CN117627669A - Rectangular jacking pipe construction method based on blind area advanced pilot tunnel expansion and excavation - Google Patents
Rectangular jacking pipe construction method based on blind area advanced pilot tunnel expansion and excavation Download PDFInfo
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- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
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- 239000003637 basic solution Substances 0.000 claims description 3
- ONCZQWJXONKSMM-UHFFFAOYSA-N dialuminum;disodium;oxygen(2-);silicon(4+);hydrate Chemical group O.[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[O-2].[Na+].[Na+].[Al+3].[Al+3].[Si+4].[Si+4].[Si+4].[Si+4] ONCZQWJXONKSMM-UHFFFAOYSA-N 0.000 claims description 3
- 230000002708 enhancing effect Effects 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention relates to the technical field of underground space construction, and particularly discloses a rectangular jacking pipe construction method based on blind area advanced pilot tunnel expansion, which comprises the following steps: s1, carrying out construction operation of an originating well and a receiving well, S2, carrying out expansion and excavation simulation of a blind area advanced pilot tunnel, S3, carrying out demonstration analysis on the working condition of subsequent rectangular jacking by using plaxis, S4, carrying out expansion and excavation construction of the blind area advanced pilot tunnel, S5, improving a soil layer rectangular push bench, S6, originating and receiving rectangular push pipes and carrying out normal jacking; the invention processes the dead zone in advance before the rectangular jacking pipe is jacked in, improves the traditional soil layer rectangular jacking machine, simulates the advanced pilot tunnel expansion of the rectangular jacking pipe dead zone by combining the finite element method FEM and the boundary element method BEM, simplifies the two-dimensional plane problem, and defines the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion, further analyzes the ground stress balance, earth surface subsidence and underground water flow, and ensures the scientificity, safety and feasibility of the advanced pilot tunnel expansion of the dead zone.
Description
Technical Field
The invention belongs to the technical field of underground space construction, and particularly relates to a rectangular jacking pipe construction method based on blind area advanced pilot tunnel expansion and excavation.
Background
In recent years, with the rapid development of urban process, the demand of urban underground space utilization is increasing, and the requirement of underground space construction is also increasing. In order to ensure the smoothness of urban ground traffic, reduce the migration workload of overground and underground barriers, accelerate the project construction progress, ensure the safety of surrounding buildings and structures and the like, the traditional open-cut cast-in-place construction technology cannot meet the requirements of project construction more and more, and instead, the technology is a rapidly developed non-slotting construction technology, namely a relatively typical non-excavation construction technology. The pipe jacking method is applied to underground space engineering construction, can effectively reduce occupation of the earth surface, and plays a positive role in protecting urban environment and reinforcing reasonable and standardized construction of underground space.
At present, the pipe jacking method construction technology mainly comprises two forms of rectangular pipe jacking and circular pipe jacking. The rectangular jacking pipe can fully utilize the structural section, improves the section utilization rate, saves about 20% of space compared with the round jacking pipe, and has more superiority in underground space engineering construction such as underground comprehensive pipe gallery, underground passage and the like.
At present, rectangular pipe jacking construction technology is still in practice fumbling stage, and response to national or industry technical standards, acceptance specifications and the like is still immature. According to the Chinese project construction standardization institute standard (T/CECS 716-2020) and the Chinese municipal engineering society standard (Utility tunnel rectangular pipe jacking technical standard (T/CMEA 14-2020), the concept that the rock stratum with single-axis compressive strength of more than 5Mpa is not suitable for rectangular pipe jacking construction is explicitly provided. In summary, the domestic rectangular jacking pipe has fewer successful cases of penetrating through the full-section rock stratum, and the rectangular jacking pipe engineering is subject to a huge jacking failure risk.
Disclosure of Invention
The invention aims to provide a rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expansion and excavation, which aims to solve the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expansion and excavation comprises the following steps:
s1, carrying out construction operation of an originating well and a receiving well;
s2, performing blind area advanced pilot tunnel expansion and excavation simulation: by combining finite element FEM and boundary element BEM, the advanced pilot tunnel expansion and excavation of the dead zone of the rectangular jacking pipe is simulated, the two-dimensional plane problem is simplified, the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion and excavation are clarified, the ground stress balance, earth surface subsidence and underground water flow are further analyzed, and the scientificity, safety and feasibility of the advanced pilot tunnel expansion and excavation of the dead zone are ensured, and the method specifically comprises the following steps:
s21, modeling the blind area advanced pilot tunnel as a boundary value problem, and determining physical parameters of a boundary, an internal area and surface and underground water flow;
s22, dividing the problem domain into a finite element grid and a boundary element grid, wherein the finite element grid is used for describing the internal area of the problem, and the boundary element grid is used for describing the boundary;
s23, establishing a discrete form of a physical equation on a finite element grid by using a finite element method to obtain displacement and stress distribution in underground engineering, wherein the discrete form comprises the following specific steps:
on a finite element mesh, the elastic equation is used:wherein (1)>Representing the gradient operator, σ is the stress tensor, obtained by the back stress-displacement relationship:
wherein C is an elastic stiffness matrix, epsilon is a strain tensor, and the displacement u is established by the following relationship:
wherein,representing the gradient operator, acting on the displacement field u for calculating the gradient of the displacement field, the gradient of u being a column vector comprising the rate of change of the displacement field in the respective coordinate direction, the sign +.>Gradient vectors denoted displacement field u;
s24, using a boundary element method to process and solve potential flow problems on the boundary to obtain the groundwater level and the permeability, wherein the method comprises the following steps:
at the boundary elementOn the grid, the groundwater flow is described using the percolation equation:
wherein,representing the gradient operator, h is a scalar field representing the head, k is the permeability, and is a constant;
calculating the gradient of a scalar field h to obtain a vector field;
multiplying the gradient vector field by the negative value of the constant k;
: calculating the divergence of the resulting vector field, representing the outflow or inflow rate of the vector field at a point;
the basic solution to the two-dimensional potential flow problem can be expressed as:
where G is a potential function, x and x' are two points in space, used to calculate the potential at the boundary;
s3, carrying out demonstration analysis on the working condition of the subsequent rectangular jacking by using plaxis general rock-soil finite element calculation software according to the blind area pretreatment scheme simulation scheme formulated in the S2, and ensuring the safety of the jacking process;
s4, performing blind area advanced pilot tunnel expansion and excavation construction: carrying out observation of portal breaking, pilot hole and grading back-expansion hole, working well backfilling, pore canal filling and pavement settlement according to simulation demonstration results in S2 and S3;
s5, improving the rectangular soil layer push bench, so as to improve the rectangular push bench and improve tunneling efficiency;
s6, rectangular jacking pipe starting receiving and normal jacking: the method comprises the steps of installing a water-stopping steel ring of a tunnel portal, installing a downhole base, installing a downhole pushing system, assembling and test running a pipe pushing machine, establishing and controlling soil pressure, measuring and rectifying posture, reducing thixotropic mud drag, improving and transporting dregs, hanging and placing pipe joints, guiding and changing roads, monitoring construction, replacing mud, performing inner waterproof construction, and dismantling and lifting the pipe pushing machine.
Preferably, the improvement of the rectangular push bench comprises:
firstly, a radial type cutter disc is selected, so that the aperture opening ratio is reduced, and the cutting rigidity of the cutter disc is improved;
secondly, optimally configuring a cutter; in addition to the center knife, the scraper and the shell knife which are arranged in the past, thirty-nine double-edge hob are additionally arranged, so that the rock breaking capacity is further improved;
thirdly, enhancing the configuration of a power system; the power system of each cutter head refers to the standard of a round hard rock pipe jacking machine, eighteen driving motors are arranged in an enlarged standard way, the main shaft is fully lengthened and thickened, and the cutting torque and power are further improved;
fourthly, performing right angle removal treatment; aiming at rectangular corners and dead zone right-angle areas, adopting an inclined plate or a conical plate to carry out smooth transition treatment;
fifthly, the slag discharging function is enhanced; cutting picks are additionally arranged on the spiral soil outlet, so that the capability of crushing rock of the bottom spiral soil outlet is further improved, and the slag discharging effect is enhanced.
Preferably, the rectangular pipe jacking machine starts construction operation; the method comprises the following steps: removing backfill in an originating well, breaking residual piles and walls of a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole door steel ring, installing an originating base, installing a debugging pushing system, assembling and debugging a rectangular pipe jacking machine, installing a hole door sealing and water stopping device, pushing the rectangular pipe jacking machine to the hole, positioning a first pipe joint and a top iron device and originating tunneling.
Preferably, the rectangular pipe jacking machine receives construction operation, and comprises the following steps: removing backfill in a receiving well, breaking residual piles and walls at a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole gate steel ring, installing a receiving base, reaching tunneling, pushing the receiving base on a rectangular pipe jacking machine, sealing the hole gate, replacing thixotropic slurry, disassembling the rectangular pipe jacking machine and transferring.
Preferably, in the running process of the rectangular push bench, the running track of the rectangular push bench is monitored in real time through a measuring system, and the track deviation is corrected in time by using a deviation correcting method; thixotropic slurry is injected between the outer wall of the pipe joint and the rock stratum to reduce drag; and injecting a muck modifier into the tunnel face or the soil bin through the grouting holes, wherein the modifier is sodium bentonite slurry, and the specific performance requirement is controlled by referring to the thixotropic slurry technical index.
Preferably, the long distance full face rock formation condition refers to: the jacking distance is more than 80m, the jacking range is all in the rock stratum, and the uniaxial compressive strength of the rock stratum reaches 30Mpa or more.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention follows the concept of 'improvement of traditional soil layer rectangular push bench and pretreatment of blind areas', the blind areas are treated in advance before rectangular push bench is jacked in, the traditional soil layer rectangular push bench is improved, the advanced pilot tunnel expansion and excavation of the rectangular push bench is simulated by combining finite element method FEM and boundary element method BEM, the two-dimensional plane problem is simplified, the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion and excavation are defined, the ground stress balance, earth surface subsidence and underground water flow are further analyzed, and the scientificity, safety and feasibility of the advanced pilot tunnel expansion and excavation of the blind areas are ensured.
(2) According to the method, by calculating the stress distribution in the underground engineering, engineering staff is helped to know the stability of the rock-soil body, and the potential rock-mass cracking or displacement problem is predicted; the displacement distribution in the underground engineering is determined, and the method can be used for evaluating the structural deformation, the stability of the underground space and the influence of the underground engineering on the surrounding environment; the behavior of underground water flow can be described by calculating the seepage equation, the underground water flow is vital to underground engineering and environmental influence, and the information such as the underground water level, the flow velocity and the flow direction can be determined by solving the seepage equation, so that the management of underground water resources, the change of the underground water level and the influence of the underground water on rectangular jacking pipe construction can be evaluated, the stability of the engineering is ensured, floods and underground water pollution are prevented, the sustainability of the underground water resources is evaluated, and the reasonable water resource management strategy is formulated.
(3) Aiming at the improvement of the traditional rectangular soil layer push bench, the invention improves the cutting rigidity of a cutter head, improves the rock breaking capacity, improves the cutting torque and power, adopts an inclined plate or a conical plate to carry out smooth transition treatment aiming at rectangular corners and dead zone right-angle areas, improves the rock breaking capacity of a bottom spiral soil outlet and strengthens the slag discharging effect.
Drawings
FIG. 1 is a flow chart of a rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expansion and excavation of the invention;
FIG. 2 is one of the plan views of the rectangular soil layer push bench of the present invention;
FIG. 3 is a second plan view of the rectangular soil layer push bench of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. 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.
As shown in fig. 1 to 3, a rectangular jacking pipe construction method based on blind area advanced pilot tunnel expansion and excavation includes:
s1, carrying out construction operation of an originating well and a receiving well;
s2, performing blind area advanced pilot tunnel expansion and excavation simulation: by combining finite element FEM and boundary element BEM, the advanced pilot tunnel expansion and excavation of the dead zone of the rectangular jacking pipe is simulated, the two-dimensional plane problem is simplified, the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion and excavation are clarified, the ground stress balance, earth surface subsidence and underground water flow are further analyzed, and the scientificity, safety and feasibility of the advanced pilot tunnel expansion and excavation of the dead zone are ensured, and the method specifically comprises the following steps:
s21, modeling the blind area advanced pilot tunnel as a boundary value problem, and determining physical parameters of a boundary, an internal area and surface and underground water flow;
s22, dividing the problem domain into a finite element grid and a boundary element grid, wherein the finite element grid is used for describing the internal area of the problem, and the boundary element grid is used for describing the boundary;
s23, establishing a discrete form of a physical equation on a finite element grid by using a finite element method to obtain displacement and stress distribution in underground engineering, wherein the discrete form comprises the following specific steps:
on a finite element mesh, the elastic equation is used:
wherein,representing the gradient operator, σ is the stress tensor, obtained by the back stress-displacement relationship:
wherein C is an elastic stiffness matrix, epsilon is a strain tensor, and the displacement u is established by the following relationship:
；
wherein,representing a gradient operator acting on the displacement field u for calculating the gradient of the displacement field, the gradient of u being a column vector comprising the rate of change of the displacement field in the respective coordinate direction,/>Gradient vectors denoted displacement field u;
the elasticity equation is used for describing the mechanical behaviors of rock and soil in underground engineering, and the elasticity equation is solved by a finite element method, so that the following beneficial effects can be obtained:
stress analysis: calculating stress distribution in underground engineering, helping engineering personnel to know stability of rock and soil mass, and predicting potential rock mass cracking or displacement problems;
determining formation parameters: relevant geological and geotechnical mechanical parameters such as density, elastic modulus, shear modulus, poisson ratio and the like of soil or rock are collected and determined, the parameters are the basis for stress analysis, and an appropriate stress analysis model is selected according to engineering characteristics. Common models include elastic models, elastoplastic models, and plastic models, with different models being suitable for different types of formations and engineering conditions.
The presence of groundwater has an important impact on the stress distribution of the underground engineering, and pore water pressure and hydrologic conditions need to be considered, and proper consideration is performed in the analysis.
And simultaneously, load conditions, including static load and dynamic load, of underground engineering are determined, and the load conditions directly influence stress distribution.
The numerical simulation method comprises the following steps: common numerical simulation methods include finite element methods (FiniteElementMethod, FEM) and finite difference methods (FiniteDifferenceMethod, FDM), which can be used to model numerical values of underground works and perform stress analysis.
Stress analysis is performed using the selected model and numerical methods by determining boundary conditions of the model, including surface conditions, lateral boundary conditions. This may involve modeling and analyzing different parts of the subsurface engineering using specialized numerical analysis software.
After analysis is completed, the results of the model, including underground stress distribution, displacement conditions and potential rock mass cracking or displacement problems, need to be interpreted, and the results of the model are compared with actual observation results to verify. And adjusting and optimizing the model according to the requirement to improve the accuracy and reliability of the model.
And (3) displacement analysis: the displacement distribution in the underground engineering is determined, and the method can be used for evaluating the structural deformation, the stability of the underground space and the influence of the underground engineering on the surrounding environment;
firstly, a numerical model is established, and the numerical method, such as a finite element method or a finite difference method, is utilized to establish the numerical model of the underground engineering, including an underground structure, a soil body, boundary conditions and the like, so as to perform displacement analysis.
Selecting a model including, but not limited to, wire elasticity, elastoplasticity, or other complex soil models;
determining static and dynamic load conditions and boundary conditions of underground engineering, wherein the static and dynamic load conditions and the boundary conditions comprise the influence of underground water, lateral support of soil body and earth surface load; and carrying out displacement analysis by using a numerical model, and simulating deformation of the underground engineering under the action of load. The analysis result is used for providing displacement information of each point of the underground engineering; and evaluating a displacement analysis result, focusing on possible deformation areas and structural stability problems, and considering factors such as bearing capacity of a soil body, strength of a rock-soil layer and the like.
Before and after actual construction, a proper monitoring scheme is formulated, deformation conditions of underground engineering are continuously monitored through measured data, so that analysis results are verified, and necessary measures are timely taken;
and (3) design optimization: by adjusting engineering parameters, such as support structures, blasting schemes, etc., the subsurface engineering design is optimized to minimize possible geological risks and damage.
S24, solving potential flow problems on the boundary by using a boundary element method to obtain the groundwater level and the permeability, wherein the potential flow problems are specifically as follows:
on the boundary element grid, the groundwater flow is described using the percolation equation:
wherein,representing the gradient operator, h is a scalar field representing the head, k is the permeability, and is a constant;
calculating the gradient of a scalar field h to obtain a vector field;
multiplying the gradient vector field by the negative value of the constant k;
: calculating the divergence of the resulting vector field, representing the outflow or inflow rate of the vector field at a point;
calculating a seepage equation, which can describe the behavior of underground water flow, is vital to underground engineering and environmental influence, and can determine the information of underground water level, flow velocity, flow direction and the like by solving the seepage equation, thereby being beneficial to evaluating the management of underground water resources, the change of the underground water level and the influence of the underground water on rectangular jacking pipe construction, ensuring the stability of the engineering, preventing floods and underground water pollution, evaluating the sustainability of the underground water resources and helping to formulate a reasonable water resource management strategy;
in-situ groundwater level monitoring is the basis for assessing groundwater resource sustainability, including measuring water level changes in wells and establishing time series data to understand seasonal and long-term trends of groundwater levels; then, hydrogeologic investigation is performed to obtain information about the groundwater system, including the distribution of groundwater layers, permeability, hydrogeologic structure, etc. This information is used to build accurate percolation equations and to simulate the groundwater flow.
And establishing a numerical model, simulating the groundwater flow by using a seepage equation and the numerical model, and performing finite element or finite difference numerical simulation by using software (such as MODIflow), wherein the established numerical model can evaluate the behaviors of the groundwater flow in different scenes.
Horizontal and vertical flow analysis, the percolation equation can be used to analyze the conditions of horizontal and vertical flows. Assessing the relative contribution of the horizontal and vertical flows; based on the model results, the total amount and the available amount of groundwater resources are evaluated. Factors such as the regeneration capacity, the replenishment and the extraction rate of the groundwater are considered to determine whether the risk of over-exploitation exists; in addition to quantity, the quality of groundwater can be evaluated, ensuring that the extracted groundwater meets quality standards for potable water and other uses.
Wherein the basic solution of the two-dimensional potential flow problem is expressed as:
where G is a potential function, x and x' are two points in space, used to calculate the potential at the boundary;
the boundary element method can effectively simulate groundwater-soil, soil-rock interfaces and the like in underground engineering and geological engineering.
S3, carrying out demonstration analysis on the working condition of the subsequent rectangular jacking by using plaxis general rock-soil finite element calculation software according to the blind area pretreatment scheme simulation scheme formulated in the S2, and ensuring the safety of the jacking process; and adopting an HSS model, and carrying out construction calculation steps strictly according to a construction sequence. Firstly, carrying out initial ground stress balance calculation, then carrying out ground stress calculation under the action of the working condition after the existing ground load and blind area pretreatment are completed, truly restoring an underground stress field, calculating stress distribution in underground engineering, solving potential flow problems on boundaries, and carrying out displacement zero clearing before the next calculation to distinguish ground load and settlement caused by subsequent construction, thereby obtaining underground water level and permeability.
And (3) establishing a model, and establishing geometric and material models of the underground structure in Plaxis, wherein the geometric and material models comprise underground rock-soil bodies, underground water, underground structures and the like. Selecting a geotechnical model (e.g., an elastic model, an elastoplastic model) and boundary conditions; defining material parameters, and inputting mechanical parameters of the rock-soil material, including elastic modulus, poisson ratio, shear modulus and the like; and determining the load, and determining the simulated load conditions, including static load and dynamic load. This may include horizontal and vertical loads from subsequent jacking as well as loads imposed by other subterranean structures.
Boundary conditions are set, and boundary conditions of the underground structure are defined, including soil surface and lateral boundary conditions. Ensuring that the boundary conditions of the model accord with actual conditions;
analyzing underground water, if the underground water has obvious influence on the engineering, analyzing the underground water, setting underground water level and hydrologic parameters, and considering the influence of pore water pressure;
performing numerical analysis, performing finite element analysis by using Plaxis, setting calculation parameters, running the analysis, and obtaining a result; the results of the analysis model, including the stress distribution, displacement field, pore water pressure, etc. of the soil body, focus on critical areas, such as top plates, side walls, etc., to evaluate the stability of the structure.
The model is divided into 28 stages to simulate the construction process of 28 pipe joints. When the jacking construction is finished, the rail top elevation sedimentation value is maximum, and the maximum value is 2.39mm.
S4, performing blind area advanced pilot tunnel expansion and excavation construction: carrying out observation of portal breaking, pilot hole and grading back-expansion hole, working well backfilling, pore canal filling and pavement settlement according to simulation demonstration results in S2 and S3;
s5, improving the rectangular soil layer push bench, so as to improve the rectangular push bench and improve tunneling efficiency;
s6, rectangular jacking pipe starting receiving and normal jacking: the method comprises the steps of installing a water-stopping steel ring of a tunnel portal, installing a downhole base, installing a downhole pushing system, assembling and test running a pipe pushing machine, establishing and controlling soil pressure, measuring and rectifying posture, reducing thixotropic mud drag, improving and transporting dregs, hanging and placing pipe joints, guiding and changing roads, monitoring construction, replacing mud, performing inner waterproof construction, and dismantling and lifting the pipe pushing machine.
The rectangular push bench is improved and comprises:
firstly, a radial type cutter disc is selected, so that the aperture opening ratio is reduced, and the cutting rigidity of the cutter disc is improved;
secondly, optimally configuring a cutter; in addition to the center knife, the scraper and the shell knife which are arranged in the past, thirty-nine double-edge hob are additionally arranged, so that the rock breaking capacity is further improved;
thirdly, enhancing the configuration of a power system; the power system of each cutter head refers to the standard of a round hard rock pipe jacking machine, eighteen driving motors are arranged in an enlarged standard way, the main shaft is fully lengthened and thickened, and the cutting torque and power are further improved;
fourthly, performing right angle removal treatment; aiming at rectangular corners and dead zone right-angle areas, adopting an inclined plate or a conical plate to carry out smooth transition treatment;
fifthly, the slag discharging function is enhanced; cutting picks are additionally arranged on the spiral soil outlet, so that the capability of crushing rock of the bottom spiral soil outlet is further improved, and the slag discharging effect is enhanced;
the rectangular pipe jacking machine is suitable, reliable, advanced and economical in shape selection and configuration, and the configuration comprises a cutter head, a cutter head driving system, a pushing system, a spiral soil outlet machine, a deviation correcting device, a soil body improvement system, a grouting system and an electric operation system;
1) The cutterhead structure should meet the following specifications:
the form, size, aperture ratio, cutting rate and stirring rate of the cutter disc meet the requirements of excavation sections and engineering conditions;
the strength, rigidity, fatigue reliability and cutter configuration of the cutterhead are determined according to geological conditions, cutting speed and pushing length;
the quantity and the positions of the cutter soil body modifier injection ports are determined according to geological conditions, cutter structures, cutter excavation sections and the like;
2) The cutterhead driving system should meet the following specifications;
the maximum design torque of the cutter head main drive meets the requirements of geological conditions, cutting and soil improvement stirring;
the rotating speed of the cutterhead is determined according to geological conditions and construction requirements, and the rotating speed is adjustable;
the main bearing seal driven by the cutter head is determined according to the thickness of the covering soil, the groundwater level, the injection pressure of the modifier, the pushing length and the like;
3) The pushing system is determined according to the sum of the pushing resistance and the required safety coefficient, and the stroke of the oil cylinder is required to meet the requirement of pipe joint installation;
4) The selection of the spiral soil outlet machine is determined according to engineering geology and hydrologic conditions, the size of the pipe pushing machine, the tunneling speed and other conditions;
5) The maximum thrust of the deviation correcting device is larger than resistance caused by the posture change of the front and rear shells, and each group of articulated hydraulic cylinders has a stroke monitoring function;
6) The soil body improvement system and the grouting system are suitable for geological conditions and have the functions of adjustable grouting speed and adjustable grouting pressure;
7) The electrical operation system can feed back deviation correcting system data, pipe pushing machine cutterhead data, spiral soil discharging machine data, front soil pressure, main top oil cylinder data, pipe pushing machine posture data, construction dynamics and the like in real time;
initiating construction operation of the rectangular pipe jacking machine; the method comprises the following steps: removing backfill in an originating well, breaking residual piles and walls of a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole door steel ring, installing an originating base, installing a debugging pushing system, assembling and debugging a rectangular pipe jacking machine, installing a hole door sealing and water stopping device, pushing the rectangular pipe jacking machine to the hole, positioning a first pipe joint and a top iron device and originating tunneling.
Specifically, the rectangular pipe pushing jack receives construction operation, and the method comprises the following steps: removing backfill in a receiving well, breaking residual piles and walls at a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole gate steel ring, installing a receiving base, reaching tunneling, pushing the receiving base on a rectangular pipe jacking machine, sealing the hole gate, replacing thixotropic slurry, disassembling the rectangular pipe jacking machine and transferring.
In the running process of the rectangular push bench, the running track of the rectangular push bench is monitored in real time through a measuring system, and the track deviation is corrected in time by utilizing a correction method; thixotropic slurry is injected between the outer wall of the pipe joint and the rock stratum to reduce drag; and injecting a muck modifier into the tunnel face or the soil bin through the grouting holes, wherein the modifier is sodium bentonite slurry, and the specific performance requirement is controlled by referring to the thixotropic slurry technical index.
The long-distance full face rock stratum condition refers to: the jacking distance is more than 80m, and the jacking range is all in the rock stratum, and the uniaxial compressive strength of the rock stratum reaches 30Mpa or more;
from the above, the invention follows the concept of 'traditional rectangular pipe push bench improvement and blind area pretreatment' of the rectangular pipe push bench, and by treating the blind area in advance before jacking the rectangular pipe push bench and improving the traditional rectangular pipe push bench of the soil layer, the advanced pilot tunnel expansion of the blind area of the rectangular pipe push bench is simulated by combining the Finite Element Method (FEM) and the Boundary Element Method (BEM), the two-dimensional plane problem is simplified, the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion are clarified, the ground stress balance, earth surface subsidence and underground water flow are further analyzed, and the scientificity, safety and feasibility of the advanced pilot tunnel expansion of the blind area are ensured;
by calculating stress distribution in underground engineering, engineering staff is helped to know the stability of a rock-soil body, and potential rock-mass cracking or displacement problems are predicted; the displacement distribution in the underground engineering is determined, and the method can be used for evaluating the structural deformation, the stability of the underground space and the influence of the underground engineering on the surrounding environment;
the behavior of underground water flow can be described by calculating a seepage equation, the method is vital to underground engineering and environmental influence, and the information such as the underground water level, the flow velocity and the flow direction can be determined by solving the seepage equation, so that the management of underground water resources, the change of the underground water level and the influence of the underground water on rectangular jacking pipe construction can be evaluated, the stability of the engineering is ensured, floods and underground water pollution are prevented, the sustainability of the underground water resources is evaluated, and the reasonable water resource management strategy is formulated;
in addition, the rectangular push bench for traditional soil layers is improved, the cutting rigidity of a cutter disc is improved, the rock breaking capacity is improved, the cutting torque and power are improved, smooth transition treatment is carried out on rectangular corners and dead zone right-angle areas by adopting inclined plates or conical plates, the rock breaking capacity of a bottom spiral soil outlet is improved, and the slag discharging effect is enhanced.
Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (6)
1. A rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expansion and excavation is characterized by comprising the following steps:
s1, carrying out construction operation of an originating well and a receiving well;
s2, performing blind area advanced pilot tunnel expansion and excavation simulation: by combining finite element FEM and boundary element BEM, the advanced pilot tunnel expansion and excavation of the dead zone of the rectangular jacking pipe is simulated, the two-dimensional plane problem is simplified, the hole position, hole size, range and permeability parameters of the advanced pilot tunnel expansion and excavation are clarified, the ground stress balance, earth surface subsidence and underground water flow are further analyzed, and the scientificity, safety and feasibility of the advanced pilot tunnel expansion and excavation of the dead zone are ensured, and the method specifically comprises the following steps:
s21, modeling the blind area advanced pilot tunnel as a boundary value problem, and determining physical parameters of a boundary, an internal area and surface and underground water flow;
s22, dividing the problem domain into a finite element grid and a boundary element grid, wherein the finite element grid is used for describing the internal area of the problem, and the boundary element grid is used for describing the boundary;
s23, establishing a discrete form of a physical equation on a finite element grid by using a finite element method to obtain displacement and stress distribution in underground engineering, wherein the discrete form comprises the following specific steps:
on a finite element mesh, the elastic equation is used:
wherein, the->Representing the gradient operator, σ is the stress tensor, obtained by the back stress-displacement relationship:
wherein C is an elastic stiffness matrix, epsilon is a strain tensor, and the displacement u is established by the following relationship:
；
wherein,representing the gradient operator, acting on the displacement field u for calculating the gradient of the displacement field, u being a column vector containing the displacement field in each caseRate of change in the direction of the individual coordinates, sign ∈ ->Gradient vectors denoted displacement field u;
s24, using a boundary element method to process and solve potential flow problems on the boundary to obtain the groundwater level and the permeability, wherein the method comprises the following steps:
on the boundary element grid, the groundwater flow may be described using the percolation equation:
wherein,representing the gradient operator, h is a scalar field representing the head, k is the permeability, and is a constant;
calculating the gradient of a scalar field h to obtain a vector field;
multiplying the gradient vector field by the negative value of the constant k;
: calculating the divergence of the resulting vector field, representing the outflow or inflow rate of the vector field at a point;
the basic solution to the two-dimensional potential flow problem is expressed as:
where G is a potential function, x and x' are two points in space, used to calculate the potential at the boundary;
s3, carrying out demonstration analysis on the working condition of the subsequent rectangular jacking by using plaxis general rock-soil finite element calculation software according to the blind area pretreatment scheme simulation scheme formulated in the S2, and ensuring the safety of the jacking process;
s4, performing blind area advanced pilot tunnel expansion and excavation construction: carrying out observation of portal breaking, pilot hole and grading back-expansion hole, working well backfilling, pore canal filling and pavement settlement according to simulation demonstration results in S2 and S3;
s5, improving the rectangular soil layer push bench, so as to improve the rectangular push bench and improve tunneling efficiency;
s6, rectangular jacking pipe starting receiving and normal jacking: the method comprises the steps of installing a water-stopping steel ring of a tunnel portal, installing a downhole base, installing a downhole pushing system, assembling and test running a pipe pushing machine, establishing and controlling soil pressure, measuring and rectifying posture, reducing thixotropic mud drag, improving and transporting dregs, hanging and placing pipe joints, guiding and changing roads, monitoring construction, replacing mud, performing inner waterproof construction, and dismantling and lifting the pipe pushing machine.
2. The rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expanding and digging, which is disclosed in claim 1, is characterized in that: the rectangular push bench is improved and comprises:
firstly, a radial type cutter disc is selected, so that the aperture opening ratio is reduced, and the cutting rigidity of the cutter disc is improved;
secondly, optimally configuring a cutter; in addition to the center knife, the scraper and the shell knife which are arranged in the past, thirty-nine double-edge hob are additionally arranged, so that the rock breaking capacity is further improved;
thirdly, enhancing the configuration of a power system; the power system of each cutter head refers to the standard of a round hard rock pipe jacking machine, eighteen driving motors are arranged in an enlarged standard way, the main shaft is fully lengthened and thickened, and the cutting torque and power are further improved;
fourthly, performing right angle removal treatment; aiming at rectangular corners and dead zone right-angle areas, adopting an inclined plate or a conical plate to carry out smooth transition treatment;
fifthly, the slag discharging function is enhanced; cutting picks are additionally arranged on the spiral soil outlet, so that the capability of crushing rock of the bottom spiral soil outlet is further improved, and the slag discharging effect is enhanced.
3. The rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expanding and digging, which is disclosed in claim 1, is characterized in that: initiating construction operation of the rectangular pipe jacking machine; the method comprises the following steps: removing backfill in an originating well, breaking residual piles and walls of a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole door steel ring, installing an originating base, installing a debugging pushing system, assembling and debugging a rectangular pipe jacking machine, installing a hole door sealing and water stopping device, pushing the rectangular pipe jacking machine to the hole, positioning a first pipe joint and a top iron device and originating tunneling.
4. The rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expanding and digging, which is disclosed in claim 1, is characterized in that: the rectangular pipe jacking machine receives construction operation, and comprises the following steps: removing backfill in a receiving well, breaking residual piles and walls at a hole, spraying anchors to seal the exposed face of the hole, installing a fixed hole gate steel ring, installing a receiving base, reaching tunneling, pushing the receiving base on a rectangular pipe jacking machine, sealing the hole gate, replacing thixotropic slurry, disassembling the rectangular pipe jacking machine and transferring.
5. The rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expanding and digging, which is disclosed in claim 1, is characterized in that: in the running process of the rectangular push bench, the running track of the rectangular push bench is monitored in real time through a measuring system, and the track deviation is corrected in time by utilizing a correction method; thixotropic slurry is injected between the outer wall of the pipe joint and the rock stratum to reduce drag; and injecting a muck modifier into the tunnel face or the soil bin through the grouting holes, wherein the modifier is sodium bentonite slurry, and the specific performance requirement is controlled by referring to the thixotropic slurry technical index.
6. The rectangular jacking pipe construction method based on the blind area advanced pilot tunnel expansion and excavation according to any one of claims 1 to 5, wherein the method comprises the following steps: the construction method is suitable for long-distance full-section rock stratum conditions, and specifically comprises the following steps: the jacking distance is more than 80m, the jacking range is all in the rock stratum, and the uniaxial compressive strength of the rock stratum reaches 30Mpa or more.
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