CN-122014263-A - High-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure and construction method

CN122014263ACN 122014263 ACN122014263 ACN 122014263ACN-122014263-A

Abstract

The invention relates to the technical field of tunnel engineering construction, in particular to a high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure and a construction method, comprising the following steps: S1, carrying out integrated design on the forepoling shed and the horizontal high-pressure jet grouting pile based on engineering geological survey data, calculating and determining design distance, overlap length and rigidity matching parameters of the forepoling shed and the horizontal high-pressure jet grouting pile, and constructing a composite structure model which takes the forepoling shed as a rigid framework and is carried cooperatively with the horizontal high-pressure jet grouting pile. According to the invention, the collaborative supporting system of rigid-flexible coupling of the advanced pipe shed and the horizontal jet grouting pile is constructed, and the jet grouting construction parameters are dynamically regulated and controlled based on the environmental parameter mapping library, so that the problems that the self-stability of the high-altitude fine sand layer is poor, the pile quality is greatly influenced by the air pressure temperature difference are effectively overcome, and the water stopping effect and the integral bearing stability of the supporting structure of the tunnel portal section under complex geology are ensured.

Inventors

Gao Shuojie
CHENG TILU
LI BO
LOU RUI
ZHAO MAN
LI HONGHONG
Cao Fengchen
DONG JUNCHAO
Guo Huanlong
Tao Huadi
Du Yilian
GAO ZHONGTAO
LI CHAO
MA YONGQIANG
Han Bingji
Ji Liansong

Assignees

中铁十四局集团第三工程有限公司
中铁十四局集团有限公司

Dates

Publication Date: 20260512
Application Date: 20251225

Claims (9)

1. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure is characterized by comprising the following steps of: S1, carrying out integrated design on an advance pipe shed and a horizontal high-pressure jet grouting pile based on engineering geological survey data, calculating and determining design distance, overlap length and rigidity matching parameters of the advance pipe shed and the horizontal high-pressure jet grouting pile, and constructing a composite structure model which takes the advance pipe shed as a rigid framework and is carried cooperatively with the horizontal high-pressure jet grouting pile; S2, horizontal high-pressure jet grouting piles are arranged at the arch part and the periphery of the tunnel portal, grouting pressure, slurry flow and drill rod lifting speed of jet grouting construction are adjusted according to environmental temperature and atmospheric pressure data acquired in real time, and the slurry water-cement ratio and additive mixing amount are adjusted on line according to grouting pressure and slurry flow feedback, so that a mutually-meshed horizontal jet grouting reinforcement layer is formed; s3, setting a surrounding rock deformation and supporting structure stress control threshold value in the tunnel excavation process, acquiring real-time data from pre-buried sensors in the advance pipe shed and the horizontal high-pressure jet grouting pile, comparing the monitoring data with the control threshold value, and adjusting excavation footage, supporting construction time and supporting parameters of the next cycle according to comparison results; S4, tunnel excavation and support structure construction are carried out, and primary support closing and secondary lining are completed.
2. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in the step S1, constructing a composite structure model which takes a forepoling shed as a rigid framework and is cooperatively borne by a horizontal high-pressure jet grouting pile specifically comprises the following steps: establishing a mechanical role definition model, setting a forepoling shed as a main flexural member, and setting a horizontal high-pressure jet grouting pile as a water stopping and supplementing bearing member; And carrying out numerical simulation calculation based on engineering geological survey data, determining the design distance between the advance pipe shed and the horizontal high-pressure jet grouting pile, the longitudinal overlap length and the rigidity matching coefficient, and establishing the composite structure model.
3. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in S2, according to the environmental temperature and the atmospheric pressure data collected in real time, the grouting pressure, the slurry flow and the drill rod lifting speed of the rotary spraying construction are adjusted specifically comprising the following steps: establishing an environment monitoring station on a construction site, and collecting the environmental temperature and atmospheric pressure data of a tunnel portal area in real time; Inputting the collected environmental temperature and atmospheric pressure data into a preset construction parameter mapping library, wherein the mapping library comprises corresponding set grouting pressure, slurry flow and drill rod lifting speed values under different environmental conditions; and according to the mapping matching result, automatically generating a control instruction to drive the high-pressure grouting pump and the drilling machine executing mechanism, and adjusting the rotary spraying construction parameters to the set values corresponding to the current environmental conditions.
4. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 3, wherein the construction of the preset construction parameter mapping library specifically comprises the following steps: performing field manufacturability pile testing before formal construction, and testing pile forming effects of different grouting pressures, slurry flow and drill rod lifting speed combinations under different atmospheric pressure and environmental temperature environments; screening out effective parameter combinations with pile forming diameters and pile body strength meeting design requirements; And establishing a corresponding relation between the effective parameter combination and corresponding environmental working condition data, and inputting the effective parameter combination into a database to form the construction parameter mapping library.
5. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in the step S2, the slurry water cement ratio and the admixture doping amount are adjusted on line according to grouting pressure and slurry flow feedback, and the forming of the mutually-meshed horizontal rotary spraying reinforcing layer specifically comprises the following steps: Monitoring grouting pressure and slurry flow in the high-pressure rotary spraying process in real time by using a sensor arranged on a grouting pipeline; Comparing the monitored grouting pressure and slurry flow with a preset reference diffusion interval value, and judging the diffusion resistance and loss condition of the slurry in the fine sand layer; according to the comparison result, the water-cement ratio of the slurry is regulated on line through an automatic slurry preparation system, and the doping amount of the early strength agent and the antifreeze agent is regulated.
6. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in S3, real-time data are collected by pre-buried sensors in a forepoling shed and a horizontal high-pressure jet grouting pile, and the monitoring data are compared with a control threshold value, and the method specifically comprises the following steps: a stress sensor and a strain sensor are arranged at the stressed part of the pile body of the horizontal high-pressure jet grouting pile; the sensor value is read in real time through an automatic data acquisition system, and the current surrounding rock deformation and supporting structure stress value are calculated; and calling a preset safety threshold corresponding to the current construction working condition stage, and comparing the calculated surrounding rock deformation and the support structure stress value with the preset safety threshold in a difference mode.
7. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in S3, the following steps are specifically included for adjusting the excavation footage, the supporting construction time and the supporting parameters of the next cycle according to the comparison result: When the comparison result shows that the monitoring data reaches or exceeds a preset early warning value, generating an early warning signal and reducing the tunnel excavation footage length of the next cycle; the exposure time of the excavation surface and the closing time of primary support construction are shortened; and the rigidity parameters of the supporting structure are increased, including the installation interval of the encrypted steel arch and the thickness of sprayed concrete.
8. The construction method of the high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure according to claim 1, wherein in S4, the tunnel excavation and supporting structure construction specifically comprises the following steps: the tunnel face is excavated in a dividing way by adopting a three-step reserved core soil method, and core soil bodies of an upper step and a middle step are reserved to support the tunnel face to be stable; erecting a steel frame along with the excavation surface, and punching a foot locking anchor pipe at the arch foot position of the steel frame, and welding and fixing the tail end of the foot locking anchor pipe with the steel frame; Spraying concrete to seal the surface of the surrounding rock, so that the primary support structure is closed into a ring; And paving a cold-proof heat-insulating layer on the inner side of the primary support structure, and molding secondary lining concrete.
9. The high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure is characterized in that, the construction method for the high-altitude shallow-buried fine sand layer tunnel portal section cooperative support structure according to any one of claims 1 to 8, comprising: The tunnel comprises profile steel frames (1) longitudinally arranged at intervals along a tunnel, guide pipes (2) fixedly arranged at the outer edges of arch parts of the profile steel frames (1), horizontal high-pressure jet grouting piles (3) arranged through the guide pipes (2), primary support concrete layers (4) covering the profile steel frames (1) and surrounding rock surfaces, cold-proof heat-insulating layers (5) paved on the inner sides of the primary support concrete layers (4) and secondary linings (6) built on the inner sides of the cold-proof heat-insulating layers (5); the guide pipes (2) are arranged at intervals along the arch contour line of the steel section frame (1), and each guide pipe (2) is welded and fixed on the outer side of the steel section frame (1); One end of the horizontal high-pressure jet grouting pile (3) penetrates through the guide pipe (2) and extends to the front of the tunnel to be driven into a rock stratum, and the horizontal high-pressure jet grouting pile (3) forms an advanced reinforcement curtain along the arch part of the tunnel; the primary support concrete layer (4) wraps the steel section steel frame (1) and the root of the guide pipe (2); the cold-proof heat-insulating layer (5) is tightly attached to the inner surface of the primary support concrete layer (4), and the secondary lining (6) is molded on the inner surface of the cold-proof heat-insulating layer (5).

Description

High-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure and construction method Technical Field The invention relates to the technical field of tunnel engineering construction, in particular to a high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure and a construction method. Background Along with the extension of traffic infrastructure construction to high-altitude complex terrain areas, tunnel portal sections often encounter extremely soft and weak stratum such as rich water powder fine sand, and the stratum has the characteristics of poor self-stabilization capability, looseness, easy rheology and the like, and the surrounding rock is usually pre-reinforced by adopting pre-support technologies such as an advanced pipe shed or a horizontal high-pressure jet grouting pile in construction, so that a protective shell is formed outside an excavation contour line to maintain stability of a tunnel face. However, the construction parameters in the prior art mostly use plain experience, and the adverse effects of high altitude low air pressure and large temperature difference environment on jet flow diffusion and slurry solidification are ignored, so that pile forming quality is discrete, a waterproof curtain is not closed, and sand burst and collapse accidents are extremely easy to induce. Disclosure of Invention In order to make up for the defects, the invention provides a high-altitude shallow-buried fine sand layer tunnel portal section cooperative supporting structure and a construction method, and aims to improve the problems that construction parameters in the prior art are mostly used in plain experience, and the negative influence of high-altitude low-pressure and large-temperature difference environments on jet flow diffusion and slurry solidification is ignored. In a first aspect, the invention provides a construction method of a tunnel portal section cooperative supporting structure of a high-altitude shallow-buried fine sand layer, which comprises the following steps: S1, carrying out integrated design on an advance pipe shed and a horizontal high-pressure jet grouting pile based on engineering geological survey data, calculating and determining design distance, overlap length and rigidity matching parameters of the advance pipe shed and the horizontal high-pressure jet grouting pile, and constructing a composite structure model which takes the advance pipe shed as a rigid framework and is carried cooperatively with the horizontal high-pressure jet grouting pile; S2, horizontal high-pressure jet grouting piles are arranged at the arch part and the periphery of the tunnel portal, grouting pressure, slurry flow and drill rod lifting speed of jet grouting construction are adjusted according to environmental temperature and atmospheric pressure data acquired in real time, and the slurry water-cement ratio and additive mixing amount are adjusted on line according to grouting pressure and slurry flow feedback, so that a mutually-meshed horizontal jet grouting reinforcement layer is formed; s3, setting a surrounding rock deformation and supporting structure stress control threshold value in the tunnel excavation process, acquiring real-time data from pre-buried sensors in the advance pipe shed and the horizontal high-pressure jet grouting pile, comparing the monitoring data with the control threshold value, and adjusting excavation footage, supporting construction time and supporting parameters of the next cycle according to comparison results; S4, tunnel excavation and support structure construction are carried out, and primary support closing and secondary lining are completed. Preferably, in the step S1, constructing a composite structure model that uses the forepoling shed as a rigid framework and cooperatively bears with the horizontal high-pressure jet grouting pile specifically includes the following steps: establishing a mechanical role definition model, setting a forepoling shed as a main flexural member, and setting a horizontal high-pressure jet grouting pile as a water stopping and supplementing bearing member; And carrying out numerical simulation calculation based on engineering geological survey data, determining the design distance between the advance pipe shed and the horizontal high-pressure jet grouting pile, the longitudinal overlap length and the rigidity matching coefficient, and establishing the composite structure model. Preferably, in the step S2, adjusting the grouting pressure, the slurry flow and the drill rod lifting speed of the rotary spraying construction according to the environmental temperature and the atmospheric pressure data acquired in real time specifically includes the following steps: establishing an environment monitoring station on a construction site, and collecting the environmental temperature and atmospheric pressure data of a tunnel portal area in real time; Inputting th