CN116043858A

CN116043858A - Layered excavation method for arch foundation pit

Info

Publication number: CN116043858A
Application number: CN202310088282.4A
Authority: CN
Inventors: 林军民; 徐浩; 马敏; 陈其达; 吴晓伟; 李娴
Original assignee: China Railway 20th Bureau Group Corp; Fifth Engineering Co Ltd of China Railway 20th Bureau Group Co Ltd
Current assignee: China Railway 20th Bureau Group Corp; Fifth Engineering Co Ltd of China Railway 20th Bureau Group Co Ltd
Priority date: 2023-01-30
Filing date: 2023-01-30
Publication date: 2023-05-02

Abstract

The invention discloses a layered excavation method of an arch foundation pit, which comprises a left-bank arch seat and a right-bank arch seat which are arranged at intervals, wherein surfaces to be excavated are arranged on the left-bank arch seat and the right-bank arch seat, and the method comprises the following steps: using a working platform to perform layering and grading on the surface to be excavated of the left bank arch seat from top to bottom along the elevation direction of the existing foundation pit slope platform to form a left six-layer slope platform; utilizing the working platform to construct the surface to be excavated of the right bank arch seat to form a right primary side slope platform; and combining the left six-layer side slope platform and the right primary side slope platform to form a secondary arch foundation pit. According to the invention, the left six-layer side slope platform and the right first-stage side slope platform are respectively formed on the left bank arch seat and the right bank arch seat, so that the method is more suitable for construction operation environments with steeper side slopes, thinner covering soil, exposed partial bedrock and limited working platform range, and provides reference for similar construction conditions.

Description

Layered excavation method for arch foundation pit

Technical Field

The invention relates to the technical field of arch foundation pit excavation, in particular to a layered arch foundation pit excavation method.

Background

In the related art, the original arch abutment needs to be excavated again under the condition that the original arch abutment is excavated to the design substrate, the topography of the original arch abutment is complex, surrounding rock of the arch abutment substrate is broken, cracks develop, and surrounding rock of the side slope of the arch abutment is in a strong weathering zone.

However, as the arch foundation pit excavation belongs to secondary excavation, slope releasing treatment is needed to be carried out again on the side slope of the excavated foundation pit, the side slope is steeper, the earth covering is thinner, part of bedrock is exposed, and the range of a working platform is limited.

Therefore, when the conventional construction method is applied to a construction environment similar to the environment, the construction efficiency is low, and the construction requirement cannot be met.

Disclosure of Invention

The main purpose of the invention is that: the method aims to solve the technical problems that when a conventional construction mode in the prior art is applied to a construction environment similar to the environment, the construction efficiency is low and the construction requirement cannot be met.

In order to achieve the above purpose, the invention adopts the following technical scheme:

the invention provides a layered excavation method of an arch foundation pit, wherein the arch foundation pit comprises an existing foundation pit slope platform, the existing foundation pit slope platform comprises a left-bank arch seat and a right-bank arch seat which are arranged at intervals, and surfaces to be excavated are arranged on the left-bank arch seat and the right-bank arch seat, and the method comprises the following steps:

Excavating a construction channel in the existing foundation pit to form a working platform;

utilizing the working platform to perform layered and graded construction on the surface to be excavated of the left bank arch seat along the elevation direction of the existing foundation pit slope platform on the left bank arch seat of the existing foundation pit slope platform to form a left six-layer slope platform;

utilizing the working platform to construct the surface to be excavated of the right bank arch seat to form a right primary side slope platform;

and combining the left six-layer side slope platform and the right primary side slope platform to form a secondary arch foundation pit.

Optionally, in the above arch abutment foundation pit layered excavation method, the left-bank arch abutment includes a plurality of steps to be blasted, and the step of forming a left six-layer slope platform by using the working platform, in which the left-bank arch abutment of the existing foundation pit slope platform is layered from top to bottom along the elevation direction of the existing foundation pit slope platform and is implemented by performing the layered construction on the surface to be excavated of the left-bank arch abutment, includes:

forming blast holes on each step to be blasted;

filling a charging structure into the blast hole to form a left bank arch seat foundation pit blasting excavation structure;

utilize left bank arch bar foundation ditch blasting excavation structure left bank arch bar forms left one-level side slope platform left side second grade side slope platform left tertiary side slope platform left quaternary side slope platform left five-level side slope platform with left six-level side slope platform, in order to form left six-layer side slope platform.

Optionally, in the above arch foundation pit layered excavation method, the step of forming a blasthole on each step to be blasted includes:

setting a minimum resistance line at the bottom side of the step to be blasted, and acquiring the length of the minimum resistance line;

setting a step upper eyebrow line on the top side of the step to be blasted, and acquiring the length of the step upper eyebrow line;

obtaining a slope angle of the step to be blasted according to the length of the minimum resistance line and the length of the step upper eyebrow line;

presetting the ultra-deep depth of the blast hole;

drilling holes on the surface of the step to be blasted according to the slope angle of the step to be blasted, the height of the step to be blasted and the ultra-deep depth of the blast holes;

according to the type of the blast hole, acquiring the drug loading quantity;

and filling the charging structure into the blast hole according to the charging amount to form the arch foundation pit blasting excavation structure.

Optionally, in the arch foundation pit layered excavation method, the types of the blastholes are multiple rows of blastholes, the multiple rows of blastholes include a front row of blastholes and a second row of blastholes arranged at intervals with the front row of blastholes, the front row of blastholes are formed by arranging a plurality of blastholes at intervals, and the second row of blastholes are formed by arranging a plurality of blastholes at intervals;

The step of obtaining the charge according to the type of the blast hole comprises the following steps:

obtaining the loading quantity of the front blast holes according to the consumption quantity of the unit explosive, the distance between the blast holes in the front blast holes, the hole depth of the front blast holes and the minimum resistance line;

and obtaining the charge of the second row of blastholes according to the consumption of the unit explosive, the distance between the blastholes in the second row of blastholes, the hole depth of the second row of blastholes and the distance between the second row of blastholes and the front row of blastholes.

Optionally, in the arch foundation pit layered excavation method, the type of the blast hole is a smooth blast hole;

the step of setting a minimum resistance line at the bottom side of the step to be blasted and obtaining the length of the minimum resistance line comprises the following steps:

acquiring the length of the minimum resistance line of the light explosion hole according to the aperture of the light explosion hole;

wherein the aperture of the light explosion hole is D _{Light source} The minimum resistance line of the light explosion hole has the length of W _{Light source} ，W _{Light source} ＝β*D _{Light source} ，15≤β≤25。

Optionally, in the above arch abutment foundation pit layered excavation method, the step of using the working platform to perform working on the surface to be excavated of the right bank arch abutment to form a right-stage slope platform includes:

Hole position lofting is carried out on the surface to be excavated of the right bank arch seat, and a hole position to be formed is obtained;

drilling the hole to be formed to form a hole to be split;

splitting the holes to be split to form splitting areas;

and forming the arch foundation pit according to the splitting area.

Optionally, in the above arch abutment foundation pit layered excavation method, the splitting the hole to be split, and the step of forming the splitting area includes:

the gun head of the splitting machine is assisted by a digging machine to be sent into the hole to be split;

and extruding the hole to be split by using the gun head, so that the surface to be excavated is split into a line, and the splitting area is formed.

Optionally, in the method for layer-by-layer excavation of an arch abutment foundation pit, before the step of splitting the hole to be split to form the splitting area, the method includes:

checking the depth of the hole to be split;

judging whether the depth of the hole to be split meets the preset depth condition or not;

if yes, splitting the hole to be split;

if not, the depth of the hole to be split is adjusted so that the depth of the hole to be split meets the preset depth condition.

Optionally, in the above arch foundation pit layered excavation method, the outer contour of the right-bank arch foundation is stepped, the arch foundation pit of the right-bank arch foundation includes a plurality of surfaces to be excavated which are sequentially stacked from top to bottom, each surface to be excavated is uniformly provided with a plurality of holes to be formed, and the plurality of surfaces to be excavated are a first surface to be excavated and a second surface to be excavated which is stacked and arranged below the first surface to be excavated, and before the step of forming the arch foundation pit according to the splitting area, the method includes:

Drilling the hole to be formed on the first surface to be excavated, and splitting construction is carried out on the first surface to be excavated to form a first splitting area;

obtaining a splitting situation according to the first splitting area;

adjusting the hole distance between the holes to be formed on the second surface to be excavated according to the splitting condition;

drilling the hole-forming position on the second surface to be excavated, and splitting construction is carried out on the second surface to be excavated to form a second splitting area.

Optionally, in the arch foundation pit layered excavation method, a row distance between the to-be-perforated positions is 80cm.

The one or more technical schemes provided by the invention can have the following advantages or at least realize the following technical effects:

according to the layered excavation method for the arch foundation pit, the left six-layer side slope platform and the right one-level side slope platform are respectively formed on the left side arch seat and the right side arch seat on the existing foundation pit side slope platform, so that the construction difficulty of the arch foundation pit is reduced, the stability of the arch foundation pit is guaranteed through the left six-layer side slope platform and the right one-level side slope platform, different construction methods are adopted for the left side arch seat and the right side arch seat, the method is more suitable for construction operation environments with steeper side slopes, thinner covering soil, exposed partial bedrock and limited working platform range, and a reference basis is provided for similar construction conditions.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are required in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings may be obtained from the drawings provided without inventive effort for a person skilled in the art.

FIG. 1 is a schematic flow chart of a construction method of a secondary structure of an arch foundation pit;

FIG. 2 is a schematic distribution diagram of a secondary excavation side slope platform of a left bank arch seat, which is related to the invention;

FIG. 3 is a schematic distribution diagram of a secondary excavation slope platform of a right bank arch seat according to the invention;

FIG. 4 is a schematic view of a charge configuration according to the present invention;

FIG. 5 is a schematic view of a charge configuration according to the present invention;

FIG. 6 is a schematic diagram of a photo-explosive hole charging structure according to the present invention;

FIG. 7 is a schematic view of a smooth blasting main blast hole and a smooth blast hole according to the present invention;

fig. 8 is a schematic drawing of a slitting and hole laying according to the present invention.

Reference numerals illustrate:

reference numerals	Name of the name	Reference numerals	Name of the name
				100	Blast hole	110	Main explosion hole
120	Light explosion hole	101	Detonator in hole
				102	Detonating tube	103	Charging section
104	Blocking section	200	Reinforced charge section
				300	Normal charging section	400	Weakening a charge segment
500	Detonating cord	600	Hole to be split
				700	Auxiliary hole

The achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It should be noted that, in the embodiment of the present invention, all directional indications (such as up, down, left, right, front, and rear … …) are merely used to explain the relative positional relationship, movement conditions, and the like between the components in a certain specific posture (as shown in the drawings), and if the specific posture is changed, the directional indication is changed accordingly.

In the present disclosure, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or system that comprises the element. In addition, the meaning of "and/or" as it appears throughout includes three parallel schemes, for example "A and/or B", including the A scheme, or the B scheme, or the scheme where A and B are satisfied simultaneously.

In the present invention, unless explicitly specified and limited otherwise, the terms "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be either a fixed connection or a removable connection or integrated; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium; the communication between the two elements can be realized, or the interaction relationship between the two elements can be realized.

In the present invention, if there is a description referring to "first", "second", etc., the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature.

In the present invention, suffixes such as "module", "assembly", "piece", "part" or "unit" used for representing elements are used only for facilitating the description of the present invention, and have no specific meaning per se. Thus, "module," "component," or "unit" may be used in combination.

The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances. In addition, the technical solutions of the embodiments may be combined with each other, but it is based on the fact that those skilled in the art can implement the combination of the technical solutions, when the technical solutions contradict each other or cannot be implemented, the combination of the technical solutions should be considered as not existing and not falling within the protection scope of the present invention.

The inventive concept of the present invention is further elucidated below in connection with some embodiments.

The invention provides a layered excavation method for an arch foundation pit.

Referring to fig. 1 to 3, fig. 1 is a schematic flow chart of a construction method of a secondary structure of an arch foundation pit according to the present invention; FIG. 2 is a schematic distribution diagram of a secondary excavation side slope platform of a left bank arch seat, which is related to the invention; fig. 3 is a schematic diagram of a secondary excavation slope platform distribution of a right bank arch abutment in accordance with the present invention.

In an embodiment of the present invention, as shown in fig. 1 to 3, an arch foundation pit layer-by-layer excavation method, where an arch foundation pit includes an existing pit slope platform, the existing pit slope platform includes a left-bank arch seat and a right-bank arch seat that are disposed at intervals, and surfaces to be excavated are disposed on the left-bank arch seat and the right-bank arch seat, the method includes:

Step S100: excavating a construction channel in an existing foundation pit to form a working platform;

step S200: utilizing a working platform, layering and grading the left bank arch seat from top to bottom along the height direction of the existing foundation pit slope platform on the left bank arch seat of the existing foundation pit slope platform, and constructing the surface to be excavated of the left bank arch seat in a grading manner to form a left six-layer slope platform;

step S300: constructing the surface to be excavated of the right bank arch seat by using a working platform to form a right primary side slope platform;

step S400: and combining the left six-layer slope platform and the right primary slope platform to form the secondary arch foundation pit.

For ease of understanding, one embodiment is shown below:

a certain bridge is a Y-shaped steel box arch bridge, the bridge crosses two banks of a river, and the river valley of a bridge site area is V-shaped. The base rocks on the two banks are exposed, the hillside is steep, the natural gradient is 60-75 degrees, the local gradient is 75-85 degrees, the water surface elevation of the river in the plain period is 590m, and the water surface width is 15-30 m.

According to the requirements of a changed drawing, the original design elevation of the left bank downstream arch seat is required to be dug down 10m deep again, the original design elevation of the left bank upstream arch seat is dug down 2m deep again, the original excavation slope of the arch seat foundation is dug down slope again, and the temporary protection and the permanent protection of the slope are increased. Considering anchor cable construction under an arch seat, a 3-level slope platform is added on the left bank and a 1-level slope platform is added on the right bank in a design drawing, and the left bank and the right bank are used as anchor cable construction platforms.

The deep gullies on the two sides of the river are not developed as a whole, the scale of the gullies is smaller, the cutting is not deep, the extension is shorter, and the gully is generally more than 690 m. The left bank topography is complete, the mountain body is male and thick, the gully is steep, and no large deep gully exists. A partner ditch at the position 350m upstream of the right bank bridge axis, the ditch opening height is 730m, the ditch length is about 150m, and the cutting depth is less than 20m; the upstream of the right bank bridge axis is 140m of fossil ditch, the ditch mouth elevation is 675m, and the ditch depth is 30 m-60 m. The rocks on the two sides of the bridge site are exposed, the lithology is thick-layer limestone, and the lithology is hard.

The upper part of the river bridge is about 550m away from the dam site of the eastern river junction, the lower part of the river bridge is 3.0km away from the built river cable-stayed bridge, the axis plane of the bridge is a straight line section, the right bank is connected with an external traffic T-shaped intersection, and the left bank is connected with a tunnel.

This secondary excavation topography is under the condition that original arch center had excavated to design basement, expands the excavation again. The topography is complex, the whole is more complete, the arch abutment base surrounding rock is broken, the crack is developed, the arch abutment lower side slope surrounding rock is in strong weathering zone, and after project arch abutment foundation excavation is completed, anchor spraying protection is carried out.

The river valley of the bridge site area is a V-shaped valley, the bedrock on two sides is exposed, the hillside is steep, the natural gradient is 60-75 degrees, and the local gradient is 75-85 degrees.

Formation lithology: the bedrock on the two sides of the bridge site is exposed, the lithology is thick-layer limestone, and the lithology is hard. System (O2) limestone in the main formation Otto system. The stratum structure is as follows:

(1) Upper update systematic lamination (Q3 al): lithology is sand gravel of alluvial area, and is distributed above the elevation of the left bank 775m, and the components of the mother rock of the gravel are mainly limestone and very little granite of the sand.

(3) System in otto system (O2): the thick layer-huge layer limestone is light gray and grey, and the aphanitic biological limestone is locally clamped.

According to on-site geological mapping and in-situ testing, the indoor test combines regional engineering experience, and the bearing capacity of foundation soil along the highway is proposed through engineering geological analysis principles. The allowable bearing capacity and pile side friction resistance of each layer of soil are as follows:

(1) sand gravel (Q3 al) [ σ0] =300 kPa [ τi ] =120 kPa;

(3) limestone (O2) [ σ0] =1300 kPa [ τi ] =1500 kPa;

hydrogeologic conditions: according to the hydrologic description in the construction drawing design file, the underground water is not seen, and the influence of the underground water on the bridge can be ignored.

Bad geological disasters: no adverse geological phenomena such as landslide, debris flow, slump and the like are found. Karst trails are represented by solution gaps and solution holes, and karst development is weaker.

The main technical standard is as follows: the road grade: a secondary road; number of lanes: two-way two lanes;

the design speed is 40km/h; service life of the design is prolonged: the main body structure is as follows: for 100 years; boom: for 20 years; bridge deck pavement: for 12 years; and (5) carrying out a longitudinal slope: bidirectional 0.5%; sixth, horizontal slope: 2.0% of a crossroad slope and 1.0% of a crossroad slope; the plane of the curve is a straight line, and the radius of the longitudinal curve is 9100m; and b, flood level design: 629.5m, corresponding frequency is 1/100; a navigation requirement: the method is free; designing a load standard:

1) Bridge structural design reference period: for 100 years; 2) Automobile load rating: road-class I; crowd load: 2.5 kN/-square meter 3) standard for anti-seismic fortification: base intensity 7 degrees, earthquake motion peak acceleration: 0.115g

4) Wind resistance design criteria: basic wind speed value: v10=25.3 m/s.

Preparing resources: (1) mechanical equipment: the material equipment part is responsible for mechanical equipment such as 200t crawler crane, down-the-hole drill, digger, dumper and the like to be in place before starting work, and overhauls and maintains the mechanical equipment. (2) preparation of materials: the material equipment part is responsible for carrying out the work of recording the initiating explosive device before starting work, so as to ensure that the initiating explosive device enters the field on time. (3) human resource preparation: the planning cost department is responsible for the approach of team operators before starting work.

Temporary water and electricity preparation: (1) temporary water: the construction water sets up temporary water tank in the platform place above the arch center, adopts the waterwheel to pull. (2) temporary electricity utilization: the power utilization is introduced into a first-stage distribution box from a transformer at a position 400m away from a construction site to provide power for the project, and the first-stage distribution box is arranged on the right side slope foot of a left bank Xie Gushan platform line.

The secondary excavation construction scheme of the arch support comprises the following steps:

1. arch seat secondary excavation construction overall scheme

The construction is a secondary excavation of arch foundation of large bridge of jing river, and mainly comprises excavation of upper side slope of arch foundation base, excavation of lower side slope of arch foundation base and protection of peripheral side slope of arch foundation.

2. Side slope and foundation pit excavation construction scheme

1.1 preparation for construction

The construction is carried out by adopting the principle of 'layered from top to bottom, grading excavation construction, excavation primary protection primary' and the like. Before the side slope is excavated, the work of preventing and draining water and cleaning the surface of the side slope is done. In the process of excavation, slope rate and platform elevation are strictly controlled, and after excavation is completed, slope is retested and renovated in time, and slope protection is carried out according to design requirements.

The construction method comprises the following steps:

the secondary excavation of the left and right shore arch seats is carried out, the left shore arch seat is a six-level slope, the elevation of the arch seat designed substrate is divided into an upper slope and a lower slope, the upper slope is a one-to-four-level slope, the lower slope is a five-level slope and a six-level slope, and the two positions for replacing and filling the foundation of the upstream and the downstream arch seats are included. The right bank arch seat is a first-level side slope.

Left bank arch base: the first-level slope is 794.491-787.648, the slope height is 6.843m, the slope ratio is 1:0.9, and the platform width is 2m; the secondary side slope 787.648-780.498 has a slope height of 7.15m, a slope ratio of 1:0.5 and a platform width of 2m; three-stage side slopes 780.498-773.417, the height of the side slopes 7.081m, the slope ratio of 1:0.5 and the platform width of 2m; four-stage side slopes 773.417-763.417, wherein the height of the side slopes is 10m, the ratio of the side slopes is 1:0.3, and the width of the platform is 2m; five-stage side slopes 763.417-755.417, wherein the height of the side slopes is 8m, the ratio of the side slopes is 1:0.25, and the width of the platform is 2m; six-level side slopes 755.417-747.417, the height of the side slopes is 8m, the ratio of the side slopes is 1:0.9, and the width of the platform is 3m; the foundation of the upstream arch abutment is replaced and filled with 763.417-761.417, the height of the replacement and filling is 2m, and the slope ratio is 1:0.1; and the foundation of the downstream arch abutment is replaced and filled 763.417-753.417, the height of the replacement and filling is 10m, and the slope ratio is 1:0.2.

Right bank abutment: the first-stage side slope is 764.417-756.417, the height of the side slope is 8m, the slope ratio is 1:0.5, and the width of the platform is about 4.2m.

Because arch seat foundation pit excavation belongs to secondary excavation, need to carry out the slope to the foundation pit side slope of digging again and put the slope treatment, and the side slope is steeper, and earthing is thinner, and part bedrock is exposed, and work platform scope is limited. The side slope is constructed by a digging machine on the downstream side of the 794.491 platform to 790.491, the digging machine is adopted to break the digging and slope repairing of the 794.491-790.491 side slope, after the digging machine is adopted to repair the side slope to 790.419, the earth covering is removed by the digging machine, and then stone drilling and blasting are carried out. The stone excavation is constructed by adopting a method with deep hole blasting as a main material and shallow hole blasting as an auxiliary material. The slope adopts smooth blasting, and the part adopts a crushing hammer for chiseling. Step-type layered excavation is carried out from top to bottom, and 2m horse ways are arranged between the stages.

In order to ensure the stability of the side slope and form a flat side slope, the side slope adopts smooth blasting, the hole diameter of blastholes is 90mm, the distance between blastholes 100 is 50cm, and a phi 90 down-the-hole drill is used for hole forming; the phi 32mm rock emulsion explosive is detonated by a non-electric millisecond detonating tube 102 detonator.

The slag stone is removed by an excavator, the slope is excavated to be subjected to primary trimming, and meanwhile, the dangerous stone is removed. And (5) carrying out retest on the slope side line and the slope rate after each layer of excavation is completed. And excavating a first stage and protecting the first stage. The scaffold and the construction platform are firstly erected before protection, and slope protection is carried out according to design protection requirements.

According to the technical scheme, the left six-layer side slope platform and the right primary side slope platform are respectively formed on the left side wall arch seat and the right side wall arch seat on the existing foundation pit side slope platform, so that the construction difficulty of an arch seat foundation pit is reduced, the stability of the arch seat foundation pit is guaranteed through the left six-layer side slope platform and the right primary side slope platform, different construction methods are adopted for the left side wall arch seat and the right side wall arch seat, the construction method is more suitable for construction operation environments with steeper side slopes, thinner covering soil and exposed partial bedrock, and the working platform has a limited range, and provides a reference basis for similar construction conditions.

Continuing to refer to fig. 1-3 and referring to fig. 4-7, fig. 4 is a schematic diagram of a charging structure according to the present invention; FIG. 5 is a schematic view of a charge configuration according to the present invention; fig. 6 is a schematic diagram of a charging structure of a photo-blast hole 120 according to the present invention; fig. 7 is a schematic diagram of a smooth blasting main blast hole 100 and a smooth blast hole 120 according to the present invention.

In an embodiment, as shown in fig. 1 to 7, the left-bank abutment includes a plurality of steps to be blasted, and the working platform is utilized to perform layering and grading on the surface to be excavated of the left-bank abutment from top to bottom along the height direction of the existing foundation pit slope platform, so that the step of forming the left six-layer slope platform includes:

Step A100: forming blast holes 100 on each step to be blasted;

step A200: filling a charge structure into the blast hole 100 to form a left bank arch foundation pit blasting excavation structure;

step A300: and forming a left primary side slope platform, a left secondary side slope platform, a left tertiary side slope platform, a left quaternary side slope platform, a left fifth side slope platform and a left sixth side slope platform on the left arch abutment by utilizing the left arch abutment foundation pit blasting excavation structure so as to form a left six-layer side slope platform.

In one embodiment, the step of forming the blastholes 100 on each step to be blasted includes:

step B100: setting a minimum resistance line at the bottom side of a step to be blasted, and acquiring the length of the minimum resistance line;

step B200: setting a step eyebrow line on the top side of a step to be blasted, and acquiring the length of the step eyebrow line;

step B300: obtaining a slope angle of the step to be blasted according to the length of the minimum resistance line and the length of the step upper eyebrow line;

step B400: presetting the ultra-deep depth of the blast hole 100;

step B500: drilling holes on the surface of the step to be blasted to form the blast hole 100 according to the slope angle of the step to be blasted, the height of the step to be blasted and the ultra-deep depth of the blast hole 100;

step B600: obtaining the charge according to the type of the blast hole 100;

Step B700: and filling the charge structure into the blast hole 100 according to the charge quantity to form an arch foundation pit blasting excavation structure.

In an embodiment, the types of the blastholes 100 are multiple rows of blastholes 100, the multiple rows of blastholes 100 include a front row of blastholes 100 and a second row of blastholes 100 spaced from the front row of blastholes 100, the front row of blastholes 100 is formed by a plurality of blastholes 100 spaced from each other, and the second row of blastholes 100 is formed by a plurality of blastholes 100 spaced from each other;

the step of obtaining the charge amount according to the type of the blasthole 100 includes:

step C100: obtaining the charge of the front blast hole 100 according to the consumption of the unit explosive, the distance between the blast holes 100 in the front blast hole 100, the hole depth of the front blast hole 100 and the minimum resistance line;

step C200: and obtaining the loading quantity of the second row of blastholes 100 according to the consumption quantity of the unit explosive, the distance between the blastholes 100 in the second row of blastholes 100, the hole depth of the second row of blastholes 100 and the distance between the second row of blastholes 100 and the front row of blastholes 100.

In one embodiment, the type of blasthole 100 is a photo blasthole 120;

step D100: acquiring the length of the minimum resistance line of the photo-blast 120 according to the aperture of the photo-blast 120;

Wherein the aperture of the light explosion hole 120 is D light, the length of the minimum resistance line of the light explosion hole 120 is W light, W light=β×d light, and β is 15-25.

For ease of understanding, one embodiment is shown below:

the excavation adopts a vertical drilling mode, and the blast hole 100 hole distribution mode is quincuncial hole distribution;

according to the site excavation height, 2m is taken in principle during construction of the engineering, and when the step height is large, the steps are excavated separately;

drilling by using a down-the-hole drill, wherein currently, a drill with the diameter phi of 40mm is mostly selected, and the aperture D=40mm is adopted;

the drilling ultra-deep is determined by determining the step height (H) and the ultra-deep (H) according to the empirical formula:

hole depth l=h/sina+h, wherein L-shot hole 100 length (m); h—step height (m); a-inclination of the borehole (°); h-ultra-deep (m) (ultra-deep formula h= (0.1-0.15) H, in actual case h=0.3-0.5 m);

according to the equipment capacity, the operation conditions and the slope gradient requirements, a proper drilling inclination angle can be selected, and according to the selected step height of 2m, the actual hole taking depth L=2.3-2.5 m, the depth parameters of the blast hole 100 are properly adjusted according to actual conditions during construction so as to ensure that the hole bottom is positioned on a planned step plane;

according to the empirical formula: wbottom= (30-50) D; in hard and hard rock mass, or when the step height H is high, a large coefficient should be taken during calculation. The construction is generally carried out by taking 0.8-1.5 m;

(6) The gun hole 100 spacing (a) and the row spacing (b); a= (1-1.5) W bottom; b= (0.8-1.0) a;

the engineering is as follows: a= (0.8-1.5) m; b= (0.6-1.2) m;

according to the engineering requirement, the filling length L is more than or equal to 1.2W bottom;

according to the characteristics, the structure and other factors of the rock in the engineering area and the practical experience, the q value is generally 0.3-0.4 kg/m < 3 >, and according to the characteristics and the structure of the rock in the engineering area, the q value is: q=0.28 to 0.35kg/m3. However, in the actual operation process, necessary adjustment should be performed in time according to the change of rock properties;

the type of explosive is 2# rock emulsion explosive, and the diameter phi of the explosive roll is 25mm;

single hole loading Q: q=qv; wherein: q—kg of charge per borehole 100; q-unit rock explosive consumption, kg/m3; v—the volume m3 of rock to be blasted, v=lab; l-hole depth; w is a resistance wire; a-hole pitch; b-row spacing;

calculating the explosive loading quantity of blasting of a plurality of rows of blast holes 100, wherein the explosive loading quantity Q=qaLW of each hole in the front row; second row of system hole loading q=qabl; the reasonable loading capacity of the single hole is calculated according to the site conditions because the heights of the excavated steps are different, the resistance lines are changed at any time, the hardness degree of the rock is different, and when the consumption q of the unit explosive is 0.35kg/m3, the selection of each parameter in the following table can be referred;

Adopting a continuous uncoupled charging structure: before charging, the single-hole charge quantity is calculated, when charging, the explosive is gently placed into the blast hole 100, the upper part of the bottom of the blast hole 100 is slightly larger, the hole opening is less, the number of the hole opening is 2/3 of that of the hole bottom, and stone powder or clay (the water content of the clay is 10% -30%) is adopted as a blocking material;

as another implementation of this embodiment: (1) the blast hole 100 arrangement: the vertical drilling mode is adopted, and the blast holes 100 are distributed in a quincunx type. The arrangement is similar to shallow hole blasting.

(2) Step height: according to the design of the drawing, the height of the step is H=10m, and according to the rock condition, the surrounding environment of the explosion zone is designed as follows: h=7m, h=10m.

(3) Selecting the specific explosive consumption q value: q is the amount of explosive consumed per unit volume (or weight) of rock of the blasting medium, and is related to the rock properties, explosive properties, borehole diameter, gradient requirements, etc. Based on the comprehensive consideration of the factors, the data of experience, experiment and similar engineering are selected and adjusted. According to the rock hardness and crack development condition of the engineering, the unit consumption is as follows:

q＝0.25～0.40kg/m ³ and (3) in the construction process, according to the pilot explosion, the pilot explosion is properly regulated.

(4) Aperture D and selection of chassis resistance line W bottom

The diameter of the adopted down-the-hole drill bit in the engineering is phi 90. The aperture is 25-50 times of the aperture according to the past construction experience, the engineering W bottom is properly selected to be 2.5-3.0 m, and the engineering W bottom can be properly adjusted according to the previous blasting effect during blasting operation.

(5) Hole depth L and ultra-deep h

The hole depth is 7m and 10m according to the actual topography and the condition of the environment around the site, the step height H is 8-12 times of the aperture, and the engineering takes h=0.5m according to the actual construction condition.

(6) Selection of pitch a and row pitch b

The hole distance a refers to the distance between the central lines of two adjacent holes in the same row of deep holes, and because the engineering is cutting excavation, and the practical experience and the empirical formula a=mW bottom are combined (m is the dense coefficient of the blast holes 100, m=0.8-1.4 m), when the engineering step height is 5m, the hole distance a=2.5-3.0 m is taken, and the row distance b is taken according to the formula b= (0.8-1.0) a, and the row distance b=2.0-2.5 m is taken; when the step height is 10m, the pitch a=3.0-3.5 m is taken, the row pitch b is taken according to the formula b= (0.8-1.0) a, the pitch b=2.5-3.0 m is taken, and the adjustment can be properly carried out according to different topography and requirements for meeting the field surrounding environment.

(7) Type of explosive

The deep hole charge variety is emulsion explosive (the diameter of the explosive roll is phi 70).

(8) Single hole loading (Q)

From the empirical formula q=q·a·b·h, where Q is the standard specific charge, a is the hole spacing, b is the row spacing, and H is the step height, the single Kong Yaoliang q5=11.5 kg (taking h=5.0 m, a=3.0 m, b=2.5 m, q=0.30 kg), q10=36 kg (taking h=10.0 m, a=4.0 m, b=3.0 m, q=0.30 kg) can be calculated.

(9) Charging structure

The charge of the blast hole 100 adopts a continuous columnar charge structure. The deep hole adopts 2 detonating bodies which are respectively arranged at 1/3 and 2/3 of the grain. During the charging process, no sundries are charged in the holes to continuously compact the explosive naturally, so as to ensure the charging density. The stemming is adopted for backfilling, and the blocking material is continuously (without overhead) naturally compacted in the backfilling process, so that the blocking quality is ensured;

according to the engineering requirements, the plugging length is generally 20-30 times of the aperture according to experience, and is 3-4.5 m according to site topography and surrounding environment conditions.

Specific blasting-related parameters are detailed in the following table

The parameters are adjusted according to the actual geological condition of the site and the explosion test effect. When the chassis resistance line is oversized, hydraulic breaking hammers or shallow hole blasting are adopted to trim the chassis resistance line to be within the designed blasting parameter allowable value according to the design requirement.

As an option for this embodiment, in a smooth blasting design: (1) step height H: the height is consistent with the design of the side slope. (2) drilling aperture D: take d=90 mm. (3) drilling inclination angle: and the method is determined according to the slope design requirement of the side slope. (4) least resistant line W light. The minimum resisting line W light of the smooth blasting is a key parameter affecting the smooth blasting effect.

W light= (15 to 25) d=1.35 to 2.25m W light=1.8 m.

(5) The distance a between the blast holes 100 is as follows:

the distance between the smooth blasting blastholes 100 can be selected as follows; aGuangdong= (10-20) D=0.9-1.8 m, wherein a small value is taken from the rock with the joint fracture relatively developed, a large value is taken from the rock with good integrity, and aGuangdong=1.5 m is taken.

(6) Uncoupled charge coefficient m: m=2 to 5, and this time is 2.8.

(7) Density q light of linear charge

Q light=0.3 to 0.45kg/m, q bottom = (1.2 to 2.0) q light at the bottom.

(8) Length L light of the light explosion hole 120: l light= (h+h)/sinθ, θ is the drilling inclination angle, 53 ° is taken, H is the ultra-deep, take 0.5m, (h+h)/sinθ=11.0+=13.6 m.

In theta-meter slope angle

(9) Charge qlight=qlight L light of blast hole 100

(10) Charging structure

The photo-explosion hole 120 adopts uncoupled charge, the emulsion explosive cartridge with phi 32mm is bound on the detonating cord 500 and the bamboo chips, the cartridge is closely attached to the detonating cord 500, and the three-section charge is divided into three sections, namely: a top 2.0m weakened charge segment 400, a middle normal charge segment 300;

A reinforced charging section 200 with the bottom (10 m step) being 2m and a reinforced charging section with 5m step being 1.2m;

(11) Charging and packing

The plugging length L is equal to or less than 1.5m, and the current time is 2.0m.

The bottom of the hole strengthens the charge. The charge linear density and the single-hole charge quantity are calculated before charging, and the explosive is uniformly and firmly bound on the detonating cord 500500 and then carefully placed in the blast hole 100100. The stuffing material is woven bag and kraft paper and is filled into the lower part of the blocking section 104104, and then the drillings or clay is backfilled, and the stuffing length is not less than 1.5m.

Slope smooth blasting design parameter summary table

According to the technical scheme, the blast holes 100 are formed in the existing foundation pit, secondary excavation is carried out on the platform to be blasted of the existing foundation pit by utilizing the blast holes 100, so that the secondary foundation pit meeting the construction requirement is formed, subsequent construction of the secondary arch foundation pit is facilitated, construction conditions are provided for subsequent construction steps, the blasting excavation effect of the blast holes 100 is improved by controlling the concrete forming structure of the blast holes 100, engineering construction quality is improved, and references are provided for similar construction modes.

The crawler-type down-the-hole drill is adopted, the slope ratio is strictly excavated according to a construction drawing, after the lofting hole site is measured, the main blasthole 110 and the pre-splitting hole are drilled, the longitudinal and transverse errors of the drilled hole site are ensured not to exceed +/-50 mm in the drilling process, the elevation errors are strictly controlled to exceed the burying depth of large-diameter stone blocks, the firm and stable placement support of the drill is ensured, and shaking cannot occur in the hole making process. And air is supplied by adopting an air compressor, the drill rod guide is ensured to be intact by adopting a dry pore-forming without water, and the diameter of the used drill bit is not smaller than the designed pore diameter. The drilling holes are deeply constructed layer by layer from top to bottom, the drilling speed and wind pressure are increased, the drilling holes are strictly controlled according to the performance of the drilling machine and the actual condition of the bottom layer, and the drilling holes are prevented from being distorted, changed in diameter and caused to collapse holes or other accidents. After the air compressor is started, the down-the-hole drill is started, and the drill angle of the drill can be adjusted according to the topography and geological conditions. After drilling, the control of the hole depth is needed to be paid attention to, and the hole depth must exceed the bottom layer of a large number of stone layers by 0.5-1.0 meter. Avoid secondary counterpoint to creep into, enough satisfies the hole requirement of drawing. The drilling process is to arrange special personnel to be responsible for recording the geological condition, the perforated holes and the hole depths in detail, and the stratum change, the drilling state, the underground water and some special conditions of each hole are fed back in time and measures are taken in the drilling process.

The crawler drill can not work in areas due to topography, and the manual pneumatic drill is used for drilling or the mechanical direct excavation is used. The depth of each excavation by adopting manual drilling is not more than 4m, and attention should be paid to the same as that of the crawler drill.

After the hole inspection by a blasting company, a blasting scheme is designed, and blasting construction is organized by adopting a reasonable blasting mode according to geological conditions and blasting design scheme and considering the slope stability requirement and environmental conditions. In the blasting construction process, the powder charge is strictly controlled according to the blasting design requirement, so that the slope rate of the slope is ensured, and the disturbance to the foundation and the stability of the slope is reduced. And safety guard and safety contact work are carried out, so that other personnel are strictly forbidden to enter the blasting area.

The left bank downstream arch abutment secondary excavation side slope blasting earth and stone side, and the front three-stage side slope slag and stone are cleaned to the foundation pit base of the downstream side arch abutment by adopting an excavator in sequence. When the side slope is excavated to the fourth-stage side slope, the side slope is abandoned to the river channel at the downstream of the jing river by adopting an excavator, and after the excavation of the sixth-stage side slope is finished, the side slope is hauled to a specified waste residue field by adopting a dump truck through the river channel.

The fifth and sixth grade slopes of the river facing are blasted to the stone, the excavator cannot mechanically slag due to the topography, and the stone slag is manually cleaned into the river below. By adopting manual slag removal, slag removal personnel wear safety protection articles such as safety helmets, anti-skid shoes, safety ropes, safety belts and the like strictly according to a project safety management method.

Through setting up big gun hole 100 on existing foundation ditch to utilize big gun hole 100 to carry out secondary excavation at the platform that waits to explode of existing foundation ditch, form the secondary foundation ditch that satisfies the construction demand, do benefit to follow-up to secondary arch seat foundation ditch and construct, provide construction conditions for follow-up construction step, and through the concrete structure that forms of control big gun hole 100, promoted the blasting excavation effect of big gun hole 100, promote engineering construction quality, provide the reference for similar construction mode.

With continued reference to fig. 1-3, and with reference to fig. 8, fig. 8 is a schematic drawing of a slitting hole layout in accordance with the present invention.

In one embodiment, as shown in fig. 1 to 3 and 8, the working platform is used to implement the to-be-excavated surface of the right bank abutment, and the step of forming the right-stage slope platform includes:

step E100: hole position lofting is carried out on the surface to be excavated of the right bank arch seat, and a hole position to be formed is obtained;

step E200: drilling a hole to be formed to form a hole to be split 600;

step E300: splitting the hole 600 to be split to form a splitting area;

step E400: and forming an arch foundation pit according to the splitting area.

In one embodiment, the step of cleaving the hole 600 to be cleaved, the step of forming a cleavage region includes:

step F100: the gun head of the splitting machine is assisted by a digging machine to be sent into the hole 600 to be split;

Step F200: the hole 600 to be split is extruded by a gun head, so that the surface to be excavated is split into a line to form a splitting area.

In an embodiment, before the step of splitting the hole 600 to be split to form the splitting area, the method for layer-by-layer excavation of the foundation pit of the abutment includes:

step G100: checking the depth of the hole 600 to be split;

step G200: judging whether the depth of the hole 600 to be split meets the preset depth condition;

step G300: if yes, splitting the hole 600 to be split;

step G400: if not, the depth of the hole 600 to be split is adjusted so that the depth of the hole 600 to be split meets the preset depth condition.

In an embodiment, the outer contour of the right-bank abutment is in a step shape, the abutment foundation pit of the right-bank abutment includes a plurality of surfaces to be excavated which are sequentially stacked from top to bottom, a plurality of holes to be formed are uniformly distributed on each surface to be excavated, the plurality of surfaces to be excavated are a first surface to be excavated and a second surface to be excavated which is stacked and arranged below the first surface to be excavated, and the method for layered excavation of the abutment foundation pit is characterized in that before the step of forming the abutment foundation pit according to a splitting area, the method comprises the following steps:

step H100: drilling a hole forming position on a first surface to be excavated, and splitting construction is carried out on the first surface to be excavated to form a first splitting area;

Step H200: obtaining a splitting situation according to the first splitting area;

step H300: adjusting the hole distance between each hole forming position on the second surface to be excavated according to the splitting condition;

step H400: and drilling a hole to be formed in the second surface to be excavated, and splitting construction is carried out on the second surface to be excavated to form a second splitting area.

In one embodiment, the row spacing between the plurality of holes to be formed is 80cm.

For ease of understanding, one embodiment is shown below:

the arch seats on both sides are located in weak weathering rock stratum, the bearing capacity of the foundation is not less than 1200kPa, and the elevation of the foundation is 763.417m. The 2# arch base is a solid integral inverted trapezoid common reinforced concrete arch base, and the outer contour dimension is 18.82m x 19.44m x 17.21m; the 3# arch support is a solid separated inverted trapezoid common reinforced concrete arch support, which is symmetrically arranged at the upstream and the downstream along the central line of the line, and the outer contour dimension is 18.8m 13.8m 17.23m.

And excavating the arch seats of the large bridge of the jing river by adopting a step method for splitting construction. After the left and right shore construction platforms are excavated to 794.491m (construction platform elevation), the left and right shore arch seats are excavated layer by adopting a step method splitting method, and the excavation height of each layer of step is 1.2m.

The left and right shore arch seats are equally divided into 4 areas, 28 steps are excavated, and the excavation height of each step is about 1.2m.

The excavation range of the first area of the left bank is 794.494-787.648 m, the excavation height is 7.478m, the slope rate of the abutment back side slope is 1:0.5, and the steps are excavated in 1-7 steps; the excavation range of the second area is 787.648-780.498 m, the excavation step height is 7.15m, the excavation slope rate is 1:0.1, and the steps are excavated in 8-13 steps; the excavation range of the third area is 780.498-771.091 m, the excavation step height is 9.407m, and the excavation slope rate is 1:0.1 and 14-21 steps are excavated; the excavation range of the fourth area is 771.091-764.417 m (the elevation of a platform in front of an arch seat is 764.417 m), the excavation step height is 6.674m, 1m is reserved, the slope rate of an excavation side slope is 1:1.18 by adopting mechanical excavation 764.417-763.417 m, and the excavation is divided into 22-28 steps; and the fifth excavation adopts mechanical slope repair, the underexcavated part of the slope part is chiseled, and the slope rate of the second-layer step slope is changed from 1:0.2 to 1:0.5. The excavation range of the first area of the right bank is 794.494-787.013 m, the excavation height is 7.478m, the slope rate of the back side slope of the abutment is 1:0.2, the slope rate of the side slopes of the two sides of the abutment is 1:0.3, and the steps are excavated in 1-7 steps; the excavation range of the second area is 787.013-780.477 m, the excavation height is 6.536m, the slope rate of the excavated side slope is 1:0.2, and the steps are excavated in 8-13 steps; the third area is excavated in a range of 780.477-771.063 m, the height of the excavated steps is 9.414m, the slope rate of the excavated side slope is 1:0.1, and the steps are excavated in 14-21 steps; the fourth layer excavation range is 771.063-764.417 m, the excavation step height is 7.646m, 1m is reserved, mechanical excavation 764.417-763.417 m is adopted, the excavation slope rate is 1:1.18, and the steps are excavated in 22-28 steps; and the fifth excavation adopts mechanical slope repair, the underexcavated part of the slope is chiseled, and the slope rate of the second-layer step slope is changed from 1:0.2 to 1:0.75. The excavation steps are shown as follows.

The foundation pit excavation process flow comprises the following steps:

according to the actual condition of the site and combining with the construction experience of similar engineering in the past, the foundation pit excavation is to be constructed by adopting a shallow hole step splitting method, the construction is performed from top to bottom in a step-by-step mode, and a slag blocking wall with 200cm is reserved at the position of a river-like side slope so as to prevent construction slag slipping and safety risks.

The splitting method comprises the following steps:

according to geological conditions and foundation pit design schemes, taking environmental conditions and safety requirements around the foundation pit into consideration, adopting a stepped down-the-hole to control splitting, namely selecting a 160cm area from the middle part of each layer below the elevation 794.417m to carry out linear drilling splitting slitting, and forming splitting extrusion surfaces. Then drill holes are split from both sides at 80cm row spacing, with each layer being about 1.2m in height.

And (3) a splitting process:

(1) Hole distribution: and (3) measuring and lofting, namely discharging the contour line according to the arch seat position, marking hole positions on a base surface, wherein the hole distances are 80cm, the pitch is 200cm, the hole depths are 120cm, the middle parts are vertical holes, the positions close to the designed side slope of the foundation pit are provided, and drilling is performed after the drilling angles are adjusted according to the gradient of the designed side slope.

(2) Drilling: drilling by using a down-the-hole drill, cleaning the hole by using high-pressure air after drilling, and temporarily plugging the hole by using geotechnical cloth or a braiding belt after cleaning the hole so as to ensure that the gun head of the splitting machine is smoothly installed.

(3) Splitting: the 6 gun heads equipped with the splitting machine are assisted by the digging machine to be sent into a drilling hole, an oil pump is started to pressurize, and the 6 gun heads simultaneously generate extrusion force on the rock mass, so that the rock mass is split into a line along the direction of the row hole.

(4) Decomposing marble: the big stone is broken by a gun machine and is decomposed into small stone blocks, so that the big stone is convenient to transport.

A ballasting method and a ballasting process:

the foundation pit of the arch base is ballasted by adopting an excavator to fill, a crawler crane to lift and a dump truck to carry out external transportation.

Each foundation pit is provided with two excavators, and is excavated in layers to explode slag and fill.

The foundation pit excavation of the No. 2 arch seat and the No. 3 arch seat is respectively provided with a 200t crawler crane, and a 6 m-8 m wide construction platform (wherein the range of 1m of the edge of the foundation pit is a protection channel) is reserved around the foundation pit excavation line for the crawler cranes to move and construct; the platform roadbed is strong wind fossil limestone, and the working requirement of the crawler crane can be met without treating bearing capacity.

The length of the largest excavation edge of the foundation pit is close to 44.36m (the 2# arch deck is in the forward direction), the maximum working radius of the excavator is 10m, and the construction requirement can be met by selecting 27.45m for the crawler crane arm length configuration in consideration of the farthest distance between the foundation pit bottom and the crane, and under the working condition configuration, the common maximum working radius is 26m, the lifting capacity is 25.4t and the counterweight is 86.3t.

200t crawler crane is equipped with 2X 2m bucket, each bucket has a capacity of 8m3 and a weight of about 16t, the hoisting steel wire ropes are arranged according to the walking 2, and the lifting speed is 60m/min.

The waste slag is transported by a 10t dump truck to an external waste slag field 2km away from the upstream of the bridge site, and the full spring shore waste slag field is positioned at an external waste slag field 500m away from the upstream of the bridge site.

According to the technical scheme, the hole 600 to be split is distributed on the surface to be excavated of the existing foundation pit, and the hole 600 to be split is utilized to carry out splitting construction on the surface to be excavated of the existing foundation pit, so that the forming difficulty of secondary excavation of the arch base foundation pit is reduced, the method is more suitable for construction operation environments with steeper side slopes, thinner covering soil, exposed partial bedrock and limited working platform range, and a reference basis is provided for similar construction conditions.

It should be noted that, the foregoing reference numerals of the embodiments of the present invention are only for describing the embodiments, and do not represent the advantages and disadvantages of the embodiments. The above embodiments are only optional embodiments of the present invention, and not limiting the scope of the present invention, and all equivalent structures or equivalent processes using the descriptions of the present invention and the accompanying drawings or direct or indirect application in other related technical fields are included in the scope of the present invention.

Claims

1. The utility model provides a arch abutment foundation ditch layering excavation method which is characterized in that, the arch abutment foundation ditch includes existing foundation ditch slope platform, existing foundation ditch slope platform includes left bank arch abutment and right bank arch abutment that the interval set up, left bank arch abutment with all be provided with the face of waiting to excavate on the right bank arch abutment, the method includes:

2. A method of layered excavation of an abutment foundation pit as set forth in claim 1, wherein said left abutment comprises a plurality of steps to be blasted, said step of using said work platform to layer and step said left abutment to be excavated of said left abutment along a height direction of said existing foundation pit slope platform from top to bottom at said left abutment of said existing foundation pit slope platform to form a left six-layer slope platform comprising:

forming blast holes on each step to be blasted;

3. A method of layered excavation of an abutment foundation pit as set forth in claim 2, wherein said step of forming blastholes in each of said steps to be blasted includes:

presetting the ultra-deep depth of the blast hole;

according to the type of the blast hole, acquiring the drug loading quantity;

4. A method of layered excavation of an arch foundation pit as recited in claim 3, wherein the type of blastholes is a plurality of rows of blastholes, the plurality of rows of blastholes including a front row of blastholes and a second row of blastholes spaced from the front row of blastholes, the front row of blastholes being formed by a plurality of the blastholes in a spaced arrangement, and the second row of blastholes being formed by a plurality of the blastholes in a spaced arrangement;

5. A method of layered excavation of an abutment foundation pit as claimed in claim 3, wherein the blastholes are of the type smooth blastholes;

6. A method of layered excavation of an abutment foundation pit as set forth in any one of claims 1 to 5, wherein the step of constructing the right side abutment to be excavated surface using the working platform, the step of forming a right side slope platform includes:

drilling the hole to be formed to form a hole to be split;

splitting the holes to be split to form splitting areas;

and forming the arch foundation pit according to the splitting area.

7. A method of layered excavation of an abutment foundation pit as defined in claim 6, wherein the step of cleaving the hole to be cleaved to form a cleavage region comprises:

8. A method of layered excavation of an abutment foundation pit as defined in claim 7, wherein prior to the step of cleaving the hole to be cleaved to form a cleavage region, the method comprises:

Checking the depth of the hole to be split;

if yes, splitting the hole to be split;

9. A method of layered excavation of a right-side abutment pit according to claim 7, wherein the outer contour of the right-side abutment pit is stepped, the abutment pit of the right-side abutment pit includes a plurality of surfaces to be excavated which are sequentially stacked from top to bottom, a plurality of holes to be formed are uniformly distributed on each of the surfaces to be excavated, and the plurality of surfaces to be excavated are a first surface to be excavated and a second surface to be excavated which is stacked below the first surface to be excavated, and before the step of forming the abutment pit according to the splitting area, the method comprises:

obtaining a splitting situation according to the first splitting area;

10. A method of layered excavation of an abutment foundation pit as set forth in claim 9, wherein the pitch between a plurality of said to-be-bored sites is 80cm.