CN-116201551-B - Construction method for excavating and supporting weak surrounding rock tunnel

CN116201551BCN 116201551 BCN116201551 BCN 116201551BCN-116201551-B

Abstract

The invention discloses a construction method for excavating and supporting a weak surrounding rock tunnel, which comprises the following steps of excavating the upper part to form an arch part, forming a protective soil body at the middle position below the arch part, arranging an upper supporting part along the wall surface of the arch part, removing the protective soil body to form an upper pilot pit together with the arch part, excavating the middle part to form a middle pilot pit for conducting the upper pilot pit, arranging a middle supporting part along the wall surface of the middle pilot pit, excavating the lower part to form a tunnel bottom pilot pit for conducting the middle pilot pit, arranging an inverted arch supporting part in the tunnel bottom pilot pit, thereby completing the excavation and supporting of a tunnel unit, returning to the step of excavating the upper part to form the arch part, forming the protective soil body at the middle position below the arch part, and arranging the upper supporting part along the wall surface of the arch part until each tunnel unit completes the excavation and supporting, thereby completing the excavation and supporting of the whole tunnel. The construction method can effectively prevent the tunnel support from invading into the secondary lining range.

Inventors

XIE JIANGSHENG
ZHAO HAIQING
FENG JUNWU
ZHANG XUHUI
GUO SHANGKUN
GUO PENGCHAO
WANG JIANJUN
SHEN YUNTAO
YU XIONGJUN

Assignees

中铁二十局集团有限公司

Dates

Publication Date: 20260512
Application Date: 20230317

Claims (5)

1. The construction method of the weak surrounding rock tunnel excavation support comprises the steps of sequentially connecting a plurality of tunnel units along the extending direction of the tunnel, the tunnel units sequentially comprise an upper part, a middle part and a lower part along the up-down direction, and the construction method is characterized by comprising the following steps of: digging the upper part of the upper part to form an arch part, so as to form a protective soil body at the middle position below the arch part, and arranging an upper support along the wall surface of the arch part; Removing the protection soil body to form an upper pilot tunnel together with the arch part, excavating the middle part to form a middle pilot tunnel for conducting the upper pilot tunnel, and arranging a middle support along the wall surface of the middle pilot tunnel; digging the lower part to form a tunnel bottom pilot pit for conducting the middle pilot pit, and arranging an inverted arch support in the tunnel bottom pilot pit so as to finish the excavation and support of one tunnel unit; Returning to the step of excavating the upper part to form an arch part so as to form a protective soil body at the middle position below the arch part and arranging an upper support along the wall surface of the arch part until each tunnel unit completes excavation and support, thereby completing the excavation and support of the whole tunnel; The step of excavating above the upper part to form an arch part to form a protective soil body at a middle position below the arch part and arranging an upper support along a wall surface of the arch part comprises the following steps: Digging and pushing the upper part according to a preset arch profile to form the arch part and the protection soil body; Spraying concrete on the wall surface of the arch part to form an upper surrounding rock protective layer; According to the shape of the arch part, an upper anchor net protective structure and an upper supporting steel frame are sequentially arranged on the outer side of the upper surrounding rock protective layer to form an arch part supporting structure; spraying concrete on the outer side of the arch support structure to connect the upper anchor net protective structure and the upper support steel frame, thereby forming the upper support; the step of excavating the middle part to form a middle pilot hole which conducts the upper pilot hole: Digging on the left side of the middle part until the digging length meets a first preset value to obtain a first pre-digging pilot pit; continuing to excavate based on the first pre-excavated pilot pit until a first preset advance rule value is met, and obtaining a left side wall pilot pit; Digging and pushing the right side of the middle part until the first preset feeding rule value is met to form a right side wall pilot pit, wherein the left side wall pilot pit and the right side wall pilot pit are in conduction arrangement; Returning to the step of ' continuing to excavate based on the first pre-excavation pilot pit ' until the excavation length meets a first preset footage value to obtain a left side wall pilot pit ' until the excavation of the middle pilot pit of a single tunnel unit is completed; in the step of arranging the middle support along the wall surface of the middle pilot tunnel, the following steps are as follows: spraying concrete on the wall surface of the middle pilot pit to form a middle surrounding rock protective layer; according to the shape of the middle pilot pit, a middle anchor net protection structure and a middle support steel frame are sequentially arranged on the outer side of the middle surrounding rock protection layer to form a side wall support structure, wherein the upper end of the side wall support structure is abutted with the lower end of the upper support; spraying concrete on the outer side of the side wall supporting structure to connect the middle anchor net protective structure with the middle supporting steel frame to obtain the middle supporting; The step of excavating the lower portion to form a tunnel bottom pit that conducts the middle pit includes: digging at the left side of the lower part until the digging length meets a second preset value to obtain a second pre-digging pilot pit; Continuing to excavate based on the second pre-excavated pilot pit until a second preset footage value is met, and obtaining a left lower pilot pit; digging and propelling the right side of the lower part until the second preset feeding rule value is met so as to form a right lower guide pit; Returning to the step of continuing to excavate based on the second pre-excavated pilot pit until a second preset footage value is met to obtain a left lower pilot pit until the excavation of the left lower pilot pit and the right lower pilot pit of the single tunnel unit is completed; The ratio of the earthwork amounts of the upper part, the middle part and the lower part in each tunnel unit is 4:1:2.
2. The construction method for excavating and supporting a weak surrounding rock tunnel according to claim 1, wherein the foot locking guide tube in the upper supporting steel frame is arranged obliquely from top to bottom in a direction deviating from the tunnel, and the free end of the foot locking guide tube in the upper supporting steel frame can extend into the upper surrounding rock.
3. The construction method for excavating and supporting a weak surrounding rock tunnel according to claim 1, wherein the length of the protection soil body along the extending direction of the tunnel is L, and L is more than or equal to 0.5m and less than or equal to 1m.
4. The construction method for excavating and supporting a weak surrounding rock tunnel according to claim 1, wherein the first preset value is A1, and the first preset footage value is A2, wherein 3m is less than or equal to A1-A2 is less than or equal to 5m.
5. The construction method of the weak surrounding rock tunnel excavation supporting of claim 1, wherein the second preset value is B1, and the second preset length is B2, wherein 3m is less than or equal to B1-B2 is less than or equal to 5m.

Description

Construction method for excavating and supporting weak surrounding rock tunnel Technical Field The invention relates to the technical field of tunnel construction, in particular to a construction method for excavating and supporting a weak surrounding rock tunnel. Background Along with the rapid development of tunnel engineering in China, more and more tunnels are built in complex areas, particularly in the process of building a weak and broken surrounding rock tunnel, due to the influences of factors such as poor geological conditions, irregular construction operation, unreasonable construction process or construction organization, the initial support arch top is easy to sink, the side wall is easy to converge, the arch frame deformation invades the secondary lining range, the tunnel construction safety is seriously threatened, the subsequent secondary lining construction is seriously influenced, and the arch frame of the invasion section is required to be removed and replaced in order to ensure the thickness of the secondary lining, so that the construction difficulty is increased, and the engineering progress is influenced. Disclosure of Invention The invention mainly aims to provide a construction method for excavating and supporting a weak surrounding rock tunnel, and aims to solve the problem that an initial supporting is easy to invade a secondary lining range in the construction process of the weak surrounding rock tunnel. In order to achieve the above object, the present invention provides a construction method for excavating and supporting a weak surrounding rock tunnel, wherein the tunnel has a plurality of tunnel units which are sequentially communicated along an extending direction thereof, each tunnel unit is sequentially provided with an upper part, a middle part and a lower part along an up-down direction, and the construction method for excavating and supporting the weak surrounding rock tunnel comprises the following steps: digging the upper part of the upper part to form an arch part, so as to form a protective soil body at the middle position below the arch part, and arranging an upper support along the wall surface of the arch part; Removing the protection soil body to form an upper pilot tunnel together with the arch part, excavating the middle part to form a middle pilot tunnel for conducting the upper pilot tunnel, and arranging a middle support along the wall surface of the middle pilot tunnel; digging the lower part to form a tunnel bottom pilot pit for conducting the middle pilot pit, and arranging an inverted arch support in the tunnel bottom pilot pit so as to finish the excavation and support of one tunnel unit; Returning to the step of excavating the upper part to form an arch part so as to form a protective soil body at the middle position below the arch part and arranging an upper support along the wall surface of the arch part until each tunnel unit completes excavation and support, thereby completing the excavation and support of the whole tunnel. Optionally, the step of "digging the upper part above the upper part to form an arch part to form a protective soil body at an intermediate position below the arch part, and disposing an upper support along a wall surface of the arch part" includes: Digging and pushing the upper part according to a preset arch profile to form the arch part and the protection soil body; Spraying concrete on the wall surface of the arch part to form an upper surrounding rock protective layer; According to the shape of the arch part, an upper anchor net protective structure and an upper supporting steel frame are sequentially arranged on the outer side of the upper surrounding rock protective layer to form an arch part supporting structure; And spraying concrete on the outer side of the arch support structure to connect the upper anchor net protective structure with the upper support steel frame, thereby forming the upper support. Optionally, in the direction that deviates from the tunnel, the lock foot pipe in the upper portion support steelframe is from top to bottom slope setting, just the free end of lock foot pipe in the upper portion support steelframe can stretch into in the upper portion country rock. Optionally, the length of the protection soil body along the extending direction of the tunnel is L, wherein L is more than or equal to 0.5m and less than or equal to 1m. Optionally, in the step of "digging the middle part to form a middle pilot hole that conducts the upper pilot hole: Digging on the left side of the middle part until the digging length meets a first preset value to obtain a first pre-digging pilot pit; continuing to excavate based on the first pre-excavated pilot pit until a first preset advance rule value is met, and obtaining a left side wall pilot pit; Digging and pushing the right side of the middle part until the first preset feeding rule value is met to form a right side wall pilot pit, wherein the left side wall pilot p