阅读说明：本技术 一种海滩上的顶管工作井和管沟的支护、止水施工方法 (Supporting and water-stopping construction method for pipe-jacking working well and pipe ditch on beach ) 是由 苏茂森 林四新 刘金江 何淼鑫 林靖伟 蔡金平 于 2020-12-29 设计创作，主要内容包括：本发明公开了一种海滩上的顶管工作井及管沟的支护、止水施工方法,顶管工作井的背水侧壁设置顶管洞口,顶管工作井的迎水侧壁与管沟连接；顶管工作井和管沟的支撑系统均包括冠梁和三道钢围檩,顶管工作井的冠梁和三道钢围檩的四个角部均设置角撑；管沟的冠梁和三道钢支撑每间隔一定距离设置一道横撑；顶管工作井和管沟均采用咬合桩围护；咬合桩的A序桩采用超缓凝素混凝土桩,缓凝时间不小于60h,咬合桩的B序桩采用钢筋混凝土桩,位于顶管工作井的顶管洞口位置的钢筋采用玻璃纤维筋；本发明的施工方法包括以下流程：修筑围堰、咬合桩施工、基坑降排水施工、顶管工作井开挖和管沟开挖。本发明能提高顶管工作井和管沟的安全性、稳定性和防水性。(The invention discloses a supporting and water-stopping construction method of a pipe-jacking working well and a pipe ditch on a beach, wherein a pipe-jacking hole is formed in the backwater side wall of the pipe-jacking working well, and the water-facing side wall of the pipe-jacking working well is connected with the pipe ditch; the supporting systems of the pipe jacking working well and the pipe trench comprise a crown beam and three steel purlins, and corner supports are arranged at four corners of the crown beam and the three steel purlins of the pipe jacking working well; a cross brace is arranged at a certain distance between the crown beam of the pipe trench and the three steel supports; the pipe-jacking working well and the pipe trench are enclosed by occlusive piles; the A-sequence pile of the occlusive pile adopts an ultra-slow-setting plain concrete pile, the slow setting time is not less than 60 hours, the B-sequence pile of the occlusive pile adopts a reinforced concrete pile, and a reinforcing steel bar positioned at a top pipe opening of the top pipe working well adopts a glass fiber reinforcing steel bar; the construction method comprises the following steps: building a cofferdam, constructing an occlusive pile, constructing a foundation pit for dewatering and drainage, excavating a pipe jacking working well and excavating a pipe trench. The invention can improve the safety, stability and waterproofness of the pipe-jacking working well and the pipe trench.)

1. A supporting and water-stopping construction method for a pipe-jacking working well and a pipe ditch on a beach is characterized in that a pipe-jacking hole is formed in the backwater side wall of the pipe-jacking working well, and the water-facing side wall of the pipe-jacking working well is connected with the pipe ditch; the supporting systems of the pipe jacking working well and the pipe trench comprise a crown beam and three steel purlins, and corner supports are arranged at four corners of the crown beam and the three steel purlins of the pipe jacking working well; a cross brace is arranged at a certain distance between the crown beam of the pipe trench and the three steel supports; the pipe jacking working well adopts an occlusive pile to enclose a closed well frame, and the pipe ditch also adopts the occlusive pile to enclose ditch walls on two sides; the A-sequence pile of the occlusive pile adopts an ultra-slow-setting plain concrete pile, the slow setting time is not less than 60 hours, the B-sequence pile of the occlusive pile adopts a reinforced concrete pile, and a reinforcing steel bar positioned at a top pipe opening of the top pipe working well adopts a glass fiber reinforcing steel bar; the construction method is characterized by comprising the following steps: building a cofferdam, constructing an occlusive pile, constructing a foundation pit drainage, excavating a pipe jacking working well and excavating a pipe ditch on the periphery of a construction position;

the occlusive pile construction process comprises the following steps:

obstacle removing construction: adopting a 360-degree full-circle cutting machine, measuring and lofting according to an obstacle clearing plane layout, placing a sleeve with the pipe diameter larger than the pile diameter of the occlusive pile at a position where an obstacle needs to be cleared, starting to rotate and press downwards, breaking the obstacle by using a punching hammer, cleaning the obstacle by using a grab bucket, backfilling and compacting a pile hole by using common soil after the obstacle is cleared, and pulling out the sleeve;

a guide wall construction step, wherein the guide wall is of a cast-in-place reinforced concrete structure; the top surface of the guide wall is higher than the ground; the diameter of a guide hole on the guide wall is larger than that of the secant pile, and the reinforcing steel bars of the guide wall are arranged in a single-layer longitudinal and transverse mode;

when the occlusive pile is constructed, firstly constructing a pile driving hole, then pouring the concrete of the A-sequence pile, and then completing the construction of the B-sequence pile before the concrete of two adjacent A-sequence piles is initially set;

the pile driving method comprises the following steps:

(1) the drilling machine is in place, the center of a drill bit and the center of a pile position are ensured to be on the same plumb line when the drilling machine is in place, and the top elevation of the steel casing is measured after the drilling machine is in place;

(2) forming a hole and taking soil, after a drilling machine is positioned, hoisting and placing a first section of steel casing with a blade tip at the end, fixing the first section of steel casing between a guide hole of a guide wall and the first section of steel casing by using a wooden plug, ensuring that the deviation between the first section of steel casing and a pile hole center is less than a set value, pressing in the first section of steel casing, continuously checking the verticality of the first section of steel casing in the pressing-in process, fixing a lower clamp of the drilling machine when the verticality of the first section of steel casing is not more than the set value, and adjusting the verticality by using an upper clamp of the drilling machine; when the perpendicularity of the first section of steel casing exceeds a set value, the first section of steel casing is pulled out and embedded again, or the drilling machine is moved forwards, backwards, leftwards and rightwards to enable the first section of steel casing to be centered; when taking soil and forming holes, taking soil from the first section of steel casing by using a grab bucket, taking soil while pressing the first section of steel casing downwards, and always keeping the bottom opening of the first section of steel casing to be ahead of the soil taking surface and the depth of the bottom opening to be not less than 2.5 m; after the first section of steel casing is completely pressed into the soil, detecting the verticality of the formed hole, if the formed hole is unqualified, carrying out deviation rectification adjustment, if the formed hole is qualified, installing a second section of steel casing, taking the soil again, and pressing down the second section of steel casing; and so on until the bottom of the pile hole reaches the designed elevation;

when pouring the concrete of the A-sequence pile, adopting an underwater concrete pouring method for construction, wherein the pouring mode adopts a conduit method and adopts a crane for matching; when the concrete is poured, the bottom end of the guide pipe is lifted to 0.5m from the bottom of the pile hole, the initial pouring amount of the concrete is ensured to bury the guide pipe by 2m, and then the guide pipe is twisted and lifted by 20 cm-30 cm to determine whether the uplift force of the guide pipe meets the requirement; when the requirements cannot be met, a crane is adopted for assisting in hoisting; during the pouring process, the concrete is ensured to be not less than 2m higher than the bottom end of the guide pipe; pouring concrete and pulling the guide pipe at the same time, and keeping the bottom end of the guide pipe lower than the concrete surface by more than 2.5m all the time;

when constructing the B-sequence piles, the method comprises the following steps:

(1) manufacturing a B-sequence pile reinforcement cage;

(2) hoisting a reinforcement cage in a pile hole of the B-order pile, and hoisting the reinforcement cage by using a main hook and an auxiliary hook of a crawler crane at three points; firstly, horizontally hoisting a reinforcement cage by using a main hook, horizontally moving to a pile hole, slowly erecting the reinforcement cage by using the matching of an auxiliary hook and the main hook until the reinforcement cage is vertically hoisted, then placing the reinforcement cage into the pile hole at one time, and after the reinforcement cage is lowered to a designed height, using a reinforcement positioning ring around the reinforcement cage to enable the axis of the reinforcement cage to be superposed with the central line of the pile hole;

(2) pouring concrete of the pile in the B sequence by the same method as that of pouring concrete of the pile in the A sequence;

when the foundation pit dewatering and drainage construction process is carried out, the construction process comprises drainage well construction and open drainage ditch excavation;

the drainage well is arranged at the corner of the foundation pit; the aperture of the drainage well is 400mm, and the inner pipe of the drainage well adopts a steel filter pipe with plum blossom-shaped openings; gravel filter materials with the grain diameter of 8-10 mm are filled between the well wall and the inner pipe and in the range of 1.5m above the bottom of the inner pipe, the gravel filter materials are filled and sealed in the range of 2m away from the well mouth by using clay, and two layers of 40-mesh nylon filter screens wrap the inner pipe; a water pump is arranged in the inner pipe at a position which is more than 3m away from the bottom of the well;

grading and excavating the open drainage ditch in the foundation pit; the drainage open trench is arranged along the slope foot at the periphery in the foundation pit, the distance from the edge of the drainage open trench to the inner wall of the enclosure structure of the foundation pit is not less than 1.5m, the width of the trench bottom is not less than 0.3m, the longitudinal gradient is not less than 0.5%, and the trench bottom is 0.5m lower than the excavation bottom of the foundation pit; a water collecting well communicated with the open drainage ditch is arranged at one corner or the diagonal position in the foundation pit, the bottom of the water collecting well is 1.0m lower than the bottom of the open drainage ditch, and water in the water collecting well is discharged to a ground municipal rainwater and sewage system by a water pump;

when the excavation process of the pipe jacking working well is carried out, the method comprises the following steps: surface layer earthwork excavation → construction of a crown beam and a corner brace → second layer earthwork excavation → first steel purlin and corner brace erection → third layer earthwork excavation → second steel purlin and corner brace erection → fourth layer earthwork excavation → third steel purlin and corner brace erection → manual bottom cleaning → cushion layer construction → pouring bottom plate concrete → construction lining;

when the earthwork is excavated, the full-section bench method is adopted for backward excavation;

excavating the surface earthwork by adopting two excavators to reach the bottom surface of the crown beam by 10cm, then performing pile head breaking and pile checking construction, and then performing crown beam and corner brace construction;

performing second-layer earthwork excavation, namely performing earthwork excavation by adopting one excavator, performing soil guiding and loading by adopting the other excavator, and performing inter-pile net-jet support, first steel enclosing purlin and corner brace erection when excavation is performed to 50cm below the bottom surface of the first steel enclosing purlin;

performing the third-layer earthwork excavation, namely performing the earthwork excavation by adopting two excavators, performing soil guiding and loading by using the other two excavators, and performing inter-pile net-jet support, second steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the second steel purlin;

performing earth excavation on a fourth layer, namely performing earth excavation by adopting two excavators, lifting and excavating earth by adopting an automobile crane, and performing inter-pile net spraying support, third steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the third steel purlin;

when the excavation is 300mm above the bottom of the foundation pit, the foundation pit is checked and accepted, the excavation is carried out to the bottom of the foundation pit manually, and then a cushion layer is constructed;

when the pipe trench excavation process is carried out, the adopted method is the same as the excavation method of the pipe-jacking working well.

2. The method of claim 1, wherein the secant pile on the backwater side of the pipe-jacking working well is reinforced by a jet grouting pile within a predetermined distance, and the connection between the secant pile on the water leading side of the pipe-jacking working well and the first secant pile on the two side walls of the pipe trench is reinforced by a jet grouting pile.

3. The method for supporting and sealing up a pipe-jacking working well and a pipe trench on a beach of claim 1, wherein the manufacturing process of the B-sequence pile reinforcement cage comprises the following steps: manufacturing a steel reinforcement cage support frame → manufacturing a stiffening hoop → marking on the stiffening hoop to determine the position of the uniformly distributed main rib → staggering the main rib by 50% of the joint position → placing the main rib on the support frame → placing the stiffening hoop, namely aligning the main rib position marking line on the circular stiffening hoop with the main rib → spot welding the main rib and the stiffening hoop → spot welding other main ribs in turn → arranging the spiral hoop according to the design interval and quincunx spot welding.

Technical Field

The invention relates to a supporting and water-stopping construction method for a pipe-jacking working well and a pipe ditch on a beach.

Background

Sewage bay drainage is a form of sewage drainage in which a sewage drainage outlet is provided in a bay and drained into the sea water. The drainage pipe led out from the sewage treatment plant is formed by connecting a land area section and a sea area section. The land area sea drainage pipe is buried to the coast on land and is connected with the sea area sea drainage pipe through a land area transition section. In order to realize the burying of the land section drainage canals without excavating or with few excavating, a non-excavating construction method, namely a pipe-jacking construction process, is adopted. The pipe jacking working well is dug firstly to implement the pipe jacking construction process, if the route of the land section drainage channel is long or has an inflection point, the pipe jacking working well pushed reversely is dug at the front end of the pipeline, and meanwhile, the pipeline receiving working well is dug at the middle position or the inflection point of the pipeline so as to receive pipelines pushed in different directions. Usually, the front end of the sea drainage channel of the land area is positioned at the coast and is connected with a sea-land butt-joint pipeline, the sea-land butt-joint pipeline is not suitable for the pushing process, and open excavation construction is adopted, namely, a pipe trench is excavated on the beach and is used for burying the sea-land butt-joint pipeline. Because the beach sand layer is loose and has a large water volume, and is often attacked by seawater and tides, the support and water stop of the pipe jacking working well and the pipe trench are particularly important.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a supporting and water-stopping construction method for a pipe-jacking working well and a pipe ditch on a beach, which effectively improves the safety, stability, waterproofness and reliability of the pipe-jacking working well and the pipe ditch, and has low construction cost and high construction efficiency.

The purpose of the invention is realized as follows: a supporting and water-stopping construction method for a pipe-jacking working well and a pipe ditch on a beach is characterized in that a pipe-jacking hole is formed in the backwater side wall of the pipe-jacking working well, and the water-facing side wall of the pipe-jacking working well is connected with the pipe ditch; the supporting systems of the pipe jacking working well and the pipe trench comprise a crown beam and three steel purlins, and corner supports are arranged at four corners of the crown beam and the three steel purlins of the pipe jacking working well; a cross brace is arranged at a certain distance between the crown beam of the pipe trench and the three steel supports; the pipe jacking working well adopts an occlusive pile to enclose a closed well frame, and the pipe ditch also adopts the occlusive pile to enclose ditch walls on two sides; the A-sequence pile of the occlusive pile adopts an ultra-slow-setting plain concrete pile, the slow setting time is not less than 60 hours, the B-sequence pile of the occlusive pile adopts a reinforced concrete pile, and a reinforcing steel bar positioned at a top pipe opening of the top pipe working well adopts a glass fiber reinforcing steel bar.

The invention relates to a supporting and water-stopping construction method of a pipe-jacking working well and a pipe ditch on a beach, which comprises the following procedures: building a cofferdam, constructing an occlusive pile, constructing a foundation pit drainage, excavating a pipe jacking working well and excavating a pipe ditch on the periphery of a construction position;

the occlusive pile construction process comprises the following steps:

obstacle removing construction: adopting a 360-degree full-circle cutting machine, measuring and lofting according to an obstacle clearing plane layout, placing a sleeve with the pipe diameter larger than the pile diameter of the occlusive pile at a position where an obstacle needs to be cleared, starting to rotate and press downwards, breaking the obstacle by using a punching hammer, cleaning the obstacle by using a grab bucket, backfilling and compacting a pile hole by using common soil after the obstacle is cleared, and pulling out the sleeve;

a guide wall construction step, wherein the guide wall is of a cast-in-place reinforced concrete structure; the top surface of the guide wall is higher than the ground; the diameter of a guide hole on the guide wall is larger than that of the secant pile, and the reinforcing steel bars of the guide wall are arranged in a single-layer longitudinal and transverse mode;

when the occlusive pile is constructed, firstly constructing a pile driving hole, then pouring the concrete of the A-sequence pile, and then completing the construction of the B-sequence pile before the concrete of two adjacent A-sequence piles is initially set;

the pile driving method comprises the following steps:

(1) the drilling machine is in place, the center of a drill bit and the center of a pile position are ensured to be on the same plumb line when the drilling machine is in place, and the top elevation of the steel casing is measured after the drilling machine is in place;

(2) forming a hole and taking soil, after a drilling machine is positioned, hoisting and placing a first section of steel casing with a blade tip at the end, fixing the first section of steel casing between a guide hole of a guide wall and the first section of steel casing by using a wooden plug, ensuring that the deviation between the first section of steel casing and a pile hole center is less than a set value, pressing in the first section of steel casing, continuously checking the verticality of the first section of steel casing in the pressing-in process, fixing a lower clamp of the drilling machine when the verticality of the first section of steel casing is not more than the set value, and adjusting the verticality by using an upper clamp of the drilling machine; when the perpendicularity of the first section of steel casing exceeds a set value, the first section of steel casing is pulled out and embedded again, or the drilling machine is moved forwards, backwards, leftwards and rightwards to enable the first section of steel casing to be centered; when taking soil and forming holes, taking soil from the first section of steel casing by using a grab bucket, taking soil while pressing the first section of steel casing downwards, and always keeping the bottom opening of the first section of steel casing to be ahead of the soil taking surface and the depth of the bottom opening to be not less than 2.5 m; after the first section of steel casing is completely pressed into the soil, detecting the verticality of the formed hole, if the formed hole is unqualified, carrying out deviation rectification adjustment, if the formed hole is qualified, installing a second section of steel casing, taking the soil again, and pressing down the second section of steel casing; and so on until the bottom of the pile hole reaches the designed elevation;

when pouring the concrete of the A-sequence pile, adopting an underwater concrete pouring method for construction, wherein the pouring mode adopts a conduit method and adopts a crane for matching; when the concrete is poured, the bottom end of the guide pipe is lifted to 0.5m from the bottom of the pile hole, the initial pouring amount of the concrete is ensured to bury the guide pipe by 2m, and then the guide pipe is twisted and lifted by 20 cm-30 cm to determine whether the uplift force of the guide pipe meets the requirement; when the requirements cannot be met, a crane is adopted for assisting in hoisting; during the pouring process, the concrete is ensured to be not less than 2m higher than the bottom end of the guide pipe; pouring concrete and pulling the guide pipe at the same time, and keeping the bottom end of the guide pipe lower than the concrete surface by more than 2.5m all the time;

when constructing the B-sequence piles, the method comprises the following steps:

(1) manufacturing a B-sequence pile reinforcement cage;

(2) hoisting a reinforcement cage in a pile hole of the B-order pile, and hoisting the reinforcement cage by using a main hook and an auxiliary hook of a crawler crane at three points; firstly, horizontally hoisting a reinforcement cage by using a main hook, horizontally moving to a pile hole, slowly erecting the reinforcement cage by using the matching of an auxiliary hook and the main hook until the reinforcement cage is vertically hoisted, then placing the reinforcement cage into the pile hole at one time, and after the reinforcement cage is lowered to a designed height, using a reinforcement positioning ring around the reinforcement cage to enable the axis of the reinforcement cage to be superposed with the central line of the pile hole;

(2) pouring concrete of the pile in the B sequence by the same method as that of pouring concrete of the pile in the A sequence;

when the foundation pit dewatering and drainage construction process is carried out, the construction process comprises drainage well construction and open drainage ditch excavation;

the drainage well is arranged at the corner of the foundation pit; the aperture of the drainage well is 400mm, and the inner pipe of the drainage well adopts a steel filter pipe with plum blossom-shaped openings; gravel filter materials with the grain diameter of 8-10 mm are filled between the well wall and the inner pipe and in the range of 1.5m above the bottom of the inner pipe, the gravel filter materials are filled and sealed in the range of 2m away from the well mouth by using clay, and two layers of 40-mesh nylon filter screens wrap the inner pipe; a water pump is arranged in the inner pipe at a position which is more than 3m away from the bottom of the well;

grading and excavating the open drainage ditch in the foundation pit; the drainage open trench is arranged along the slope foot at the periphery in the foundation pit, the distance from the edge of the drainage open trench to the inner wall of the enclosure structure of the foundation pit is not less than 1.5m, the width of the trench bottom is not less than 0.3m, the longitudinal gradient is not less than 0.5%, and the trench bottom is 0.5m lower than the excavation bottom of the foundation pit; a water collecting well communicated with the open drainage ditch is arranged at one corner or the diagonal position in the foundation pit, the bottom of the water collecting well is 1.0m lower than the bottom of the open drainage ditch, and water in the water collecting well is discharged to a ground municipal rainwater and sewage system by a water pump;

when the excavation process of the pipe jacking working well is carried out, the method comprises the following steps: surface layer earthwork excavation → construction of a crown beam and a corner brace → second layer earthwork excavation → first steel purlin and corner brace erection → third layer earthwork excavation → second steel purlin and corner brace erection → fourth layer earthwork excavation → third steel purlin and corner brace erection → manual bottom cleaning → cushion layer construction → pouring bottom plate concrete → construction lining;

when the earthwork is excavated, the full-section bench method is adopted for backward excavation;

excavating the surface earthwork by adopting two excavators to reach the bottom surface of the crown beam by 10cm, then performing pile head breaking and pile checking construction, and then performing crown beam and corner brace construction;

performing second-layer earthwork excavation, namely performing earthwork excavation by adopting one excavator, performing soil guiding and loading by adopting the other excavator, and performing inter-pile net-jet support, first steel enclosing purlin and corner brace erection when excavation is performed to 50cm below the bottom surface of the first steel enclosing purlin;

performing the third-layer earthwork excavation, namely performing the earthwork excavation by adopting two excavators, performing soil guiding and loading by using the other two excavators, and performing inter-pile net-jet support, second steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the second steel purlin;

performing earth excavation on a fourth layer, namely performing earth excavation by adopting two excavators, lifting and excavating earth by adopting an automobile crane, and performing inter-pile net spraying support, third steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the third steel purlin;

when the excavation is 300mm above the bottom of the foundation pit, the foundation pit is checked and accepted, the excavation is carried out to the bottom of the foundation pit manually, and then a cushion layer is constructed;

when the pipe trench excavation process is carried out, the adopted method is the same as the excavation method of the pipe-jacking working well.

In the supporting and water-stopping construction method for the pipe-jacking working well and the pipe trench located on the sandy beach, the rotary jet piles are adopted for reinforcement within a set distance range outside the occlusive piles on the back water side of the pipe-jacking working well, and the joints of the occlusive piles on the water diversion side of the pipe-jacking working well and the first occlusive piles on the two side walls of the pipe trench are also respectively reinforced by the rotary jet piles.

The pipe jacking working well on the beach and the supporting and water stopping construction method of the pipe trench are characterized in that the manufacturing process of the B-sequence pile reinforcement cage comprises the following steps: manufacturing a steel reinforcement cage support frame → manufacturing a stiffening hoop → marking on the stiffening hoop to determine the position of the uniformly distributed main rib → staggering the main rib by 50% of the joint position → placing the main rib on the support frame → placing the stiffening hoop, namely aligning the main rib position marking line on the circular stiffening hoop with the main rib → spot welding the main rib and the stiffening hoop → spot welding other main ribs in turn → arranging the spiral hoop according to the design interval and quincunx spot welding.

The construction method of the pipe jacking working well and the pipe trench on the beach has the following characteristics: aiming at the condition that the pipe-jacking working well and the pipe trench are rich in water at seaside sand beach, cofferdams are built at the periphery of the construction position to prevent sea waves from scouring, so that the construction position is in a dry construction environment, interlocking piles are adopted as fender piles of the pipe-jacking working well and the pipe trench, cutting interlocking is implemented between two existing A-sequence piles through B-sequence piles, tight interlocking between piles is guaranteed, a good integral continuous structure is formed, the pipe-jacking working well and the pipe trench are effectively supported, an effective waterproof barrier can be formed, the safety performance of the pipe-jacking working well and the pipe trench is high, the stability is high, the waterproof performance is enhanced, the construction cost is low, and the construction efficiency is high.

Drawings

FIG. 1 is a plan view of a pipe jacking working well and a pipe trench related to the construction method of the present invention;

FIG. 2 is a top pipe plan view of the top pipe work well;

FIG. 3 is a plan view of three steel supports of the pipe jacking working well;

FIG. 4 is a cross-sectional view of a push pipe work well;

FIG. 5 is a cross-sectional view of the trench;

FIG. 6 is an axial cross-sectional view of a drainage well employed in the method of construction of the present invention;

fig. 7 is a view from a-a in fig. 6.

Detailed Description

The invention will be further explained with reference to the drawings.

Referring to fig. 1 to 5, the pipe-jacking working well and the supporting and water-stopping construction method of the pipe trench on the beach of the present invention relate to a pipe-jacking working well which is rectangular, and has an inner dimension of length × width × depth of 15.5m × 6.2m × 14.05m, a bottom plate concrete thickness of 600mm, an inner width of the pipe trench of 4.8m, and a depth of 12.8m to 13.3 m; the backwater side wall of the pipe-jacking working well is provided with a pipe-jacking hole, and the water-facing side wall of the pipe-jacking working well is connected with the pipe ditch; the supporting system of the pipe jacking working well comprises a reinforced concrete crown beam and three steel enclosing purlins, wherein corner supports are arranged at four corners of the crown beam and the three steel enclosing purlins; the supporting system of the pipe trench comprises a reinforced concrete crown beam and three steel purlins; the crown beam and the three steel supports are respectively provided with a cross brace at intervals of 5 m; the pipe jacking working well adopts a phi 1000 multiplied by 750mm secant pile to enclose a closed rectangular well frame; the pipe ditch also adopts a phi 1000 multiplied by 750mm secant pile to enclose the ditch walls on the two sides; the A-sequence pile of the occlusive pile adopts an ultra-slow-setting plain concrete pile, the slow setting time is not less than 60 hours, the B-sequence pile of the occlusive pile adopts a reinforced concrete pile, and a glass fiber reinforcement is adopted to replace a reinforcing steel bar at a position of a pipe-jacking hole of the pipe-jacking working well; a jet grouting pile with the diameter of phi 1000mm is adopted for reinforcement within the range of 5.8m outside the secant pile on the backwater side of the pipe-jacking working well; and the joints of the secant piles at the water diversion side of the pipe jacking working well and the first secant piles at the two side walls of the pipe ditch are respectively reinforced by adopting the jet grouting piles with the diameter phi of 1000 mm.

The invention relates to a supporting and water-stopping construction method of a pipe-jacking working well and a pipe ditch on a beach, which comprises the following procedures: building a cofferdam, constructing an occlusive pile, constructing a jet grouting pile, constructing a foundation pit for dewatering and drainage, excavating a pipe jacking working well and excavating a pipe trench.

When the cofferdam building process is carried out, a cofferdam is built at the periphery of the construction positions of the pipe-jacking working well and the pipe trench, a bag body is made of a composite geotechnical anti-seepage film, a bag opening is sewn after sand is filled in the bag body, then a concave cofferdam closed with a revetment sideline is stacked layer by sand bags, and then the outer side of the cofferdam is protected by film bag concrete.

The occlusive pile construction process comprises the following steps:

obstacle removing construction: adopting a 360-degree full-circle cutting machine, measuring and lofting according to an obstacle clearing plane layout diagram, then placing a sleeve pipe with the diameter of 2m at a position where an obstacle needs to be cleared, starting to rotate and press downwards, utilizing a punching hammer to break the obstacle, then cleaning the obstacle by using a grab bucket, backfilling and compacting a pile hole by adopting common soil after the obstacle is cleared, and pulling out the sleeve pipe;

a guide wall construction step, wherein the guide wall is of a cast-in-place reinforced concrete structure, and the strength of concrete is C20 concrete; the top surface of the guide wall is 100mm higher than the ground; the diameter of a guide hole in the guide wall is 30mm larger than that of the secant pile, the thickness of the guide wall is 350mm, the width of the guide wall is 1.5m, reinforcing steel bars of the guide wall are arranged in a single-layer longitudinal and transverse mode, the longitudinal and transverse intervals are 150mm, and the diameter of the reinforcing steel bars is 10 mm;

when the occlusive pile is constructed, firstly constructing a pile driving hole, then pouring the concrete of the A-sequence pile, and then completing the construction of the B-sequence pile before the concrete of two adjacent A-sequence piles is initially set;

the pile driving method comprises the following steps:

(1) the drilling machine is in place, before the drilling machine is placed, the ground around the pile hole is tamped to ensure that the body of the drilling machine is stably placed, when the drilling machine is in place, the center of a drill bit and the center of the pile position are on the same plumb line, the centering error is less than 10mm, and after the drilling machine is in place, the height of the top mark of the steel casing is measured;

(2) forming a hole and taking soil, after a drilling machine is positioned, hoisting and placing a first section of steel casing with a blade tip at the end, wherein the verticality of the embedded first section of casing is the key for determining the verticality of a pile hole, and the guide hole of the guide wall and the first section of steel casing are fixed by a wood plug to prevent the end head of the first section of steel casing from shifting during pressure application; ensuring that the deviation between the first section of steel casing and the center of a pile hole is less than 2cm, pressing in the first section of steel casing, continuously checking the verticality of the first section of steel casing by using a total station or a plumb bob in the pressing-in process, fixing a lower clamp of a drilling machine when the verticality of the first section of steel casing is not more than a set value, and adjusting the verticality by using an upper clamp of the drilling machine; when the perpendicularity of the first section of steel casing exceeds a set value, the first section of steel casing is pulled out and embedded again, or the drilling machine is moved forwards, backwards, leftwards and rightwards to enable the first section of steel casing to be centered; when taking soil and forming holes, taking soil from the first section of steel casing by using a grab bucket, taking soil while pressing the first section of steel casing downwards, and always keeping the bottom opening of the first section of steel casing to be ahead of the soil taking surface and the depth of the bottom opening to be not less than 2.5 m; after the first section of steel casing is completely pressed into the soil, 1.5m is exposed above the ground, the second section of steel casing is convenient to connect, the verticality of the formed hole is detected, deviation rectification adjustment is performed if the formed hole is unqualified, the second section of steel casing is installed if the formed hole is qualified, soil is taken while the second section of steel casing is pressed down, and the like is performed until the bottom of the pile hole reaches the designed elevation;

when pouring the concrete of the A-sequence pile, adopting an underwater concrete pouring method for construction, wherein the pouring mode adopts a conduit method and adopts a crane for matching; when the concrete is poured, the bottom end of the guide pipe is lifted to 0.5m from the bottom of the pile hole, the initial pouring amount of the concrete is ensured to bury the guide pipe by 2m, and then the guide pipe is twisted and lifted by 20 cm-30 cm to determine whether the uplift force of the guide pipe meets the requirement; when the requirements cannot be met, a crane is adopted for assisting in hoisting; during the pouring process, the concrete is ensured to be not less than 2m higher than the bottom end of the guide pipe; pouring concrete and pulling the guide pipe at the same time, and keeping the bottom end of the guide pipe lower than the concrete surface by more than 2.5m all the time;

when constructing the B-sequence piles, the method comprises the following steps:

(1) manufacturing a B-sequence pile reinforcement cage, wherein the manufacturing process comprises the following steps: manufacturing a reinforcement cage support frame → manufacturing a stiffening hoop → marking on the stiffening hoop to determine the position of uniformly distributed main ribs → staggering the main ribs by 50% of the joint position → placing the main ribs on the support frame → placing the stiffening hoop, namely aligning the main rib position marking line on the circular stiffening hoop with the main ribs → spot welding the main ribs and the stiffening hoop → spot welding other main ribs in turn → arranging spiral hoops according to the design interval and spot welding in a quincunx shape; when manufacturing a B-sequence pile reinforcement cage positioned on the backwater side of the pipe-jacking working well, adopting glass fiber reinforcement instead of steel bars at the position of the pipe-jacking hole; the length of the glass fiber reinforcement is 1m larger than the diameter of the top pipe opening, so that the glass fiber reinforcement can cover the top pipe opening and the upper part and the lower part of the top pipe opening by 0.5m respectively, and the upper part and the lower part of the glass fiber reinforcement are lapped with the reinforcing steel bars by 2m respectively; the position of the top pipe opening is provided with a glass fiber rib, so that the tunneling machine can normally exit the opening; if the reinforcing steel bars are adopted at the position of the top pipe opening, the reinforcing steel bars can be clamped at the head of the heading machine when the heading machine breaks the opening door, so that the normal heading of the heading machine is influenced;

(2) hoisting the pile reinforcement cage of the sequence B pile in the pile hole of the sequence B pile, and hoisting the pile reinforcement cage of the sequence B pile by using a main hook and an auxiliary hook of a crawler crane at three points; firstly, horizontally hoisting the reinforcement cage of the pile in the sequence B by using a main hook, translating to the position of a pile hole, then slowly erecting the reinforcement cage of the pile in the sequence B by using the matching of an auxiliary hook and the main hook until the reinforcement cage of the pile in the sequence B is vertically hoisted, hoisting the reinforcement cage of the pile in the sequence B into the pile hole at one time, lowering the reinforcement cage of the pile in the sequence B to a designed height, and then enabling the axis of the reinforcement cage of the pile in the sequence B to be superposed with the central line of the pile hole by using a reinforcement positioning ring around the reinforcement cage of the pile in the sequence B;

(3) and (3) pouring concrete of the pile in the B sequence by the same method as that of pouring concrete of the pile in the A sequence.

The foundation pit dewatering and drainage adopts a mode of mainly dewatering the dewatering well and secondarily draining the open drainage ditch; when the foundation pit dewatering and drainage construction process is carried out, the construction process comprises drainage well construction and open drainage ditch excavation;

the drainage well is arranged at the corner of the foundation pit; the inner pipe of the drainage well adopts a steel strainer with plum blossom-shaped openings; gravel filter materials with the grain diameter of 8-10 mm are filled between the well wall and the inner pipe and above the bottom of the inner pipe by 1.5m, and the gravel filter materials are filled and sealed by clay within 2m from the well mouth so as to prevent surface water from being back-filled into the well; in order to ensure good water permeability around the inner pipe and prevent fine sand from permeating, two layers of 40-mesh nylon filter screens are wrapped outside the inner pipe and bound by wire meshes; arranging a water pump in the inner pipe at a position more than 3m away from the bottom of the well (see figures 6 and 7);

grading and excavating the open drainage ditch in the foundation pit; the open drain is arranged in the foundation pit in a grading manner; the drainage open trench is arranged along the slope foot at the periphery in the foundation pit, the distance from the edge of the drainage open trench to the inner wall of the enclosure structure of the foundation pit is not less than 1.5m, the width of the trench bottom is not less than 0.3m, the longitudinal gradient is not less than 0.5%, and the trench bottom is 0.5m lower than the excavation bottom of the foundation pit; and a water collecting well communicated with the open drainage ditch is arranged at one corner or the diagonal position in the foundation pit, the bottom of the water collecting well is 1.0m lower than the bottom of the open drainage ditch, and water in the water collecting well is discharged to a ground municipal rainwater and sewage system by a water pump.

When the excavation process of the pipe jacking working well is carried out, the method comprises the following steps: surface layer earthwork excavation → construction of a crown beam and a corner brace → second layer earthwork excavation → first steel purlin and corner brace erection → third layer earthwork excavation → second steel purlin and corner brace erection → fourth layer earthwork excavation → third steel purlin and corner brace erection → manual bottom cleaning → cushion layer construction → pouring bottom plate concrete → construction lining;

when the earthwork is excavated, the full-section bench method is adopted for backward excavation;

excavating the surface earthwork by adopting two excavators to reach the bottom surface of the crown beam by 10cm, then performing pile head breaking and pile checking construction, and then performing crown beam and corner brace construction;

performing second-layer earthwork excavation, namely performing earthwork excavation by adopting one excavator, performing soil guiding and loading by adopting the other excavator, and performing inter-pile net-jet support and first steel purlin and corner brace erection when excavation is performed to 50cm below the bottom surface of the first steel purlin;

performing the third-layer earthwork excavation, namely performing the earthwork excavation by adopting two excavators, performing soil guiding and loading by using the other two excavators, and performing inter-pile net-jet support and second steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the second steel purlin;

performing the fourth layer of earthwork excavation, namely performing the earthwork excavation by adopting two excavators, lifting and excavating by adopting an automobile crane, and performing inter-pile net spraying support and third steel purlin and corner brace erection when excavating to 50cm below the bottom surface of the third steel purlin;

and when the excavation is carried out to 300mm above the bottom of the foundation pit, the foundation pit is checked and accepted, the excavation is carried out to the bottom of the foundation pit manually, and then a cushion layer is constructed.

When the pipe trench excavation process is carried out, the adopted method is the same as the excavation method of the pipe-jacking working well.

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.