CN216922119U - Guide structure of underground-excavated jacking pipe in soft soil layer under existing railway line - Google Patents

Abstract

The utility model discloses a guide structure of a subsurface excavated pipe jacking under an existing railway line in a soft soil layer, which comprises a jacking working pit and a jacking receiving pit which are respectively arranged at two sides of a roadbed body, wherein the pit walls of the jacking working pit and the jacking receiving pit are composed of an outer Larsen steel sheet pile and an inner concrete side wall, the ground surfaces of the jacking working pit and the jacking receiving pit are both bottom-sealed concrete ground surfaces, the concrete ground surfaces are respectively provided with four support seats which are arranged at intervals from left to right, from front to back, a guide steel pipe is fixedly arranged between the support seats at the same side, the guide steel pipes respectively penetrate through the roadbed body, the guide steel pipes are respectively filled with concrete, two guide steel pipes which are pushed into the working pit are provided with supporting jacking pipe joints, the back of the jacking working pit is provided with a jacking back wall body, and an included angle formed by the axes of the two guide steel pipes and the axes of the jacking pipe joints is a, a is a right angle or an acute angle.

Description

Guide structure of underground-excavated jacking pipe in soft soil layer under existing railway line

Technical Field

The utility model relates to a guide structure of a subsurface excavated jacking pipe in a soft soil layer under an existing railway line, which can conveniently limit the displacement in different directions in the jacking process of the jacking pipe so as to improve the jacking precision of the jacking pipe.

Background

The pipeline crossing project under the existing operation railway line generally adopts two modes of open excavation construction and underground excavation jacking. During open cut construction, line protection measures (such as erecting a D-shaped steel temporary beam) are needed to protect an existing line, the existing line is excavated to form an inverted trapezoidal working surface, and then cast-in-place or hoisting construction of a box body or a pipe joint is carried out. The investment is high, the project implementation period is long, and the influence on an operation line is large. Therefore, undermining jacking is generally the preferred mode of pipeline crossing engineering. However, when the soil layer is soft soil (such as collapsible loess) or a zone with a high ground water level, the underground excavation jacking implementation can encounter a bottleneck. The underground excavation jacking construction generally adopts two modes of a muddy water balance method or a manual earth excavation method. The mud-water balance method has wide applicable geological range, such as soft soil layers of high groundwater, mucky soil and the like, but has the disadvantages of huge and complicated auxiliary equipment and mud-water treatment equipment, large water and electricity consumption and high construction cost, and meanwhile, the equipment is difficult to find and is long in relocation distance in some remote areas. Meanwhile, in the implementation of soft foundation engineering, the working condition that the mud-water balancing machine is settled due to the large self weight happens occasionally. When the reinforced concrete casing is jacked by manually excavating soil, the direction of the reinforced concrete casing is generally guided by a guide rail on the outer side of a roadbed, and after the reinforced concrete casing enters the roadbed, the displacement of the reinforced concrete casing is limited by the lateral limiting effect of a soil body. Meanwhile, due to the influence of the soft foundation and the underground water, the risk of sedimentation also exists. In order to ensure that the central line and the elevation position of the jacked casing meet the design requirements, the advancing track of the jacking pipe needs to be continuously checked in the jacking process, and the measurement work is frequent and complex. Meanwhile, according to the deviation of the jacking pipe, small-angle deviation correction is required for multiple times, so that the condition that the pipeline is out of the way is avoided.

Disclosure of Invention

In order to solve the problem of central line and elevation deviation of the jacking pipe when the reinforced concrete casing pipe is dug and jacked in soft soil under the existing railway line, the utility model provides the guide structure of the dug jacking pipe in the soft soil under the existing railway line, which has high implementation precision, can control the lateral deviation of the jacking pipe in the jacking process, reduces manual deviation correction, improves the engineering safety and accelerates the construction speed. And, through the adjustment to guide structure, can reduce the vertical load that soft soil foundation bore, reduce the possibility that the pipe coupling takes off the mouth in the jacking process.

The technical scheme adopted by the utility model for solving the technical problem is as follows:

a guide structure for underground excavation of a jacking pipe in a soft soil layer under an existing railway line comprises a jacking working pit and a jacking receiving pit which are respectively arranged at two sides of a roadbed body, wherein the walls of the jacking working pit and the jacking receiving pit are composed of an outer Larsen steel sheet pile and an inner concrete side wall, the ground of the jacking working pit and the ground of the jacking receiving pit are both bottom-sealed concrete ground, the concrete ground is respectively provided with a left side and a right side, the back that advances the work hole is being set up the back wall body that advances, the contained angle that constitutes between two direction steel pipe axes and the pipe coupling axis that advances is a, and a is right angle or acute angle.

When the underground excavation jacking construction is carried out, a working pit and a receiving pit are firstly dug at two ends of a jacking pipeline, and the working pit and the receiving pit generally adopt protective measures (such as driving Larsen steel sheet piles and the like). Pouring bottom sealing concrete in the working pit, building a back wall body, and installing a jack, a guide rail and the like.

And then setting a guide structure in the roadbed soil body, wherein the guide structure consists of a plurality of seamless steel pipes (even number), and dragging the steel pipes into the working pit from the receiving pit along the trend of the jacking pipe in a mode of trial drilling and back pulling by adopting a horizontal directional drill. A plurality of steel pipes need to be symmetrically arranged on two sides of the center line of the jacking pipe and are arranged in the 180-degree horizontal line at the center of the jacking pipe or in the range below the horizontal line, and the outer walls of the steel pipes are tightly attached to the outer wall of the jacking pipe. In this embodiment, preferably 2 guide steel pipes are taken.

And (3) casting a support on the bottom sealing concrete in situ, extending two ends of the guide steel pipe out to the support for a certain distance, fixing the guide steel pipe by adopting a buckling and pressing steel plate, and pouring concrete into the full section of the steel pipe to improve the bending rigidity of the steel pipe. And then, hoisting the first pipe joint into the working pit, and after adjusting the elevation and the central position of the pipe joint, starting jacking.

When the guide steel pipe is arranged below the 180-degree horizontal line at the center of the jacking pipe, the weight of the jacking pipe is borne by the guide steel pipe and the foundation soil simultaneously. The guide steel pipe bears part, resultant force is connected with the center of the guide steel pipe through the jacking pipe, the action point is positioned on the contact surface of the outer wall, and the action point is decomposed into two component forces of vertical downward transmission and horizontal outward transmission on the contact surface, so that all downward gravity of the jacking pipe is decomposed into soil bodies on two sides, the vertical load transmitted downward from the bottom of the jacking pipe is reduced, and the settlement probability of the jacking pipe is reduced.

In addition, the position of the guide steel pipe has adjustability, and the closer the position of the guide steel pipe is to the horizontal center line of the jacking pipe, the stronger the capability of controlling the left and right deviation is; the closer the position of the guide steel pipe is to the vertical center line of the top pipe, the stronger the capability of bearing the gravity of the top pipe. The angle alpha between the center of the guide steel pipe and the center connecting line of the jacking pipe is adjusted, and the number of the guide steel pipes is increased, so that the function of the guide steel pipes can be optimized in different geologies.

The utility model has the beneficial effects that: the guide structure in the technical scheme is implemented by adopting the horizontal directional drill, so that the direction can be conveniently controlled in the soft soil, the implementation precision is high, the hole forming error is more about 5-8 mm, the limit on the displacement of the jacking pipe is higher than the reliability of the soil body, complicated manual deviation rectification adjustment is not needed in the construction, the safety of engineering implementation is improved, the jacking time can be greatly shortened, and the interference to the existing line is reduced. Meanwhile, the adjustable function of the guide structure decomposes the transmission direction of vertical load, can be flexibly selected according to different types of geological working conditions, and enlarges the application range of the underground excavation jacking method.

Description of the drawings:

the utility model is further illustrated with reference to the following figures and examples.

FIG. 1: pushing into the working pit longitudinal section drawing;

FIG. 2: pushing into a working pit plane layout drawing;

FIG. 3: a cross-sectional view;

in the figure: 1. jacking into a working pit; 2. jacking into a receiving pit; 3. jacking into the back wall; 4. sealing bottom concrete; 5. a guide steel pipe support; 6. guiding a steel pipe; 7. larsen steel sheet piles; 8. concrete side walls; 9. jacking the pipe joint; 10. a roadbed body;

alpha-the control angle of the guide steel pipes is the included angle between the circle centers of the two guide steel pipes and two lines behind the line connecting the circle centers of the jacking pipes.

Detailed Description

A guide structure of a subsurface excavated pipe jacking under an existing railway line in a soft soil layer comprises a jacking working pit 1 and a jacking receiving pit 2 which are respectively arranged at two sides of a roadbed body 10, the pit walls of the jacking working pit 1 and the jacking receiving pit 2 are composed of an outer Larsen steel sheet pile 7 and an inner side concrete side wall 8, the ground of the jacking working pit and the jacking receiving pit are both bottom-sealed concrete ground 4, the concrete ground 4 is respectively provided with four supports 5 which are arranged at intervals left, right, front and back, a guide steel pipe 6 is fixedly arranged between the supports 5 at the same side, the guide steel pipes 6 respectively penetrate through the roadbed body 10, the concrete is respectively filled in the guide steel pipes 6, two guide steel pipes in the jacking working pit are provided with supporting jacking pipe joints 9, the back of the jacking working pit is provided with a jacking back wall body 3, and the included angle a is formed between the axes of the two guide steel pipes 6 and the axes of the jacking pipe joints 9, a is a right angle or an acute angle.

In fig. 1: driving Larsen steel sheet piles 7, excavating a jacking working pit 1 and a jacking receiving pit 2, pouring back sealing concrete 4, a back wall body 3 and a concrete side wall 8, and pouring a guide steel pipe support 5 on the back sealing concrete 4 in a cast-in-place mode. And (3) trial drilling along the pipe jacking direction by using a directional drill, horizontally dragging the guide steel pipe 6 from the jacking receiving pit 2 into the jacking working pit 1, and fixing the guide steel pipe on the support 5 through a buckling steel plate. The hoisting jacking pipes 9 are located on the guide steel pipes and are jacked into the roadbed 10 section by section (3 m/section).

In fig. 3: the guide steel pipes 6 are positioned at two sides of the top pipe 9, and alpha is an included angle formed after the connection line of the circle centers of the two guide steel pipes 6 and the circle center of the top pipe 9. Along with the gradual reduction of the control angle alpha, the vertical load of the upper portion that the push pipe bottom soil body bore reduces gradually, and the push pipe dead weight is born by direction steel pipe and soil body jointly. In actual working conditions, the geological bearing capacity can be flexibly selected by combining the geological bearing capacity. In the present embodiment, α =90 ° is preferably adopted.

Claims (1)

1. The utility model provides a guide structure of secretly digging push pipe in soft soil layer under existing railway line, includes the top that is setting up respectively in road bed body both sides and advances work hole and top and advance and receive the hole, characterized by: the foundation pit wall of the jacking working pit and the jacking receiving pit is composed of Larsen steel sheet piles on the outer side and concrete side walls on the inner side, the ground of the jacking working pit and the ground of the jacking receiving pit are both bottom-sealed concrete ground, four supports which are arranged at intervals are arranged on the concrete ground at left, right, front and back, a guide steel pipe is fixedly arranged between the supports on the same side, the guide steel pipe penetrates through the roadbed body respectively, concrete is filled in the guide steel pipe respectively, jacking pipe joints are placed and supported on the two guide steel pipes in the jacking working pit, a jacking back wall body is arranged on the back of the jacking working pit, the included angle formed between the axes of the two guide steel pipes and the axes of the jacking pipe joints is a, and the a is a right angle or an acute angle.

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