CN112227401A

CN112227401A - Method for constructing bearing platform by filling stones in underwater stone abrupt slope area

Info

Publication number: CN112227401A
Application number: CN202010958986.9A
Authority: CN
Inventors: 周文
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2020-09-14
Filing date: 2020-09-14
Publication date: 2021-01-15

Abstract

The invention discloses a bearing platform construction method for filling stones and building an island in an underwater rocky abrupt slope region, which utilizes grouting steel sleeves, coarse steel bars and cement-water glass double-liquid slurry to form a composite small-sized anti-skidding pile so as to resist the downward slippage of a filled island body towards the middle of a river, reduce the island building area and the backfilling engineering quantity, save the construction period and the cost and ensure the construction safety. The lateral stability of the foundation pit of the later bearing platform can be improved without taking out the grouting steel sleeve, and the excavation safety of the foundation pit is ensured. The cement-water glass double-slurry is adopted for carrying out curtain grouting on the periphery of the foundation pit and back cover grouting on the bottom of the foundation pit, water stop of the bearing platform foundation pit is carried out, the water stop effect is good, secondary water stop is not needed in subsequent bearing platform foundation pit excavation, and the maximization of economy, safety and practicability is realized. Compared with the prior art, the method does not need large-scale equipment and a large number of steel structures, and has the advantages of safe structure, single process and good economical efficiency. The problem of the difficult construction of bearing platform in the rock mass abrupt slope district under water is solved.

Description

Method for constructing bearing platform by filling stones in underwater stone abrupt slope area

Technical Field

The invention relates to the technical field of bearing platform construction, in particular to a bearing platform construction method for filling stones in an underwater stone abrupt slope area and building an island.

Background

In recent years, traffic networks are being built on a large scale in various places of China, bridges are often adopted on each traffic network as a common structural form crossing rivers, lakes and seas, and when the bridges are constructed by water bearing platforms, the following methods are generally adopted:

(1) the construction method of the steel cofferdam comprises the following steps: when the bearing platform is in water, a steel sheet pile cofferdam or a steel cofferdam is arranged firstly to place pile groups in the cofferdam, then concrete is poured into the river bottom in the cofferdam to seal the bottom, water is pumped out after solidification to enable the pile groups to be in dry land, then a bearing platform steel bar formwork is installed, and bearing platform concrete is poured. The steel cofferdam is suitable for the soft layer riverbed generally, but for the rocky steep slope riverbed, the steel sheet piles cannot be inserted and driven, and the steel cofferdam is difficult to lower.

(2) A bored pile enclosing construction method: when the bearing platform is in the water condition, the island is built to form a stable platform, then holes are drilled above the stable platform to form row piles or secant piles, and then waterproof curtain construction is carried out among the piles. And (4) installing an inner support, excavating, sealing the bottom of the building enclosure, pumping water, and constructing a reinforced concrete bearing platform. The drilling equipment in the waterside rocky abrupt slope area is difficult to place, the construction period of punching operation is long, and the cost is high.

(3) The construction method of the underground continuous wall comprises the following steps: after the platform is formed, a guide channel is excavated, a guide wall is built, an underground continuous wall is constructed in the guide wall in a dividing mode, a reinforcement cage is placed after slag is removed, underwater concrete pouring is carried out, and a stable underground continuous wall enclosure structure is formed. And (4) installing an inner support, excavating, sealing the bottom of the building enclosure, pumping water, and constructing a reinforced concrete bearing platform. Underground continuous wall equipment is large, a waterside rocky abrupt slope area is difficult to place, a building island side slope is subjected to large load, a platform is unsafe, and construction cost is high.

Disclosure of Invention

The invention aims to provide a bearing platform construction method for filling stones and building an island in an underwater stone steep slope area, which is convenient for bearing platform construction in the underwater stone steep slope area.

The technical scheme adopted by the invention is as follows: a method for filling stones in an underwater stone abrupt slope region to construct an island construction bearing platform comprises the following steps:

s10, building foundation: throwing a gabion at the slope bottom, pouring and filling stone ballast from a bank side to an underwater stone steep slope area in the range of a bearing platform until the island body is exposed out of the water surface, and injecting cement-water glass double-liquid slurry into the filled island body after the island body is filled to reinforce the island body;

s20, reinforcing the island body by using the slide-resistant piles: drilling a hole on the island surface to penetrate into bedrock, and putting a composite small-sized anti-skidding pile consisting of a steel sleeve, a coarse steel bar and cement-water glass double-liquid slurry into the drilled hole to reinforce the filled island body;

s30, foundation pit grouting and bottom sealing: curtain grouting is carried out on the periphery of the foundation pit, bottom sealing grouting is carried out in the foundation pit, water stopping of the foundation pit is further completed, and finally a foundation pit construction bearing platform is excavated.

Has the advantages that: the grouting steel sleeve, the thick steel bar and the cement-water glass double-liquid slurry are used for forming the composite small-sized anti-slip pile to resist the filled island body from slipping downwards in the river, so that the island building area and the backfilling engineering quantity are reduced, the construction period and the cost are saved, and the construction safety is ensured. Meanwhile, the lateral stability of the foundation pit of the later-stage cushion cap can be improved without taking out the grouting steel sleeve, and the excavation safety of the foundation pit is guaranteed. The cement-water glass double-slurry is adopted for carrying out curtain grouting on the periphery of the foundation pit, back cover grouting at the bottom of the foundation pit is used for carrying out bearing platform foundation pit water stopping, the water stopping effect is good, secondary water stopping is not needed in subsequent bearing platform foundation pit excavation, and the maximization of economy, safety and practicability is realized. Compared with the prior art, the method does not need large-scale equipment and a large number of steel structures, and has the advantages of safe structure, single process and good economical efficiency. The problem of the difficult construction of bearing platform in the rock mass abrupt slope district under water is solved.

Further, the step between the step S20 and the step S30 further includes the steps of: s25, circularly building the island and reinforcing: and thirdly, filling ballast again to widen the island body, injecting cement-water glass double-liquid slurry into the newly widened island body, constructing the composite small-sized anti-skid pile for reinforcement, and circularly reciprocating until the area of the artificial island body reaches the area size required by the construction bearing platform.

Further, in the step S10, an underwater measuring instrument is used to measure the underwater topography at the position near the side slope of the bearing platform, and the island building range and the backfill amount are calculated according to the size of the bearing platform.

Further, the gabion is dumped at the calculated theoretical toe position by underwater terrain analysis.

And further, strain model analysis is carried out according to the distribution condition of rock soil, and slope stability is analyzed by adopting a finite element strength reduction method.

Further, in the step S30, during curtain grouting, the grouting amount at the contact surface of the gravel backfill layer and the rock is increased.

Further, in the step S20, the steel sleeve penetrates the gravel backfill layer to enter 8-10m below the surface of the bedrock.

Further, step S30 includes curtain holes and back cover holes, the curtain holes are arranged at intervals of 1.5m × 1.0m and outside the foundation pit of the platform, and the back cover holes are arranged at intervals of 1.5m × 1.5m and within the range of the platform.

Furthermore, the curtain hole and the bottom sealing hole are formed by adopting a down-the-hole drill, and are drilled with a pipe, and the holes are drilled in a sequence and section mode.

Drawings

The invention is further illustrated with reference to the following figures and examples:

FIG. 1 is a construction flow chart of an embodiment of the present invention;

FIG. 2 is a schematic diagram of an island backfill layout according to an embodiment of the present invention;

FIG. 3 is a drill floor plan of an embodiment of the present invention;

FIG. 4 is a drill floor plan of an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1 to 4, the invention provides a method for filling stones in an underwater stone steep slope area to build an island construction bearing platform, which comprises the following steps:

s10, building foundation: throwing a gabion 2 at the slope bottom, pouring stone ballast from the bank side to an underwater stone steep slope region in the range of the bearing platform 1 until the island body 3 is exposed out of the water surface, and injecting cement-water glass double-liquid slurry into the filled island body 3 to reinforce the island body 3 after the island body 3 is filled;

s20, reinforcing the island body 3 by the slide-resistant piles 4: drilling a hole on the island surface to penetrate into bedrock, and putting a composite small-sized anti-slide pile 4 consisting of a steel sleeve, a coarse steel bar and cement-water glass double-liquid slurry into the drilled hole to reinforce the filled island body 3;

s30, foundation pit grouting and bottom sealing: curtain grouting is carried out on the periphery of the foundation pit, bottom sealing grouting is carried out in the foundation pit, water stopping of the foundation pit is further completed, and finally the foundation pit construction bearing platform 1 is excavated.

According to the method for constructing the bearing platform by filling the stones in the underwater rocky abrupt slope region and constructing the island, the grouting steel sleeve, the thick steel bars and the cement-water glass double-liquid slurry are utilized to form the composite small-sized anti-skidding pile 4 so as to resist the filling island body 3 from slipping downwards in the river, the island constructing area and the backfilling amount are reduced, the construction period and the cost are saved, and the construction safety can be ensured. Meanwhile, the lateral stability of the foundation pit of the later-stage bearing platform 1 can be improved without taking out the grouting steel sleeve, and the excavation safety of the foundation pit is ensured. The cement-water glass double-slurry is adopted for carrying out curtain grouting on the periphery of the foundation pit and back cover grouting on the bottom of the foundation pit for carrying out foundation pit water stop on the bearing platform 1, the water stop effect is good, secondary water stop is not needed in the foundation pit excavation of the subsequent bearing platform 1, and the maximization of economy, safety and practicability is realized. Compared with the prior art, the method does not need large-scale equipment and a large number of steel structures, and has the advantages of safe structure, single process and good economical efficiency. The problem of the bearing platform 1 construction difficulty in the underwater rocky abrupt slope area is solved.

Preferably, the method between step S20 and step S30 further comprises the steps of: s25, circularly building the island and reinforcing: and (3) filling ballast again to widen the island body 3, injecting cement-water glass double-liquid slurry into the newly widened island body 3, constructing the composite small-sized anti-skid pile 4 for reinforcement, and circularly reciprocating until the area of the artificial island body 3 reaches the area size required by the construction bearing platform 1. The stability of the island body is improved by circularly building and reinforcing the island, and a stable working surface is provided for the construction of the bearing platform 1. And repeating the methods of grouting the contact surface, inserting and beating a steel pipe sleeve, grouting and the like until the island is built to the design requirement range.

Preferably, in the step S10, an underwater measuring instrument is used to measure the underwater topography near the side slope of the bearing platform 1, the island construction range and the backfill square amount are calculated according to the size of the bearing platform 1, and an initial backfill construction scheme is drawn up. According to the measurement result of the underwater measuring instrument, strain model analysis can be established, the rock and soil distribution condition is analyzed, and a backfill region slope stability analysis model diagram is established, so that the drilling position, the water level line and the backfill range of the reinforced steel sleeve are accurately planned, the construction period is shortened, and the island building efficiency is improved.

Preferably, the gabion 2 is dumped at the position of the theoretical slope toe through underwater terrain analysis, the gabion 2 is accurately dumped to the slope toe, the problem that the island building area is too small and needs secondary treatment or is too large is solved, and the construction time and the construction cost are saved.

Preferably, strain model analysis is carried out according to rock and soil distribution conditions, slope stability is analyzed by adopting a finite element strength reduction method, slope stability safety coefficient is analyzed, the overall stability of the slope is guaranteed through theoretical analysis, actual construction difficulty is reduced, and construction time and cost are reduced.

Preferably, in step S30, during curtain grouting, grouting is performed between the backfill layer and the rock contact surface, so as to increase the grouting amount at the rock contact surface and the gravel backfill layer, thereby improving the stability of the interface and ensuring the overall stability of the island body 2.

Preferably, in step S20, the steel sleeve penetrates the gravel backfill layer, the coarse steel bars are inserted into the steel sleeve, the steel sleeve enters 8-10m below the surface of the bedrock, and cement-water glass double-liquid slurry is injected under high pressure for reinforcement to form the composite small slide-resistant pile 4, so that the slide force under the slope is reduced, the stability of the slope is improved, and the overall slide is prevented.

Preferably, step S30 includes curtain holes and back cover holes, the curtain holes 5 are spaced 1.5m by 1.0m apart and are disposed outside the foundation pit of the platform 1, and the back cover holes 6 are spaced 1.5m by 1.5m apart and are disposed within the platform 1.

Preferably, the curtain hole 5 and the bottom sealing hole 6 are formed by adopting a down-the-hole drill, the following pipe is drilled, the sequential and sectional drilling is adopted, and the following steel pipe is not taken out in the later period, so that the lateral stability of the foundation pit is improved, and the excavation safety of the foundation pit is ensured.

In particular, the invention provides an embodiment, which is positioned at the upstream of the Lhasa bank of the Tibetan wood bridge, the arch support part of the Lassa is positioned below the water level of the Yalu Tibetan Bujiang river, the underwater side slope is steep, the mountain is granite, the downstream 1.2km is a wood-storing hydropower station, because large-area underwater filling is not allowed to form an underwater hidden platform, the island filling in large-scale construction is difficult, the underwater topography is measured firstly after comparison and selection, throwing a gabion 2 at the bottom of the steep slope, then building an island by using stones and ballast of tunnel blasting construction to perform primary filling construction of an island body 3, pouring and filling the ballast to perform partial island building, performing high-pressure cement-water glass double-liquid slurry grouting in the ballast, simultaneously, a geological drilling machine is used for drilling into the bed rock of the steep side slope, the steel sleeve penetrates through the island building surface and goes deep below the rock surface, inserting 4 thick steel bars with the diameter of 32mm into the steel sleeve, and injecting cement-water glass double-liquid slurry at high pressure for reinforcement; continuously pouring and filling stone slag for the second time to build the island, performing cement-water glass double-liquid-slurry high-pressure grouting in the newly widened island body 3, drilling a drilling machine below bedrock, inserting a steel sleeve and a coarse steel bar, and performing cement-water glass double-liquid-slurry grouting in the steel sleeve; and repeating the above work in a circulating manner until the whole island building work is completed. The technology utilizes cement-water glass double-liquid slurry to reinforce and fill the ballast to build the island, utilizes the grouting steel sleeve, the coarse steel bars and the cement-water glass double-liquid slurry to form the composite small-sized anti-sliding pile 4 to resist the filling island body 3 from sliding downwards in the river, reduces the island building area and the backfilling engineering quantity, saves the construction period and the cost, and can ensure the construction safety.

The specific construction method comprises the following steps:

(1) measuring the underwater topography of the position near the side slope of the bearing platform 1 by using an underwater measuring instrument, calculating the island building range and the backfill square amount according to the size of the bearing platform 1, and drawing up an initial backfill construction scheme.

(2) And (5) analyzing a strain model. And three rock-soil materials are created according to rock-soil distribution conditions by combining related exploration data. The size of the broken stone filled soil modeling grid is 1.5m, the strongly weathered granite is 4m, and the moderately weathered granite is 6 m. The stone filling, the strongly weathered granite and the moderately weathered granite all adopt a Moore-Coulomb constitutive model. The boundary condition adopts hinged support, the self gravity and water pressure are considered by external load, the slope stability is analyzed by adopting a finite element Strength Reduction Method (SRM), and the slope stability safety coefficient is 0.98 through analysis. The overall stability of the side slope can be ensured after the following measures are carried out:

1) performing anti-scouring treatment on the slope bottom of the pile filling, and performing a check gabion 2 on the slope bottom;

2) in the curtain grouting process, the grouting amount of the contact surface between the gravel backfill layer and the rock is increased, and the stability of the interface is improved;

3) in the curtain grouting process, the depth of the curtain grouting steel pipe is increased, and the curtain grouting steel pipe penetrates through the gravel backfill layer and enters 8-10m below the surface of the bedrock, so that the sliding force under the side slope is reduced, the stability of the side slope is improved, and the integral sliding is prevented.

(3) And (4) throwing and filling the check gabion 2 at the position of the theoretical slope toe according to the underwater measured terrain. And after the backfilling is finished, carrying out underwater topography measurement, and confirming a backfilling range and a new underwater topography line.

(4) And (4) island construction backfilling and underwater grouting. The backfill material adopts the hole ballast of tunnel blasting construction and the existing earth and stones of the nearby mountain slope, and the filler is directly transferred to the position of the bearing platform 1 by the cooperation of a loader, an excavator and a dumper truck. Filling stone ballast to the outside from the side line of the road to build the island, throwing and filling the block stones in the filling area to the normal water level elevation, using a loader to squeeze and level, and gradually expanding the throwing and filling range.

After the island is built for the first time, grouting is carried out in stone ballast on the island building surface, and grouting is carried out by adopting cement-water glass double-liquid slurry with good solidification and water stop effects, so that the grouting amount of the contact surface between the gravel backfill layer and the rock is increased, and the stability of the interface is improved. Then immediately drilling the steel flower tube below the bed rock of the steep slope by using a geological drilling machine (the steel sleeve tube extends 8-10m below the rock surface), inserting the steel flower tube, inserting 4 thick steel bars with the diameter of 32mm into the steel flower tube, injecting cement-water glass double-liquid slurry for reinforcement under high pressure, and ensuring the integral stability of the curtain. And (5) performing secondary stone ballast filling and island building on the outer side, repeating the methods of contact surface grouting, steel sleeve inserting grouting and the like until the island building reaches the design requirement range.

(5) Grouting the curtain and the back cover. After the island building platform is refilled, the foundation pit excavation of the bearing platform 1 is started, the curtain grouting water stop and the back cover grouting water stop are combined to stop water, and the foundation pit of the bearing platform 1 is excavated vertically through a concrete retaining wall.

The curtain holes 5 are formed by adopting a down-the-hole drill, drilling is carried out along with a pipe, and the interval between the curtain holes 5 is arranged to be 1.5 x 1.0m and is arranged outside a foundation pit of the bearing platform 1. The aperture of the opening is 110 mm and 130mm, and the opening is drilled with 108mm steel pipes in sequence and section. The steel pipe later stage of following the pipe does not take out to improve the lateral stability of foundation ditch, guarantee foundation ditch excavation safety. So the steel pipe of curtain hole 5 plays two roles, and first guarantee that pore-forming is stable in earlier stage, not hole collapse, second increase foundation ditch lateral rigidity, improve foundation ditch stability.

The bottom sealing holes 6 are formed by adopting a down-the-hole drill, and drilled with a pipe, and the interval between the bottom sealing holes 6 is 1.5 x 1.5m and is arranged in the range of the bearing platform 1. The construction method is the same as curtain drilling. And after the strength of the grouting water stopping slurry meets the requirement, the construction of the bearing platform 1 is started, the foundation pit is vertically excavated from top to bottom, a reinforced concrete retaining wall is adopted, and after the base is checked and accepted to remove slag, the steel bars and the concrete at the bearing platform 1 are constructed.

While the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art.

Claims

1. A method for filling stones in an underwater stone abrupt slope region to construct an island construction bearing platform is characterized by comprising the following steps:

2. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: the method between the step S20 and the step S30 further comprises the steps of: s25, circularly building the island and reinforcing: and thirdly, filling ballast again to widen the island body, injecting cement-water glass double-liquid slurry into the newly widened island body, constructing the composite small-sized anti-skid pile for reinforcement, and circularly reciprocating until the area of the artificial island body reaches the area size required by the construction bearing platform.

3. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: in the step S10, an underwater measuring instrument is used to measure the underwater topography near the side slope of the bearing platform, and the island building range and the backfill square amount are calculated according to the size of the bearing platform.

4. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: and (4) throwing and filling the gabion at the position of the calculated theoretical toe through underwater terrain analysis.

5. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: and (3) carrying out strain model analysis through rock and soil distribution conditions, and analyzing the slope stability by adopting a finite element strength reduction method.

6. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: in the step S30, in the curtain grouting process, the grouting amount at the contact surface between the gravel backfill layer and the rock is increased.

7. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: in the step S20, the steel sleeve penetrates through the gravel backfill layer and enters 8-10m below the surface of the bedrock.

8. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: and step S30 comprises curtain drilling holes and back cover drilling holes, wherein the curtain drilling holes are arranged at intervals of 1.5m by 1.0m and are arranged outside the foundation pit of the bearing platform, and the back cover drilling holes are arranged at intervals of 1.5m by 1.5m and are arranged in the range of the bearing platform.

9. The method for filling stones and constructing the island according to the underwater rocky abrupt slope region, which is characterized in that: and forming the curtain hole and the bottom sealing hole by adopting a down-the-hole drill, drilling along with a pipe, and drilling by adopting a sequence and a subsection mode.