阅读说明：本技术 一种独塔单索面预应力斜拉桥精准爆破拆除方法 (Accurate blasting demolition method for single-tower single-cable-plane prestressed cable-stayed bridge ) 是由 陈德志 罗鹏 李本伟 陈晨 徐顺香 胡浩川 安玉东 周应军 周祥磊 于 2020-05-12 设计创作，主要内容包括：本发明公开了一种独塔单索面预应力斜拉桥精准爆破拆除方法。包括以下步骤：S1：标出索塔爆破切口支撑部分与爆破部分的切口分界线,将爆破切口分为梯形爆破部分与支撑部分；S2：机械破碎主梁两侧桥面,使主梁两侧分离；S3：标出索塔、主梁、主墩孔位,在索塔爆破切口梯形爆破部分、索塔爆破切口支撑部分底部、主梁、主墩钻凿炮孔；S4：沿索塔梯形爆破部分与支撑部分切口分界线连续钻凿分界贯穿孔,分界贯穿孔与切口分界线相切,布置在梯形爆破部分一侧,形成贯穿分界面；S5：平行钻凿与炮孔深度相同的补偿孔；S6：沿索塔爆破切口梯形爆破部分水平方向间隔破碎表皮混凝土,割断露出的包裹钢筋；S7：装药、堵塞、联网、起爆。本方法钻凿炮孔容易、工作量小,斜拉索两端不会弹出,在空中甩动,且背向临时便桥倾倒,安全性好。(The invention discloses a precise blasting demolition method for a single-pylon single-cable-surface prestressed cable-stayed bridge. The method comprises the following steps: s1: marking a cut boundary line of a supporting part and a blasting part of the cable tower blasting cut, and dividing the blasting cut into a trapezoidal blasting part and a supporting part; s2: mechanically crushing bridge decks on two sides of a main beam to separate the two sides of the main beam; s3: marking the hole positions of the cable tower, the main beam and the main pier, and drilling blast holes in the trapezoidal blasting part of the cable tower blasting notch, the bottom of the supporting part of the cable tower blasting notch, the main beam and the main pier; s4: continuously drilling a boundary through hole along the cut boundary of the cable tower trapezoid blasting part and the support part, wherein the boundary through hole is tangent to the cut boundary and is arranged on one side of the trapezoid blasting part to form a penetrating boundary; s5: drilling compensation holes with the same depth as the blast hole in parallel; s6: breaking the skin concrete at intervals along the horizontal direction of the trapezoid blasting part of the blasting notch of the cable tower, and cutting off the exposed wrapping steel bars; s7: charging, blocking, networking and detonating. The method has the advantages of easy blast hole drilling, small workload, no ejection of two ends of the stay cable, swinging in the air, back-to-back dumping of the temporary.)

1. The method for accurately blasting and dismantling the single-tower single-cable-plane prestressed cable-stayed bridge is characterized by comprising the following steps of:

s1: marking a cut boundary line of a supporting part and a blasting part of the cable tower blasting cut, and dividing the blasting cut into a trapezoidal blasting part and a supporting part;

s2: mechanically crushing bridge decks on two sides of a main beam to separate the two sides of the main beam;

s3: marking the hole positions of the cable tower, the main beam and the main pier, and drilling blast holes in the trapezoidal blasting part of the cable tower blasting notch, the bottom of the supporting part of the cable tower blasting notch, the main beam and the main pier;

s4: continuously drilling a boundary through hole along the cut boundary of the cable tower trapezoid blasting part and the support part, wherein the boundary through hole is tangent to the cut boundary and is arranged on one side of the trapezoid blasting part to form a penetrating boundary;

s5: in blast holes drilled by the cable tower and the main pier, compensating holes with the same depth as the blast holes are drilled in parallel;

s6: breaking the skin concrete at intervals along the horizontal direction of the trapezoid blasting part of the blasting notch of the cable tower, and cutting off the exposed wrapping steel bars;

s7: charging, blocking, networking and detonating, wherein the detonating sequence of the cable tower blasting notch, the two sides of the main beam and the main pier blasting point is controlled by using detonator delay time; the cable tower is directionally inclined along the vertical cable surface, and the main beam and the main pier collapse in situ.

2. The method for precisely blasting demolition of an individual tower single-cable-side prestressed cable-stayed bridge according to claim 1, wherein in the step S1, at the lower end point of the boundary line of the cut, the horizontal width of the supporting part is 0.6-1.2 m, and the horizontal width ratio of the supporting part to the blasting part is 1: 2.4-3.5, the cut boundary line inclines towards the dumping direction, and the oblique angle is 45-70 degrees.

3. The method for precisely blasting demolition of an independent tower single-cable-face prestressed cable-stayed bridge according to claim 1, wherein in the step S2, the width of the mechanical crushing area of the bridge deck is 1-1.5 m.

4. The method for precisely blasting demolition of an individual tower single-cable-side prestressed cable-stayed bridge according to claim 1, wherein in step S3, the distance between the bottom of blasting holes of blasting cut portions of cable towers and the boundary line of the cut portions is 20-30 cm, 2-3 rows of blasting holes are arranged at the bottom of supporting portions, and the row distance is not more than 30 cm.

5. The method for precisely blasting demolition of an individual tower single-cable-plane prestressed cable-stayed bridge according to claim 1, wherein in the step S4, the diameter of the boundary through hole is 7-9 cm.

6. The method for precisely blasting demolition of an independent tower single-cable-plane prestressed cable-stayed bridge according to claim 1, wherein in step S5, every 4 blast holes of the cable-tower blasting part are grouped, 1 compensation hole is drilled at the diagonal intersection point of each group of blast holes, and 1 blast hole is drilled at the center line in odd number, with the diameter of 7-9 cm; every 6 blast holes of three rows of blast holes under the main pier are in a group, 2 compensation holes are drilled at the intersection point of the diagonal lines of each group of blast holes, 1 blast hole is drilled at the central line in an odd number mode, and the diameter of each blast hole is 7 cm-9 cm.

7. The method for accurately blasting demolition of an individual tower single-cable-side prestressed cable-stayed bridge according to claim 1, wherein in the step S5, concrete skins of 10-15 cm are crushed at an interval of 60-80 cm in the horizontal direction, two sides of a corner are crushed by 10-15 cm respectively, and the crushing height is not more than 20 cm.

8. The method for precisely blasting demolition of an individual tower single-cable-plane prestressed cable-stayed bridge according to claim 1, wherein in S6, the blasting sequence is a cable tower blasting notch blasting portion, a cable tower blasting notch supporting portion bottom, two sides of a main beam, and a main pier; the cable tower blasting part is detonated from two sides to the middle in a delayed mode, and the total delay time is not more than 200 ms; simultaneously detonating the cable tower supporting parts; two sides of the main beam are detonated simultaneously; the main pier is detonated from two sides to the middle in a delayed mode, and the total delay time does not exceed 500 ms; the explosion interval between the cable tower blasting notch blasting part and the cable tower blasting notch supporting part is 500-700 ms, the detonation interval between the cable tower blasting notch blasting part and the cable tower blasting notch supporting part and the main beam two sides is 1000-1500 ms, and the detonation interval between the cable tower blasting notch blasting part and the main pier is 3500-4500 ms.

Technical Field

The invention belongs to the technical field of engineering blasting, particularly relates to blasting demolition of a cable-stayed bridge, and particularly relates to an accurate blasting demolition method for a single-pylon single-cable-side prestressed cable-stayed bridge.

Background

The reason of the cable-stayed bridge is from the 50 s of the last century, the traffic pressure is low, the bridge construction technology and building materials are limited, and the early cable-stayed bridge is mostly a single-tower single-cable-plane prestressed cable-stayed bridge. With the development of bridge construction technology and building materials, the cable tower type is changed from single tower type to A type, inverted Y type and H type with better stability, and the cable surface is changed into parallel double cable surfaces, oblique cable surfaces and the like. The existing single-tower single-cable-plane prestressed cable-stayed bridge has the problems of poor stability, insufficient traffic capacity and approximate service life, and all the existing single-tower single-cable-plane prestressed cable-stayed bridges are dismantled and rebuilt. Before the temporary.

The existing method for dismantling the cable-stayed bridge mainly comprises the following steps: and a reverse construction sequence manual mechanical dismantling method and a blasting dismantling method. The cable-stayed bridge consists of a main pier, a cable tower, a main girder and a stay cable, the reverse construction sequence manual mechanical dismantling of the special structure with the symmetrical balance mechanics has the defects of poor safety, high cost, long period and the like, and the blasting dismantling method is safer, more economic and more efficient and becomes the preferred method for dismantling the cable-stayed bridge.

The existing method for demolishing the cable-stayed bridge by blasting comprises the following steps: in-situ collapse blasting, parallel cable surface directional blasting and cable tower vertical cable surface directional blasting.

In-situ collapse blasting: a plurality of explosion points are arranged on the cable tower, and the explosion points are arranged at each stress point of the main pier and the main beam, so that the cable tower is broken into a plurality of sections and collapses in situ with the main pier and the main beam. The method has the advantages of multiple explosion points, long construction period and high cost; a platform needs to be built for high-altitude operation; the cable tower has high explosion point, large single explosive consumption, large impact on a temporary bridge due to far throwing of blasting flyings, large scattering area and no contribution to quick recovery of traffic after explosion; the cable tower is big and firm, and the blasting in-situ collapse range is uncontrollable, can't guarantee the safety of next-door temporary bridge.

Directional blasting of parallel cable surfaces of the cable towers: blasting points are arranged at the bottom of the cable tower, the main pier, the main beam and the anchoring end of each stay cable on one side, so that the stay cables on one side are all disconnected with the main beam, the cable tower is pulled by the stay cables on the other side, the parallel cable surfaces collapse in a directional mode, and the main pier and the main beam collapse in situ. The reinforcing steel bars at the anchoring end of the stay cable are staggered and are abnormally dense, blast holes are difficult to drill, the construction period is long, the economic benefit is poor, and the reliability that the anchoring end of the stay cable is quickly and completely separated from the main beam at the moment of blasting is low; the stay cable is popped up at the moment of blasting and thrown in the air, so that the safety of the temporary; the parallel temporary suspension bridge of cable tower collapses, strikes the bridge floor that collapses, and the disintegrating slag side direction protection degree of difficulty that flies off is big, the effect is poor, seriously influences temporary suspension bridge safety.

Directional blasting of the vertical cable surface of the cable tower: the prestressed cable-stayed bridge is generally used for cable-stayed bridges with A-type, inverted Y-type and H-type cable towers, is not applied to single-tower single-cable-surface prestressed cable-stayed bridges, and is derived from the following technical difficulties.

(1) The width of the cross section of the cable tower in the direction vertical to the cable plane is smaller, and is far smaller than the height of the cable tower, the cable tower belongs to a slender rod, a cable-stayed system consisting of the cable tower, the stay cable, the main beam and the main pier is mutually restrained at the moment of forming a blasting notch, and the width ratio of the supporting part to the blasting part and the detonation time difference of each part are of great importance.

(2) The single-tower cable tower is different from A type, inverted Y type and H type, only has 1 supporting point, and how to utilize explosive explosion to destroy reinforced concrete in the toppling direction without destroying reinforced concrete of the supporting part, and a trapezoidal blasting notch which accords with theoretical design is formed in the toppling direction.

(3) The cable tower has large section size, the bottom is made of solid reinforced concrete, the reinforcing steel bars have high strength, are staggered and dense transversely and vertically, and cannot be broken by explosion, so that the condition that a large amount of concrete is separated from the restraint of the staggered reinforcing steel bars at the moment of explosion cannot be ensured, and the support capability of an explosion notch part is lost.

Disclosure of Invention

The invention provides a precise blasting demolition method for a single-pylon single-cable-plane prestressed cable-stayed bridge, aiming at the problems in the prior art.

In order to achieve the purpose, the technical solution of the invention is as follows: an accurate blasting demolition method for a single-tower single-cable-plane prestressed cable-stayed bridge comprises the following steps:

s1: marking a cut boundary line of a supporting part and a blasting part of the cable tower blasting cut, and dividing the blasting cut into a trapezoidal blasting part and a supporting part;

s2: mechanically crushing bridge decks on two sides of a main beam to separate the two sides of the main beam;

s3: marking the hole positions of the cable tower, the main beam and the main pier, and drilling blast holes in the trapezoidal blasting part of the cable tower blasting notch, the bottom of the supporting part of the cable tower blasting notch, the main beam and the main pier;

s4: continuously drilling a boundary through hole along the cut boundary of the cable tower trapezoid blasting part and the support part, wherein the boundary through hole is tangent to the cut boundary and is arranged on one side of the trapezoid blasting part to form a penetrating boundary;

s5: in blast holes drilled by the cable tower and the main pier, compensating holes with the same depth as the blast holes are drilled in parallel;

s6: breaking the skin concrete at intervals along the horizontal direction of the trapezoid blasting part of the blasting notch of the cable tower, and cutting off the exposed wrapping steel bars;

s7: charging, blocking, networking and detonating, wherein the detonating sequence of the cable tower blasting notch, the two sides of the main beam and the main pier blasting point is controlled by using detonator delay time; the cable tower is directionally inclined along the vertical cable surface, and the main beam and the main pier collapse in situ.

According to the embodiment of the present invention, in step S1, at the lower end of the boundary line of the cut, the horizontal width of the supporting portion is 0.6 to 1.2m, and the horizontal width ratio of the supporting portion to the blasting portion is 1: 2.4-3.5, wherein the cut boundary line inclines towards the dumping direction, and the oblique angle is 45-70 degrees; this is the best effect.

According to the embodiment of the invention, in the step S2, the width of the mechanical crushing area of the bridge deck is 1-1.5 m; this is the best effect.

According to the embodiment of the invention, in the step S3, the distance between the bottom of each blast hole of the cable tower blasting notch blasting part and the boundary line of the notch is 20-30 cm, 2-3 rows of blast holes are distributed at the bottom of the supporting part, and the row distance does not exceed 30 cm; this is the best effect.

According to the embodiment of the invention, in the step S4, the diameter of the boundary through hole is 7-9 cm; this is the best effect.

According to the embodiment of the invention, in the step S5, every 4 blastholes of the cable tower blasting part are grouped, 1 compensation hole is drilled at the intersection point of the diagonal line of each group of blastholes, and if the blastholes are singular, 1 compensation hole is drilled at the center line in multiple ways, and the diameter is 7-9 cm; three rows of blast holes under the main pier are formed into a group of 6 blast holes, 2 compensation holes are drilled at the diagonal intersection points of each group of blast holes, 1 blast hole is drilled at the center line in an odd number, and the diameter of each blast hole is 7-9 cm; this is the best effect.

According to the embodiment of the invention, in the step S5, 10-15 cm concrete skins are crushed at intervals of 60-80 cm in the horizontal direction, 10-15 cm concrete skins are crushed at two sides of a corner respectively, and the crushing height is not more than 20 cm; this is the best effect.

According to the embodiment of the invention, in the step S6, the initiation sequence includes a cable tower blasting notch blasting portion, the bottom of a cable tower blasting notch supporting portion, two sides of a main beam, and a main pier; the cable tower blasting part is detonated from two sides to the middle in a delayed mode, and the total delay time is not more than 200 ms; simultaneously detonating the cable tower supporting parts; two sides of the main beam are detonated simultaneously; the main pier is detonated from two sides to the middle in a delayed mode, and the total delay time does not exceed 500 ms; the explosion interval between the cable tower blasting notch blasting part and the cable tower blasting notch supporting part is 500-700 ms, the detonation interval between the cable tower blasting notch blasting part and the cable tower blasting notch supporting part and the main beam two sides is 1000-1500 ms, and the detonation interval between the cable tower blasting notch blasting part and the main pier is 3500-4500 ms; this is the best effect.

The beneficial technical effects of the invention are as follows: the boundary through hole is used for forming a penetrating interface, the cable tower blasting notch blasting part and the supporting part are separated in advance, the blasting stress wave and the blasting gas generated by the blasting part explosive cannot directly act on the supporting part, good buffering is achieved, a new free surface is provided for the blasting part, and the breaking effect of the concrete of the blasting part is facilitated; the penetration is uniformly distributed in the blast hole, so that the effect of providing more free surfaces and compensation space is achieved, and the smooth cage falling of the concrete at the moment of blasting is facilitated; the wrapping steel bars are cut at intervals, so that the integral binding capacity of the steel bar mesh is reduced, the smooth cage falling of concrete at the moment of blasting is facilitated, the supporting capacity of the blasting part is lost, and a blasting notch is formed; a small amount of explosive is filled at the bottom of the supporting part, detonation is delayed for 500-700 ms than that of the blasting notch blasting part, and after the cable tower forms a forward dumping trend, the concrete of the supporting part is loosened to be connected up and down, so that the cable tower connection mode is changed from a fixed end to a hinge, and deflection of the cable tower is facilitated; detonating the blasting part of the two sides of the main beam in 1000-1500 ms after the blasting notch is lagged, so that the restraint of the two sides of the main beam is removed, and the rapid expansion of the cable tower toppling trend is facilitated to be changed into stable toppling; the main pier lags behind a blasting notch blasting part and detonates 3500-4500 ms, the bottom support is kept before the cable tower forms a stable dumping state, and the cable tower and the main beam collapse in situ after the cable tower forms the stable dumping state.

According to the technical scheme for blasting and dismantling the cable-stayed bridge, the blasting effect is that the cable tower is directionally inclined in a direction perpendicular to a cable plane, and the main beam and the main pier collapse in situ, so that the precise blasting method combining directional blasting and in-situ collapse is formed. Compared with the reverse construction sequence manual machine dismantling method, the method has the advantages of high safety, short construction period and low cost; compared with in-situ collapse blasting and cable tower parallel cable surface directional blasting, only 1 blasting point is needed to be arranged at the bottom of the cable tower, on the two sides of the main pier and on the two sides of the main beam respectively, drilling blastholes are easy, workload is small, two ends of the stay cable cannot be popped up and swing in the air, the stay cable topples over backwards to the temporary bridge, and safety is good.

Drawings

Fig. 1 is a schematic diagram of cable tower blasting notch treatment and blast hole arrangement surface development.

Fig. 2 is a schematic front view and a schematic top view of the main beam pavement crushing and blast hole arrangement.

Fig. 3 is a schematic front view and a schematic top view of the arrangement of main pier blast holes.

Fig. 4 is a schematic diagram of the explosion point of the single-pylon single-cable-surface prestressed cable-stayed bridge.

In the figure: 1-a cut-off line; 2-a trapezoidal blasting part; 3-a support portion; 4-a bridge deck mechanical crushing area; 5-blast hole; 5-1-blasting a trapezoidal blasting part blast hole of the cable tower blasting notch; 5-2-supporting part of blast holes by cable tower blasting cuts; 5-3-blast holes on two sides of the main beam; 5-4-main pier blast holes; 6-demarcating a through hole; 9-a cable tower; 10-a main beam; 11-main pier.

Detailed Description

The present invention is further described below in conjunction with the following detailed description, which is intended to further illustrate the principles of the invention and is not intended to limit the invention in any way, but is equivalent or analogous to the present invention without departing from its scope.

The total length of a certain single-pylon single-cable-surface prestressed cable-stayed bridge is 260m, the width of a bridge deck is 24.7m, the height of the bridge deck of the cable-pylon is 64m, the width of the bridge deck is 5m in the direction parallel to the cable surface, the width of the bridge deck is 2.7m in the direction perpendicular to the cable surface, 9 pairs of inclined cables are arranged in parallel, the length of the inclined cables is 20-112 m, and a temporary bridge is built.

The existing blasting method can not reliably ensure the safety of the temporary bridges, and has large workload and can not meet the requirement of the construction period.

Therefore, the method for the accurate directional blasting demolition of the vertical cable plane of the single-pylon single-cable-plane prestressed cable-stayed bridge is adopted for demolition.

(1) Marking a supporting part 3 of the cable tower blasting notch and a cutting boundary 1 of the blasting part, and dividing the blasting notch into a trapezoidal blasting part 2 and the supporting part 3; at the lower end point of the cut boundary line 1, the horizontal width of the support portion 3 was 0.7m, and the cut boundary line 1 was inclined at an angle of 65 ° in the falling direction.

(2) And (3) mechanically crushing bridge floors on two sides of the main beam 10 to separate the two sides of the main beam 10, wherein the width of a mechanical crushing area 4 of the bridge floors is 1.5 m.

(3) Marking the hole positions of a cable tower 9, a main beam 10 and a main pier 11, and drilling blast holes 5 in a cable tower 9 blasting notch trapezoidal blasting part 2, the bottom of a cable tower 9 blasting notch supporting part 3, the main beam 10 and the main pier 11; 5-1 part of blast holes of the trapezoid blasting part of the cable tower blasting notch, 20cm of distance between the bottom of the hole and the boundary line of the notch, 5-2 parts of blast holes of the supporting part of the cable tower blasting notch, 5-3 parts of blast holes on two sides of the main beam and 5-4 parts of blast holes of the main pier.

(4) A boundary through-hole 6 having a diameter of 7cm was continuously drilled along the cut boundary line 1, and the boundary through-hole 6 was arranged in a tangent to the cut boundary line 1 on the blasting portion 2 side to form a penetrating boundary.

(5) Using every 4 blast holes of 5-1 blast holes of a cable tower blasting notch blasting part as a group, drilling compensation holes 7 with the same depth as the blast holes in parallel by using a diagonal intersection point of each group of blast holes as a center, and drilling 1 blast holes at the center line in odd number with the diameter of 7 cm; and (3) drilling compensation holes 7 with the same depth as the blast holes in parallel by taking the diagonal intersection point of each group of blast holes as the center, wherein 1 blast hole is drilled in the middle line in an odd number, and the diameter of each blast hole is 7 cm.

(6) The surface concrete is crushed at intervals in the horizontal direction along the blasting part 2 (between two rows of blast holes and at any convenient construction position) of the blasting notch of the cable tower, the surface is crushed at intervals of 60cm by 10-15 cm, the two sides of the corner are respectively crushed by 10-15 cm, the crushing height is 20cm, and the exposed wrapping steel bar 8 is cut off.

(7) Charging, blocking, networking and detonating, and controlling the detonating sequence of the cable tower blasting notch, the two sides of the main beam and the main pier blasting point by using the detonator delay time. The cable tower blasting part 2 is divided into 5 areas uniformly, and is detonated from two sides to the middle by adopting in-hole delay, wherein the delay time is 0ms and 50 ms; 110 ms; simultaneously detonating the cable tower supporting parts; two sides of the main beam are detonated simultaneously; the main pier adopts external delay, and is detonated from two sides to the middle, and the delay time of connecting a detonator is 50 ms; the blasting intervals of the cable tower blasting notch blasting part, the cable tower blasting notch supporting part, the two sides of the main beam and the main pier are respectively 650ms, 1500ms and 4500 ms; the cable tower 9 is directionally inclined vertically to the cable plane, and the main beam 10 and the main pier 11 are collapsed in situ.