological Engineering, Geotechnical Engineering field, especially relate to a kind of base pit dewatering seepage action of ground water visual Simulation test method based on transparent sand.

Background technology

In recent years, along with the development of China's fundamental construction, increasing deep basal pit meets with the environmental protection problem in piestic water and Precipitation Process.Particularly in building dense district, how to balance precipitation and the outer drawdown of foundation ditch in foundation ditch, thus the settlement issues that control precipitation brings out becomes the focus of research.Along with the research that deepens continuously in base pit dewatering field, the wall in base pit dewatering process-well interactively progressively by numerous scholars and engineering staff approve.But due to the restriction by geologic condition and observation method, under wall-well effect, piestic water Seepage mode and turbulent phenomenon can not be viewed directly.

Summary of the invention

A kind of base pit dewatering seepage action of ground water visual Simulation test method based on transparent sand provided to overcome above-mentioned technological deficiency is provided.

Object of the present invention can be achieved through the following technical solutions:

A kind of base pit dewatering seepage action of ground water visual Simulation test method based on transparent sand, it is characterized in that, this method relates to content and comprises transparent sand model test parameter similarity relation, transparent sand material formulation, pore fluid preparation, tracer agent preparation, model equipment design and experiment process.

Described transparent sand model test parameter similarity relation is derived according to model experiment similar theory and is drawn.First determine that geometric similarity is than 1:100, test parameters similarity relation is derived as follows:

(1) according to Darcy's law

Known α _p=α _l=100, α _g=1, α _ρ=*, α _μ=*, α _k=*, α _d=*

${\mathrm{\α}}_K=\frac{{\mathrm{\α}}_k{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_g}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_k{\mathrm{\α}}_{\mathrm{\ρ}}}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(I\right)$

${\mathrm{\α}}_{\mathrm{\ν}}=\frac{{\mathrm{\α}}_p}{{\mathrm{\α}}_l}\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(II\right)$

${\mathrm{\α}}_t=\frac{{\mathrm{\α}}_l}{{\mathrm{\α}}_{\mathrm{\ν}}}=100\frac{{\mathrm{\α}}_{\mathrm{\μ}}}{{\mathrm{\α}}_k}---\left(III\right)$

${\mathrm{\α}}_Q={\mathrm{\α}}_A{\mathrm{\α}}_{\mathrm{\ν}}={\mathrm{\α}}_l^2{\mathrm{\α}}_{\mathrm{\ν}}=10000\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(IV\right)$

${\mathrm{\α}}_{R_e}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_{\mathrm{\ν}}{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_k{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}^2}---\left(V\right)$

In formula: α _subscriptrepresent a certain physical parameter value under prototype condition with the ratio under Model Condition, wherein _subscriptcan be expressed as following physical quantity: physical dimension l, unit is m; Pressure p, unit is Pa; Average velocity ν, unit is m/s; Fluid density ρ, unit is kg/m ³; ; Coefficient of dynamic viscosity μ, unit is Pas, gravity acceleration g, and unit is m/s ²; Coefficient of permeability K, unit is m/d; The permeability k of pore media, unit is md, and it is only relevant with the character of solid skeletal; Reynolds number R _e; Solid skeletal mean particle size d, unit is m; * represent constant, test or additive method need be utilized to determine;

(2) according to Fu Xihaimo formula

Known α _p=α _l=100, α _g=1, α _ρ=*, α _μ=*, α _k=*, α _β=*, α _d=*

${\mathrm{\α}}_{\mathrm{\ν}}=\frac{-\frac{{\mathrm{\α}}_{\mathrm{\μ}}}{{\mathrm{\α}}_k}+{(\frac{{\mathrm{\α}}_{\mathrm{\μ}}^2}{{\mathrm{\α}}_k^2}+4{\mathrm{\α}}_{\mathrm{\β}}{\mathrm{\α}}_{\mathrm{\ρ}})}^{\frac{1}{2}}}{2{\mathrm{\α}}_{\mathrm{\β}}{\mathrm{\α}}_{\mathrm{\ρ}}}---\left(VI\right)$

${\mathrm{\α}}_t=\frac{{\mathrm{\α}}_l}{{\mathrm{\α}}_{\mathrm{\ν}}}=\frac{100}{{\mathrm{\α}}_{\mathrm{\ν}}}---\left(VII\right)$

${\mathrm{\α}}_Q={\mathrm{\α}}_A{\mathrm{\α}}_{\mathrm{\ν}}={\mathrm{\α}}_l^2{\mathrm{\α}}_{\mathrm{\ν}}=10000{\mathrm{\α}}_{\mathrm{\ν}}---\left(VIII\right)$

${\mathrm{\α}}_{R_e}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_{\mathrm{\ν}}{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(IX\right)$

In formula: β is Non-Darcy's flow inertial coefficient, only relevant with permeability with the porosity of solid skeletal; Other _subscriptthe physical quantity represented is identical with (1) part.

Described transparent sand material is formulated by different-grain diameter purity fused sand, and be warranty test similarity to the full extent, tekite sand distribution of particles should or uniform zoom consistent with realistic simulation layer of sand distribution of particles.

Described pore fluid is formulated by different refractivity White Mineral Oil, and be warranty test transparency and similarity, formulated pore fluid refractive index is 1.4585, and should ensure that the hydrodynamic force coefficient of viscosity is less than 1 × 10 ^-2pas.

Described tracer agent filters purification by formulated pore fluid reinforcing body chemical dyestuff and makes, and for ensureing tracer agent stability, need carry out Time Effect and diffusion test before the test, selecting optimum color and concentration.

" model equipment " of the present invention, this part content can adopt routine techniques to realize, therefore instructions does not disclose its detailed construction.Described model equipment comprises agent structure, determines head boundary, downcast well pipe, water-stop curtain, tracer agent releasing means, layering hole pressure measuring device, high-speed camera.Described agent structure size should meet maximum waterpower border requirement, also should ensure leakproofness simultaneously; Described top head boundary should be arranged on beyond waterpower border, and guaranteed water level cone of depression is complete; Described downcast well pipe, water-stop curtain should determine size according to the geometric similarity ratio in similarity relation; Tracer agent releasing means should be arranged on the keypoint part intending observation as far as possible, but needs to consider device issuable effect that blocks water in transparent sand simultaneously, and thin mozzle and needle tubing should be adopted to discharge tracer agent; Described layering hole pressure measuring device for measuring layering pore water pressure in process of the test, but is cancellation element issuable effect that blocks water in transparent sand, and sidewall piezometric tube should be adopted to measure; Described high-speed camera is for taking flow of tracer state, and shooting process high speed camera lens needs just to being observed region, and ensures that shooting speed is greater than fluid-flow rate.

Described experiment process should comprise following step:

(1) in die body structure according to the transparent sand material of test design layering landfill;

(2) in the process of filling, ad-hoc location installs downcast well pipe, water-stop curtain, tracer agent releasing means, layering hole pressure measuring device according to test design;

(3) to annotate in transparent sand material pore fluid by determining head boundary;

(4) by airtight for die body structure, utilize vacuum pump to be extracted out by bubble in pore fluid, improve test sand transparency;

(5) open downcast well pipe, according to constant flow or determine head mode and extract pore fluid, determine head boundary place simultaneously and remain stable level;

(6) by tracer agent releasing means release tracer agent, high-speed camera is utilized to take flow of tracer state;

(7) layering hole pressure measuring device is utilized to measure the distribution of layering pore water pressure and change in process of the test.

To sum up, the inventive method principle is: according to model experiment similar theory, determines test parameters similarity relation, selects and prepare transparent sand and pore fluid according to similarity relation, and selects suitable tracer material, and design a model device determine experiment process.

In concrete enforcement, need first determine test parameters similarity relation, binding tests prototype condition prepares the transparent sand material of specific grain composition, and prepare corresponding pore fluid, by Time Effect and diffusion test preparation tracer agent, lay mode and operating condition of test according to the testing requirements device that designs a model.The transparent sand material of layering landfill, in the process of filling, ad-hoc location installs downcast well pipe according to test design, water-stop curtain, tracer agent releasing means, layering hole pressure measuring device, to annotate in transparent sand material pore fluid by determining head boundary, by airtight for die body structure, vacuum pump is utilized to be extracted out by bubble in pore fluid, open downcast well pipe, according to constant flow or determine head mode and extract pore fluid, determine head boundary place simultaneously and remain stable level, by tracer agent releasing means release tracer agent, high-speed camera is utilized to take flow of tracer state, layering hole pressure measuring device is utilized to measure the distribution of layering pore water pressure and change in process of the test.

Accompanying drawing explanation

Fig. 1 is techniqueflow chart of the present invention;

Embodiment

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

Embodiment

In specific embodiment, as shown in Figure 1, first test parameters similarity relation is determined, binding tests prototype condition prepares the transparent sand material of specific grain composition, and prepare corresponding pore fluid, by Time Effect and diffusion test preparation tracer agent, lay mode and operating condition of test according to the testing requirements device that designs a model.The transparent sand material of layering landfill, in the process of filling, ad-hoc location installs downcast well pipe according to test design, water-stop curtain, tracer agent releasing means, layering hole pressure measuring device, to annotate in transparent sand material pore fluid by determining head boundary, by airtight for die body structure, vacuum pump is utilized to be extracted out by bubble in pore fluid, open downcast well pipe, according to constant flow or determine head mode and extract pore fluid, determine head boundary place simultaneously and remain stable level, by tracer agent releasing means release tracer agent, high-speed camera is utilized to take flow of tracer state, layering hole pressure measuring device is utilized to measure the distribution of layering pore water pressure and change in process of the test.

Claims (1)

1. the base pit dewatering seepage action of ground water visual Simulation test method based on transparent sand, it is characterized in that, this method relates to content and comprises the determination of transparent sand model test parameter similarity relation, transparent sand material formulation, pore fluid preparation, tracer agent preparation, model equipment design, then carries out experiment process;

Described transparent sand model test parameter similarity relation comprises following two parts:

(1) according to Darcy's law

Known α _p=α _l=100, α _g=1, α _ρ=*, α _μ=*, α _k=*, α _d=*

${\mathrm{\α}}_K=\frac{{\mathrm{\α}}_k{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_g}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_k{\mathrm{\α}}_{\mathrm{\ρ}}}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(I\right)$

${\mathrm{\α}}_{\mathrm{\ν}}=\frac{{\mathrm{\α}}_p}{{\mathrm{\α}}_l}\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(II\right)$

${\mathrm{\α}}_t=\frac{{\mathrm{\α}}_l}{{\mathrm{\α}}_{\mathrm{\ν}}}=100\frac{{\mathrm{\α}}_{\mathrm{\μ}}}{{\mathrm{\α}}_k}---\left(III\right)$

${\mathrm{\α}}_Q={\mathrm{\α}}_A{\mathrm{\α}}_{\mathrm{\ν}}={\mathrm{\α}}_l^2{\mathrm{\α}}_{\mathrm{\ν}}=10000\frac{{\mathrm{\α}}_k}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(IV\right)$

${\mathrm{\α}}_{R_e}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_{\mathrm{\ν}}{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_k{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}^2}---\left(V\right)$

In formula: α _subscriptrepresent a certain physical parameter value under prototype condition with the ratio under Model Condition, wherein _subscriptcan be expressed as following physical quantity: physical dimension l, unit is m; Pressure p, unit is Pa; Average velocity ν, unit is m/s; Fluid density ρ, unit is kg/m ³; Coefficient of dynamic viscosity μ, unit is Pas, gravity acceleration g, and unit is m/s ²; Coefficient of permeability K, unit is m/d; The permeability k of pore media, unit is md, and it is only relevant with the character of solid skeletal; Reynolds number R _e; Solid skeletal mean particle size d, unit is m; * represent constant, test or additive method need be utilized to determine;

(2) according to Fu Xihaimo formula

Known α _p=α _l=100, α _g=1, α _ρ=*, α _μ=*, α _k=*, α _β=*, α _d=*

${\mathrm{\α}}_{\mathrm{\ν}}=\frac{-\frac{{\mathrm{\α}}_{\mathrm{\μ}}}{{\mathrm{\α}}_k}+{(\frac{{\mathrm{\α}}_{\mathrm{\μ}}^2}{{\mathrm{\α}}_k^2}+4{\mathrm{\α}}_{\mathrm{\β}}{\mathrm{\α}}_{\mathrm{\ρ}})}^{\frac{1}{2}}}{2{\mathrm{\α}}_{\mathrm{\β}}{\mathrm{\α}}_{\mathrm{\ρ}}}---\left(VI\right)$

${\mathrm{\α}}_t=\frac{{\mathrm{\α}}_l}{{\mathrm{\α}}_{\mathrm{\ν}}}=\frac{100}{{\mathrm{\α}}_{\mathrm{\ν}}}---\left(VII\right)$

${\mathrm{\α}}_Q={\mathrm{\α}}_A{\mathrm{\α}}_{\mathrm{\ν}}={\mathrm{\α}}_l^2{\mathrm{\α}}_{\mathrm{\ν}}=10000{\mathrm{\α}}_{\mathrm{\ν}}---\left(VIII\right)$

${\mathrm{\α}}_{R_e}=\frac{{\mathrm{\α}}_{\mathrm{\ρ}}{\mathrm{\α}}_{\mathrm{\ν}}{\mathrm{\α}}_d}{{\mathrm{\α}}_{\mathrm{\μ}}}---\left(IX\right)$

In formula: β is Non-Darcy's flow inertial coefficient, only relevant with permeability with the porosity of solid skeletal; Other _subscriptthe physical quantity represented is identical with (1) part;

Described transparent sand material is formulated by different-grain diameter purity fused sand, and tekite sand distribution of particles should or uniform zoom consistent with realistic simulation layer of sand distribution of particles;

Described experiment process should comprise following step:

(1) in die body structure according to the transparent sand material of test design layering landfill;

(2) in the process of filling, ad-hoc location installs downcast well pipe, water-stop curtain, tracer agent releasing means, layering hole pressure measuring device according to test design;

(3) to annotate in transparent sand material pore fluid by determining head boundary;

(4) by airtight for die body structure, utilize vacuum pump to be extracted out by bubble in pore fluid, improve test sand transparency;

(5) open downcast well pipe, according to constant flow or determine head mode and extract pore fluid, determine head boundary place simultaneously and remain stable level;

(6) by tracer agent releasing means release tracer agent, high-speed camera is utilized to take flow of tracer state;

(7) layering hole pressure measuring device is utilized to measure the distribution of layering pore water pressure and change in process of the test.