阅读说明：本技术 一种桥梁群桩基础浅眼***空气袋减振结构及施工方法 (Bridge group pile foundation shallow hole blasting air bag vibration reduction structure and construction method ) 是由 龙立敦 李少方 王朝国 陈元忠 张凯 周旭 汪志伟 于 2020-07-01 设计创作，主要内容包括：本发明公开了一种桥梁群桩基础浅眼爆破空气袋减振结构及施工方法,其特征在于,包括炮眼(1),在炮眼(1)内设有炸药(3),炸药(3)两端设置空气袋(2)。就爆破效果而言,在本发明减振措施下,爆破效果良好,对工效影响很小。空气袋措施可很好的实现预期减振目标,在实际工程中,结合成本分析,采用空气袋措施仅增加15.6元,因此,空气袋成为群桩施工爆破减震的最优选择。(The invention discloses a bridge pile group foundation shallow hole blasting air bag vibration reduction structure and a construction method, and is characterized by comprising a blast hole (1), wherein an explosive (3) is arranged in the blast hole (1), and air bags (2) are arranged at two ends of the explosive (3). In terms of blasting effect, the blasting effect is good and the influence on work efficiency is small under the vibration reduction measure of the invention. The air bag measures can well achieve the expected damping target, in the actual engineering, the cost analysis is combined, and only 15.6 yuan is added by adopting the air bag measures, so that the air bag becomes the optimal selection for pile group construction blasting damping.)

1. A bridge pile group foundation shallow hole blasting air bag vibration reduction structure is characterized by comprising a blast hole (1), wherein an explosive (3) is arranged in the blast hole (1), and air bags (2) are arranged at two ends of the explosive (3).

2. The bridge pile group foundation shallow hole blasting air bag vibration reduction structure according to claim 1, wherein an air bag (2), an explosive (3), an air bag (2) and stemming (4) are sequentially arranged in the blasthole (1).

3. The air bag damping structure for shallow hole blasting of bridge pile group foundation according to claim 1, wherein the air bag (2) is cylindrical.

4. The bridge pile group foundation shallow hole blasting air bag damping structure according to claim 3, wherein the length of the air bag (2) is 15-25cm, and the diameter is 25-45 mm.

5. The air bag damping structure for the shallow hole blasting of the bridge pile group foundation according to claim 4, wherein the length of the air bag (2) is 20cm, and the diameter of the air bag is 35 mm.

6. The bridge pile group foundation shallow hole blasting air bag vibration reduction structure according to claim 1, wherein the blast hole (1) comprises a peripheral hole (5) and a cut hole (6), and an air bag (2), an explosive (3), an air bag (2) and stemming (4) are sequentially arranged in the peripheral hole (5) and the cut hole (6).

7. The air bag damping structure for shallow hole blasting of bridge pile group foundation according to claim 1, wherein the air bag (2) is a water bag or a mortar bag.

8. The shallow hole blasting air bag vibration reduction construction method for the bridge pile group foundation according to any one of claims 1 to 6, characterized by comprising the following steps:

A. drilling a blast hole (1) at a blasting position according to design requirements;

B. inflating and sealing the plastic bag to manufacture an air bag (2);

C. placing an air bag (2) at the bottom of the blast hole (1), then filling the explosive (3), then placing the air bag (2) and then plugging the blast hole (1) by using stemming (4) to finish charging;

D. and detonating after safety is confirmed.

Technical Field

The invention relates to a blasting vibration reduction construction method, in particular to a shallow hole blasting air bag vibration reduction structure of a bridge group pile foundation and a construction method.

Background

The pile group foundation is the most common foundation form in the design of high piers and high towers of high-speed highway bridges in mountainous areas. The shallow hole blasting manual hole digging construction is used as an efficient and economic digging mode under the limitation of terrain, and is widely applied to pile foundation construction of highway bridge groups in mountainous areas. Engineering practices prove that in the process of blasting operation of a pile foundation, partial energy of explosives is transmitted around in the form of seismic waves to generate a seismic effect, when the seismic effect is strong and the wave velocity is high, the protective walls of adjacent pile holes and newly-poured pile body concrete are adversely affected, cracks appear in the protective walls and the pile body concrete, and finally potential safety hazards and potential quality hazards are formed. Therefore, in the shallow blasting excavation construction process of the bridge pile group foundation, blasting vibration reduction measures are needed to be adopted to control blasting vibration transmitted to adjacent piles.

At present, researches on blast damping measures mainly focus on two aspects: firstly, weakening the detonation source, such as reducing the maximum dosage, adjusting the differential time and the like; and secondly, changing the physical properties of the propagation medium, such as excavating vibration reduction grooves, vibration isolation holes and the like. However, in a highway project, piers and towers adopting a group pile foundation are often key work of the project, the requirement on the construction period is high, the work efficiency can be reduced and the construction progress can be delayed by adopting a method of reducing the drug amount to realize vibration reduction, the clear distance between the group pile foundation piles is small, the hole depth is large, and a vibration reduction groove can not be used obviously. Chinese patent 201611211317.5 discloses a vibration-damping blasting method for controlling vibration-damping of slurry in holes of tunnel, which uses bagged slurry to fill holes to achieve the purpose of vibration damping, but the method charges the holes at intervals, the vibration-damping measure for filling holes with slurry bags is not high in the utilization rate of blastholes, and the number of holes in the holes needs to be encrypted to achieve the same blasting effect, which further increases the total explosive loading, and finally leads to the enhancement of explosion source, the reduction of vibration-damping effect and the increase of cost. Meanwhile, the mud bag is complex to manufacture and fill, the labor cost is high, the blocking effect of the mud on the blasting vibration wave is poor compared with that of air, and according to engineering experience, the water pressure blasting has no obvious effect on blasting vibration reduction. .

Disclosure of Invention

The invention aims to provide a shallow hole blasting air bag vibration reduction structure for a bridge pile group foundation and a construction method. The invention has the characteristics of simple structure, low cost and good vibration damping effect.

The technical scheme of the invention is as follows: a vibration damping structure for shallow hole blasting air bags on a bridge pile group foundation comprises a blasthole, wherein explosives are arranged in the blasthole, and air bags are arranged at two ends of the explosives.

According to the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the air bag, the explosive, the air bag and the stemming are sequentially arranged in the blasting hole.

In the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the air bag is cylindrical.

According to the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the length of the air bag is 15-25cm, and the diameter of the air bag is 25-45 mm.

According to the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the length of the air bag is 20cm, and the diameter of the air bag is 35 mm.

According to the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the blast hole comprises the peripheral hole and the cut hole, and the air bag, the explosive, the air bag and the stemming are sequentially arranged in the peripheral hole and the cut hole.

In the shallow hole blasting air bag vibration reduction structure for the bridge pile group foundation, the air bag is a water bag or a mortar bag.

The shallow hole blasting air bag vibration reduction construction method for the bridge pile group foundation comprises the following steps:

A. drilling a blast hole at the blasting position according to the design requirement;

B. inflating and sealing the plastic bag to obtain an air bag;

C. placing an air bag at the bottom of the blast hole, then filling the explosive, then placing the air bag, and then plugging the blast hole with stemming to finish charging;

D. and detonating after safety is confirmed.

The invention has the beneficial effects that: according to the regulations of blasting safety regulations (GB6722-2014), the safe allowable particle vibration speed of underground shallow hole blasting on a traffic tunnel (simulated dado) is 10-20 cm/s, and the allowable particle vibration speed of newly cast mass concrete (simulated pile body concrete) in the 7-day age is 10-12 cm/s. To prove the effectiveness of the method of the invention, the applicant carried out blasting vibration reduction experiments. The experiments were divided into the following two groups:

(1) reference experimental group: the operation is carried out according to the blasting design scheme without any vibration reduction and vibration isolation measures, as shown in figure 2, the left side is a blasting operation hole 7 of a reference experiment, the right side of the blasting operation hole 7 is a wave velocity testing hole 8, a sensor 10 is arranged on a concrete protecting wall 9 of the wave velocity testing hole 8 at the position opposite to the center of a blasting source of the blasting operation hole 7 and at the same elevation, the size of seismic waves generated by blasting when the seismic waves are transmitted to the concrete protecting wall 9 is measured, and the vibration reduction efficiency of the vibration isolation hole and the air bag is evaluated by taking the value as a reference value.

(2) An air bag set: by adopting the method, the air bag is added into the blast hole to form a charging structure of the air bag, the explosive, the air bag and the stemming, and the charging amount of each blast hole and the arrangement position of the sensor are consistent with the reference experiment composition scheme.

The experiment adopts a TC-4850 Blasting vibration meter produced by Chengdu Zhongzhong Ke measurement and control Limited company to carry out Blasting vibration test, the tester is provided with an X, Y and Z three-dimensional integrated speed sensor and three-vector synthesis analysis software (shooting vibration analysis CBVA) software matched with the X, Y and Z three-dimensional integrated speed sensor. The experimental results are as follows:

(1) figure 3 shows the blast vibration waveform

(2) The maximum vibration speed and frequency are shown in Table 1

Table 1 blasting vibration test results

Tab.1 Result of Blasting Vibration Test

As can be seen from Table 1, the vibration frequency generated by the underground shallow-hole blasting is large, the half-wave dominant frequency is above 50Hz, the natural vibration frequency of the structure is usually low, and the influence of the vibration wave frequency on the adjacent pile foundations is small, so that the vibration wave speed is only used as an index for measuring the blasting influence. As can be seen from table 1 and fig. 3, before any vibration reduction measures are taken, the maximum value of the vibration wave speed transmitted to the adjacent pile hole retaining wall by the manual hole digging shallow hole blasting operation reaches 40.82cm/s, which is slightly larger than the theoretical value calculated by the sarofsky formula, and the vibration speed of the mass point is far higher than the allowable mass point for the safety of newly poured mass concrete in a traffic tunnel and 7 days of age specified by blasting safety regulations (GB6722-2014), and the necessity of taking the vibration reduction measures is also proved. By adding the air bag measure, the maximum wave velocity is reduced to 11.89cm/s, the reduction amplitude reaches 70.9 percent, and the requirement of blasting in blasting safety regulations (GB6722-2014) on safe allowable particle vibration velocity of a traffic tunnel and newly poured mass concrete in 7-day age is basically met. Meanwhile, in terms of blasting effect, the blasting effect is good and the influence on work efficiency is small under the vibration reduction measure of the invention.

Experiments show that the air bag measures can well achieve the expected damping target, in the actual engineering, the cost analysis is combined, and only 15.6 yuan is added by adopting the air bag measures, so that the air bag becomes the optimal selection for blasting damping in pile group construction.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a reference experimental plan view;

fig. 3 is a diagram of a burst vibration waveform.

Detailed Description

The invention is further illustrated by the following figures and examples, which are not to be construed as limiting the invention.

Example 1 of the invention:

a bridge pile group foundation shallow hole blasting air bag vibration reduction structure comprises a blasthole 1, wherein explosives 3 are arranged in the blasthole 1, and air bags 2 are arranged at two ends of the explosives 3.

More specifically, an air bag 2, an explosive 3, an air bag 2 and stemming 4 are sequentially arranged in the blasthole 1.

The air bag 2 is cylindrical, and can also be in the conventional shape, such as an elliptic cylinder, a cuboid or other three-dimensional shapes.

The length of the air bag 2 is 15-25cm, the diameter is 25-45mm, and the vibration reduction effect is good. More preferably, the length of the air bag 2 is 20cm, and the diameter is 35 mm.

According to the design scheme of the blasting blasthole, the blasthole 1 comprises a peripheral hole 5 and a cut hole 6, and an air bag 2, an explosive 3, an air bag 2 and stemming 4 are sequentially arranged in the peripheral hole 5 and the cut hole 6.

The air bag 2 can also be a water bag or a mortar bag.

The shallow hole blasting air bag vibration reduction construction method for the bridge pile group foundation comprises the following steps:

A. drilling a blast hole 1 at a blasting position according to design requirements;

B. inflating and sealing the plastic bag to manufacture an air bag 2;

C. placing an air bag 2 at the bottom of the blast hole 1, then filling explosive 3, then placing the air bag 2, and then plugging the blast hole 1 with stemming 4 to finish charging;

D. and detonating after safety is confirmed.

Example 2 of the invention:

a bridge pile group foundation shallow hole blasting air bag vibration reduction structure comprises a blasthole 1, wherein explosives 3 are arranged in the blasthole 1, and air bags 2 are arranged at two ends of the explosives 3.

More specifically, an air bag 2, an explosive 3, an air bag 2 and stemming 4 are sequentially arranged in the blasthole 1. The air bag 2 is cylindrical.

The length of the air bag 2 is 18-22cm, and the diameter is 30-40 mm.

According to the design scheme of the blasting blasthole, the blasthole 1 comprises a peripheral hole 5 and a cut hole 6, and an air bag 2, an explosive 3, an air bag 2 and stemming 4 are sequentially arranged in the peripheral hole 5 and the cut hole 6.

The bridge pile group foundation shallow hole blasting air bag vibration reduction construction method is as in embodiment 1.

Example 3 of the invention:

a bridge pile group foundation shallow hole blasting air bag vibration reduction structure comprises a blasthole 1, wherein explosives 3 are arranged in the blasthole 1, and air bags 2 are arranged at two ends of the explosives 3.

More specifically, an air bag 2, an explosive 3, an air bag 2 and stemming 4 are sequentially arranged in the blasthole 1, namely the air bags 2 are arranged at two ends of the explosive 3. The air bag 2 is cylindrical.

The length of the air bag 2 is 19-21cm, and the diameter is 33-37 mm.

The bridge pile group foundation shallow hole blasting air bag vibration reduction construction method is as in embodiment 1.

The above description is only for the purpose of illustrating the present invention and the appended claims, and the scope of the present invention is not limited thereto, and any person skilled in the art can substitute or change the technical solution and the inventive concept of the present invention within the technical scope of the present invention.