CN104446168A - High-wave impedance concrete as well as preparation method and application thereof - Google Patents

Abstract

The invention discloses a high-wave impedance concrete, a preparation method and an application thereof. The high-wave impedance concrete includes cement, water, iron sand and a high-efficiency water reducer, wherein the water-cement ratio is 0.24 to 0.28, and the mass of cement and iron sand The ratio is 1: (1.6~3.0), and the quality of superplasticizer is 1.0%~2.0% of the cement quality. In the present invention, cement, water, iron sand and high-efficiency water reducer are mixed and gelled to form high-wave impedance concrete, and the slurry formed by cement and water wraps and hardens the iron sand to form stones; the high-efficiency water reducer reduces water consumption and improves stone formation. Density; at the same time, use iron sand to increase the density of concrete and increase the propagation speed of concrete longitudinal waves, so as to obtain concrete with high wave impedance, which can improve the reflection ability of blast shock waves.

Description

A kind of high wave impedance concrete, preparation method and application thereof

technical field

The invention belongs to the technical field of engineering blasting, and relates to a high-wave impedance concrete, a preparation method and an application thereof, which can be used to manufacture hole bottom energy-dissipating bases required in blasting and excavation of rock foundations.

Background technique

In the blasting and excavation process of rock foundations in water conservancy and hydropower projects, transportation, mining and other fields, there are problems that need to be solved when using blasting method to excavate rock mass, such as rapid construction, excavation forming, and fine damage control.

The traditional rock foundation excavation method adopts step blasting and reserves a protective layer. Since the excavation of the protective layer is usually divided into three layers, the construction efficiency is low and the construction progress is affected. On this basis, the primary blasting method of filling the bottom of the hole with a flexible protective layer has been developed. Because the material of the flexible protective layer is flammable and has limited buffering effect on the blast shock wave, the depth of damage to the bottom of the hole is still relatively large. In recent years, the excavation method of horizontal pre-splitting supplemented by shallow hole bench blasting has been developed. Although this method is relatively advanced and can effectively obtain a flat rock base, since horizontal pre-splitting requires a vertical working face, each working face needs to be excavated. The excavation footage is relatively short, which affects the construction progress and duration. In order to efficiently and quickly complete the forming excavation of the rock foundation, it is urgent to realize the vertical hole one-time blasting technology.

Through the energy-gathering-dissipating base at the bottom of the hole, one-time blasting, excavation, damage control and rapid construction of the vertical hole can be realized during the excavation of the rock foundation. The blasting shock wave is reflected, and the energy of the blasting shock wave is induced to gather in the horizontal direction, so that the rock mass between adjacent holes can be fully broken, and the blasting damage of the blasting shock wave to the bottom of the vertical blasting hole can be reduced, so as to realize the blasting and excavation of the vertical hole in the rock foundation.

In order to realize blasting and excavation forming of the energy-gathering-dissipating base, it is necessary to use high-wave impedance materials to make the energy-gathering-dissipating base. At present, steel is mostly used to make the energy-gathering-dissipating base. The forming and processing of steel materials is difficult, costly, and time-consuming. Difficult to apply on a large scale.

Contents of the invention

Aiming at the deficiencies in the prior art, the present invention provides a high wave impedance concrete with convenient molding, low cost, suitable for large-scale application, which can improve the energy utilization rate of drilling and blasting and the flatness of the bottom of the hole, a preparation method and its application.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A high-wave impedance concrete, including cement, water, iron sand and high-efficiency water reducer, wherein the water-cement ratio is 0.24 to 0.28, the mass ratio of cement and iron sand is 1: (1.6 to 3.0), and the quality of the high-efficiency water reducer is cement 1.0% to 2.0% of the mass.

The above cement is Portland cement with a strength grade above 42.5 or Portland cement mixed with mixed materials or other types of cement.

Preferably, the particle size of the iron sand is not greater than 5mm, and the fineness modulus is 2.3-3.0, which is equivalent to the grade of medium sand.

The preparation method of above-mentioned high wave impedance concrete, comprises steps:

Step 1, weighing cement, water, iron sand and superplasticizer in proportion, dissolving superplasticizer in part of water to make superplasticizer solution;

Step 2, mixing cement and iron sand, adding superplasticizer solution and remaining water at the same time.

During mixing, cement and water form a slurry to wrap iron sand, and cement stones are formed after the cement hardens.

The above-mentioned high-wave impedance concrete can be used to prepare the energy-gathering-energy-dissipating base, specifically:

Determine the size of the energy-gathering-energy-dissipating base according to the diameter of the blasting hole in the blast zone, and make a forming mold according to the size of the gathering-energy-dissipating base; introduce the above-mentioned high-wave impedance concrete mixture into the forming mold, vibrate and compact it, and demould after final setting, and then Carry out maintenance.

In the present invention, cement, water, iron sand and high-efficiency water reducer are mixed and gelled to form high-wave impedance concrete, and the slurry formed by cement and water wraps and hardens the iron sand to form stones; the high-efficiency water reducer reduces water consumption and improves stone formation. Density; at the same time, use iron sand to increase the density of concrete and increase the propagation speed of concrete longitudinal waves, so as to obtain concrete with high wave impedance, which can improve the reflection ability of blast shock waves.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Using concrete to replace the steel plate and cast iron materials used in the preparation of the traditional energy-gathering-energy-dissipating base avoids the difficulty of forming and processing metal materials, and is economical and convenient.

2. Raw materials are easy to purchase, and the production conditions are similar to those of concrete production. The construction sites of water conservancy, mining, and transportation all have production and maintenance conditions. The production conditions are easy to meet and are suitable for large-scale production.

3. The wave impedance of concrete is high, and it can be used as an energy-gathering-energy-dissipating base to change the direction of blasting shock waves, which can significantly improve the energy utilization rate of drilling and blasting and the flatness of the bottom of the hole, and reduce the damage of blasting shock waves to the bottom of the blasthole, thereby improving Preserve the flatness of the rock mass.

Description of drawings

Figure 1 is a microscopic schematic diagram of high wave impedance concrete;

Fig. 2 is a schematic diagram of three-dimensional dissection of the energy-gathering-energy-dissipating base;

Fig. 3 is an application demonstration diagram of the energy-gathering-energy-dissipating base;

Fig. 4 is a mechanism diagram of the energy gathering-energy dissipating base.

In the figure, 1-iron sand; 2-cement stones; 3-detonator; 4-explosives; C, D-reflected blast shock wave.

Detailed ways

The technical solutions of the present invention will be further described below through examples.

Example

The rock foundation blasting excavation project of a hydropower station needs to ensure the flatness of the foundation surface. The deep hole step blasting is adopted. In order to realize rapid construction, the vertical hole is required to be blasted at one time. In order to obtain a relatively flat foundation surface and ensure the flatness of the hole bottom, it is necessary to install the hole bottom energy-dissipating base. A kind of high wave impedance concrete is designed to improve the energy utilization efficiency of drilling and blasting and the flatness of the bottom of the hole ^. Reach 4300 ~ 4600m/s. It is known that the diameter of the blast hole during the excavation process is 105mm, and the technical requirement is that the average fluctuation difference is not greater than 0.1m

The preparation process of the energy-gathering-energy-dissipating base in this example is as follows:

Step 1: Make the mould for the gathering-energy dissipating base.

According to the diameter of the blast hole in the blast area, determine the size of the energy-gathering-dissipation base, and make the forming mold according to the size of the energy-gathering-dissipation base.

Step 2: According to the range of mix ratio and combined with the site conditions, conduct a field test to check the technical indicators of the concrete.

(1) In this embodiment, two sets of high-wave impedance concrete mix ratios are designed:

Option 1: The water-cement ratio is 0.28, the mass ratio of cement and iron sand is 1:1.6, the quality of superplasticizer is 1% of the mass of cement, and the concentration of superplasticizer solution is 33%.

Scheme 2: The water-cement ratio is 0.24, the mass ratio of cement and iron sand is 1:3.0, the quality of superplasticizer is 2% of the mass of cement, and the concentration of superplasticizer solution is 33%.

According to the above mix ratio and combined with the total amount of concrete required, calculate the amount of each raw material, and consider a certain amount of surplus, and accurately weigh the required materials according to the calculated amount.

(2) Mixing concrete.

When mixing, use a forced mixer to mix, mix and mix the weighed cement and iron sand evenly, while keeping the mixing, add the high-efficiency water-reducing agent solution dissolved in part of the water, and then use the remaining water to rinse the high-efficiency water-reducing agent The container of the solution is added 3 times and all are added, and after being completely stirred evenly, the stirring is stopped.

(3) Forming, demoulding and maintenance.

The concrete mixture was vibrated to fill the concrete standard part mold. The concrete mixture obtained in Scheme 1 and Scheme 2 were poured into 3 concrete standard specimens for quality inspection. The standard specimens were vibrated and compacted until the final Release the mold after setting, weigh the mass, and calculate the actual density according to its volume. The actual density of the concrete mixture obtained in the first plan is 3500.3kg/m ³ , and the actual density of the concrete mixture obtained in the second plan is 4501.5kg/m ³ , meet the design requirements, and be cured under the standard concrete curing conditions.

(4) Concrete quality inspection.

During the curing process, the longitudinal wave velocity of the standard specimen was measured with an acoustic wave instrument at 7 days and 28 days. The 7-day longitudinal wave velocity of the concrete standard specimens of scheme 1 and scheme 2 was 3900-4200m/s, and the 28-day longitudinal wave velocity was 4300-4600m/s , among them, the 7-day average P-wave velocity of the concrete standard in Scheme 1 is 4082m/s, and the 28-day average P-wave velocity is 4426m/s; the 7-day average P-wave velocity of the concrete standard in Scheme 2 is 4115m/s, and the 28-day average It is 4532m/s, all meet the design requirements.

Step 3: Optimizing the mix ratio and preparing the energy-gathering-dissipating base.

In order to obtain a better effect, the mix ratio of Scheme 2 is selected as the final production concrete; according to the above steps: weighing→mixing→molding→curing to prepare the energy-gathering-energy-dissipating base.

Step 4: Device installation and blasting.

Install the final cured energy-gathering-energy-dissipating base (5) on the blast hole bottom cushion (7) at the bottom of the blasthole, see Figure 3, and fill the explosive (4) to block, and the explosive (4) is emulsion explosive, and the charge roll The diameter is 70mm, the length of the charge section is 6m, the bottom cushion of the blasthole is 50cm, the length of the plugging section is 2m, the charge of each blasthole is 22-25kg, the row spacing between blastholes is 2.5m*2.5m, and the unit consumption is 0.46kg/ ^m3 , 4 holes for one sound, the maximum single sound dose is 92kg. After confirming the safety of the detonation network, detonate the explosives (4) in the blast hole through the detonator (3).

Step 5: Effect check.

For the blasting excavation of vertical holes in rock foundation, in order to obtain better flatness, it is required to reduce the blast shock wave energy acting on the bottom of the blast hole. The working principle of the energy-gathering-energy-dissipating base is to reflect the explosion shock wave energy to the horizontal direction, as shown in Figure 4, to increase the fragmentation in the horizontal direction and reduce the fragmentation degree of the rock mass at the bottom of the hole, so as to achieve the purpose of improving the flatness of the bottom of the hole. The index reflecting the energy utilization efficiency of the energy-gathering-energy-dissipating base is the energy reflection coefficient. The higher the coefficient, the higher the horizontal utilization rate, and vice versa.

Reflection coefficient Z ₁ and Z ₂ are the wave impedance of the accumulating-energy dissipating base and the wave impedance of the stress wave propagating wave medium respectively; wave impedance Z=ρC, ρ is the material density, and C is the longitudinal wave velocity of the material.

Calculate the reflection coefficient of the 28-day-old high-wave impedance concrete obtained in Scheme 2, the propagation medium emulsified explosive density ρ = 1000kg/m ³ and the longitudinal wave velocity C = 3600, and calculate the reflection coefficient λ of the 28-day-old high-wave impedance concrete obtained in Scheme 2 = 49.0%. It can be seen here that the high wave impedance concrete of the present invention can effectively improve the blasting energy utilization efficiency, effectively reflect the explosion shock wave energy acting on the bottom of the hole to the horizontal direction, reduce the crushing of the bottom of the hole by blasting, increase the horizontal crushing, and improve the efficiency of the hole. Flatness of the bottom and rock foundations.

After the blasting is completed, use the acoustic wave detection device to measure the rock-breaking range and hole bottom damage in the horizontal direction of the excavated rock mass. Compared with the blasting without using the energy-gathering-energy-dissipating base, the use of the concrete energy-gathering-dissipating base of the present invention makes the horizontal direction broken. The rock range is increased by 18% to 22%, the damage depth at the bottom of the hole is not greater than 1m, and the actual energy utilization efficiency is increased by not less than 20% based on the rock breaking range and damage judgment.

After the blasting, the bottom fluctuation difference detection of the blast hole is carried out. Use a steel tape measure to measure the height difference of the residual ridge in the test area, use a horizontal rope to draw a horizontal line at the highest point of the residual ridge, and measure the height difference from the horizontal line to the lowest point of the residual ridge. After testing, the average undulation of the bottom of the blasting hole in the test area is 0.04m, meeting the requirement that the undulation is less than 0.1.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which the present invention belongs can make various modifications or supplements to the described specific embodiments or adopt similar methods to replace them, but they will not deviate from the spirit of the present invention or go beyond the definition of the appended claims range.

Although terms such as accumulating-energy-dissipating base and high-wave-impedance concrete to improve the energy utilization efficiency of drilling and blasting and the flatness of the hole bottom are frequently used in this paper, the possibility of using other terms is not excluded. These terms are used only for the purpose of describing and explaining the essence of the present invention more conveniently; interpreting them as any kind of additional limitation is against the spirit of the present invention.

Claims (6)

1. A high wave impedance concrete, characterized in that: Including cement, water, iron sand and high-efficiency superplasticizer, wherein the water-cement ratio is 0.24-0.28, the mass ratio of cement and iron sand is 1: (1.6-3.0), and the quality of high-efficiency water-reducer is 1.0%~2.0 of the cement mass %. 2. The high wave impedance concrete as claimed in claim 1, characterized in that: The particle size of the iron sand is not greater than 5mm, and the fineness modulus is 2.3-3.0. 3. the preparation method of the described high wave impedance concrete of claim 1 is characterized in that, comprises the step: Step 1, weighing cement, water, iron sand and superplasticizer in proportion, dissolving superplasticizer in part of water to make superplasticizer solution; Step 2, mixing cement and iron sand, adding superplasticizer solution and remaining water at the same time. 4. the preparation method of high wave impedance concrete as claimed in claim 3 is characterized in that: The mass concentration of the superplasticizer solution is 33%. 5. the application of the described high wave impedance concrete of claim 1, is characterized in that: It is used to prepare gathering-energy dissipating base. 6. the application of high wave impedance concrete as claimed in claim 5, is characterized in that: The described base for preparing the energy-gathering-energy dissipation is specifically: Determine the size of the energy-gathering-dissipation device according to the diameter of the blast hole in the blast area, and make a forming mold according to the size of the energy-gathering-dissipating device; introduce the above-mentioned high-wave impedance concrete mixture into the forming mold, vibrate and compact it, and demould after final setting, and then Carry out maintenance.